From 43ef6abcbb6010593a000a0d42303f138b9f5b4c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 10 Sep 2016 17:54:23 -0400 Subject: [PATCH] Improve unreachability recognition in elog() macro. Some experimentation with an older version of gcc showed that it is able to determine whether "if (elevel_ >= ERROR)" is compile-time constant if elevel_ is declared "const", but otherwise not so much. We had accounted for that in ereport() but were too miserly with braces to make it so in elog(). I don't know how many currently-interesting compilers have the same quirk, but in case it will save some code space, let's make sure that elog() is on the same footing as ereport() for this purpose. Back-patch to 9.3 where we introduced pg_unreachable() calls into elog/ereport. --- src/include/utils/elog.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h index 8e906611953..a16f92501d2 100644 --- a/src/include/utils/elog.h +++ b/src/include/utils/elog.h @@ -216,12 +216,13 @@ extern int getinternalerrposition(void); #else /* !HAVE__BUILTIN_CONSTANT_P */ #define elog(elevel, ...) \ do { \ - int elevel_; \ elog_start(__FILE__, __LINE__, PG_FUNCNAME_MACRO); \ - elevel_ = (elevel); \ - elog_finish(elevel_, __VA_ARGS__); \ - if (elevel_ >= ERROR) \ - pg_unreachable(); \ + { \ + const int elevel_ = (elevel); \ + elog_finish(elevel_, __VA_ARGS__); \ + if (elevel_ >= ERROR) \ + pg_unreachable(); \ + } \ } while(0) #endif /* HAVE__BUILTIN_CONSTANT_P */ #else /* !HAVE__VA_ARGS */