https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71463
Bug ID: 71463
Summary: "ignoring attributes on template argument" in -O1 and
above
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mail at milianw dot de
Target Milestone: ---
I've seen this error with gcc (GCC) 6.1.1 20160501 and code like this:
~~~~~~~~~~~~~~
#include <cstdlib>
template<typename T> struct foo {};
foo<decltype(&::malloc)> emit_unexpected_warning;
int main() { return 0; }
~~~~~~~~~~~~~~
compiling it without optimizations shows no warning, but from -O1 and onwards I
get the unexpected warning on ignored template argument attributes:
~~~~~~~~~~~~~~~
$ g++ -std=c++11 -Wall -Wpedantic -O0 test.cpp
# no warnings
$ g++ -std=c++11 -Wall -Wpedantic -O1 test.cpp
test.cpp:9:24: warning: ignoring attributes on template argument ‘void*
(*)(size_t) throw () {aka void* (*)(long unsigned int) throw ()}’
[-Wignored-attributes]
foo<decltype(&::malloc)> emit_unexpected_warning;
~~~~~~~~~~~~~~~
Clang does not emit any such warning. I believe it's a false-positive,
especially considering that it only shows up in -O1 and higher, but not -O0.
