Add comment about why "((void) 0)" is used in copy macros.

bmomjian · bmomjian · commit 1a0ebe6152e5 · 2009-06-03T14:48:33.000Z
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.309 2009/05/29 13:54:52 meskes Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.310 2009/06/03 14:48:33 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -175,7 +175,8 @@ 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.
+ * function call overhead in tight COPY loops.  "((void) 0)" is used to silence
+ * compiler warnings.
  *
  * 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.

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.309 2009/05/29 13:54:52 meskes Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.310 2009/06/03 14:48:33 momjian Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -175,7 +175,8 @@ typedef struct`
`175`	`175`	`/*`
`176`	`176`	`* These macros centralize code used to process line_buf and raw_buf buffers.`
`177`	`177`	`* They are macros because they often do continue/break control and to avoid`
`178`		`- * function call overhead in tight COPY loops.`
	`178`	`+ * function call overhead in tight COPY loops. "((void) 0)" is used to silence`
	`179`	`+ * compiler warnings.`
`179`	`180`	`*`
`180`	`181`	`* We must use "if (1)" because "do {} while(0)" overrides the continue/break`
`181`	`182`	`* processing. See http://www.cit.gu.edu.au/~anthony/info/C/C.macros.`