https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95239
Bug ID: 95239
Summary: Unable to ignore -Wattribute-warning in macro
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: e...@coeus-group.com
Target Milestone: ---
Created attachment 48573
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48573&action=edit
Test case
I'm trying to create a macro which evaluates an expression while ignoring
warnings generated by the warning attribute. Basically, a slightly simplified
version of what I want is:
#define IGNORE_WARNING_ATTR(expr) (__extension__({ \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Wattribute-warning\"") \
int tmp = expr; \
_Pragma("GCC diagnostic pop") \
tmp; \
}))
However, when I use it I still see the warning.
If I don't use a macro, but instead just do
int c = (__extension__({
_Pragma("GCC diagnostic push")
_Pragma("GCC diagnostic ignored \"-Wattribute-warning\"")
int tmp = foo(argc);
_Pragma("GCC diagnostic pop")
tmp;
}));
It works as intended; no warning.
If I use the macro version and preprocess the source file first, then compile
the preprocessed file separately, it works.
If I compile with g++ it works.
Using the attached test case, I get:
$ gcc -E -o warn-pp.c warn.c && gcc -o warn warn-pp.c
$ g++ -o warn warn.c
$ gcc -o warn warn.c
warn.c: In function ‘main’:
warn.c:23:31: warning: call to ‘foo’ declared with attribute warning: Calling
foo [-Wattribute-warning]
23 | int b = IGNORE_WARNING_ATTR(foo(argc));
| ^~~~~~~~~
warn.c:4:15: note: in definition of macro ‘IGNORE_WARNING_ATTR’
4 | int tmp = expr; \
| ^~~~
