https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109365
--- Comment #6 from Benjamin Priour <vultkayn at gcc dot gnu.org> --- (In reply to David Malcolm from comment #5) > (In reply to Benjamin Priour from comment #4) > > (In reply to Benjamin Priour from comment #3) > > Here's a link to the reproducer: > https://godbolt.org/z/Wa3fqjrTK > with the fields renamed to avoid reusing the name "a". > > > > [...snip...] > > > > > > > > > <bb 3> : > > > *a.0_11 ={v} {CLOBBER}; > > > operator delete (a.0_11, 8); > > > > > [...snip...] > > > > > > Entry statement of bb3 is the one actually detected as > > > -Wanalyzer-double-free. > > > > Given the above IPA, we cannot just ignore the assignment statement, as it > > could really be an injurious statement, not just a pre-deallocation > > statement at it is now. > > Ths assignment statement: > *a.0_11 ={v} {CLOBBER}; > is a "clobber", which is a special-case of assignment, generated by the > frontends when something is going out of scope, or becoming invalid. > > We could potentially just special-case such ass > Wouldn't considering "clobber" as a trigger for double-delete also lead to many false positives ? I'm not yet 100% familiar with and when this "clobber" appears. [...snip...] > > > > struct A > > { > > ... > > ~A() {} > > } > > > > ... > > > > <bb 3> : > > A::~A (a.0_12); > > operator delete (a.0_12, 8); > > > > > > The warnings stay the same, though it is now more reliable to check for a > > destructor call, instead any random single assignment. > > There's a sense in which it does make sense to complain about > use-after-delete in the destructor (when the destructor is non-empty): the > memory is being accessed after deletion. Maybe this case would make more > sense to the user? (albeit being rather verbose) I believe in the case of a non-empty destructor, "double-delete" would be more on point than "use-after-delete", as ultimately the issue is the second call to delete. "double-delete" immediately warns about the actual issue, whereas if the first "delete" is not as obvious as in the above test case, a "use-after-delete" might confuse the user. "use-after-delete" could mislead the user to believe there is something wrong with their destructor, although only their double delete is.
