On Sat, Nov 12, 2011 at 4:42 PM, Jason Merrill <ja...@redhat.com> wrote: > Now that we have a way of explicitly marking a variable as dead, we can use > that to indicate the end of a temporary's lifetime by adding it as a cleanup > for that temporary. Since gimple_push_cleanup still deals in trees I needed > to tweak a couple of places to avoid trying to treat a clobber as a real > CONSTRUCTOR, but the changes were small. > > One somewhat surprising thing that showed up as a result of this change were > some failures in the libstdc++ testsuite. When I investigated, I found that > the tests were relying on temporaries living longer than they should: > >> const int& x = std::max(1, 2); > > > Since std::max takes its arguments by const reference and returns one of > them, x ends up as a dangling reference to the temporary containing 2, which > dies at the end of the declaration-statement. This patch breaks the > testcase because now the temporary stack slots get reused by the next > statement, so by the time we look at x it no longer points to a 2. I've > fixed the tests by removing the references on the variables. > > Tested x86_64-pc-linux-gnu, applying to trunk.
This caused: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53220 -- H.J.
