On Mon, Apr 2, 2018 at 11:05 AM, Roman Lebedev via Phabricator via cfe-commits <cfe-commits@lists.llvm.org> wrote:
> lebedev.ri added a comment. > > In https://reviews.llvm.org/D44883#1054326, @thakis wrote: > > > In https://reviews.llvm.org/D44883#1048751, @dblaikie wrote: > > > > > Historically Clang's policy on warnings was, I think, much more > > > conservative than it seems to be today. There was a strong desire not > to > > > implement off-by-default warnings, and to have warnings with an > > > exceptionally low false-positive rate - maybe the user-defined > operator > > > detection was either assumed to, or demonstrated to, have a > sufficiently > > > high false positive rate to not meet that high bar. > > > > > > This is still the case. For a new warning, you should evaluate some > large open-source codebase and measure true positive and false positive > rate and post the numbers here. > > > I did run it on stage-2 of LLVM itself. The only 'false-positives' so far > are already present in trunk: > https://godbolt.org/g/SXc4Wd > > void test_int () { > int b; > static_assert(noexcept(b &= b), "" ); > } > void test_byte () { > std::byte b; > static_assert(noexcept(b &= (std::byte &)b), "" ); > } > > <source>:4:30: warning: explicitly assigning value of variable of type > 'int' to itself [-Wself-assign] > > static_assert(noexcept(b &= b), "" ); > > ~ ^ ~ > > Should it really warn when in unevaluated context? > Dunno, but trunk already does that. Should that be changed? > > Which other large codebase do you want me to evaluate, so we can talk > facts? > Either of OpenOffice, Firefox, or Chromium have been used in the past for warning evaluation. > >> (as for the flag splitting - that was sometimes done if the new variant > of > >> a flag had enough bug-finding power that an existing codebase using the > >> existing flag behavior would need significant cleanup - by having the > new > >> functionality under another flag name, existing codebases upgrading to > a > >> newer compiler wouldn't be forced to either do all that cleanup > up-front or > >> disable the flag & risk regressions... ) > > > > > Repository: > rC Clang > > https://reviews.llvm.org/D44883 > > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >
_______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
