validation: cannot cast to a pointer

Bug: tint:73
Change-Id: I913509b4d5bd502c7699364db4e7a02f8895cc58
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/54760
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Auto-Submit: Sarah Mashayekhi <sarahmashay@google.com>

src/resolver/ptr_ref_validation_test.cc

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include "src/ast/bitcast_expression.h"
 #include "src/ast/struct_block_decoration.h"
 #include "src/resolver/resolver.h"
 #include "src/resolver/resolver_test_helper.h"
@@ -114,6 +115,19 @@ TEST_F(ResolverPtrRefValidationTest, InferredPtrAccessMismatch) {
             "'ptr<storage, i32, read_write>'");
 }
 
+TEST_F(ResolverTest, Expr_Bitcast_ptr) {
+  auto* vf = Var("vf", ty.f32());
+  auto* bitcast = create<ast::BitcastExpression>(
+      Source{{12, 34}}, ty.pointer<i32>(ast::StorageClass::kFunction),
+      Expr("vf"));
+  auto* ip =
+      Const("ip", ty.pointer<i32>(ast::StorageClass::kFunction), bitcast);
+  WrapInFunction(Decl(vf), Decl(ip));
+
+  EXPECT_FALSE(r()->Resolve());
+  EXPECT_EQ(r()->error(), "12:34 error: cannot cast to a pointer");
+}
+
 }  // namespace
 }  // namespace resolver
 }  // namespace tint

src/resolver/resolver.cc

@@ -1680,6 +1680,10 @@ bool Resolver::Bitcast(ast::BitcastExpression* expr) {
   if (!ty) {
     return false;
   }
+  if (ty->Is<sem::Pointer>()) {
+    diagnostics_.add_error("cannot cast to a pointer", expr->source());
+    return false;
+  }
   SetType(expr, ty, expr->type()->FriendlyName(builder_->Symbols()));
   return true;
 }
@@ -1861,6 +1865,10 @@ bool Resolver::Constructor(ast::ConstructorExpression* expr) {
     // Now that the argument types have been determined, make sure that they
     // obey the constructor type rules laid out in
     // https://gpuweb.github.io/gpuweb/wgsl.html#type-constructor-expr.
+    if (type->Is<sem::Pointer>()) {
+      diagnostics_.add_error("cannot cast to a pointer", expr->source());
+      return false;
+    }
     if (auto* vec_type = type->As<sem::Vector>()) {
       return ValidateVectorConstructor(type_ctor, vec_type);
     }

src/resolver/validation_test.cc

@@ -728,6 +728,18 @@ TEST_F(ResolverValidationTest, OffsetAndAlignAndSizeDecoration) {
             "decorations");
 }
 
+TEST_F(ResolverTest, Expr_Constructor_Cast_Pointer) {
+  auto* vf = Var("vf", ty.f32());
+  auto* c = create<ast::TypeConstructorExpression>(
+      Source{{12, 34}}, ty.pointer<i32>(ast::StorageClass::kFunction),
+      ExprList(vf));
+  auto* ip = Const("ip", ty.pointer<i32>(ast::StorageClass::kFunction), c);
+  WrapInFunction(Decl(vf), Decl(ip));
+
+  EXPECT_FALSE(r()->Resolve());
+  EXPECT_EQ(r()->error(), "12:34 error: cannot cast to a pointer");
+}
+
 TEST_F(ResolverValidationTest, Expr_Constructor_Array_ZeroValue_Pass) {
   // array<u32, 10>();
   auto* tc = array<u32, 10>();