[Bug lto/93732] New: [10 Regression] Incorrect symbol type when activating LTO a compile step

[laurent.stacul at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93732

            Bug ID: 93732
           Summary: [10 Regression] Incorrect symbol type when activating
                    LTO a compile step
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: laurent.stacul at gmail dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

Hello,

With gcc (GCC) 10.0.1 20200211 and the following program:

#ifdef __cplusplus
extern "C" {
#endif
char nm_test_var;
void nm_test_func(void);
void nm_test_func(void){}
#ifdef __cplusplus
}
#endif
int main(){nm_test_var='a';nm_test_func();return(0);}

If you compile with the LTO support, with the command:

$  gcc -c  -DNDEBUG -O3 -std=gnu17 -fno-working-directory -ggdb3 -flto
-ffat-lto-objects -fuse-linker-plugin conftest.c

The symbol nm_test_var will be flagged as in text section.

$ nm conftest.o
00000000 T main
00000000 T nm_test_func
00000000 T nm_test_var

Whereas, compiling without LTO support as follow:

$ $  gcc -c  -DNDEBUG -O3 -std=gnu17 -fno-working-directory -ggdb3 -fno-lto
-ffat-lto-objects -fuse-linker-plugin conftest.c

Will give:

$ nm conftest.o
0000000000000000 T main
0000000000000000 T nm_test_func
0000000000000000 B nm_test_var

I also compared with gcc (GCC) 9.2.1 20191112. With or without LTO, the result
is the same but the symbol nm_test_var is neither in the text section not in
the BSS one, but in the common section:

00000000 T main
00000000 T nm_test_func
00000000 C nm_test_var

For info, this leads to errors when you build libtoolized libraries (error at
configure step).

Regards,
Laurent