Generic template and forward in stringstream.

This CL updates the templates in the StringStream to match more types.
All of the internal `operator<<` methods have been converted over to
StringStream. The precision was increased in order to better match the
precision needed to read back as a double.

Bug: tint:1686
Change-Id: Iaa15cf247f174967dd1014647ba5a74804997c22
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/122080
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>

src/tint/ast/binary_expression.h

@@ -297,10 +297,10 @@ constexpr const char* Operator(BinaryOp op) {
     return "<invalid>";
 }
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param op the BinaryOp
-/// @return the std::ostream so calls can be chained
+/// @return the stream so calls can be chained
-inline std::ostream& operator<<(std::ostream& out, BinaryOp op) {
+inline utils::StringStream& operator<<(utils::StringStream& out, BinaryOp op) {
     out << FriendlyName(op);
     return out;
 }

src/tint/ast/builtin_texture_helper_test.cc

@@ -23,6 +23,45 @@
 using namespace tint::number_suffixes;  // NOLINT
 
 namespace tint::ast::builtin::test {
+namespace {
+
+utils::StringStream& operator<<(utils::StringStream& out, const TextureKind& kind) {
+    switch (kind) {
+        case TextureKind::kRegular:
+            out << "regular";
+            break;
+        case TextureKind::kDepth:
+            out << "depth";
+            break;
+        case TextureKind::kDepthMultisampled:
+            out << "depth-multisampled";
+            break;
+        case TextureKind::kMultisampled:
+            out << "multisampled";
+            break;
+        case TextureKind::kStorage:
+            out << "storage";
+            break;
+    }
+    return out;
+}
+
+utils::StringStream& operator<<(utils::StringStream& out, const TextureDataType& ty) {
+    switch (ty) {
+        case TextureDataType::kF32:
+            out << "f32";
+            break;
+        case TextureDataType::kU32:
+            out << "u32";
+            break;
+        case TextureDataType::kI32:
+            out << "i32";
+            break;
+    }
+    return out;
+}
+
+}  // namespace
 
 TextureOverloadCase::TextureOverloadCase(ValidTextureOverload o,
                                          const char* desc,
@@ -80,57 +119,24 @@ TextureOverloadCase::TextureOverloadCase(ValidTextureOverload o,
 TextureOverloadCase::TextureOverloadCase(const TextureOverloadCase&) = default;
 TextureOverloadCase::~TextureOverloadCase() = default;
 
-std::ostream& operator<<(std::ostream& out, const TextureKind& kind) {
-    switch (kind) {
-        case TextureKind::kRegular:
-            out << "regular";
-            break;
-        case TextureKind::kDepth:
-            out << "depth";
-            break;
-        case TextureKind::kDepthMultisampled:
-            out << "depth-multisampled";
-            break;
-        case TextureKind::kMultisampled:
-            out << "multisampled";
-            break;
-        case TextureKind::kStorage:
-            out << "storage";
-            break;
-    }
-    return out;
-}
-
-std::ostream& operator<<(std::ostream& out, const TextureDataType& ty) {
-    switch (ty) {
-        case TextureDataType::kF32:
-            out << "f32";
-            break;
-        case TextureDataType::kU32:
-            out << "u32";
-            break;
-        case TextureDataType::kI32:
-            out << "i32";
-            break;
-    }
-    return out;
-}
-
 std::ostream& operator<<(std::ostream& out, const TextureOverloadCase& data) {
-    out << "TextureOverloadCase " << static_cast<int>(data.overload) << "\n";
+    utils::StringStream str;
-    out << data.description << "\n";
+    str << "TextureOverloadCase " << static_cast<int>(data.overload) << "\n";
-    out << "texture_kind:      " << data.texture_kind << "\n";
+    str << data.description << "\n";
-    out << "sampler_kind:      ";
+    str << "texture_kind:      " << data.texture_kind << "\n";
+    str << "sampler_kind:      ";
     if (data.texture_kind != TextureKind::kStorage) {
-        out << data.sampler_kind;
+        str << data.sampler_kind;
     } else {
-        out << "<unused>";
+        str << "<unused>";
     }
-    out << "\n";
+    str << "\n";
-    out << "access:            " << data.access << "\n";
+    str << "access:            " << data.access << "\n";
-    out << "texel_format:      " << data.texel_format << "\n";
+    str << "texel_format:      " << data.texel_format << "\n";
-    out << "texture_dimension: " << data.texture_dimension << "\n";
+    str << "texture_dimension: " << data.texture_dimension << "\n";
-    out << "texture_data_type: " << data.texture_data_type << "\n";
+    str << "texture_data_type: " << data.texture_data_type << "\n";
+
+    out << str.str();
     return out;
 }
 

src/tint/ast/diagnostic_control.h

@@ -15,7 +15,6 @@
 #ifndef SRC_TINT_AST_DIAGNOSTIC_CONTROL_H_
 #define SRC_TINT_AST_DIAGNOSTIC_CONTROL_H_
 
-#include <ostream>
 #include <string>
 #include <unordered_map>
 

src/tint/ast/float_literal_expression.cc

@@ -37,7 +37,7 @@ const FloatLiteralExpression* FloatLiteralExpression::Clone(CloneContext* ctx) c
     return ctx->dst->create<FloatLiteralExpression>(src, value, suffix);
 }
 
-std::ostream& operator<<(std::ostream& out, FloatLiteralExpression::Suffix suffix) {
+utils::StringStream& operator<<(utils::StringStream& out, FloatLiteralExpression::Suffix suffix) {
     switch (suffix) {
         default:
             return out;

src/tint/ast/float_literal_expression.h

@@ -56,11 +56,11 @@ class FloatLiteralExpression final : public Castable<FloatLiteralExpression, Lit
     const Suffix suffix;
 };
 
-/// Writes the float literal suffix to the std::ostream.
+/// Writes the float literal suffix to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param suffix the suffix to write
 /// @returns out so calls can be chained
-std::ostream& operator<<(std::ostream& out, FloatLiteralExpression::Suffix suffix);
+utils::StringStream& operator<<(utils::StringStream& out, FloatLiteralExpression::Suffix suffix);
 
 }  // namespace tint::ast
 

src/tint/ast/int_literal_expression.cc

@@ -35,7 +35,7 @@ const IntLiteralExpression* IntLiteralExpression::Clone(CloneContext* ctx) const
     return ctx->dst->create<IntLiteralExpression>(src, value, suffix);
 }
 
-std::ostream& operator<<(std::ostream& out, IntLiteralExpression::Suffix suffix) {
+utils::StringStream& operator<<(utils::StringStream& out, IntLiteralExpression::Suffix suffix) {
     switch (suffix) {
         default:
             return out;

src/tint/ast/int_literal_expression.h

@@ -55,11 +55,11 @@ class IntLiteralExpression final : public Castable<IntLiteralExpression, Literal
     const Suffix suffix;
 };
 
-/// Writes the integer literal suffix to the std::ostream.
+/// Writes the integer literal suffix to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param suffix the suffix to write
 /// @returns out so calls can be chained
-std::ostream& operator<<(std::ostream& out, IntLiteralExpression::Suffix suffix);
+utils::StringStream& operator<<(utils::StringStream& out, IntLiteralExpression::Suffix suffix);
 
 }  // namespace tint::ast
 

src/tint/ast/interpolate_attribute.h

@@ -15,7 +15,6 @@
 #ifndef SRC_TINT_AST_INTERPOLATE_ATTRIBUTE_H_
 #define SRC_TINT_AST_INTERPOLATE_ATTRIBUTE_H_
 
-#include <ostream>
 #include <string>
 
 #include "src/tint/ast/attribute.h"

src/tint/ast/pipeline_stage.cc

@@ -16,7 +16,7 @@
 
 namespace tint::ast {
 
-std::ostream& operator<<(std::ostream& out, PipelineStage stage) {
+utils::StringStream& operator<<(utils::StringStream& out, PipelineStage stage) {
     switch (stage) {
         case PipelineStage::kNone: {
             out << "none";

src/tint/ast/pipeline_stage.h

@@ -15,17 +15,17 @@
 #ifndef SRC_TINT_AST_PIPELINE_STAGE_H_
 #define SRC_TINT_AST_PIPELINE_STAGE_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::ast {
 
 /// The pipeline stage
 enum class PipelineStage { kNone = -1, kVertex, kFragment, kCompute };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param stage the PipelineStage
-/// @return the std::ostream so calls can be chained
+/// @return the stream so calls can be chained
-std::ostream& operator<<(std::ostream& out, PipelineStage stage);
+utils::StringStream& operator<<(utils::StringStream& out, PipelineStage stage);
 
 }  // namespace tint::ast
 

src/tint/ast/unary_op.cc

@@ -16,7 +16,7 @@
 
 namespace tint::ast {
 
-std::ostream& operator<<(std::ostream& out, UnaryOp mod) {
+utils::StringStream& operator<<(utils::StringStream& out, UnaryOp mod) {
     switch (mod) {
         case UnaryOp::kAddressOf: {
             out << "address-of";

src/tint/ast/unary_op.h

@@ -15,7 +15,7 @@
 #ifndef SRC_TINT_AST_UNARY_OP_H_
 #define SRC_TINT_AST_UNARY_OP_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::ast {
 
@@ -28,10 +28,10 @@ enum class UnaryOp {
     kNot,          // !EXPR
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param mod the UnaryOp
-/// @return the std::ostream so calls can be chained
+/// @return the stream so calls can be chained
-std::ostream& operator<<(std::ostream& out, UnaryOp mod);
+utils::StringStream& operator<<(utils::StringStream& out, UnaryOp mod);
 
 }  // namespace tint::ast
 

src/tint/bench/benchmark.cc

@@ -15,7 +15,7 @@
 #include "src/tint/bench/benchmark.h"
 
 #include <filesystem>
-#include <sstream>
+#include <iostream>
 #include <utility>
 #include <vector>
 

src/tint/builtin/access.cc

@@ -40,7 +40,7 @@ Access ParseAccess(std::string_view str) {
     return Access::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, Access value) {
+utils::StringStream& operator<<(utils::StringStream& out, Access value) {
     switch (value) {
         case Access::kUndefined:
             return out << "undefined";

src/tint/builtin/access.h

@@ -23,7 +23,7 @@
 #ifndef SRC_TINT_BUILTIN_ACCESS_H_
 #define SRC_TINT_BUILTIN_ACCESS_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 
@@ -35,10 +35,10 @@ enum class Access {
     kWrite,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the Access
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, Access value);
+utils::StringStream& operator<<(utils::StringStream& out, Access value);
 
 /// ParseAccess parses a Access from a string.
 /// @param str the string to parse

src/tint/builtin/access.h.tmpl

@@ -17,7 +17,7 @@ See:
 #ifndef SRC_TINT_BUILTIN_ACCESS_H_
 #define SRC_TINT_BUILTIN_ACCESS_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 

src/tint/builtin/address_space.cc

@@ -55,7 +55,7 @@ AddressSpace ParseAddressSpace(std::string_view str) {
     return AddressSpace::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, AddressSpace value) {
+utils::StringStream& operator<<(utils::StringStream& out, AddressSpace value) {
     switch (value) {
         case AddressSpace::kUndefined:
             return out << "undefined";

src/tint/builtin/address_space.h

@@ -23,7 +23,7 @@
 #ifndef SRC_TINT_BUILTIN_ADDRESS_SPACE_H_
 #define SRC_TINT_BUILTIN_ADDRESS_SPACE_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 
@@ -41,10 +41,10 @@ enum class AddressSpace {
     kWorkgroup,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the AddressSpace
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, AddressSpace value);
+utils::StringStream& operator<<(utils::StringStream& out, AddressSpace value);
 
 /// ParseAddressSpace parses a AddressSpace from a string.
 /// @param str the string to parse

src/tint/builtin/address_space.h.tmpl

@@ -17,7 +17,7 @@ See:
 #ifndef SRC_TINT_BUILTIN_ADDRESS_SPACE_H_
 #define SRC_TINT_BUILTIN_ADDRESS_SPACE_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 

src/tint/builtin/attribute.cc

@@ -76,7 +76,7 @@ Attribute ParseAttribute(std::string_view str) {
     return Attribute::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, Attribute value) {
+utils::StringStream& operator<<(utils::StringStream& out, Attribute value) {
     switch (value) {
         case Attribute::kUndefined:
             return out << "undefined";

src/tint/builtin/attribute.h

@@ -23,7 +23,7 @@
 #ifndef SRC_TINT_BUILTIN_ATTRIBUTE_H_
 #define SRC_TINT_BUILTIN_ATTRIBUTE_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 /// \cond DO_NOT_DOCUMENT
 /// There is a bug in doxygen where this enum conflicts with the ast::Attribute
@@ -50,10 +50,10 @@ enum class Attribute {
     kWorkgroupSize,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the Attribute
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, Attribute value);
+utils::StringStream& operator<<(utils::StringStream& out, Attribute value);
 
 /// ParseAttribute parses a Attribute from a string.
 /// @param str the string to parse

src/tint/builtin/attribute.h.tmpl

@@ -17,7 +17,7 @@ See:
 #ifndef SRC_TINT_BUILTIN_ATTRIBUTE_H_
 #define SRC_TINT_BUILTIN_ATTRIBUTE_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 /// \cond DO_NOT_DOCUMENT
 /// There is a bug in doxygen where this enum conflicts with the ast::Attribute

src/tint/builtin/builtin.cc

@@ -241,7 +241,7 @@ Builtin ParseBuiltin(std::string_view str) {
     return Builtin::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, Builtin value) {
+utils::StringStream& operator<<(utils::StringStream& out, Builtin value) {
     switch (value) {
         case Builtin::kUndefined:
             return out << "undefined";

src/tint/builtin/builtin.h

@@ -23,7 +23,7 @@
 #ifndef SRC_TINT_BUILTIN_BUILTIN_H_
 #define SRC_TINT_BUILTIN_BUILTIN_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 
@@ -102,10 +102,10 @@ enum class Builtin {
     kVec4U,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the Builtin
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, Builtin value);
+utils::StringStream& operator<<(utils::StringStream& out, Builtin value);
 
 /// ParseBuiltin parses a Builtin from a string.
 /// @param str the string to parse

src/tint/builtin/builtin.h.tmpl

@@ -18,7 +18,7 @@ See:
 #ifndef SRC_TINT_BUILTIN_BUILTIN_H_
 #define SRC_TINT_BUILTIN_BUILTIN_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 

src/tint/builtin/builtin_value.cc

@@ -70,7 +70,7 @@ BuiltinValue ParseBuiltinValue(std::string_view str) {
     return BuiltinValue::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, BuiltinValue value) {
+utils::StringStream& operator<<(utils::StringStream& out, BuiltinValue value) {
     switch (value) {
         case BuiltinValue::kUndefined:
             return out << "undefined";

src/tint/builtin/builtin_value.h

@@ -23,7 +23,7 @@
 #ifndef SRC_TINT_BUILTIN_BUILTIN_VALUE_H_
 #define SRC_TINT_BUILTIN_BUILTIN_VALUE_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 
@@ -45,10 +45,10 @@ enum class BuiltinValue {
     kWorkgroupId,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the BuiltinValue
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, BuiltinValue value);
+utils::StringStream& operator<<(utils::StringStream& out, BuiltinValue value);
 
 /// ParseBuiltinValue parses a BuiltinValue from a string.
 /// @param str the string to parse

src/tint/builtin/builtin_value.h.tmpl

@@ -14,7 +14,7 @@ See:
 #ifndef SRC_TINT_BUILTIN_BUILTIN_VALUE_H_
 #define SRC_TINT_BUILTIN_BUILTIN_VALUE_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 

src/tint/builtin/diagnostic_rule.cc

@@ -22,9 +22,10 @@
 
 #include "src/tint/builtin/diagnostic_rule.h"
 
-#include <ostream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 /// ParseDiagnosticRule parses a DiagnosticRule from a string.
@@ -40,7 +41,7 @@ DiagnosticRule ParseDiagnosticRule(std::string_view str) {
     return DiagnosticRule::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, DiagnosticRule value) {
+utils::StringStream& operator<<(utils::StringStream& out, DiagnosticRule value) {
     switch (value) {
         case DiagnosticRule::kUndefined:
             return out << "undefined";

src/tint/builtin/diagnostic_rule.cc.tmpl

@@ -12,9 +12,10 @@ See:
 
 #include "src/tint/builtin/diagnostic_rule.h"
 
-#include <ostream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 {{ Eval "ParseEnum" (Sem.Enum "diagnostic_rule")}}

src/tint/builtin/diagnostic_rule.h

@@ -25,6 +25,8 @@
 
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 /// The diagnostic rule.
@@ -34,10 +36,10 @@ enum class DiagnosticRule {
     kDerivativeUniformity,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the DiagnosticRule
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, DiagnosticRule value);
+utils::StringStream& operator<<(utils::StringStream& out, DiagnosticRule value);
 
 /// ParseDiagnosticRule parses a DiagnosticRule from a string.
 /// @param str the string to parse

src/tint/builtin/diagnostic_rule.h.tmpl

@@ -15,6 +15,8 @@ See:
 
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 /// The diagnostic rule.

src/tint/builtin/diagnostic_severity.cc

@@ -58,7 +58,7 @@ DiagnosticSeverity ParseDiagnosticSeverity(std::string_view str) {
     return DiagnosticSeverity::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, DiagnosticSeverity value) {
+utils::StringStream& operator<<(utils::StringStream& out, DiagnosticSeverity value) {
     switch (value) {
         case DiagnosticSeverity::kUndefined:
             return out << "undefined";

src/tint/builtin/diagnostic_severity.h

@@ -23,12 +23,12 @@
 #ifndef SRC_TINT_BUILTIN_DIAGNOSTIC_SEVERITY_H_
 #define SRC_TINT_BUILTIN_DIAGNOSTIC_SEVERITY_H_
 
-#include <ostream>
 #include <string>
 #include <unordered_map>
 
 #include "src/tint/builtin/diagnostic_rule.h"
 #include "src/tint/diagnostic/diagnostic.h"
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 
@@ -41,10 +41,10 @@ enum class DiagnosticSeverity {
     kWarning,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the DiagnosticSeverity
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, DiagnosticSeverity value);
+utils::StringStream& operator<<(utils::StringStream& out, DiagnosticSeverity value);
 
 /// ParseDiagnosticSeverity parses a DiagnosticSeverity from a string.
 /// @param str the string to parse

src/tint/builtin/diagnostic_severity.h.tmpl

@@ -13,10 +13,10 @@ See:
 #ifndef SRC_TINT_BUILTIN_DIAGNOSTIC_SEVERITY_H_
 #define SRC_TINT_BUILTIN_DIAGNOSTIC_SEVERITY_H_
 
-#include <ostream>
 #include <string>
 #include <unordered_map>
 
+#include "src/tint/utils/string_stream.h"
 #include "src/tint/builtin/diagnostic_rule.h"
 #include "src/tint/diagnostic/diagnostic.h"
 

src/tint/builtin/extension.cc

@@ -49,7 +49,7 @@ Extension ParseExtension(std::string_view str) {
     return Extension::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, Extension value) {
+utils::StringStream& operator<<(utils::StringStream& out, Extension value) {
     switch (value) {
         case Extension::kUndefined:
             return out << "undefined";

src/tint/builtin/extension.h

@@ -23,8 +23,7 @@
 #ifndef SRC_TINT_BUILTIN_EXTENSION_H_
 #define SRC_TINT_BUILTIN_EXTENSION_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
-
 #include "src/tint/utils/unique_vector.h"
 
 namespace tint::builtin {
@@ -41,10 +40,10 @@ enum class Extension {
     kF16,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the Extension
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, Extension value);
+utils::StringStream& operator<<(utils::StringStream& out, Extension value);
 
 /// ParseExtension parses a Extension from a string.
 /// @param str the string to parse

src/tint/builtin/extension.h.tmpl

@@ -14,8 +14,7 @@ See:
 #ifndef SRC_TINT_BUILTIN_EXTENSION_H_
 #define SRC_TINT_BUILTIN_EXTENSION_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
-
 #include "src/tint/utils/unique_vector.h"
 
 namespace tint::builtin {

src/tint/builtin/interpolation_sampling.cc

@@ -43,7 +43,7 @@ InterpolationSampling ParseInterpolationSampling(std::string_view str) {
     return InterpolationSampling::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, InterpolationSampling value) {
+utils::StringStream& operator<<(utils::StringStream& out, InterpolationSampling value) {
     switch (value) {
         case InterpolationSampling::kUndefined:
             return out << "undefined";

src/tint/builtin/interpolation_sampling.h

@@ -23,9 +23,10 @@
 #ifndef SRC_TINT_BUILTIN_INTERPOLATION_SAMPLING_H_
 #define SRC_TINT_BUILTIN_INTERPOLATION_SAMPLING_H_
 
-#include <ostream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 /// The interpolation sampling.
@@ -36,10 +37,10 @@ enum class InterpolationSampling {
     kSample,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the InterpolationSampling
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, InterpolationSampling value);
+utils::StringStream& operator<<(utils::StringStream& out, InterpolationSampling value);
 
 /// ParseInterpolationSampling parses a InterpolationSampling from a string.
 /// @param str the string to parse

src/tint/builtin/interpolation_sampling.h.tmpl

@@ -13,9 +13,10 @@ See:
 #ifndef SRC_TINT_BUILTIN_INTERPOLATION_SAMPLING_H_
 #define SRC_TINT_BUILTIN_INTERPOLATION_SAMPLING_H_
 
-#include <ostream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 /// The interpolation sampling.

src/tint/builtin/interpolation_type.cc

@@ -42,7 +42,7 @@ InterpolationType ParseInterpolationType(std::string_view str) {
     return InterpolationType::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, InterpolationType value) {
+utils::StringStream& operator<<(utils::StringStream& out, InterpolationType value) {
     switch (value) {
         case InterpolationType::kUndefined:
             return out << "undefined";

src/tint/builtin/interpolation_type.h

@@ -23,9 +23,10 @@
 #ifndef SRC_TINT_BUILTIN_INTERPOLATION_TYPE_H_
 #define SRC_TINT_BUILTIN_INTERPOLATION_TYPE_H_
 
-#include <ostream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 /// The interpolation type.
@@ -36,10 +37,10 @@ enum class InterpolationType {
     kPerspective,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the InterpolationType
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, InterpolationType value);
+utils::StringStream& operator<<(utils::StringStream& out, InterpolationType value);
 
 /// ParseInterpolationType parses a InterpolationType from a string.
 /// @param str the string to parse

src/tint/builtin/interpolation_type.h.tmpl

@@ -13,9 +13,10 @@ See:
 #ifndef SRC_TINT_BUILTIN_INTERPOLATION_TYPE_H_
 #define SRC_TINT_BUILTIN_INTERPOLATION_TYPE_H_
 
-#include <ostream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::builtin {
 
 /// The interpolation type.

src/tint/builtin/texel_format.cc

@@ -82,7 +82,7 @@ TexelFormat ParseTexelFormat(std::string_view str) {
     return TexelFormat::kUndefined;
 }
 
-std::ostream& operator<<(std::ostream& out, TexelFormat value) {
+utils::StringStream& operator<<(utils::StringStream& out, TexelFormat value) {
     switch (value) {
         case TexelFormat::kUndefined:
             return out << "undefined";

src/tint/builtin/texel_format.h

@@ -23,7 +23,7 @@
 #ifndef SRC_TINT_BUILTIN_TEXEL_FORMAT_H_
 #define SRC_TINT_BUILTIN_TEXEL_FORMAT_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 
@@ -49,10 +49,10 @@ enum class TexelFormat {
     kRgba8Unorm,
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the TexelFormat
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, TexelFormat value);
+utils::StringStream& operator<<(utils::StringStream& out, TexelFormat value);
 
 /// ParseTexelFormat parses a TexelFormat from a string.
 /// @param str the string to parse

src/tint/builtin/texel_format.h.tmpl

@@ -14,7 +14,7 @@ See:
 #ifndef SRC_TINT_BUILTIN_TEXEL_FORMAT_H_
 #define SRC_TINT_BUILTIN_TEXEL_FORMAT_H_
 
-#include <ostream>
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::builtin {
 

src/tint/cmd/helper.cc

@@ -14,6 +14,7 @@
 
 #include "src/tint/cmd/helper.h"
 
+#include <iostream>
 #include <utility>
 #include <vector>
 

src/tint/cmd/info.cc

@@ -13,6 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <iostream>
+
 #if TINT_BUILD_SPV_READER
 #include "spirv-tools/libspirv.hpp"
 #endif  // TINT_BUILD_SPV_READER

src/tint/diagnostic/formatter.cc

@@ -16,6 +16,7 @@
 
 #include <algorithm>
 #include <iterator>
+#include <utility>
 #include <vector>
 
 #include "src/tint/diagnostic/diagnostic.h"
@@ -85,8 +86,8 @@ struct Formatter::State {
     /// @param msg the value or string to write to the printer
     /// @returns this State so that calls can be chained
     template <typename T>
-    State& operator<<(const T& msg) {
+    State& operator<<(T&& msg) {
-        stream << msg;
+        stream << std::forward<T>(msg);
         return *this;
     }
 

src/tint/diagnostic/printer.h

@@ -16,7 +16,6 @@
 #define SRC_TINT_DIAGNOSTIC_PRINTER_H_
 
 #include <memory>
-#include <sstream>
 #include <string>
 
 #include "src/tint/utils/string_stream.h"

src/tint/fuzzers/tint_common_fuzzer.cc

@@ -17,6 +17,7 @@
 #include <cassert>
 #include <cstring>
 #include <fstream>
+#include <iostream>
 #include <memory>
 #include <sstream>
 #include <string>

src/tint/inspector/test_inspector_builder.cc

@@ -273,7 +273,11 @@ ast::Type InspectorBuilder::GetCoordsType(type::TextureDimension dim, ast::Type
         case type::TextureDimension::kCubeArray:
             return ty.vec3(scalar);
         default:
-            [=]() { FAIL() << "Unsupported texture dimension: " << dim; }();
+            [=]() {
+                utils::StringStream str;
+                str << dim;
+                FAIL() << "Unsupported texture dimension: " << str.str();
+            }();
     }
     return ast::Type{};
 }

src/tint/intrinsics.def

@@ -544,8 +544,8 @@ match workgroup
 @must_use @const fn abs<N: num, T: fia_fiu32_f16>(vec<N, T>) -> vec<N, T>
 @must_use @const fn acos<T: fa_f32_f16>(@test_value(0.96891242171) T) -> T
 @must_use @const fn acos<N: num, T: fa_f32_f16>(@test_value(0.96891242171) vec<N, T>) -> vec<N, T>
-@must_use @const fn acosh<T: fa_f32_f16>(@test_value(2.0) T) -> T
+@must_use @const fn acosh<T: fa_f32_f16>(@test_value(1.5430806348) T) -> T
-@must_use @const fn acosh<N: num, T: fa_f32_f16>(@test_value(2.0) vec<N, T>) -> vec<N, T>
+@must_use @const fn acosh<N: num, T: fa_f32_f16>(@test_value(1.5430806348) vec<N, T>) -> vec<N, T>
 @must_use @const fn all(bool) -> bool
 @must_use @const fn all<N: num>(vec<N, bool>) -> bool
 @must_use @const fn any(bool) -> bool
@@ -658,8 +658,8 @@ match workgroup
 @must_use @const fn refract<N: num, T: fa_f32_f16>(vec<N, T>, vec<N, T>, T) -> vec<N, T>
 @must_use @const fn reverseBits<T: iu32>(T) -> T
 @must_use @const fn reverseBits<N: num, T: iu32>(vec<N, T>) -> vec<N, T>
-@must_use @const fn round<T: fa_f32_f16>(@test_value(3.4) T) -> T
+@must_use @const fn round<T: fa_f32_f16>(@test_value(3.5) T) -> T
-@must_use @const fn round<N: num, T: fa_f32_f16>(@test_value(3.4) vec<N, T>) -> vec<N, T>
+@must_use @const fn round<N: num, T: fa_f32_f16>(@test_value(3.5) vec<N, T>) -> vec<N, T>
 @must_use @const fn saturate<T: fa_f32_f16>(@test_value(2) T) -> T
 @must_use @const fn saturate<T: fa_f32_f16, N: num>(@test_value(2) vec<N, T>) -> vec<N, T>
 @must_use @const("select_bool") fn select<T: scalar>(T, T, bool) -> T

src/tint/ir/binary.h

@@ -15,8 +15,6 @@
 #ifndef SRC_TINT_IR_BINARY_H_
 #define SRC_TINT_IR_BINARY_H_
 
-#include <ostream>
-
 #include "src/tint/castable.h"
 #include "src/tint/ir/instruction.h"
 #include "src/tint/symbol_table.h"

src/tint/ir/binary_test.cc

@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <sstream>
-
 #include "src/tint/ir/instruction.h"
 #include "src/tint/ir/test_helper.h"
 #include "src/tint/utils/string_stream.h"

src/tint/ir/bitcast.h

@@ -15,8 +15,6 @@
 #ifndef SRC_TINT_IR_BITCAST_H_
 #define SRC_TINT_IR_BITCAST_H_
 
-#include <ostream>
-
 #include "src/tint/castable.h"
 #include "src/tint/ir/instruction.h"
 #include "src/tint/symbol_table.h"

src/tint/ir/bitcast_test.cc

@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <sstream>
-
 #include "src/tint/ir/instruction.h"
 #include "src/tint/ir/test_helper.h"
 #include "src/tint/utils/string_stream.h"

src/tint/ir/builder_impl_test.cc

@@ -1836,8 +1836,8 @@ TEST_F(IR_BuilderImplTest, EmitExpression_Binary_Compound) {
     EXPECT_EQ(d.AsString(), R"(%1 (u32) = 3 >> 4
 %2 (u32) = %1 (u32) + 9
 %3 (bool) = 1 < %2 (u32)
-%4 (f32) = 2.299999952 * 5.5
+%4 (f32) = 2.29999995231628417969 * 5.5
-%5 (f32) = 6.699999809 / %4 (f32)
+%5 (f32) = 6.69999980926513671875 / %4 (f32)
 %6 (bool) = 2.5 > %5 (f32)
 %7 (bool) = %3 (bool) && %6 (bool)
 )");

src/tint/ir/constant.h

@@ -15,8 +15,6 @@
 #ifndef SRC_TINT_IR_CONSTANT_H_
 #define SRC_TINT_IR_CONSTANT_H_
 
-#include <ostream>
-
 #include "src/tint/constant/value.h"
 #include "src/tint/ir/value.h"
 #include "src/tint/symbol_table.h"

src/tint/ir/constant_test.cc

@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <sstream>
-
 #include "src/tint/ir/test_helper.h"
 #include "src/tint/ir/value.h"
 #include "src/tint/utils/string_stream.h"
@@ -34,7 +32,7 @@ TEST_F(IR_ConstantTest, f32) {
     EXPECT_EQ(1.2_f, c->value->As<constant::Scalar<f32>>()->ValueAs<f32>());
 
     c->ToString(str, b.builder.ir.symbols);
-    EXPECT_EQ("1.200000048", str.str());
+    EXPECT_EQ("1.20000004768371582031", str.str());
 
     EXPECT_TRUE(c->value->Is<constant::Scalar<f32>>());
     EXPECT_FALSE(c->value->Is<constant::Scalar<f16>>());

src/tint/ir/debug.cc

@@ -14,7 +14,6 @@
 
 #include "src/tint/ir/debug.h"
 
-#include <sstream>
 #include <unordered_map>
 #include <unordered_set>
 

src/tint/ir/disassembler.h

@@ -15,7 +15,6 @@
 #ifndef SRC_TINT_IR_DISASSEMBLER_H_
 #define SRC_TINT_IR_DISASSEMBLER_H_
 
-#include <sstream>
 #include <string>
 #include <unordered_map>
 #include <unordered_set>

src/tint/ir/instruction.h

@@ -15,8 +15,6 @@
 #ifndef SRC_TINT_IR_INSTRUCTION_H_
 #define SRC_TINT_IR_INSTRUCTION_H_
 
-#include <ostream>
-
 #include "src/tint/castable.h"
 #include "src/tint/ir/value.h"
 #include "src/tint/symbol_table.h"

src/tint/ir/temp.h

@@ -15,8 +15,6 @@
 #ifndef SRC_TINT_IR_TEMP_H_
 #define SRC_TINT_IR_TEMP_H_
 
-#include <ostream>
-
 #include "src/tint/ir/value.h"
 #include "src/tint/symbol_table.h"
 #include "src/tint/utils/string_stream.h"

src/tint/ir/temp_test.cc

@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <sstream>
-
 #include "src/tint/ir/temp.h"
 #include "src/tint/ir/test_helper.h"
 #include "src/tint/utils/string_stream.h"

src/tint/ir/value.h

@@ -15,8 +15,6 @@
 #ifndef SRC_TINT_IR_VALUE_H_
 #define SRC_TINT_IR_VALUE_H_
 
-#include <ostream>
-
 #include "src/tint/castable.h"
 #include "src/tint/symbol_table.h"
 #include "src/tint/type/type.h"

src/tint/number.cc

@@ -17,10 +17,10 @@
 #include <algorithm>
 #include <cmath>
 #include <cstring>
-#include <ostream>
 
 #include "src/tint/debug.h"
 #include "src/tint/utils/bitcast.h"
+#include "src/tint/utils/string_stream.h"
 
 namespace tint {
 namespace {
@@ -50,7 +50,7 @@ constexpr uint32_t kMinF32BiasedExpForF16SubnormalNumber = 103;
 
 }  // namespace
 
-std::ostream& operator<<(std::ostream& out, ConversionFailure failure) {
+utils::StringStream& operator<<(utils::StringStream& out, ConversionFailure failure) {
     switch (failure) {
         case ConversionFailure::kExceedsPositiveLimit:
             return out << "value exceeds positive limit for type";

src/tint/number.h

@@ -20,11 +20,11 @@
 #include <functional>
 #include <limits>
 #include <optional>
-#include <ostream>
 
 #include "src/tint/traits.h"
 #include "src/tint/utils/compiler_macros.h"
 #include "src/tint/utils/result.h"
+#include "src/tint/utils/string_stream.h"
 
 // Forward declaration
 namespace tint {
@@ -175,11 +175,11 @@ struct Number : NumberBase<Number<T>> {
 };
 
 /// Writes the number to the ostream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param num the Number
-/// @return the std::ostream so calls can be chained
+/// @return the stream so calls can be chained
 template <typename T>
-inline std::ostream& operator<<(std::ostream& out, Number<T> num) {
+inline utils::StringStream& operator<<(utils::StringStream& out, Number<T> num) {
     return out << num.value;
 }
 
@@ -314,10 +314,10 @@ enum class ConversionFailure {
 };
 
 /// Writes the conversion failure message to the ostream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param failure the ConversionFailure
-/// @return the std::ostream so calls can be chained
+/// @return the stream so calls can be chained
-std::ostream& operator<<(std::ostream& out, ConversionFailure failure);
+utils::StringStream& operator<<(utils::StringStream& out, ConversionFailure failure);
 
 /// Converts a number from one type to another, checking that the value fits in the target type.
 /// @returns the resulting value of the conversion, or a failure reason.

src/tint/program_id.h

@@ -16,10 +16,10 @@
 #define SRC_TINT_PROGRAM_ID_H_
 
 #include <stdint.h>
-#include <iostream>
 #include <utility>
 
 #include "src/tint/debug.h"
+#include "src/tint/utils/string_stream.h"
 
 namespace tint {
 
@@ -71,11 +71,11 @@ inline ProgramID ProgramIDOf(ProgramID id) {
     return id;
 }
 
-/// Writes the ProgramID to the std::ostream.
+/// Writes the ProgramID to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param id the program identifier to write
 /// @returns out so calls can be chained
-inline std::ostream& operator<<(std::ostream& out, ProgramID id) {
+inline utils::StringStream& operator<<(utils::StringStream& out, ProgramID id) {
     out << "Program<" << id.Value() << ">";
     return out;
 }

src/tint/reader/spirv/construct.h

@@ -16,7 +16,6 @@
 #define SRC_TINT_READER_SPIRV_CONSTRUCT_H_
 
 #include <memory>
-#include <sstream>
 #include <string>
 
 #include "src/tint/utils/string_stream.h"

src/tint/reader/spirv/fail_stream.h

@@ -19,7 +19,7 @@
 
 namespace tint::reader::spirv {
 
-/// A FailStream object accumulates values onto a given std::ostream,
+/// A FailStream object accumulates values onto a given stream,
 /// and can be used to record failure by writing the false value
 /// to given a pointer-to-bool.
 class FailStream {

src/tint/reader/spirv/function.h

@@ -28,6 +28,7 @@
 #include "src/tint/reader/spirv/attributes.h"
 #include "src/tint/reader/spirv/construct.h"
 #include "src/tint/reader/spirv/parser_impl.h"
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::reader::spirv {
 
@@ -178,11 +179,11 @@ struct BlockInfo {
     utils::Vector<uint32_t, 4> phis_needing_state_vars;
 };
 
-/// Writes the BlockInfo to the ostream
+/// Writes the BlockInfo to the stream
-/// @param o the ostream
+/// @param o the stream
 /// @param bi the BlockInfo
-/// @returns the ostream so calls can be chained
+/// @returns the stream so calls can be chained
-inline std::ostream& operator<<(std::ostream& o, const BlockInfo& bi) {
+inline utils::StringStream& operator<<(utils::StringStream& o, const BlockInfo& bi) {
     o << "BlockInfo{"
       << " id: " << bi.id << " pos: " << bi.pos << " merge_for_header: " << bi.merge_for_header
       << " continue_for_header: " << bi.continue_for_header
@@ -353,11 +354,11 @@ struct DefInfo {
     SkipReason skip = SkipReason::kDontSkip;
 };
 
-/// Writes the DefInfo to the ostream
+/// Writes the DefInfo to the stream
-/// @param o the ostream
+/// @param o the stream
 /// @param di the DefInfo
-/// @returns the ostream so calls can be chained
+/// @returns the stream so calls can be chained
-inline std::ostream& operator<<(std::ostream& o, const DefInfo& di) {
+inline utils::StringStream& operator<<(utils::StringStream& o, const DefInfo& di) {
     o << "DefInfo{"
       << " inst.result_id: " << di.inst.result_id();
     if (di.local.has_value()) {

src/tint/reader/spirv/function_cfg_test.cc

@@ -2598,10 +2598,11 @@ TEST_F(SpvParserCFGTest, VerifyHeaderContinueMergeOrder_HeaderDoesNotStrictlyDom
     fe.ComputeBlockOrderAndPositions();
     fe.RegisterMerges();
     EXPECT_FALSE(fe.VerifyHeaderContinueMergeOrder());
+
+    utils::StringStream result;
+    result << *fe.GetBlockInfo(50) << std::endl << *fe.GetBlockInfo(20) << std::endl;
     EXPECT_THAT(p->error(), Eq("Header 50 does not strictly dominate its merge block 20"))
-        << *fe.GetBlockInfo(50) << std::endl
+        << result.str() << Dump(fe.block_order());
-        << *fe.GetBlockInfo(20) << std::endl
-        << Dump(fe.block_order());
 }
 
 TEST_F(SpvParserCFGTest,
@@ -2634,10 +2635,10 @@ TEST_F(SpvParserCFGTest,
     fe.ComputeBlockOrderAndPositions();
     fe.RegisterMerges();
     EXPECT_FALSE(fe.VerifyHeaderContinueMergeOrder());
+    utils::StringStream str;
+    str << *fe.GetBlockInfo(50) << std::endl << *fe.GetBlockInfo(20) << std::endl;
     EXPECT_THAT(p->error(), Eq("Loop header 50 does not dominate its continue target 20"))
-        << *fe.GetBlockInfo(50) << std::endl
+        << str.str() << Dump(fe.block_order());
-        << *fe.GetBlockInfo(20) << std::endl
-        << Dump(fe.block_order());
 }
 
 TEST_F(SpvParserCFGTest, VerifyHeaderContinueMergeOrder_MergeInsideContinueTarget) {
@@ -2752,10 +2753,15 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_FunctionIsOnlyIfSelectionAnd
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 2u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,4) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [0,3) begin_id:10 end_id:99 depth:1 parent:Function@10 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[1].get());
@@ -2798,10 +2804,15 @@ TEST_F(SpvParserCFGTest,
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 2u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,6) begin_id:5 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [1,4) begin_id:10 end_id:99 depth:1 parent:Function@5 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(5)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
@@ -2842,10 +2853,15 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_SwitchSelection) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 2u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,5) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ SwitchSelection [0,4) begin_id:10 end_id:99 depth:1 parent:Function@10 in-c-l-s:SwitchSelection@10 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[1].get());
@@ -2879,12 +2895,17 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_SingleBlockLoop) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 2u);
+
+    utils::StringStream str;
+    str << constructs;
+
     // A single-block loop consists *only* of a continue target with one block in
     // it.
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,3) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ Continue [1,2) begin_id:20 end_id:99 depth:1 parent:Function@10 in-c:Continue@20 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[1].get());
@@ -2925,11 +2946,16 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_MultiBlockLoop_HeaderIsNotCo
     fe.RegisterMerges();
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,6) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ Continue [3,5) begin_id:40 end_id:99 depth:1 parent:Function@10 in-c:Continue@40 }
   Construct{ Loop [1,3) begin_id:20 end_id:40 depth:1 parent:Function@10 scope:[1,5) in-l:Loop@20 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[2].get());
@@ -2973,10 +2999,14 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_MultiBlockLoop_HeaderIsConti
     fe.RegisterMerges();
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,6) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ Continue [1,5) begin_id:20 end_id:99 depth:1 parent:Function@10 in-c:Continue@20 }
-})")) << constructs;
+})")) << str.str();
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[1].get());
@@ -3020,13 +3050,18 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_MergeBlockIsAlsoSingleBlockL
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 3u);
+
+    utils::StringStream str;
+    str << constructs;
+
     // A single-block loop consists *only* of a continue target with one block in
     // it.
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,4) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [0,2) begin_id:10 end_id:50 depth:1 parent:Function@10 }
   Construct{ Continue [2,3) begin_id:50 end_id:99 depth:1 parent:Function@10 in-c:Continue@50 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[1].get());
@@ -3068,12 +3103,17 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_MergeBlockIsAlsoMultiBlockLo
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,5) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [0,2) begin_id:10 end_id:50 depth:1 parent:Function@10 }
   Construct{ Continue [3,4) begin_id:60 end_id:99 depth:1 parent:Function@10 in-c:Continue@60 }
   Construct{ Loop [2,3) begin_id:50 end_id:60 depth:1 parent:Function@10 scope:[2,4) in-l:Loop@50 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[1].get());
@@ -3127,12 +3167,17 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_If_If) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,9) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [0,8) begin_id:10 end_id:99 depth:1 parent:Function@10 }
   Construct{ IfSelection [1,3) begin_id:20 end_id:40 depth:2 parent:IfSelection@10 }
   Construct{ IfSelection [5,7) begin_id:50 end_id:89 depth:2 parent:IfSelection@10 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[2].get());
@@ -3187,13 +3232,18 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_Switch_If) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     // The ordering among siblings depends on the computed block order.
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,8) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ SwitchSelection [0,7) begin_id:10 end_id:99 depth:1 parent:Function@10 in-c-l-s:SwitchSelection@10 }
   Construct{ IfSelection [1,3) begin_id:50 end_id:89 depth:2 parent:SwitchSelection@10 in-c-l-s:SwitchSelection@10 }
   Construct{ IfSelection [4,6) begin_id:20 end_id:49 depth:2 parent:SwitchSelection@10 in-c-l-s:SwitchSelection@10 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[3].get());
@@ -3237,11 +3287,16 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_If_Switch) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 3u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,5) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [0,4) begin_id:10 end_id:99 depth:1 parent:Function@10 }
   Construct{ SwitchSelection [1,3) begin_id:20 end_id:89 depth:2 parent:IfSelection@10 in-c-l-s:SwitchSelection@20 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[2].get());
@@ -3291,12 +3346,17 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_Loop_Loop) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,8) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ Continue [4,6) begin_id:50 end_id:89 depth:1 parent:Function@10 in-c:Continue@50 }
   Construct{ Loop [1,4) begin_id:20 end_id:50 depth:1 parent:Function@10 scope:[1,6) in-l:Loop@20 }
   Construct{ Continue [2,3) begin_id:30 end_id:40 depth:2 parent:Loop@20 in-l:Loop@20 in-c:Continue@30 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[2].get());
@@ -3346,12 +3406,17 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_Loop_If) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,7) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ Continue [5,6) begin_id:80 end_id:99 depth:1 parent:Function@10 in-c:Continue@80 }
   Construct{ Loop [1,5) begin_id:20 end_id:80 depth:1 parent:Function@10 scope:[1,6) in-l:Loop@20 }
   Construct{ IfSelection [2,4) begin_id:30 end_id:49 depth:2 parent:Loop@20 in-l:Loop@20 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[2].get());
@@ -3397,12 +3462,16 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_LoopContinue_If) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,6) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ Continue [2,5) begin_id:30 end_id:99 depth:1 parent:Function@10 in-c:Continue@30 }
   Construct{ Loop [1,2) begin_id:20 end_id:30 depth:1 parent:Function@10 scope:[1,5) in-l:Loop@20 }
   Construct{ IfSelection [2,4) begin_id:30 end_id:49 depth:2 parent:Continue@30 in-c:Continue@30 }
-})")) << constructs;
+})")) << str.str();
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[2].get());
@@ -3441,11 +3510,15 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_If_SingleBlockLoop) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 3u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,4) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [0,3) begin_id:10 end_id:99 depth:1 parent:Function@10 }
   Construct{ Continue [1,2) begin_id:20 end_id:89 depth:2 parent:IfSelection@10 in-c:Continue@20 }
-})")) << constructs;
+})")) << str.str();
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[2].get());
@@ -3490,12 +3563,17 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_Nest_If_MultiBlockLoop) {
     EXPECT_TRUE(fe.LabelControlFlowConstructs());
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     EXPECT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,7) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ IfSelection [0,6) begin_id:10 end_id:99 depth:1 parent:Function@10 }
   Construct{ Continue [3,5) begin_id:40 end_id:89 depth:2 parent:IfSelection@10 in-c:Continue@40 }
   Construct{ Loop [1,3) begin_id:20 end_id:40 depth:2 parent:IfSelection@10 scope:[1,5) in-l:Loop@20 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[1].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[3].get());
@@ -3540,12 +3618,17 @@ TEST_F(SpvParserCFGTest, LabelControlFlowConstructs_LoopInterallyDiverge) {
     ASSERT_TRUE(FlowLabelControlFlowConstructs(&fe)) << p->error();
     const auto& constructs = fe.constructs();
     EXPECT_EQ(constructs.Length(), 4u);
+
+    utils::StringStream str;
+    str << constructs;
+
     ASSERT_THAT(ToString(constructs), Eq(R"(ConstructList{
   Construct{ Function [0,6) begin_id:10 end_id:0 depth:0 parent:null }
   Construct{ Continue [4,5) begin_id:90 end_id:99 depth:1 parent:Function@10 in-c:Continue@90 }
   Construct{ Loop [1,4) begin_id:20 end_id:90 depth:1 parent:Function@10 scope:[1,5) in-l:Loop@20 }
   Construct{ IfSelection [1,4) begin_id:20 end_id:90 depth:2 parent:Loop@20 in-l:Loop@20 }
-})")) << constructs;
+})")) << str.str();
+
     // The block records the nearest enclosing construct.
     EXPECT_EQ(fe.GetBlockInfo(10)->construct, constructs[0].get());
     EXPECT_EQ(fe.GetBlockInfo(20)->construct, constructs[3].get());

src/tint/reader/spirv/function_logical_test.cc

@@ -532,9 +532,10 @@ TEST_F(SpvFUnordTest, FUnordEqual_Vector) {
     auto fe = p->function_emitter(100);
     EXPECT_TRUE(fe.EmitBody()) << p->error();
     auto ast_body = fe.ast_body();
-    EXPECT_THAT(test::ToString(p->program(), ast_body),
+    EXPECT_THAT(
-                HasSubstr("let x_1 : vec2<bool> = "
+        test::ToString(p->program(), ast_body),
-                          "!((vec2<f32>(50.0f, 60.0f) != vec2<f32>(60.0f, 50.0f)));"));
+        HasSubstr(
+            "let x_1 : vec2<bool> = !((vec2<f32>(50.0f, 60.0f) != vec2<f32>(60.0f, 50.0f)));"));
 }
 
 TEST_F(SpvFUnordTest, FUnordNotEqual_Scalar) {
@@ -567,9 +568,10 @@ TEST_F(SpvFUnordTest, FUnordNotEqual_Vector) {
     auto fe = p->function_emitter(100);
     EXPECT_TRUE(fe.EmitBody()) << p->error();
     auto ast_body = fe.ast_body();
-    EXPECT_THAT(test::ToString(p->program(), ast_body),
+    EXPECT_THAT(
-                HasSubstr("let x_1 : vec2<bool> = "
+        test::ToString(p->program(), ast_body),
-                          "!((vec2<f32>(50.0f, 60.0f) == vec2<f32>(60.0f, 50.0f)));"));
+        HasSubstr(
+            "let x_1 : vec2<bool> = !((vec2<f32>(50.0f, 60.0f) == vec2<f32>(60.0f, 50.0f)));"));
 }
 
 TEST_F(SpvFUnordTest, FUnordLessThan_Scalar) {
@@ -602,9 +604,10 @@ TEST_F(SpvFUnordTest, FUnordLessThan_Vector) {
     auto fe = p->function_emitter(100);
     EXPECT_TRUE(fe.EmitBody()) << p->error();
     auto ast_body = fe.ast_body();
-    EXPECT_THAT(test::ToString(p->program(), ast_body),
+    EXPECT_THAT(
-                HasSubstr("let x_1 : vec2<bool> = "
+        test::ToString(p->program(), ast_body),
-                          "!((vec2<f32>(50.0f, 60.0f) >= vec2<f32>(60.0f, 50.0f)));"));
+        HasSubstr(
+            "let x_1 : vec2<bool> = !((vec2<f32>(50.0f, 60.0f) >= vec2<f32>(60.0f, 50.0f)));"));
 }
 
 TEST_F(SpvFUnordTest, FUnordLessThanEqual_Scalar) {
@@ -637,9 +640,10 @@ TEST_F(SpvFUnordTest, FUnordLessThanEqual_Vector) {
     auto fe = p->function_emitter(100);
     EXPECT_TRUE(fe.EmitBody()) << p->error();
     auto ast_body = fe.ast_body();
-    EXPECT_THAT(test::ToString(p->program(), ast_body),
+    EXPECT_THAT(
-                HasSubstr("let x_1 : vec2<bool> = "
+        test::ToString(p->program(), ast_body),
-                          "!((vec2<f32>(50.0f, 60.0f) > vec2<f32>(60.0f, 50.0f)));"));
+        HasSubstr(
+            "let x_1 : vec2<bool> = !((vec2<f32>(50.0f, 60.0f) > vec2<f32>(60.0f, 50.0f)));"));
 }
 
 TEST_F(SpvFUnordTest, FUnordGreaterThan_Scalar) {
@@ -672,9 +676,10 @@ TEST_F(SpvFUnordTest, FUnordGreaterThan_Vector) {
     auto fe = p->function_emitter(100);
     EXPECT_TRUE(fe.EmitBody()) << p->error();
     auto ast_body = fe.ast_body();
-    EXPECT_THAT(test::ToString(p->program(), ast_body),
+    EXPECT_THAT(
-                HasSubstr("let x_1 : vec2<bool> = "
+        test::ToString(p->program(), ast_body),
-                          "!((vec2<f32>(50.0f, 60.0f) <= vec2<f32>(60.0f, 50.0f)));"));
+        HasSubstr(
+            "let x_1 : vec2<bool> = !((vec2<f32>(50.0f, 60.0f) <= vec2<f32>(60.0f, 50.0f)));"));
 }
 
 TEST_F(SpvFUnordTest, FUnordGreaterThanEqual_Scalar) {
@@ -707,10 +712,10 @@ TEST_F(SpvFUnordTest, FUnordGreaterThanEqual_Vector) {
     auto fe = p->function_emitter(100);
     EXPECT_TRUE(fe.EmitBody()) << p->error();
     auto ast_body = fe.ast_body();
-    EXPECT_THAT(test::ToString(p->program(), ast_body),
+    EXPECT_THAT(
-                HasSubstr("let x_1 : vec2<bool> = !(("
+        test::ToString(p->program(), ast_body),
-                          "vec2<f32>(50.0f, 60.0f) < vec2<f32>(60.0f, 50.0f)"
+        HasSubstr(
-                          "));"));
+            "let x_1 : vec2<bool> = !((vec2<f32>(50.0f, 60.0f) < vec2<f32>(60.0f, 50.0f)));"));
 }
 
 using SpvLogicalTest = SpvParserTestBase<::testing::Test>;

src/tint/reader/spirv/namer.cc

@@ -15,7 +15,6 @@
 #include "src/tint/reader/spirv/namer.h"
 
 #include <algorithm>
-#include <sstream>
 #include <unordered_set>
 
 #include "src/tint/debug.h"

src/tint/reader/spirv/parser_impl_handle_test.cc

@@ -1645,7 +1645,7 @@ INSTANTIATE_TEST_SUITE_P(
                         R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;)",
-                        "textureGatherCompare(x_20, x_10, coords12, 0.200000003f)"},
+                        "textureGatherCompare(x_20, x_10, coords12, 0.20000000298023223877f)"},
         // OpImageDrefGather 2DDepth ConstOffset signed
         ImageAccessCase{"%float 2D 1 0 0 1 Unknown",
                         "%result = OpImageDrefGather "
@@ -1653,7 +1653,7 @@ INSTANTIATE_TEST_SUITE_P(
                         R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;)",
-                        "textureGatherCompare(x_20, x_10, coords12, 0.200000003f, "
+                        "textureGatherCompare(x_20, x_10, coords12, 0.20000000298023223877f, "
                         "vec2<i32>(3i, 4i))"},
         // OpImageDrefGather 2DDepth ConstOffset unsigned
         ImageAccessCase{"%float 2D 1 0 0 1 Unknown",
@@ -1663,7 +1663,7 @@ INSTANTIATE_TEST_SUITE_P(
                         R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;)",
-                        "textureGatherCompare(x_20, x_10, coords12, 0.200000003f, "
+                        "textureGatherCompare(x_20, x_10, coords12, 0.20000000298023223877f, "
                         "vec2<i32>(vec2<u32>(3u, 4u)))"},
         // OpImageDrefGather 2DDepth Array
         ImageAccessCase{"%float 2D 1 1 0 1 Unknown",
@@ -1673,7 +1673,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d_array;)",
                         "textureGatherCompare(x_20, x_10, coords123.xy, "
-                        "i32(round(coords123.z)), 0.200000003f)"},
+                        "i32(round(coords123.z)), 0.20000000298023223877f)"},
         // OpImageDrefGather 2DDepth Array ConstOffset signed
         ImageAccessCase{"%float 2D 1 1 0 1 Unknown",
                         "%result = OpImageDrefGather "
@@ -1682,7 +1682,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d_array;)",
                         "textureGatherCompare(x_20, x_10, coords123.xy, "
-                        "i32(round(coords123.z)), 0.200000003f, vec2<i32>(3i, 4i))"},
+                        "i32(round(coords123.z)), 0.20000000298023223877f, vec2<i32>(3i, 4i))"},
         // OpImageDrefGather 2DDepth Array ConstOffset unsigned
         ImageAccessCase{"%float 2D 1 1 0 1 Unknown",
                         "%result = OpImageDrefGather "
@@ -1692,7 +1692,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d_array;)",
                         "textureGatherCompare(x_20, x_10, coords123.xy, "
-                        "i32(round(coords123.z)), 0.200000003f, "
+                        "i32(round(coords123.z)), 0.20000000298023223877f, "
                         "vec2<i32>(vec2<u32>(3u, 4u)))"},
         // OpImageDrefGather DepthCube
         ImageAccessCase{"%float Cube 1 0 0 1 Unknown",
@@ -1701,7 +1701,7 @@ INSTANTIATE_TEST_SUITE_P(
                         R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_cube;)",
-                        "textureGatherCompare(x_20, x_10, coords123, 0.200000003f)"},
+                        "textureGatherCompare(x_20, x_10, coords123, 0.20000000298023223877f)"},
         // OpImageDrefGather DepthCube Array
         ImageAccessCase{"%float Cube 1 1 0 1 Unknown",
                         "%result = OpImageDrefGather "
@@ -1710,7 +1710,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_cube_array;)",
                         "textureGatherCompare(x_20, x_10, coords1234.xyz, "
-                        "i32(round(coords1234.w)), 0.200000003f)"}}));
+                        "i32(round(coords1234.w)), 0.20000000298023223877f)"}}));
 
 INSTANTIATE_TEST_SUITE_P(
     ImageSampleImplicitLod,
@@ -1829,7 +1829,7 @@ INSTANTIATE_TEST_SUITE_P(
 )",
                         R"(
   let x_200 : vec4<f32> = vec4<f32>(textureSample(x_20, x_10, coords12), 0.0f, 0.0f, 0.0f);
-  let x_210 : f32 = textureSampleCompare(x_20, x_30, coords12, 0.200000003f);
+  let x_210 : f32 = textureSampleCompare(x_20, x_30, coords12, 0.20000000298023223877f);
 )"}));
 
 INSTANTIATE_TEST_SUITE_P(
@@ -1844,7 +1844,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;
 )",
-                        R"(textureSampleCompare(x_20, x_10, coords12, 0.200000003f))"},
+                        R"(textureSampleCompare(x_20, x_10, coords12, 0.20000000298023223877f))"},
         // ImageSampleDrefImplicitLod - arrayed
         ImageAccessCase{
             "%float 2D 0 1 0 1 Unknown",
@@ -1853,7 +1853,7 @@ INSTANTIATE_TEST_SUITE_P(
             R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d_array;)",
-            R"(textureSampleCompare(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.200000003f))"},
+            R"(textureSampleCompare(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.20000000298023223877f))"},
         // ImageSampleDrefImplicitLod with ConstOffset
         ImageAccessCase{
             "%float 2D 0 0 0 1 Unknown",
@@ -1863,7 +1863,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;
 )",
-            R"(textureSampleCompare(x_20, x_10, coords12, 0.200000003f, vec2<i32>(3i, 4i)))"},
+            R"(textureSampleCompare(x_20, x_10, coords12, 0.20000000298023223877f, vec2<i32>(3i, 4i)))"},
         // ImageSampleDrefImplicitLod arrayed with ConstOffset
         ImageAccessCase{
             "%float 2D 0 1 0 1 Unknown",
@@ -1872,7 +1872,7 @@ INSTANTIATE_TEST_SUITE_P(
             R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d_array;)",
-            R"(textureSampleCompare(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.200000003f, vec2<i32>(3i, 4i)))"}));
+            R"(textureSampleCompare(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.20000000298023223877f, vec2<i32>(3i, 4i)))"}));
 
 INSTANTIATE_TEST_SUITE_P(
     ImageSampleDrefExplicitLod,
@@ -1881,14 +1881,15 @@ INSTANTIATE_TEST_SUITE_P(
     // Another test checks cases where the Lod is not float constant 0.
     ::testing::Values(
         // 2D
-        ImageAccessCase{"%float 2D 1 0 0 1 Unknown",
+        ImageAccessCase{
-                        "%result = OpImageSampleDrefExplicitLod "
+            "%float 2D 1 0 0 1 Unknown",
-                        "%float %sampled_image %coords12 %depth Lod %float_0",
+            "%result = OpImageSampleDrefExplicitLod "
-                        R"(@group(0) @binding(0) var x_10 : sampler_comparison;
+            "%float %sampled_image %coords12 %depth Lod %float_0",
+            R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;
 )",
-                        R"(textureSampleCompareLevel(x_20, x_10, coords12, 0.200000003f))"},
+            R"(textureSampleCompareLevel(x_20, x_10, coords12, 0.20000000298023223877f))"},
         // 2D array
         ImageAccessCase{
             "%float 2D 1 1 0 1 Unknown",
@@ -1897,7 +1898,7 @@ INSTANTIATE_TEST_SUITE_P(
             R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d_array;)",
-            R"(textureSampleCompareLevel(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.200000003f))"},
+            R"(textureSampleCompareLevel(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.20000000298023223877f))"},
         // 2D, ConstOffset
         ImageAccessCase{
             "%float 2D 1 0 0 1 Unknown",
@@ -1908,7 +1909,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;
 )",
-            R"(textureSampleCompareLevel(x_20, x_10, coords12, 0.200000003f, vec2<i32>(3i, 4i)))"},
+            R"(textureSampleCompareLevel(x_20, x_10, coords12, 0.20000000298023223877f, vec2<i32>(3i, 4i)))"},
         // 2D array, ConstOffset
         ImageAccessCase{
             "%float 2D 1 1 0 1 Unknown",
@@ -1918,15 +1919,16 @@ INSTANTIATE_TEST_SUITE_P(
             R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_2d_array;)",
-            R"(textureSampleCompareLevel(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.200000003f, vec2<i32>(3i, 4i)))"},
+            R"(textureSampleCompareLevel(x_20, x_10, coords123.xy, i32(round(coords123.z)), 0.20000000298023223877f, vec2<i32>(3i, 4i)))"},
         // Cube
-        ImageAccessCase{"%float Cube 1 0 0 1 Unknown",
+        ImageAccessCase{
-                        "%result = OpImageSampleDrefExplicitLod "
+            "%float Cube 1 0 0 1 Unknown",
-                        "%float %sampled_image %coords123 %depth Lod %float_0",
+            "%result = OpImageSampleDrefExplicitLod "
-                        R"(@group(0) @binding(0) var x_10 : sampler_comparison;
+            "%float %sampled_image %coords123 %depth Lod %float_0",
+            R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_cube;)",
-                        R"(textureSampleCompareLevel(x_20, x_10, coords123, 0.200000003f))"},
+            R"(textureSampleCompareLevel(x_20, x_10, coords123, 0.20000000298023223877f))"},
         // Cube array
         ImageAccessCase{
             "%float Cube 1 1 0 1 Unknown",
@@ -1935,7 +1937,7 @@ INSTANTIATE_TEST_SUITE_P(
             R"(@group(0) @binding(0) var x_10 : sampler_comparison;
 
 @group(2) @binding(1) var x_20 : texture_depth_cube_array;)",
-            R"(textureSampleCompareLevel(x_20, x_10, coords1234.xyz, i32(round(coords1234.w)), 0.200000003f))"}));
+            R"(textureSampleCompareLevel(x_20, x_10, coords1234.xyz, i32(round(coords1234.w)), 0.20000000298023223877f))"}));
 
 INSTANTIATE_TEST_SUITE_P(
     ImageSampleExplicitLod_UsingLod,
@@ -2308,7 +2310,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;
 )",
-            R"(textureSampleCompare(x_20, x_10, (coords123.xy / coords123.z), 0.200000003f, 0.0f))"},
+            R"(textureSampleCompare(x_20, x_10, (coords123.xy / coords123.z), 0.20000000298023223877f, 0.0f))"},
 
         // OpImageSampleProjDrefImplicitLod 2D depth-texture, Lod ConstOffset
         ImageAccessCase{
@@ -2320,7 +2322,7 @@ INSTANTIATE_TEST_SUITE_P(
 
 @group(2) @binding(1) var x_20 : texture_depth_2d;
 )",
-            R"(textureSampleCompareLevel(x_20, x_10, (coords123.xy / coords123.z), 0.200000003f, 0.0f, vec2<i32>(3i, 4i)))"}));
+            R"(textureSampleCompareLevel(x_20, x_10, (coords123.xy / coords123.z), 0.20000000298023223877f, 0.0f, vec2<i32>(3i, 4i)))"}));
 
 /////
 // End projection sampling

src/tint/reader/spirv/usage.cc

@@ -14,8 +14,6 @@
 
 #include "src/tint/reader/spirv/usage.h"
 
-#include <sstream>
-
 #include "src/tint/utils/string_stream.h"
 
 namespace tint::reader::spirv {
@@ -24,7 +22,7 @@ Usage::Usage() {}
 Usage::Usage(const Usage& other) = default;
 Usage::~Usage() = default;
 
-std::ostream& Usage::operator<<(std::ostream& out) const {
+utils::StringStream& Usage::operator<<(utils::StringStream& out) const {
     out << "Usage(";
     if (IsSampler()) {
         out << "Sampler(";

src/tint/reader/spirv/usage.h

@@ -17,6 +17,8 @@
 
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::reader::spirv {
 
 /// Records the properties of a sampler or texture based on how it's used
@@ -73,7 +75,7 @@ class Usage {
     /// Emits this usage to the given stream
     /// @param out the output stream.
     /// @returns the modified stream.
-    std::ostream& operator<<(std::ostream& out) const;
+    utils::StringStream& operator<<(utils::StringStream& out) const;
 
     /// Equality operator
     /// @param other the RHS of the equality test.
@@ -122,11 +124,11 @@ class Usage {
     bool is_storage_write_ = false;
 };
 
-/// Writes the Usage to the ostream
+/// Writes the Usage to the stream
-/// @param out the ostream
+/// @param out the stream
 /// @param u the Usage
-/// @returns the ostream so calls can be chained
+/// @returns the stream so calls can be chained
-inline std::ostream& operator<<(std::ostream& out, const Usage& u) {
+inline utils::StringStream& operator<<(utils::StringStream& out, const Usage& u) {
     return u.operator<<(out);
 }
 

src/tint/reader/wgsl/parser_impl_expression_test.cc

@@ -468,7 +468,7 @@ struct Case {
 static bool ParsedAsTemplateArgumentList(BinaryOperatorInfo lhs_op, BinaryOperatorInfo rhs_op) {
     return lhs_op.bit == kOpLt && rhs_op.bit & (kOpGt | kOpGe | kOpShr);
 }
-static std::ostream& operator<<(std::ostream& o, const Case& c) {
+static utils::StringStream& operator<<(utils::StringStream& o, const Case& c) {
     return o << "a " << c.lhs_op.symbol << " b " << c.rhs_op.symbol << " c ";
 }
 

src/tint/reader/wgsl/token.h

@@ -353,7 +353,7 @@ class Token {
     std::variant<int64_t, double, std::string, std::string_view> value_;
 };
 
-inline std::ostream& operator<<(std::ostream& out, Token::Type type) {
+inline utils::StringStream& operator<<(utils::StringStream& out, Token::Type type) {
     out << Token::TypeToName(type);
     return out;
 }

src/tint/resolver/builtin_test.cc

@@ -2070,7 +2070,7 @@ INSTANTIATE_TEST_SUITE_P(ResolverTest,
 namespace texture_builtin_tests {
 
 enum class Texture { kF32, kI32, kU32 };
-inline std::ostream& operator<<(std::ostream& out, Texture data) {
+inline utils::StringStream& operator<<(utils::StringStream& out, Texture data) {
     if (data == Texture::kF32) {
         out << "f32";
     } else if (data == Texture::kI32) {
@@ -2087,7 +2087,9 @@ struct TextureTestParams {
     builtin::TexelFormat format = builtin::TexelFormat::kR32Float;
 };
 inline std::ostream& operator<<(std::ostream& out, TextureTestParams data) {
-    out << data.dim << "_" << data.type;
+    utils::StringStream str;
+    str << data.dim << "_" << data.type;
+    out << str.str();
     return out;
 }
 
@@ -2110,7 +2112,11 @@ class ResolverBuiltinTest_TextureOperation : public ResolverTestWithParam<Textur
             case type::TextureDimension::kCubeArray:
                 return ty.vec3(scalar);
             default:
-                [=]() { FAIL() << "Unsupported texture dimension: " << dim; }();
+                [=]() {
+                    utils::StringStream str;
+                    str << dim;
+                    FAIL() << "Unsupported texture dimension: " << str.str();
+                }();
         }
         return ast::Type{};
     }
@@ -2448,8 +2454,11 @@ TEST_P(ResolverBuiltinTest_Texture, Call) {
 
     if (std::string(param.function) == "textureDimensions") {
         switch (param.texture_dimension) {
-            default:
+            default: {
-                FAIL() << "invalid texture dimensions: " << param.texture_dimension;
+                utils::StringStream str;
+                str << param.texture_dimension;
+                FAIL() << "invalid texture dimensions: " << str.str();
+            }
             case type::TextureDimension::k1d:
                 EXPECT_TRUE(TypeOf(call)->Is<type::U32>());
                 break;

src/tint/resolver/const_eval_binary_op_test.cc

@@ -1607,7 +1607,7 @@ TEST_F(ResolverConstEvalTest, NonShortCircuit_And_Invalid_Materialize) {
         "179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558"
         "632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245"
         "490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168"
-        "738177180919299881250404026184124858368.000000000 cannot be represented as 'f32'");
+        "738177180919299881250404026184124858368.0 cannot be represented as 'f32'");
 }
 
 TEST_F(ResolverConstEvalTest, ShortCircuit_And_Error_Materialize) {
@@ -1658,7 +1658,7 @@ TEST_F(ResolverConstEvalTest, NonShortCircuit_Or_Invalid_Materialize) {
         "179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558"
         "632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245"
         "490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168"
-        "738177180919299881250404026184124858368.000000000 cannot be represented as 'f32'");
+        "738177180919299881250404026184124858368.0 cannot be represented as 'f32'");
 }
 
 TEST_F(ResolverConstEvalTest, ShortCircuit_Or_Error_Materialize) {

src/tint/resolver/const_eval_builtin_test.cc

@@ -2025,10 +2025,10 @@ std::vector<Case> Pack2x16floatCases() {
         C({Vec(f32(10), f32(-10.5))}, Val(u32(0xc940'4900))),
 
         E({Vec(f32(0), f32::Highest())},
-          "12:34 error: value 340282346638528859811704183484516925440.000000000 cannot be "
+          "12:34 error: value 340282346638528859811704183484516925440.0 cannot be "
           "represented as 'f16'"),
         E({Vec(f32::Lowest(), f32(0))},
-          "12:34 error: value -340282346638528859811704183484516925440.000000000 cannot be "
+          "12:34 error: value -340282346638528859811704183484516925440.0 cannot be "
           "represented as 'f16'"),
     };
 }
@@ -2850,16 +2850,15 @@ std::vector<Case> QuantizeToF16Cases() {
           Vec(0x0.034p-14_f, -0x0.034p-14_f, 0x0.068p-14_f, -0x0.068p-14_f)),
 
         // Value out of f16 range
-        E({65504.003_f}, "12:34 error: value 65504.003906250 cannot be represented as 'f16'"),
+        E({65504.003_f}, "12:34 error: value 65504.00390625 cannot be represented as 'f16'"),
-        E({-65504.003_f}, "12:34 error: value -65504.003906250 cannot be represented as 'f16'"),
+        E({-65504.003_f}, "12:34 error: value -65504.00390625 cannot be represented as 'f16'"),
-        E({0x1.234p56_f},
+        E({0x1.234p56_f}, "12:34 error: value 81979586966978560.0 cannot be represented as 'f16'"),
-          "12:34 error: value 81979586966978560.000000000 cannot be represented as 'f16'"),
         E({0x4.321p65_f},
-          "12:34 error: value 154788719192723947520.000000000 cannot be represented as 'f16'"),
+          "12:34 error: value 154788719192723947520.0 cannot be represented as 'f16'"),
         E({Vec(65504.003_f, 0_f)},
-          "12:34 error: value 65504.003906250 cannot be represented as 'f16'"),
+          "12:34 error: value 65504.00390625 cannot be represented as 'f16'"),
         E({Vec(0_f, -0x4.321p65_f)},
-          "12:34 error: value -154788719192723947520.000000000 cannot be represented as 'f16'"),
+          "12:34 error: value -154788719192723947520.0 cannot be represented as 'f16'"),
     };
 }
 INSTANTIATE_TEST_SUITE_P(  //

src/tint/resolver/const_eval_conversion_test.cc

@@ -431,8 +431,7 @@ TEST_F(ResolverConstEvalTest, Vec3_Convert_Large_f32_to_f16) {
     WrapInFunction(expr);
 
     EXPECT_FALSE(r()->Resolve());
-    EXPECT_EQ(r()->error(),
+    EXPECT_EQ(r()->error(), "12:34 error: value 10000000000.0 cannot be represented as 'f16'");
-              "12:34 error: value 10000000000.000000000 cannot be represented as 'f16'");
 }
 
 TEST_F(ResolverConstEvalTest, Vec3_Convert_Small_f32_to_f16) {

src/tint/resolver/const_eval_runtime_semantics_test.cc

@@ -363,7 +363,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, Exp_F32_Overflow) {
     auto result = const_eval.exp(a->Type(), utils::Vector{a}, {});
     ASSERT_TRUE(result);
     EXPECT_EQ(result.Get()->ValueAs<f32>(), 0.f);
-    EXPECT_EQ(error(), R"(warning: e^1000.000000000 cannot be represented as 'f32')");
+    EXPECT_EQ(error(), R"(warning: e^1000.0 cannot be represented as 'f32')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, Exp2_F32_Overflow) {
@@ -371,7 +371,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, Exp2_F32_Overflow) {
     auto result = const_eval.exp2(a->Type(), utils::Vector{a}, {});
     ASSERT_TRUE(result);
     EXPECT_EQ(result.Get()->ValueAs<f32>(), 0.f);
-    EXPECT_EQ(error(), R"(warning: 2^1000.000000000 cannot be represented as 'f32')");
+    EXPECT_EQ(error(), R"(warning: 2^1000.0 cannot be represented as 'f32')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, ExtractBits_I32_TooManyBits) {
@@ -476,7 +476,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, Pack2x16Float_OutOfRange) {
     auto result = const_eval.pack2x16float(create<type::U32>(), utils::Vector{vec}, {});
     ASSERT_TRUE(result);
     EXPECT_EQ(result.Get()->ValueAs<u32>(), 0x51430000);
-    EXPECT_EQ(error(), R"(warning: value 75250.000000000 cannot be represented as 'f16')");
+    EXPECT_EQ(error(), R"(warning: value 75250.0 cannot be represented as 'f16')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, Pow_F32_Overflow) {
@@ -502,7 +502,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, QuantizeToF16_OutOfRange) {
     auto result = const_eval.quantizeToF16(create<type::U32>(), utils::Vector{a}, {});
     ASSERT_TRUE(result);
     EXPECT_EQ(result.Get()->ValueAs<u32>(), 0);
-    EXPECT_EQ(error(), R"(warning: value 75250.000000000 cannot be represented as 'f16')");
+    EXPECT_EQ(error(), R"(warning: value 75250.0 cannot be represented as 'f16')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, Sqrt_F32_OutOfRange) {
@@ -536,7 +536,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, Convert_F32_TooHigh) {
     EXPECT_EQ(result.Get()->ValueAs<f32>(), f32::kHighestValue);
     EXPECT_EQ(
         error(),
-        R"(warning: value 179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000000 cannot be represented as 'f32')");
+        R"(warning: value 179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.0 cannot be represented as 'f32')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, Convert_F32_TooLow) {
@@ -546,7 +546,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, Convert_F32_TooLow) {
     EXPECT_EQ(result.Get()->ValueAs<f32>(), f32::kLowestValue);
     EXPECT_EQ(
         error(),
-        R"(warning: value -179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000000 cannot be represented as 'f32')");
+        R"(warning: value -179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.0 cannot be represented as 'f32')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, Convert_F16_TooHigh) {
@@ -554,7 +554,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, Convert_F16_TooHigh) {
     auto result = const_eval.Convert(create<type::F16>(), a, {});
     ASSERT_TRUE(result);
     EXPECT_EQ(result.Get()->ValueAs<f32>(), f16::kHighestValue);
-    EXPECT_EQ(error(), R"(warning: value 1000000.000000000 cannot be represented as 'f16')");
+    EXPECT_EQ(error(), R"(warning: value 1000000.0 cannot be represented as 'f16')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, Convert_F16_TooLow) {
@@ -562,7 +562,7 @@ TEST_F(ResolverConstEvalRuntimeSemanticsTest, Convert_F16_TooLow) {
     auto result = const_eval.Convert(create<type::F16>(), a, {});
     ASSERT_TRUE(result);
     EXPECT_EQ(result.Get()->ValueAs<f32>(), f16::kLowestValue);
-    EXPECT_EQ(error(), R"(warning: value -1000000.000000000 cannot be represented as 'f16')");
+    EXPECT_EQ(error(), R"(warning: value -1000000.0 cannot be represented as 'f16')");
 }
 
 TEST_F(ResolverConstEvalRuntimeSemanticsTest, Vec_Overflow_SingleComponent) {

src/tint/resolver/intrinsic_table.inl

@@ -14092,8 +14092,8 @@ constexpr IntrinsicInfo kBuiltins[] = {
   },
   {
     /* [2] */
-    /* fn acosh<T : fa_f32_f16>(@test_value(2) T) -> T */
+    /* fn acosh<T : fa_f32_f16>(@test_value(1.5430806348) T) -> T */
-    /* fn acosh<N : num, T : fa_f32_f16>(@test_value(2) vec<N, T>) -> vec<N, T> */
+    /* fn acosh<N : num, T : fa_f32_f16>(@test_value(1.5430806348) vec<N, T>) -> vec<N, T> */
     /* num overloads */ 2,
     /* overloads */ &kOverloads[287],
   },
@@ -14526,8 +14526,8 @@ constexpr IntrinsicInfo kBuiltins[] = {
   },
   {
     /* [66] */
-    /* fn round<T : fa_f32_f16>(@test_value(3.4) T) -> T */
+    /* fn round<T : fa_f32_f16>(@test_value(3.5) T) -> T */
-    /* fn round<N : num, T : fa_f32_f16>(@test_value(3.4) vec<N, T>) -> vec<N, T> */
+    /* fn round<N : num, T : fa_f32_f16>(@test_value(3.5) vec<N, T>) -> vec<N, T> */
     /* num overloads */ 2,
     /* overloads */ &kOverloads[383],
   },

src/tint/resolver/uniformity.cc

@@ -15,7 +15,6 @@
 #include "src/tint/resolver/uniformity.h"
 
 #include <limits>
-#include <sstream>
 #include <string>
 #include <utility>
 #include <vector>

src/tint/resolver/uniformity_test.cc

@@ -13,7 +13,6 @@
 // limitations under the License.
 
 #include <memory>
-#include <sstream>
 #include <string>
 #include <tuple>
 #include <utility>

src/tint/sem/behavior.cc

@@ -16,7 +16,7 @@
 
 namespace tint::sem {
 
-std::ostream& operator<<(std::ostream& out, Behavior behavior) {
+utils::StringStream& operator<<(utils::StringStream& out, Behavior behavior) {
     switch (behavior) {
         case Behavior::kReturn:
             return out << "Return";

src/tint/sem/behavior.h

@@ -31,11 +31,11 @@ enum class Behavior {
 /// Behaviors is a set of Behavior
 using Behaviors = utils::EnumSet<Behavior>;
 
-/// Writes the Behavior to the std::ostream.
+/// Writes the Behavior to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param behavior the Behavior to write
 /// @returns out so calls can be chained
-std::ostream& operator<<(std::ostream& out, Behavior behavior);
+utils::StringStream& operator<<(utils::StringStream& out, Behavior behavior);
 
 }  // namespace tint::sem
 

src/tint/sem/binding_point.h

@@ -18,10 +18,10 @@
 #include <stdint.h>
 
 #include <functional>
-#include <ostream>
 
 #include "src/tint/reflection.h"
 #include "src/tint/utils/hash.h"
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::sem {
 
@@ -49,10 +49,10 @@ struct BindingPoint {
 };
 
 /// Prints the BindingPoint @p bp to @p o
-/// @param o the std::ostream to write to
+/// @param o the stream to write to
 /// @param bp the BindingPoint
-/// @return the std::ostream so calls can be chained
+/// @return the stream so calls can be chained
-inline std::ostream& operator<<(std::ostream& o, const BindingPoint& bp) {
+inline utils::StringStream& operator<<(utils::StringStream& o, const BindingPoint& bp) {
     return o << "[group: " << bp.group << ", binding: " << bp.binding << "]";
 }
 

src/tint/sem/builtin_type.cc

@@ -22,8 +22,6 @@
 
 #include "src/tint/sem/builtin_type.h"
 
-#include <sstream>
-
 namespace tint::sem {
 
 BuiltinType ParseBuiltinType(const std::string& name) {
@@ -608,7 +606,7 @@ const char* str(BuiltinType i) {
     return "<unknown>";
 }
 
-std::ostream& operator<<(std::ostream& out, BuiltinType i) {
+utils::StringStream& operator<<(utils::StringStream& out, BuiltinType i) {
     out << str(i);
     return out;
 }

src/tint/sem/builtin_type.cc.tmpl

@@ -13,8 +13,6 @@ See:
 
 #include "src/tint/sem/builtin_type.h"
 
-#include <sstream>
-
 namespace tint::sem {
 
 BuiltinType ParseBuiltinType(const std::string& name) {
@@ -38,7 +36,7 @@ const char* str(BuiltinType i) {
     return "<unknown>";
 }
 
-std::ostream& operator<<(std::ostream& out, BuiltinType i) {
+utils::StringStream& operator<<(utils::StringStream& out, BuiltinType i) {
     out << str(i);
     return out;
 }

src/tint/sem/builtin_type.h

@@ -23,9 +23,10 @@
 #ifndef SRC_TINT_SEM_BUILTIN_TYPE_H_
 #define SRC_TINT_SEM_BUILTIN_TYPE_H_
 
-#include <sstream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::sem {
 
 /// Enumerator of all builtin functions
@@ -159,7 +160,7 @@ const char* str(BuiltinType i);
 
 /// Emits the name of the builtin function type. The spelling, including case,
 /// matches the name in the WGSL spec.
-std::ostream& operator<<(std::ostream& out, BuiltinType i);
+utils::StringStream& operator<<(utils::StringStream& out, BuiltinType i);
 
 /// All builtin function
 constexpr BuiltinType kBuiltinTypes[] = {

src/tint/sem/builtin_type.h.tmpl

@@ -14,9 +14,10 @@ See:
 #ifndef SRC_TINT_SEM_BUILTIN_TYPE_H_
 #define SRC_TINT_SEM_BUILTIN_TYPE_H_
 
-#include <sstream>
 #include <string>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::sem {
 
 /// Enumerator of all builtin functions
@@ -39,7 +40,7 @@ const char* str(BuiltinType i);
 
 /// Emits the name of the builtin function type. The spelling, including case,
 /// matches the name in the WGSL spec.
-std::ostream& operator<<(std::ostream& out, BuiltinType i);
+utils::StringStream& operator<<(utils::StringStream& out, BuiltinType i);
 
 /// All builtin function
 constexpr BuiltinType kBuiltinTypes[] = {

src/tint/sem/sampler_texture_pair.h

@@ -17,9 +17,9 @@
 
 #include <cstdint>
 #include <functional>
-#include <ostream>
 
 #include "src/tint/sem/binding_point.h"
+#include "src/tint/utils/string_stream.h"
 
 namespace tint::sem {
 
@@ -45,10 +45,10 @@ struct SamplerTexturePair {
 };
 
 /// Prints the SamplerTexturePair @p stp to @p o
-/// @param o the std::ostream to write to
+/// @param o the stream to write to
 /// @param stp the SamplerTexturePair
-/// @return the std::ostream so calls can be chained
+/// @return the stream so calls can be chained
-inline std::ostream& operator<<(std::ostream& o, const SamplerTexturePair& stp) {
+inline utils::StringStream& operator<<(utils::StringStream& o, const SamplerTexturePair& stp) {
     return o << "[sampler: " << stp.sampler_binding_point
              << ", texture: " << stp.sampler_binding_point << "]";
 }

src/tint/source.cc

@@ -15,7 +15,6 @@
 #include "src/tint/source.h"
 
 #include <algorithm>
-#include <sstream>
 #include <string_view>
 #include <utility>
 
@@ -122,7 +121,7 @@ Source::FileContent::~FileContent() = default;
 
 Source::File::~File() = default;
 
-std::ostream& operator<<(std::ostream& out, const Source& source) {
+utils::StringStream& operator<<(utils::StringStream& out, const Source& source) {
     auto rng = source.range;
 
     if (source.file) {

src/tint/source.h

@@ -16,12 +16,13 @@
 #ifndef SRC_TINT_SOURCE_H_
 #define SRC_TINT_SOURCE_H_
 
-#include <iostream>
 #include <string>
 #include <string_view>
 #include <tuple>
 #include <vector>
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint {
 
 /// Source describes a range of characters within a source file.
@@ -191,35 +192,36 @@ class Source {
     const File* file = nullptr;
 };
 
-/// Writes the Source::Location to the std::ostream.
+/// Writes the Source::Location to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param loc the location to write
 /// @returns out so calls can be chained
-inline std::ostream& operator<<(std::ostream& out, const Source::Location& loc) {
+inline utils::StringStream& operator<<(utils::StringStream& out, const Source::Location& loc) {
     out << loc.line << ":" << loc.column;
     return out;
 }
 
-/// Writes the Source::Range to the std::ostream.
+/// Writes the Source::Range to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param range the range to write
 /// @returns out so calls can be chained
-inline std::ostream& operator<<(std::ostream& out, const Source::Range& range) {
+inline utils::StringStream& operator<<(utils::StringStream& out, const Source::Range& range) {
     out << "[" << range.begin << ", " << range.end << "]";
     return out;
 }
 
-/// Writes the Source to the std::ostream.
+/// Writes the Source to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param source the source to write
 /// @returns out so calls can be chained
-std::ostream& operator<<(std::ostream& out, const Source& source);
+utils::StringStream& operator<<(utils::StringStream& out, const Source& source);
 
-/// Writes the Source::FileContent to the std::ostream.
+/// Writes the Source::FileContent to the stream.
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param content the file content to write
 /// @returns out so calls can be chained
-inline std::ostream& operator<<(std::ostream& out, const Source::FileContent& content) {
+inline utils::StringStream& operator<<(utils::StringStream& out,
+                                       const Source::FileContent& content) {
     out << content.data;
     return out;
 }

src/tint/templates/enums.tmpl.inc

@@ -47,10 +47,10 @@ enum class {{$enum}} {
 {{-   end }}
 };
 
-/// @param out the std::ostream to write to
+/// @param out the stream to write to
 /// @param value the {{$enum}}
 /// @returns `out` so calls can be chained
-std::ostream& operator<<(std::ostream& out, {{$enum}} value);
+utils::StringStream& operator<<(utils::StringStream& out, {{$enum}} value);
 
 /// Parse{{$enum}} parses a {{$enum}} from a string.
 /// @param str the string to parse
@@ -90,11 +90,11 @@ constexpr const char* k{{$enum}}Strings[] = {
 
 {{- /* ------------------------------------------------------------------ */ -}}
 {{-                         define "EnumOStream"                             -}}
-{{- /* Implements the std::ostream 'operator<<()' function to print the   */ -}}
+{{- /* Implements the stream 'operator<<()' function to print the         */ -}}
 {{- /* provided sem.Enum.                                                 */ -}}
 {{- /* ------------------------------------------------------------------ */ -}}
 {{- $enum := Eval "EnumName" $ -}}
-std::ostream& operator<<(std::ostream& out, {{$enum}} value) {
+    utils::StringStream& operator<<(utils::StringStream& out, {{$enum}} value) {
     switch (value) {
         case {{$enum}}::kUndefined:
             return out << "undefined";