From 3f3cd75858f7017a4167d3816e2c47da2f1ec06a Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 3 Jun 2009 15:06:48 +0000 Subject: [PATCH] Improve comment about 'if (1)' hack in copy.c macros. --- src/backend/commands/copy.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c index 2acdf46d2f..caa82d1a01 100644 --- a/src/backend/commands/copy.c +++ b/src/backend/commands/copy.c @@ -175,11 +175,13 @@ typedef struct /* * These macros centralize code used to process line_buf and raw_buf buffers. * They are macros because they often do continue/break control and to avoid - * function call overhead in tight COPY loops. "((void) 0)" is used to silence - * compiler warnings. + * function call overhead in tight COPY loops. * - * We must use "if (1)" because "do {} while(0)" overrides the continue/break - * processing. See http://www.cit.gu.edu.au/~anthony/info/C/C.macros. + * We must use "if (1)" because the usual "do {...} while(0)" wrapper would + * prevent the continue/break processing from working. We end the "if (1)" + * with "else ((void) 0)" to ensure the "if" does not unintentionally match + * any "else" in the calling code, and to avoid any compiler warnings about + * empty statements. See http://www.cit.gu.edu.au/~anthony/info/C/C.macros. */ /* -- 2.39.5