[Bug binutils/26662] New: nm minor case 'c' symbol type (when LTO activated)

[laurent.stacul at amadeus dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=26662

            Bug ID: 26662
           Summary: nm minor case 'c' symbol type (when LTO activated)
           Product: binutils
           Version: 2.35
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: laurent.stacul at amadeus dot com
  Target Milestone: ---

Hello,

If I compile the following program (extracted from configure scripts)

$ cat conftest.c
#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);}

And compile it with the following command:

$ gcc -c -DNDEBUG -O3 -flto -ffat-lto-objects -fuse-linker-plugin -std=gnu11
-fno-working-directory -ggdb3 conftest.c

Using the nm provided by Ubuntu 20.04 (GNU nm (GNU Binutils for Ubuntu) 2.34) I
have:

docker@e53efdc30d6e:~$ nm conftest.o
00000000 T main
00000000 T nm_test_func
00000000 C nm_test_var

Now if I use a recent nm (2.35), I get:
00000000 T main
00000000 T nm_test_func
00000000 c nm_test_var

Now it is minor case 'c' which I cannot find in the manpage.

Note that I tried to compile the program with several versions on GCC with the
same output in nm.
- gcc (Ubuntu 9.3.0-10ubuntu2) 9.3.0
- gcc (GCC) 8.4.1 20200803
- gcc (GCC) 9.3.1 20200803

When I disable LTO,

$ gcc -c -DNDEBUG -O3 -fno-lto -fuse-linker-plugin -std=gnu11
-fno-working-directory -ggdb3 conftest.c

I have the same output with nm 2.34 and 2.35:

0000000000000001 C nm_test_var

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

Regards,
Laurent

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