[Bug lto/50367] New: -flto and -Wl,--as-needed combination removes some needed libraries

[Bug lto/50367] New: -flto and -Wl,--as-needed combination removes some needed libraries

[krisztian.kocsis at optimaster dot eu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50367

             Bug #: 50367
           Summary: -flto and -Wl,--as-needed combination removes some
                    needed libraries
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: krisztian.kocsis@optimaster.eu


Created attachment 25250
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25250
Verbose linker output.

When I try to build udev with gcc-4.6.1, the accelerometer module fails to link
because of undefined references to sqrt, atan, etc. Unfortunately -lm is
explicitly specified. If I remove -flto or -Wl,--as-needed, the module links
successfully.

Verbose linker output is attached.

[Bug lto/50367] -flto and -Wl,--as-needed combination removes some needed libraries

[doko at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50367

Matthias Klose <doko at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |doko at gcc dot gnu.org

--- Comment #1 from Matthias Klose <doko at gcc dot gnu.org> 2011-09-19 21:14:50 UTC ---
$ cat test-flto.c 
#include <math.h>
#include <stdio.h>

int main()
{
        printf("%le\n", gamma(42));
        return 0;
}


$ gcc -Wl,--as-needed -flto test-flto.c -lm
/tmp/ccXjDUDX.ltrans0.ltrans.o: In function `main':
ccXjDUDX.ltrans0.o:(.text+0xd): undefined reference to `gamma'
collect2: ld returned 1 exit status

$ gcc -B/usr/lib/gold-ld/ -Wl,--as-needed -flto -o test-flto test-flto.c -lm
does work

[Bug lto/50367] -flto and -Wl,--as-needed combination removes some needed libraries

[doko at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50367

--- Comment #2 from Matthias Klose <doko at gcc dot gnu.org> 2011-09-19 21:21:53 UTC ---
http://sourceware.org/bugzilla/show_bug.cgi?id=13201

[Bug lto/50367] -flto and -Wl,--as-needed combination removes some needed libraries

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50367

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |amodra at gmail dot com
         Resolution|                            |INVALID

--- Comment #3 from Alan Modra <amodra at gmail dot com> 2011-09-20 02:07:39 UTC ---
Not a gcc bug.