https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91318
Bug ID: 91318
Summary: warnings about unused internal macros with
-Wunused-macros and #pragma GCC optimize
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: phd at phd dot re
Target Milestone: ---
GCC shows annoying warnings about unused internal macros when using
-Wunused-macros parameter to compile code containing #pragma GCC optimize
-- a.cpp
-----------------------------------------------------------------------
#pragma GCC optimize ("fast-math")
#pragma GCC optimize ("finite-math-only")
int main() {}
--------------------------------------------------------------------------------
command:
gcc -Wunused-macros a.cpp
-- result
----------------------------------------------------------------------
a.cpp:2:41: warning: macro "__FAST_MATH__" is not used [-Wunused-macros]
2 | #pragma GCC optimize ("finite-math-only")
| ^
a.cpp:2:41: warning: macro "__NO_MATH_ERRNO__" is not used [-Wunused-macros]
a.cpp:4:13: warning: macro "__FINITE_MATH_ONLY__" is not used [-Wunused-macros]
4 | int main() {}
| ^
--------------------------------------------------------------------------------
live demo:
https://godbolt.org/z/flbv97
