Please follow the instructions listed in <http://gcc.gnu.org/bugs.html> as
mentioned by the error message. In particular, we need a preprocessed
testcase.

AFAIK -O0 compiles OK, -O1 fails and cause internal compiler error.

Only encountered with c++ code.

g++ --save-temps -c -omain.o -O -I. -Igenerators -Igenerators/unix -Igenerators/win32 -Igenerators/mac -IE:\msys\1.0\qt-all-opensource-src-4.5.2/include -IE:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore -IE:\msys\1.0\qt-all-opensource-src-4.5.2/include -IE:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore -IE:\msys\1.0\qt-all-opensource-src-4.5.2/src/corelib/global -IE:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtScript -IE:\msys\1.0\qt-all-opensource-src-4.5.2/mkspecs/win32-g++ -DQT_NO_TEXTCODEC -DQT_NO_UNICODETABLES -DQT_LITE_COMPONENT -DQT_NO_PCRE -DQT_NODLL -DQT_NO_STL -DQT_NO_COMPRESS -DUNICODE -DHAVE_QCONFIG_CPP -DQT_BUILD_QMAKE -DQT_NO_THREAD -DQT_NO_QOBJECT -DQT_NO_GEOM_VARIANT -DQT_NO_DATASTREAM -DQMAKE_OPENSOURCE_EDITION main.cpp
In file included from E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/qstring.h:2,
                 from E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/../../src/corelib/io/qiodevice.h:51,
                 from E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/qiodevice.h:2,
                 from E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/../../src/corelib/io/qdatastream.h:46,
                 from E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/qdatastream.h:2,
                 from E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/../../src/corelib/tools/qstringlist.h:47,
                 from E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/qstringlist.h:2,
                 from project.h:46,
                 from main.cpp:43:
E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/../../src/corelib/tools/qstring.h: In member function 'QCharRef::operator QChar() const':
E:\msys\1.0\qt-all-opensource-src-4.5.2/include/QtCore/../../src/corelib/tools/qstring.h:782: internal compiler error: in tree_nrv, at tree-nrv.c:143
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
make: *** [main.o] Error 1

Created attachment 18454 [details]
Preprocessed test case.

Created attachment 18455 [details]
saves

Reducing (seems to work with 4.5).

Confirmed.

class QString { };
QString fixString(QString string);
static QString fixPathToLocalOS(const QString &in)                              { 
  return fixString(in);
}
void __attribute__((__optimize__ ("0")))
foo(void) { }
void runQMake(QString pfile)
{ 
  fixPathToLocalOS(pfile);
}


triggered by __attribute__((__optimize__ ("0"))) on the unrelated function foo.

Mike, this is yours.

The problem is that the optimization saving/restoring infrastructure seems to ignore OVERRIDE_OPTIONS.  i386 OPTIMIZATION_OPTIONS sets flag_pcc_struct_return to 2 and expects OVERRIDE_OPTIONS to set it to 0 resp. 1 if it is still 2, but as OVERRIDE_OPTIONS isn't called, it remains set to 2, which is treated as if it was 1.

Target optimization has many issues. See PR 37565.

Mark, I don't think this should be P1, __optimize__ attribute is new in 4.4 (so considering it regression is already quite weird, though the attribute is ignored in older releases, so technically it is a regression, albeit one wouldn't use it with pre-4.4), but more importantly is known to be broken in many ways.

I think the question is whether the use of __optimize__ is in a standard Qt release.  If it is, then I'm quite concerned; it's bad if GCC 4.4.2 can't build Qt/KDE.

(TBH, I'm concerned anyhow; if __optimize__ is unreliable, then perhaps we should be ignoring/warning about it in 4.4.x until we get it solid...)

Hmm I haven't noticed this bug has been fixed a week ago, since [Revision 151627], it was still reproducible at [Revision 151584] which was just a day before.
Thanks!!

I can confirm this is fixed in gcc-4_4-branch.
Thank you.