diff options
| author | Tom Lane | 2009-06-03 15:06:48 +0000 |
|---|---|---|
| committer | Tom Lane | 2009-06-03 15:06:48 +0000 |
| commit | 3f3cd75858f7017a4167d3816e2c47da2f1ec06a (patch) | |
| tree | a7bb1a0a4a4b046febff5061cd0a4fa888a2b5c7 | |
| parent | ccc9b0a873e683b48d19f0256b014a17879421c6 (diff) | |
Improve comment about 'if (1)' hack in copy.c macros.
| -rw-r--r-- | src/backend/commands/copy.c | 10 |
1 files 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. */ /* |