commit 5b853eebc6cc851cd6b621e34baf5defd169661c
author dan sinclair <dj2@everburning.com> Mon Jun 22 20:44:27 2020 +0000
committer David Neto <dneto@google.com> Mon Jun 22 20:44:27 2020 +0000
tree 3f89de3afb653c040e593e4907842b2f00251247
parent 9c88ea59886c56cfe2c213d89e0798f55dc4a9c7

Support the zero initializer syntax.

This Cl updates the system to allow zero initializers. This allows:

```
var a : vec3<f32> = vec3<f32>();
```

Bug: tint:34
Change-Id: I84d6b431914c4ddf112ed375fae028d912f4a080
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/23660
Reviewed-by: David Neto <dneto@google.com>

src/reader/wgsl/parser_impl.cc

diff --git a/src/reader/wgsl/parser_impl.cc b/src/reader/wgsl/parser_impl.cc
index 1886d62..63e426b 100644
--- a/src/reader/wgsl/parser_impl.cc
+++ b/src/reader/wgsl/parser_impl.cc
@@ -1943,7 +1943,7 @@
 
 // primary_expression
 //   : (IDENT NAMESPACE)* IDENT
-//   | type_decl PAREN_LEFT argument_expression_list PAREN_RIGHT
+//   | type_decl PAREN_LEFT argument_expression_list* PAREN_RIGHT
 //   | const_literal
 //   | paren_rhs_stmt
 //   | CAST LESS_THAN type_decl GREATER_THAN paren_rhs_stmt
@@ -2043,9 +2043,13 @@
       return nullptr;
     }
 
-    auto params = argument_expression_list();
-    if (has_error())
-      return nullptr;
+    t = peek();
+    ast::ExpressionList params;
+    if (!t.IsParenRight() && !t.IsEof()) {
+      params = argument_expression_list();
+      if (has_error())
+        return nullptr;
+    }
 
     t = next();
     if (!t.IsParenRight()) {

src/reader/wgsl/parser_impl_primary_expression_test.cc

diff --git a/src/reader/wgsl/parser_impl_primary_expression_test.cc b/src/reader/wgsl/parser_impl_primary_expression_test.cc
index a5fd1d9..c2558e9 100644
--- a/src/reader/wgsl/parser_impl_primary_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_primary_expression_test.cc
@@ -98,6 +98,18 @@
   EXPECT_EQ(ident->literal()->AsSint()->value(), 4);
 }
 
+TEST_F(ParserImplTest, PrimaryExpression_TypeDecl_ZeroConstructor) {
+  auto* p = parser("vec4<i32>()");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
+  ASSERT_NE(e, nullptr);
+  ASSERT_TRUE(e->IsConstructor());
+  ASSERT_TRUE(e->AsConstructor()->IsTypeConstructor());
+  auto* ty = e->AsConstructor()->AsTypeConstructor();
+
+  ASSERT_EQ(ty->values().size(), 0u);
+}
+
 TEST_F(ParserImplTest, PrimaryExpression_TypeDecl_InvalidTypeDecl) {
   auto* p = parser("vec4<if>(2., 3., 4., 5.)");
   auto e = p->primary_expression();