[Bug binutils/25356] New: nm reports wrong symbol types on lto objects (using linker plugin)

[calvin.walton at kepstin dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=25356

            Bug ID: 25356
           Summary: nm reports wrong symbol types on lto objects (using
                    linker plugin)
           Product: binutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: calvin.walton at kepstin dot ca
  Target Milestone: ---

Using the following example C file:

int foo;
int bar = 0;

And compiling the file normally, with gcc -c -o test.o test.c, the nm output
looks like this:
0000000000000000 B bar
0000000000000004 C foo

And with gcc -fno-common -c -o test.o test.c:
0000000000000004 B bar
0000000000000000 B foo

But when compiling with lto, and using the linker plugin with nm, it returns
incorrect symbol types:

With gcc -flto -c -o test.o test.c:
00000000 T bar
00000000 C foo

With gcc -flto -fno-common -c -o test.o test.c:
00000000 T bar
00000000 T foo

In both cases, it's reporting the symbols as being in the text (code) section.
This behaviour confuses the libtool configure-time check used by the
global_symbol_pipe feature (causing linking errors when compiling packages that
use the libtool -export-symbols-regex feature in combination with gcc -flto,
particularly when also using -fno-common)
Link to thread about the libtool issue:
https://lists.gnu.org/archive/html/libtool/2020-01/msg00022.html

I'm guessing that this is probably due to a limitation of how nm is using the
linker plugin interface? The symbols that the plugin reports using the
ld_plugin_add_symbols linker interface method don't include section
information.

I'm currently using:
gcc (GCC) 9.2.1 20190827 (Red Hat 9.2.1-1)
Copyright (C) 2019 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.
GNU nm version 2.32-30.fc31
Copyright (C) 2019 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) any later version.
This program has absolutely no warranty.

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