[Bug libc/13411] New: glibc fails to build with gcc 4.7

[Bug libc/13411] New: glibc fails to build with gcc 4.7

[matz at suse dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

             Bug #: 13411
           Summary: glibc fails to build with gcc 4.7
           Product: glibc
           Version: 2.14
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper.fsp@gmail.com
        ReportedBy: matz@suse.de
    Classification: Unclassified


This is also http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51117 .
gcc can emit calls to _Unwind_Resume for files compiled with -fexceptions,
new GCCs do this more often than earlier.  This currently leads to a linking
failure due to symbols defined twice:

cc   -nostdlib -nostartfiles -r -o /var/tmp/glibc-build/libc_pic.os \
 -Wl,-d -Wl,--whole-archive /var/tmp/glibc-build/libc_pic.a -o
/var/tmp/glibc-build/libc_pic.os
gcc   -nostdlib -nostartfiles -r -o /var/tmp/glibc-build/elf/librtld.map.o
'-Wl,-(' /var/tmp/glibc-build/elf/dl-allobjs.os /var/tmp/glibc-build/libc_
pic.a -lgcc '-Wl,-)' -Wl,-Map,/var/tmp/glibc-build/elf/librtld.mapT
/var/tmp/glibc-build/libc_pic.a(dl-addr.os): In function
`_dl_addr_inside_object':
/var/tmp/glibc/elf/dl-addr.c:155: multiple definition of
`_dl_addr_inside_object'
/var/tmp/glibc-build/elf/dl-allobjs.os:/var/tmp/glibc/elf/dl-open.c:673: first
defined here

The problem is that dl-addr.so is included in the link, due to this
symbol requirement chain:

dl-allobjs.os (_Unwind_Resume)
unwind-resume.os (__GI___libc_fatal)
libc_fatal.os (__GI___backtrace_symbols_fd)
backtracesymfd.os (__GI__dl_addr)
dl-addr.os

Somehow this chains needs to be broken by either providing one of these
symbols from dl-allobjs.os already, or by not compiling the respective files
with -fexceptions.

I'm not sure why they are compiled with -fexceptions,
-fasynchronous-unwind-tables ought to be enough to make
unwinding through these routines work (it's related to cancellation points,
right?)

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[Bug libc/13411] glibc fails to build with gcc 4.7

[matz at suse dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

--- Comment #1 from Michael Matz <matz at suse dot de> 2011-11-15 15:48:12 UTC ---
This patch (removing some -fexceptions, but retaining the unwind tables)
lets me build current git glibc without adverse effects on the testsuite:

diff --git a/elf/Makefile b/elf/Makefile
index f20f52d..3fe9f06 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -126,8 +126,8 @@ distribute  := rtld-Rules \
                   tst-initorder.c \
                   tst-initorder2.c

-CFLAGS-dl-runtime.c = -fexceptions -fasynchronous-unwind-tables
-CFLAGS-dl-lookup.c = -fexceptions -fasynchronous-unwind-tables
+CFLAGS-dl-runtime.c = -fasynchronous-unwind-tables
+CFLAGS-dl-lookup.c = -fasynchronous-unwind-tables
 CFLAGS-dl-iterate-phdr.c = $(uses-callbacks)

 include ../Makeconfig
diff --git a/io/Makefile b/io/Makefile
index 0f3b555..c905823 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -76,7 +76,7 @@ distribute    := ftwtest-sh

 include ../Rules

-CFLAGS-fcntl.c = -fexceptions -fasynchronous-unwind-tables
+CFLAGS-fcntl.c = -fasynchronous-unwind-tables
 CFLAGS-poll.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-ppoll.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-lockf.c = -fexceptions

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[Bug libc/13411] glibc fails to build with gcc 4.7

[cryptooctoploid at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

Octoploid <cryptooctoploid at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cryptooctoploid at gmail
                   |                            |dot com

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[Bug libc/13411] glibc fails to build with gcc 4.7

[ibolton at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

Ian Bolton <ibolton at gcc dot gnu.org> changed:

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

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[Bug libc/13411] glibc fails to build with gcc 4.7

[hjl.tools at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl.tools at gmail dot com

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[Bug libc/13411] glibc fails to build with gcc 4.7

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

--- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> 2011-11-17 08:40:50 UTC ---
What has changed that gcc now needs to emit exception regions?

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[Bug libc/13411] glibc fails to build with gcc 4.7

[matz at suse dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

--- Comment #3 from Michael Matz <matz at suse dot de> 2011-11-17 15:15:01 UTC ---
Since r179618 GCC uses cleanup regions to implement proper tracking of
points where scopes are left.  Under -fexceptions this includes exception
edges leading from possibly throwing calls to outside the containing scope.

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[Bug libc/13411] glibc fails to build with gcc 4.7

[mpolacek at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

Marek Polacek <mpolacek at redhat dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |mpolacek at redhat dot com

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[Bug libc/13411] glibc fails to build with gcc 4.7

[cryptooctoploid at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13411

Octoploid <cryptooctoploid at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID

--- Comment #4 from Octoploid <cryptooctoploid at gmail dot com> 2011-12-14 10:48:19 UTC ---
Turned out it was a gcc bug after all. It was fixed yesterday.
Closing this one as invalid.

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[Bug libc/13411] glibc fails to build with gcc 4.7

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=13411

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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