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* [Bug libstdc++/22207] New: Spurious 'might be used uninitialized' warnings in STL headers with -O2 @ 2005-06-27 23:08 brian at dessent dot net 2005-06-27 23:10 ` [Bug libstdc++/22207] " brian at dessent dot net ` (4 more replies) 0 siblings, 5 replies; 6+ messages in thread From: brian at dessent dot net @ 2005-06-27 23:08 UTC (permalink / raw) To: gcc-bugs The following reduced test case causes spurious -Wuninitialized warnings, but only with -O2: ----- #include <vector> #include <string> class OptionSet { public: OptionSet (); std::vector<std::string> const &nonOptions() const; private: std::vector<std::string> nonoptions; }; OptionSet::OptionSet() { nonoptions = std::vector<std::string> (); } std::vector<std::string> const & OptionSet::nonOptions() const { return nonoptions; } ----- $ g++ -Wuninitialized -O2 -c spurious_uninitialized_testcase.cc /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_vector.h: In member function `std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = std::string, _Alloc = std::allocator<std::string>]': /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_vector.h:715: warning: '__result' might be used uninitialized in this function /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_uninitialized.h:82: warning: '__cur' might be used uninitialized in this function /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_uninitialized.h:82: warning: '__cur' might be used uninitialized in this function $ g++ -v Reading specs from /usr/lib/gcc/i686-pc-cygwin/3.4.4/specs Configured with: /gcc/gcc-3.4.4/gcc-3.4.4-1/configure --verbose --prefix=/usr --exec-prefix=/usr --sysconfdir=/etc --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --enable-languages=c,ada,c++,d,f77,java,objc --enable-nls --without-included-gettext --enable-version-specific-runtime-libs --without-x --enable-libgcj --disable-java-awt --with-system-zlib --enable-interpreter --disable-libgcj-debug --enable-threads=posix --enable-java-gc=boehm --disable-win32-registry --enable-sjlj-exceptions --enable-hash-synchronization --enable-libstdcxx-debug : (reconfigured) Thread model: posix gcc version 3.4.4 (cygming special) (gdc 0.12, using dmd 0.125) ----- The warnings only occur at -O2 and seem to have something to do with inlining. This causes our build that uses "-Wall -Werror" to die whereas it had no problem with this warning in gcc-3.3. I'm sensitive to the fact that it's impossible for the compiler to get this warning correct every time, and the reason for the use of "might be" in the warning text. It's acceptible to emit warnings about things that may not actually be the case, and normally I would just modify the build environment to disable that warning or lose -Werror. But in this case, the code in question is in the STL and is completely out of the hands of the user, and I don't think it's unreasonable to expect to be able to compile STL-based code with -Werror -Wall. -- Summary: Spurious 'might be used uninitialized' warnings in STL headers with -O2 Product: gcc Version: 3.4.4 Status: UNCONFIRMED Severity: normal Priority: P2 Component: libstdc++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: brian at dessent dot net CC: gcc-bugs at gcc dot gnu dot org GCC host triplet: i686-pc-cygwin http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22207 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/22207] Spurious 'might be used uninitialized' warnings in STL headers with -O2 2005-06-27 23:08 [Bug libstdc++/22207] New: Spurious 'might be used uninitialized' warnings in STL headers with -O2 brian at dessent dot net @ 2005-06-27 23:10 ` brian at dessent dot net 2005-06-27 23:15 ` [Bug middle-end/22207] " pinskia at gcc dot gnu dot org ` (3 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: brian at dessent dot net @ 2005-06-27 23:10 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From brian at dessent dot net 2005-06-27 23:10 ------- Created an attachment (id=9163) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9163&action=view) Preprocessed source for testcase -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22207 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/22207] Spurious 'might be used uninitialized' warnings in STL headers with -O2 2005-06-27 23:08 [Bug libstdc++/22207] New: Spurious 'might be used uninitialized' warnings in STL headers with -O2 brian at dessent dot net 2005-06-27 23:10 ` [Bug libstdc++/22207] " brian at dessent dot net @ 2005-06-27 23:15 ` pinskia at gcc dot gnu dot org 2005-09-06 11:07 ` dave dot korn at artimi dot com ` (2 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-06-27 23:15 UTC (permalink / raw) To: gcc-bugs -- What |Removed |Added ---------------------------------------------------------------------------- Component|libstdc++ |middle-end GCC host triplet|i686-pc-cygwin | GCC target triplet| |i686-pc-cygwin Keywords| |diagnostic http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22207 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/22207] Spurious 'might be used uninitialized' warnings in STL headers with -O2 2005-06-27 23:08 [Bug libstdc++/22207] New: Spurious 'might be used uninitialized' warnings in STL headers with -O2 brian at dessent dot net 2005-06-27 23:10 ` [Bug libstdc++/22207] " brian at dessent dot net 2005-06-27 23:15 ` [Bug middle-end/22207] " pinskia at gcc dot gnu dot org @ 2005-09-06 11:07 ` dave dot korn at artimi dot com 2005-09-06 11:28 ` james at juranfamily dot org 2005-09-06 18:59 ` ian at airs dot com 4 siblings, 0 replies; 6+ messages in thread From: dave dot korn at artimi dot com @ 2005-09-06 11:07 UTC (permalink / raw) To: gcc-bugs -- What |Removed |Added ---------------------------------------------------------------------------- CC| |dave dot korn at artimi dot | |com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22207 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/22207] Spurious 'might be used uninitialized' warnings in STL headers with -O2 2005-06-27 23:08 [Bug libstdc++/22207] New: Spurious 'might be used uninitialized' warnings in STL headers with -O2 brian at dessent dot net ` (2 preceding siblings ...) 2005-09-06 11:07 ` dave dot korn at artimi dot com @ 2005-09-06 11:28 ` james at juranfamily dot org 2005-09-06 18:59 ` ian at airs dot com 4 siblings, 0 replies; 6+ messages in thread From: james at juranfamily dot org @ 2005-09-06 11:28 UTC (permalink / raw) To: gcc-bugs -- What |Removed |Added ---------------------------------------------------------------------------- CC| |james at juranfamily dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22207 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/22207] Spurious 'might be used uninitialized' warnings in STL headers with -O2 2005-06-27 23:08 [Bug libstdc++/22207] New: Spurious 'might be used uninitialized' warnings in STL headers with -O2 brian at dessent dot net ` (3 preceding siblings ...) 2005-09-06 11:28 ` james at juranfamily dot org @ 2005-09-06 18:59 ` ian at airs dot com 4 siblings, 0 replies; 6+ messages in thread From: ian at airs dot com @ 2005-09-06 18:59 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From ian at airs dot com 2005-09-06 18:59 ------- Confirmed that this happens with 3.4 for the i686-pc-cygwin target, though not for the i686-pc-linux-gnu target. It is fixed in current mainline for both targets. -- What |Removed |Added ---------------------------------------------------------------------------- CC| |ian at airs dot com Status|UNCONFIRMED |NEW Ever Confirmed| |1 Known to fail| |3.4.4 Known to work| |4.1.0 Last reconfirmed|0000-00-00 00:00:00 |2005-09-06 18:59:23 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22207 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2005-09-06 18:59 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2005-06-27 23:08 [Bug libstdc++/22207] New: Spurious 'might be used uninitialized' warnings in STL headers with -O2 brian at dessent dot net 2005-06-27 23:10 ` [Bug libstdc++/22207] " brian at dessent dot net 2005-06-27 23:15 ` [Bug middle-end/22207] " pinskia at gcc dot gnu dot org 2005-09-06 11:07 ` dave dot korn at artimi dot com 2005-09-06 11:28 ` james at juranfamily dot org 2005-09-06 18:59 ` ian at airs dot com
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