From 4b2a254793be50e31d43d4bfd813da8d141494b8 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 26 Jan 2015 15:53:37 -0500 Subject: [PATCH] Add a note to PG_TRY's documentation about volatile safety. We had better memorialize what the actual requirements are for this. --- src/include/utils/elog.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h index fe5dec03a7..b5cfc9cbc8 100644 --- a/src/include/utils/elog.h +++ b/src/include/utils/elog.h @@ -332,6 +332,13 @@ extern PGDLLIMPORT ErrorContextCallback *error_context_stack; * not without taking thought for what will happen during ereport(FATAL). * The PG_ENSURE_ERROR_CLEANUP macros provided by storage/ipc.h may be * helpful in such cases. + * + * Note: if a local variable of the function containing PG_TRY is modified + * in the PG_TRY section and used in the PG_CATCH section, that variable + * must be declared "volatile" for POSIX compliance. This is not mere + * pedantry; we have seen bugs from compilers improperly optimizing code + * away when such a variable was not marked. Beware that gcc's -Wclobbered + * warnings are just about entirely useless for catching such oversights. *---------- */ #define PG_TRY() \ -- 2.40.0