On Wed, May 13, 2020 at 4:13 PM Kyotaro Horiguchi <horikyota....@gmail.com> wrote:
> At Tue, 12 May 2020 17:12:51 -0400, Tom Lane <t...@sss.pgh.pa.us> wrote in > > Alvaro Herrera <alvhe...@2ndquadrant.com> writes: > > > Fixed one straggler in contrib, and while testing it I realized why > > > ccache doesn't pay attention to the changes I was doing in the file: > > > ccache compares the *preprocessed* version of the file and only if that > > > differs from the version that was cached last, ccache sends the new one > > > to the compiler; and of course these comments are not present in the > > > preprocessed version, so changing only the comment accomplishes > nothing. > > > You have to touch one byte outside of any comments. > > > > Ugh. So the only way ccache could avoid this is to drop the > > preprocessed-file comparison check if -Wimplicit-fallthrough is on. > > Doesn't really sound like something we'd want to ask them to do. > > > > > I bet this is going to bite someone ... maybe we'd be better off going > > > all the way to -Wimplicit-fallthrough=5 and use the > > > __attribute__((fallthrough)) stuff instead. > > > > I'm not really in favor of the __attribute__ solution --- seems too > > gcc-specific. FALLTHROUGH-type comments are understood by other > > sorts of tools besides gcc. > > > > In practice, it doesn't seem like this'll be a huge problem once > > we're past the initial fixup stage. We can revisit it later if > > that prediction proves wrong, of course. > > FWIW, I got a warning for jsonpath_gram.c. > > > jsonpath_gram.c:1026:16: warning: this statement may fall through > [-Wimplicit-fallthrough=] > > if (*++yyp != '\\') > > ^ > > jsonpath_gram.c:1029:11: note: here > > default: > > ^~~~~~~ > > jsonpath_gram.c:1025 > > case '\\': > > if (*++yyp != '\\') > > goto do_not_strip_quotes; > > /* Fall through. */ > > default: > > It is generated code by bison. > > $ bison --version > bison (GNU Bison) 3.0.4 > > I just found this just serval minutes ago. Upgrading your bison to the latest version (3.6) is ok. I'd like we have a better way to share this knowledge through. I spend ~30 minutes to troubleshooting this issue. Best Regards Andy Fan
