[Bug c++/40146] Unexplained "'<anonymous>' is used uninitialized in this function" warning

["matt at use dot net" <gcc-bugzilla@gcc.gnu.org>]

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------- Comment #11 from matt at use dot net  2010-01-10 22:01 -------
I get this same problem when compiling scummvm (http://scummvm.org) on Ubuntu
9.10/amd64 using the default GCC 4.4.1:

g++ -O1 -finline-small-functions -finline-functions
-Wp,-MMD,"engines/sci/.deps/console.d",-MQ,"engines/sci/console.o",-MP -Wall
-Werror -g -ansi -W -Wno-unused-parameter -Wno-empty-body -pedantic
-Wno-long-long -Wno-multichar -Wno-unknown-pragmas -Wno-reorder
-fno-strict-aliasing  -Wpointer-arith -Wcast-qual -Wcast-align -Wshadow
-Wimplicit -Wnon-virtual-dtor -Wwrite-strings -fno-rtti -fno-exceptions
-fcheck-new -Wuninitialized -DSCUMMVM_SVN_REVISION=\"47235\" -DHAVE_CONFIG_H
-DUNIX -DDATA_PATH=\"/usr/local/share/scummvm\"
-DPLUGIN_DIRECTORY=\"/usr/local/lib/scummvm\" -DSDL_BACKEND
-DENABLE_SCUMM=STATIC_PLUGIN -DENABLE_SCUMM_7_8 -DENABLE_HE
-DENABLE_AGI=STATIC_PLUGIN -DENABLE_AGOS=STATIC_PLUGIN -DENABLE_AGOS2
-DENABLE_CINE=STATIC_PLUGIN -DENABLE_CRUISE=STATIC_PLUGIN
-DENABLE_DRACI=STATIC_PLUGIN -DENABLE_DRASCULA=STATIC_PLUGIN
-DENABLE_GOB=STATIC_PLUGIN -DENABLE_GROOVIE=STATIC_PLUGIN -DENABLE_GROOVIE2
-DENABLE_KYRA=STATIC_PLUGIN -DENABLE_LOL -DENABLE_LURE=STATIC_PLUGIN
-DENABLE_M4=STATIC_PLUGIN -DENABLE_MADE=STATIC_PLUGIN
-DENABLE_MOHAWK=STATIC_PLUGIN -DENABLE_PARALLACTION=STATIC_PLUGIN
-DENABLE_QUEEN=STATIC_PLUGIN -DENABLE_SAGA=STATIC_PLUGIN -DENABLE_IHNM
-DENABLE_SAGA2 -DENABLE_SCI=STATIC_PLUGIN -DENABLE_SCI32
-DENABLE_SKY=STATIC_PLUGIN -DENABLE_SWORD1=STATIC_PLUGIN
-DENABLE_SWORD2=STATIC_PLUGIN -DENABLE_TEENAGENT=STATIC_PLUGIN
-DENABLE_TINSEL=STATIC_PLUGIN -DENABLE_TOUCHE=STATIC_PLUGIN
-DENABLE_TUCKER=STATIC_PLUGIN -I. -I. -I./engines -I/usr/include/SDL
-D_GNU_SOURCE=1 -D_REENTRANT -c engines/sci/console.cpp -o
engines/sci/console.o
cc1plus: warnings being treated as errors
In file included from ./common/array.h:29,
                 from ./common/fs.h:28,
                 from ./engines/engine.h:30,
                 from ./engines/sci/sci.h:29,
                 from engines/sci/console.cpp:28:
./common/algorithm.h: In function ‘void Common::sort(T, T, StrictWeakOrdering)
[with T = Common::ListInternal::Iterator<Sci::ResourceId>, StrictWeakOrdering =
Sci::ResourceIdLess]’:
./common/algorithm.h:207: error: ‘<anonymous>’ may be used uninitialized in
this function
./common/algorithm.h:207: error: ‘<anonymous>’ may be used uninitialized in
this function
./common/algorithm.h:208: error: ‘<anonymous>’ may be used uninitialized in
this function
./common/algorithm.h:208: error: ‘<anonymous>’ may be used uninitialized in
this function
./common/algorithm.h:207: error: ‘<anonymous>’ may be used uninitialized in
this function
./common/algorithm.h:208: error: ‘<anonymous>’ may be used uninitialized in
this function


The issue does not occur with gcc-4.3 or gcc-4.5.20091228. I noticed the issue
when compiling with -O3, but reduced it to the above commandline. (Something
undocumented must happen at -O1, because putting the individual options for -O1
on the commandline  didn't reproduce the issue.)

Pre-processed sources are attached.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40146