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From: "olegendo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/53579] New: libstdc++ configure atomicity tests use CXXFLAGS instead of CXXFLAGS_FOR_TARGET
Date: Tue, 05 Jun 2012 00:18:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53579

             Bug #: 53579
           Summary: libstdc++ configure atomicity tests use CXXFLAGS
                    instead of CXXFLAGS_FOR_TARGET
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: olegendo@gcc.gnu.org


When trying to fix PR 29366 by removing config/cpu/sh/atomicity.h I've noticed
that libstdc++'s configure would refuse to pick up
config/cpu/generic/atomicity_builtins.

On the SH target atomicity builtins have to be enabled by either -msoft-atomic
or -mhard-atomic.  For sh-linux -msoft-atomic is enabled by default.  When
building a cross toolchain (top level make) CFLAGS_FOR_TARGET /
CXXFLAGS_FOR_TARGET can be used to enable the atomicity builtins.  However,
libstdc++ configure uses CXXFLAGS when testing for atomicity builtins
availability, so it will default to using config/cpu/generic/atomicity_mutex.

I'm not quite sure where the fix should go, either in the top level
configure/makefile (which fails to set CXXFLAGS to CXXFLAGS_FOR_TARGET for
libstdc++ configure) or libstdc++ itself, because when libstdc++ is actually
compiled CXXFLAGS_FOR_TARGET is passed to xgcc as expected.