Convert @binding to an expression

This CL updates the binding attribute to store an expression
instead of a single value. The parser always produces an
IntLiteralExpression at the moment.

Bug: tint:1633
Change-Id: I14b2a61b5bcdea66e9e24df7afbb55fb60be785e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/100440
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/tint/ast/binding_attribute.cc

@@ -22,7 +22,10 @@ TINT_INSTANTIATE_TYPEINFO(tint::ast::BindingAttribute);
 
 namespace tint::ast {
 
-BindingAttribute::BindingAttribute(ProgramID pid, NodeID nid, const Source& src, uint32_t val)
+BindingAttribute::BindingAttribute(ProgramID pid,
+                                   NodeID nid,
+                                   const Source& src,
+                                   const ast::Expression* val)
     : Base(pid, nid, src), value(val) {}
 
 BindingAttribute::~BindingAttribute() = default;
@@ -34,7 +37,8 @@ std::string BindingAttribute::Name() const {
 const BindingAttribute* BindingAttribute::Clone(CloneContext* ctx) const {
     // Clone arguments outside of create() call to have deterministic ordering
     auto src = ctx->Clone(source);
-    return ctx->dst->create<BindingAttribute>(src, value);
+    auto* value_ = ctx->Clone(value);
+    return ctx->dst->create<BindingAttribute>(src, value_);
 }
 
 }  // namespace tint::ast

src/tint/ast/binding_attribute.h

@@ -18,6 +18,7 @@
 #include <string>
 
 #include "src/tint/ast/attribute.h"
+#include "src/tint/ast/expression.h"
 
 namespace tint::ast {
 
@@ -28,8 +29,8 @@ class BindingAttribute final : public Castable<BindingAttribute, Attribute> {
     /// @param pid the identifier of the program that owns this node
     /// @param nid the unique node identifier
     /// @param src the source of this node
-    /// @param value the binding value
-    BindingAttribute(ProgramID pid, NodeID nid, const Source& src, uint32_t value);
+    /// @param value the binding value expression
+    BindingAttribute(ProgramID pid, NodeID nid, const Source& src, const ast::Expression* value);
     ~BindingAttribute() override;
 
     /// @returns the WGSL name for the attribute
@@ -41,8 +42,8 @@ class BindingAttribute final : public Castable<BindingAttribute, Attribute> {
     /// @return the newly cloned node
     const BindingAttribute* Clone(CloneContext* ctx) const override;
 
-    /// the binding value
-    const uint32_t value;
+    /// the binding value expression
+    const ast::Expression* const value;
 };
 
 }  // namespace tint::ast

src/tint/ast/binding_attribute_test.cc

@@ -17,11 +17,12 @@
 namespace tint::ast {
 namespace {
 
+using namespace tint::number_suffixes;  // NOLINT
 using BindingAttributeTest = TestHelper;
 
 TEST_F(BindingAttributeTest, Creation) {
-    auto* d = create<BindingAttribute>(2u);
-    EXPECT_EQ(2u, d->value);
+    auto* d = Binding(2_a);
+    EXPECT_TRUE(d->value->Is<IntLiteralExpression>());
 }
 
 }  // namespace

src/tint/ast/builtin_texture_helper_test.cc

@@ -143,7 +143,7 @@ const ast::Type* TextureOverloadCase::BuildResultVectorComponentType(ProgramBuil
 const ast::Variable* TextureOverloadCase::BuildTextureVariable(ProgramBuilder* b) const {
     utils::Vector attrs{
         b->create<ast::GroupAttribute>(0u),
-        b->create<ast::BindingAttribute>(0u),
+        b->Binding(0_a),
     };
     switch (texture_kind) {
         case ast::builtin::test::TextureKind::kRegular:
@@ -175,10 +175,7 @@ const ast::Variable* TextureOverloadCase::BuildTextureVariable(ProgramBuilder* b
 }
 
 const ast::Variable* TextureOverloadCase::BuildSamplerVariable(ProgramBuilder* b) const {
-    utils::Vector attrs = {
-        b->create<ast::GroupAttribute>(0u),
-        b->create<ast::BindingAttribute>(1u),
-    };
+    utils::Vector attrs = {b->Group(0u), b->Binding(1_a)};
     return b->GlobalVar("sampler", b->ty.sampler(sampler_kind), attrs);
 }
 

src/tint/ast/variable_test.cc

@@ -106,7 +106,7 @@ TEST_F(VariableTest, WithAttributes) {
 }
 
 TEST_F(VariableTest, HasBindingPoint_BothProvided) {
-    auto* var = Var("my_var", ty.i32(), StorageClass::kFunction, Binding(2), Group(1));
+    auto* var = Var("my_var", ty.i32(), StorageClass::kFunction, Binding(2_a), Group(1));
     EXPECT_TRUE(var->HasBindingPoint());
 }
 
@@ -116,7 +116,7 @@ TEST_F(VariableTest, HasBindingPoint_NeitherProvided) {
 }
 
 TEST_F(VariableTest, HasBindingPoint_MissingGroupAttribute) {
-    auto* var = Var("my_var", ty.i32(), StorageClass::kFunction, Binding(2));
+    auto* var = Var("my_var", ty.i32(), StorageClass::kFunction, Binding(2_a));
     EXPECT_FALSE(var->HasBindingPoint());
 }