Add TINT_ASSERT()

Replacement for the places where we currently use assert(), and there is no sensible place to put the error into a diag::List.

Change-Id: Id154340b0353f8a3e8962771263f1cc87dce2aa4
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44047
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/debug.h

@@ -88,4 +88,20 @@ class InternalCompilerError {
 #define TINT_UNREACHABLE(diagnostics) \
   TINT_ICE(diagnostics) << "TINT_UNREACHABLE "
 
+/// TINT_ASSERT() is a macro for checking the expression is true, triggering a
+/// TINT_ICE if it is not.
+/// The ICE message contains the callsite's file and line.
+/// @warning: Unlike TINT_ICE() and TINT_UNREACHABLE(), TINT_ASSERT() does not
+/// append a message to an existing tint::diag::List. As such, TINT_ASSERT()
+/// may silently fail in builds where SetInternalCompilerErrorReporter() is not
+/// called. Only use in places where there's no sensible place to put proper
+/// error handling.
+#define TINT_ASSERT(condition)                                      \
+  do {                                                              \
+    if (!(condition)) {                                             \
+      tint::diag::List diagnostics;                                 \
+      TINT_ICE(diagnostics) << "TINT_ASSERT(" << #condition << ")"; \
+    }                                                               \
+  } while (false)
+
 #endif  // SRC_DEBUG_H_

src/debug_test.cc

@@ -28,5 +28,13 @@ TEST(DebugTest, Unreachable) {
       "internal compiler error");
 }
 
+TEST(DebugTest, AssertTrue) {
+  TINT_ASSERT(true);
+}
+
+TEST(DebugTest, AssertFalse) {
+  EXPECT_FATAL_FAILURE({ TINT_ASSERT(false); }, "internal compiler error");
+}
+
 }  // namespace
 }  // namespace tint