Add type determination for the unless statement

This CL adds type determination for Unless statements.

Bug: tint:5
Change-Id: I0e8721d3c282ca8dcf9e7954f309c14e437b5272
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/18839
Reviewed-by: David Neto <dneto@google.com>

src/type_determiner.cc

@@ -26,6 +26,7 @@
 #include "src/ast/scalar_constructor_expression.h"
 #include "src/ast/switch_statement.h"
 #include "src/ast/type_constructor_expression.h"
+#include "src/ast/unless_statement.h"
 
 namespace tint {
 
@@ -150,6 +151,11 @@ bool TypeDeterminer::DetermineResultType(ast::Statement* stmt) {
     }
     return true;
   }
+  if (stmt->IsUnless()) {
+    auto u = stmt->AsUnless();
+    return DetermineResultType(u->condition()) &&
+           DetermineResultType(u->body());
+  }
 
   error_ = "unknown statement type for type determination";
   return false;

src/type_determiner_test.cc

@@ -35,6 +35,7 @@
 #include "src/ast/type/i32_type.h"
 #include "src/ast/type/vector_type.h"
 #include "src/ast/type_constructor_expression.h"
+#include "src/ast/unless_statement.h"
 
 namespace tint {
 namespace {
@@ -328,6 +329,36 @@ TEST_F(TypeDeterminerTest, Stmt_Switch) {
   EXPECT_TRUE(rhs_ptr->result_type()->IsF32());
 }
 
+TEST_F(TypeDeterminerTest, Stmt_Unless) {
+  ast::type::I32Type i32;
+  ast::type::F32Type f32;
+
+  auto lhs = std::make_unique<ast::ScalarConstructorExpression>(
+      std::make_unique<ast::IntLiteral>(&i32, 2));
+  auto lhs_ptr = lhs.get();
+
+  auto rhs = std::make_unique<ast::ScalarConstructorExpression>(
+      std::make_unique<ast::FloatLiteral>(&f32, 2.3f));
+  auto rhs_ptr = rhs.get();
+
+  ast::StatementList body;
+  body.push_back(std::make_unique<ast::AssignmentStatement>(std::move(lhs),
+                                                            std::move(rhs)));
+
+  ast::UnlessStatement unless(
+      std::make_unique<ast::ScalarConstructorExpression>(
+          std::make_unique<ast::IntLiteral>(&i32, 3)),
+      std::move(body));
+
+  EXPECT_TRUE(td()->DetermineResultType(&unless));
+  ASSERT_NE(unless.condition()->result_type(), nullptr);
+  ASSERT_NE(lhs_ptr->result_type(), nullptr);
+  ASSERT_NE(rhs_ptr->result_type(), nullptr);
+  EXPECT_TRUE(unless.condition()->result_type()->IsI32());
+  EXPECT_TRUE(lhs_ptr->result_type()->IsI32());
+  EXPECT_TRUE(rhs_ptr->result_type()->IsF32());
+}
+
 TEST_F(TypeDeterminerTest, Expr_Constructor_Scalar) {
   ast::type::F32Type f32;
   ast::ScalarConstructorExpression s(