[wgsl-writer] Emit array stride decoration.

This CL adds array stride decorations to the WGSL writer.

Bug: tint:179
Change-Id: I39d7625e1bdc876bbf9a83da7af76eb98bd09c28
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/26002
Reviewed-by: David Neto <dneto@google.com>

src/writer/wgsl/generator_impl.cc

diff --git a/src/writer/wgsl/generator_impl.cc b/src/writer/wgsl/generator_impl.cc
index 951c78d..dac8d3c 100644
--- a/src/writer/wgsl/generator_impl.cc
+++ b/src/writer/wgsl/generator_impl.cc
@@ -356,6 +356,11 @@
     out_ << alias->name();
   } else if (type->IsArray()) {
     auto* ary = type->AsArray();
+
+    if (ary->has_array_stride()) {
+      out_ << "[[stride " << ary->array_stride() << "]] ";
+    }
+
     out_ << "array<";
     if (!EmitType(ary->type())) {
       return false;

src/writer/wgsl/generator_impl_type_test.cc

diff --git a/src/writer/wgsl/generator_impl_type_test.cc b/src/writer/wgsl/generator_impl_type_test.cc
index 1cbc223..48c8fc3 100644
--- a/src/writer/wgsl/generator_impl_type_test.cc
+++ b/src/writer/wgsl/generator_impl_type_test.cc
@@ -55,6 +55,16 @@
   EXPECT_EQ(g.result(), "array<bool, 4>");
 }
 
+TEST_F(WgslGeneratorImplTest, EmitType_Array_WithStride) {
+  ast::type::BoolType b;
+  ast::type::ArrayType a(&b, 4);
+  a.set_array_stride(16);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&a)) << g.error();
+  EXPECT_EQ(g.result(), "[[stride 16]] array<bool, 4>");
+}
+
 TEST_F(WgslGeneratorImplTest, EmitType_RuntimeArray) {
   ast::type::BoolType b;
   ast::type::ArrayType a(&b);