[Bug other/61146] New: wide-int error when building GCC with clang

["olegendo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61146

            Bug ID: 61146
           Summary: wide-int error when building GCC with clang
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: olegendo at gcc dot gnu.org

Created attachment 32776
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32776&action=edit
compressed build log

Building an SH cross GCC on OSX with clang results in the following errors:

../../gcc-trunk/gcc/wide-int.cc:1269:23: error: invalid use of a cast in a
inline asm context requiring an l-value: remove the cast or build with
-fheinous-gnu-extensions
          umul_ppmm (val[1], val[0], op1.ulow (), op2.ulow ());
          ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../gcc-trunk/gcc/../include/longlong.h:505:24: note: expanded from macro
'umul_ppmm'
           : "=a" ((UDItype) (w0)),                                     \
                              ^
../../gcc-trunk/gcc/wide-int.cc:1269:15: error: invalid use of a cast in a
inline asm context requiring an l-value: remove the cast or build with
-fheinous-gnu-extensions
          umul_ppmm (val[1], val[0], op1.ulow (), op2.ulow ());
          ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../gcc-trunk/gcc/../include/longlong.h:506:24: note: expanded from macro
'umul_ppmm'
             "=d" ((UDItype) (w1))                                      \
                              ^
../../gcc-trunk/gcc/wide-int.cc:1278:22: error: invalid use of a cast in a
inline asm context requiring an l-value: remove the cast or build with
-fheinous-gnu-extensions
          umul_ppmm (upper, val[0], op1.ulow (), op2.ulow ());
          ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../gcc-trunk/gcc/../include/longlong.h:505:24: note: expanded from macro
'umul_ppmm'
           : "=a" ((UDItype) (w0)),                                     \
                              ^
../../gcc-trunk/gcc/wide-int.cc:1278:15: error: invalid use of a cast in a
inline asm context requiring an l-value: remove the cast or build with
-fheinous-gnu-extensions
          umul_ppmm (upper, val[0], op1.ulow (), op2.ulow ());
          ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../gcc-trunk/gcc/../include/longlong.h:506:24: note: expanded from macro
'umul_ppmm'
             "=d" ((UDItype) (w1))

The full log is attached, which shows also other (spurious) warnings.

The problem can be worked around by setting
export CFLAGS="-fheinous-gnu-extensions"
export CXXFLAGS="-fheinous-gnu-extensions"
export CFLAGS_FOR_TARGET="-O2"
export CXXFLAGS_FOR_TARGET="-O2"

The *FLAGS_FOR_TARGET are required or else they will be set to *FLAGS, which
will pass -fheinous-gnu-extensions to the SH xgcc when building libgcc etc. (PR
25672)

The clang version on my OSX system:
clang -v
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.1.0
Thread model: posix