Emit variable statements

This Cl updates the WGSL writer to output variable statements.

Bug: tint:4
Change-Id: Ic557ea0c1b366644a8496dd43e4cfd85b9e8a84f
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/17281
Reviewed-by: David Neto <dneto@google.com>

src/CMakeLists.txt

@@ -429,6 +429,7 @@ if(${TINT_BUILD_WGSL_WRITER})
     writer/wgsl/generator_impl_unary_method_test.cc
     writer/wgsl/generator_impl_unary_op_test.cc
     writer/wgsl/generator_impl_unless_test.cc
+    writer/wgsl/generator_impl_variable_statement_test.cc
     writer/wgsl/generator_impl_variable_test.cc
   )
 endif()

src/writer/wgsl/generator_impl.cc

@@ -39,7 +39,6 @@
 #include "src/ast/regardless_statement.h"
 #include "src/ast/relational_expression.h"
 #include "src/ast/return_statement.h"
-#include "src/ast/unless_statement.h"
 #include "src/ast/set_decoration.h"
 #include "src/ast/statement.h"
 #include "src/ast/struct.h"
@@ -55,6 +54,8 @@
 #include "src/ast/unary_derivative_expression.h"
 #include "src/ast/unary_method_expression.h"
 #include "src/ast/unary_op_expression.h"
+#include "src/ast/unless_statement.h"
+#include "src/ast/variable_statement.h"
 
 namespace tint {
 namespace writer {
@@ -678,6 +679,9 @@ bool GeneratorImpl::EmitStatement(ast::Statement* stmt) {
   if (stmt->IsReturn()) {
     return EmitReturn(stmt->AsReturn());
   }
+  if (stmt->IsVariable()) {
+    return EmitVariable(stmt->AsVariable()->variable());
+  }
   if (stmt->IsUnless()) {
     return EmitUnless(stmt->AsUnless());
   }

src/writer/wgsl/generator_impl_unless_test.cc

@@ -53,4 +53,3 @@ TEST_F(GeneratorImplTest, Emit_Unless) {
 }  // namespace wgsl
 }  // namespace writer
 }  // namespace tint
-

src/writer/wgsl/generator_impl_variable_statement_test.cc

@@ -0,0 +1,48 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <memory>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "src/ast/type/f32_type.h"
+#include "src/ast/variable.h"
+#include "src/ast/variable_statement.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, Emit_VariableStatement) {
+  ast::type::F32Type f32;
+  auto var =
+      std::make_unique<ast::Variable>("a", ast::StorageClass::kNone, &f32);
+
+  ast::VariableStatement stmt(std::move(var));
+
+  GeneratorImpl g;
+  g.increment_indent();
+
+  ASSERT_TRUE(g.EmitStatement(&stmt)) << g.error();
+  EXPECT_EQ(g.result(), "  var a : f32;\n");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint