https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125170
Bug ID: 125170
Summary: [15 Regression] ICE in gimple_add_tmp_var on co_await
of pointer-to-member-function call
Product: gcc
Version: 15.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: piersh at hotmail dot com
Target Milestone: ---
Created attachment 64355
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=64355&action=edit
pre-processed repro
A coroutine member function that does `co_await` on a call made through a
pointer-to-member-function — `co_await (this->*pmf)()` — ICEs in
gimple_add_tmp_var on GCC 15.1.1. GCC 14 accepts the same code (regression).
A direct call (`co_await this->bar()`) is accepted; the ICE only fires when
the awaited call is dispatched through a pmf.
Reduced test case (19 lines, only <coroutine> required):
#include <coroutine>
struct Future {
struct promise_type {
Future get_return_object() { return {}; }
std::suspend_never initial_suspend() noexcept { return {}; }
std::suspend_never final_suspend() noexcept { return {}; }
void return_void() {}
void unhandled_exception() {}
};
bool await_ready() { return true; }
void await_suspend(std::coroutine_handle<>) {}
void await_resume() {}
};
struct Foo {
Future test(Future (Foo::*fn)()) {
co_await (this->*fn)();
co_return;
}
};
Command:
g++ -std=c++20 -c bug.cpp
Output:
bug.cpp: In function 'void Foo::test(...Frame*)':
bug.cpp:18:29: internal compiler error: in gimple_add_tmp_var, at
gimplify.cc:834
18 | co_await (this->*fn)();
| ~~~~~~~~~~~^~
Status by version:
GCC 14 : accepts (clean compile) -- reporter verified
GCC 15.1 : ICE
trunk : not tested by reporter
Compiler details:
gcc version 15.1.1 20250521 (Red Hat 15.1.1-2) (GCC)
Target: x86_64-redhat-linux
Configured with: --enable-bootstrap --enable-languages=c,c++,fortran,lto
--enable-checking=release --with-arch_64=x86-64-v3
--enable-host-pie --enable-host-bind-now
(full configure line available; trimmed for brevity)
Host: Rocky Linux 10.1, x86_64, kernel 6.6.87.2 (WSL2).
Notes / shape of the trigger:
- `pmf` may be a function parameter, a local variable, or captured by
value or reference into a coroutine lambda — all forms ICE identically.
- `-fcoroutines` is not needed (implied by `-std=c++20`); `-std=gnu++20`
reproduces equivalently.
- No optimization flags or sanitizers are required.
- `-Wall -Wextra` clean before the ICE; no diagnostics other than the ICE.
Preprocessed source attached.
