Branch: refs/heads/yves/alternate_pr_for_21296
Home: https://github.com/Perl/perl5
Commit: 65a3b460d5372231b3324bf30f67d298cba36c95
https://github.com/Perl/perl5/commit/65a3b460d5372231b3324bf30f67d298cba36c95
Author: Yves Orton <demer...@gmail.com>
Date: 2023-07-27 (Thu, 27 Jul 2023)
Changed paths:
M regexec.c
Log Message:
-----------
regexec.c - restructure code that boils down to a constant conditional
See also https://github.com/Perl/perl5/pull/21296.
When PERL_SAWAMPERSAND is not defined then Pl_sawampersand is defined
to be (SAWAMPERSAND_LEFT|SAWAMPERSAND_MIDDLE|SAWAMPERSAND_RIGHT).
Which means that the clause in the first if block:
&& !(PL_sawampersand & SAWAMPERSAND_RIGHT)
and the clause in the second if block:
&& !(PL_sawampersand & SAWAMPERSAND_LEFT)
will never be true. Thus neither of these blocks will execute in a
normal build where PERL_SAWAMPERSAND is not defined.
Nevertheless some versions of Clang notice that a related expression
guarded by these clauses is also constant, and mixes '&' and '&&'
together and then warns about it:
$ clang-17 ... regexec.c
regexec.c:3589:21: warning: use of logical '&&' with constant operand
[-Wconstant-logical-operand]
3588 | if ((PL_sawampersand & SAWAMPERSAND_RIGHT)
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3589 | && min > RXp_OFFS_END(prog,0)
| ^
regexec.c:3589:21: note: use '&' for a bitwise operation
3589 | && min > RXp_OFFS_END(prog,0)
| ^~
| &
regexec.c:3589:21: note: remove constant to silence this warning
Restructuring the clauses into a nested if should fix this. Along the
way we fix a related I32/SSize_t mismatch, and eliminate an unnecessary
duplicate use of RXp_OFFS_END(prog,0) call, which these days is a more
complex and expensive macro than it once was.
Thanks to the github user @Logikable for calling this to our attention
with a different patch.
