wgsl-reader: treat function formal params as const
They should only be singly-assigned.
This is required because consts can hold pointers, but
var's cannot. And we need to support pointer arguments.
Bug: tint:275
Change-Id: I00a58734725bd08d40df71c736854a93c364a33c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/30923
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
diff --git a/src/reader/wgsl/parser_impl.cc b/src/reader/wgsl/parser_impl.cc
index 33a487f..09f5348 100644
--- a/src/reader/wgsl/parser_impl.cc
+++ b/src/reader/wgsl/parser_impl.cc
@@ -1991,8 +1991,14 @@
return {};
for (;;) {
- ret.push_back(std::make_unique<ast::Variable>(
- source, name, ast::StorageClass::kNone, type));
+ auto var = std::make_unique<ast::Variable>(source, name,
+ ast::StorageClass::kNone, type);
+ // Formal parameters are treated like a const declaration where the
+ // initializer value is provided by the call's argument. The key point is
+ // that it's not updatable after intially set. This is unlike C or GLSL
+ // which treat formal parameters like local variables that can be updated.
+ var->set_is_const(true);
+ ret.push_back(std::move(var));
t = peek();
if (!t.IsComma())
diff --git a/src/reader/wgsl/parser_impl_param_list_test.cc b/src/reader/wgsl/parser_impl_param_list_test.cc
index ca8c38e..1d0b12a 100644
--- a/src/reader/wgsl/parser_impl_param_list_test.cc
+++ b/src/reader/wgsl/parser_impl_param_list_test.cc
@@ -38,6 +38,7 @@
EXPECT_EQ(e[0]->name(), "a");
EXPECT_EQ(e[0]->type(), i32);
+ EXPECT_TRUE(e[0]->is_const());
}
TEST_F(ParserImplTest, ParamList_Multiple) {
@@ -52,12 +53,15 @@
EXPECT_EQ(e[0]->name(), "a");
EXPECT_EQ(e[0]->type(), i32);
+ EXPECT_TRUE(e[0]->is_const());
EXPECT_EQ(e[1]->name(), "b");
EXPECT_EQ(e[1]->type(), f32);
+ EXPECT_TRUE(e[1]->is_const());
EXPECT_EQ(e[2]->name(), "c");
EXPECT_EQ(e[2]->type(), vec2);
+ EXPECT_TRUE(e[1]->is_const());
}
TEST_F(ParserImplTest, ParamList_Empty) {
