https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95457
Bug ID: 95457
Summary: Inadequate diagnostics on constrained coroutines
Product: gcc
Version: 10.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: a...@cloudius-systems.com
Target Milestone: ---
Created attachment 48651
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48651&action=edit
test case
If a coroutine_traits specialization fails, and if the constraints is not
satisfied, gcc reports that it cannot find the promise type. However, it does
not report on the constraint failure, as it usually does with concepts.
The diagnostics for the attached test case are:
g++ -std=c++20 -fcoroutines constrained-coroutine.cc -o
constrained-coroutine
constrained-coroutine.cc: In function ‘dummy_coroutine foo(int&&)’:
constrained-coroutine.cc:31:5: error: unable to find the promise type for this
coroutine
31 | co_return x;
| ^~~~~~~~~
cc1plus: warning: control reaches end of non-void function [-Wreturn-type]
