https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86377
Bug ID: 86377
Summary: extern int errno; is treated as buggy function
declaration [-Werror=strict-prototypes]
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: um at mutluit dot com
Target Milestone: ---
Created attachment 44344
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44344&action=edit
The output file of -save-temps (ie. the "file.i" file)
test file extern_var_bug.c:
-----------------
#include <errno.h>
extern int errno;
int main(int argc, char* argv[])
{
return errno;
}
Output:
-------
extern_var_bug.c:2:16: error: function declaration isn't a prototype
[-Werror=strict-prototypes]
extern int errno;
^
extern_var_bug.c: In function 'main':
extern_var_bug.c:4:14: warning: unused parameter 'argc' [-Wunused-parameter]
int main(int argc, char* argv[])
~~~~^~~~
extern_var_bug.c:4:26: warning: unused parameter 'argv' [-Wunused-parameter]
int main(int argc, char* argv[])
~~~~~~^~~~~~
cc1: all warnings being treated as errors
Compiler and compile command:
-----------------------------
# gcc-latest is v9 from svn trunk on x86_64
$ gcc-latest --version
gcc-latest (GCC) 9.0.0 20180701 (experimental) [trunk revision 262287]
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
gcc-latest -c -DHAVE_CONFIG_H -fopt-info -Wall -Wextra -Werror -Wpedantic
-pedantic -g0 -DNDEBUG -Ofast \
-I. -I../../gcc_trunk/libiberty/../include -W -Wall -Wwrite-strings \
-Wc++-compat -Wstrict-prototypes -Wshadow=local -pedantic -D_GNU_SOURCE
-fpic \
\
-Wno-error=stringop-truncation -Wno-error=unused-parameter \
\
-x c \
-fno-strict-aliasing -fwrapv \
-save-temps \
\
extern_var_bug.c \
Remarks:
--------
- The compile error happens only if <errno.h> was included, and only if
compiled as C.
- The same error originally happened in
../../gcc_trunk/libiberty/pex-common.c:28:1: error: function declaration isn't
a prototype [-Werror=strict-prototypes]
extern int errno;
^~~~~~
when building with nearly almost all warnings enabled and -g0 -DNDEBUG.
