[PATCH] D49099: Remove qualtype qualifier in coroutine error to prevent assert in debug

[Tanoy Sinha via Phabricator via cfe-commits]

tks2103 created this revision.
tks2103 added reviewers: modocache, GorNishanov.

A forward-declared coroutine_traits should trip an error; we need
a complete type.

Unfortunately, in debug mode only, we trip an assert when attempting
to provide the fully qualified type for the error message.
If you try to compile a program with a forward-declared
coroutine_traits in debug mode, clang will crash.

I've included a test for the behavior and removed the q modifier
on the error message. This prevents the crash in debug mode and
does not change the behavior for the error message on a
forward-declaration of a coroutine_traits type.

Test Plan:
I've included a test for the forward-declaration.


Repository:
  rC Clang

https://reviews.llvm.org/D49099

Files:
  include/clang/Basic/DiagnosticSemaKinds.td
  test/SemaCXX/coroutine-traits-undefined-template.cpp


Index: test/SemaCXX/coroutine-traits-undefined-template.cpp
===================================================================
--- /dev/null
+++ test/SemaCXX/coroutine-traits-undefined-template.cpp
@@ -0,0 +1,21 @@
+// test/SemaCXX/coroutine-traits-undefined-template.cpp
+
+// This file contains references to sections of the Coroutines TS, which can be
+// found at http://wg21.link/coroutines.
+
+// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -verify %s -fcxx-exceptions -fexceptions -Wunused-result
+
+namespace std {
+namespace experimental {
+
+template<typename ...T>
+struct coroutine_traits {
+  struct promise_type {};
+};
+
+template<> struct coroutine_traits<void>; // expected-note {{forward declaration of 'std::experimental::coroutine_traits<void>'}}
+}} // namespace std::experimental
+
+void uses_forward_declaration() {
+  co_return; // expected-error {{this function cannot be a coroutine: missing definition of specialization 'coroutine_traits<void>'}}
+}
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -9071,7 +9071,7 @@
   "this function cannot be a coroutine: %0 is an incomplete type">;
 def err_coroutine_type_missing_specialization : Error<
   "this function cannot be a coroutine: missing definition of "
-  "specialization %q0">;
+  "specialization %0">;
 def err_coroutine_promise_incompatible_return_functions : Error<
   "the coroutine promise type %0 declares both 'return_value' and 'return_void'">;
 def err_coroutine_promise_requires_return_function : Error<


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