Module Name: src
Committed By: christos
Date: Sun Mar 28 14:28:56 UTC 2021
Modified Files:
src/share/misc: style
Log Message:
Clarify and explain the rationale for parentheses in sizeof and return as
discussed.
To generate a diff of this commit:
cvs rdiff -u -r1.61 -r1.62 src/share/misc/style
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/misc/style
diff -u src/share/misc/style:1.61 src/share/misc/style:1.62
--- src/share/misc/style:1.61 Sun Mar 28 10:16:16 2021
+++ src/share/misc/style Sun Mar 28 10:28:56 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: style,v 1.61 2021/03/28 14:16:16 christos Exp $ */
+/* $NetBSD: style,v 1.62 2021/03/28 14:28:56 christos Exp $ */
/*
* The revision control tag appears first, with a blank line after it.
@@ -30,7 +30,7 @@
#include <sys/cdefs.h>
__COPYRIGHT("@(#) Copyright (c) 2008\
The NetBSD Foundation, inc. All rights reserved.");
-__RCSID("$NetBSD: style,v 1.61 2021/03/28 14:16:16 christos Exp $");
+__RCSID("$NetBSD: style,v 1.62 2021/03/28 14:28:56 christos Exp $");
/*
* VERY important single-line comments look like this.
@@ -351,10 +351,26 @@ function(int a1, int a2, float fl, int a
char fourteen, fifteen, sixteen;
/*
- * Casts and sizeof's are not followed by a space. NULL is any
- * pointer type, and doesn't need to be cast, so use NULL instead
- * of (struct foo *)0 or (struct foo *)NULL. Also, test pointers
- * against NULL. I.e. use:
+ * Casts and sizeof's are not followed by a space.
+ *
+ * We parenthesize sizeof expressions to clarify their precedence:
+ *
+ * sizeof(e) + 4
+ * not:
+ * sizeof e + 4
+ *
+ * We don't put a space before the parenthesis so that it looks like
+ * a function call. We always parenthesize the sizeof expression for
+ * consistency.
+ *
+ * On the other hand, we don't parenthesize the return statement
+ * because there is never a precedence ambiguity situation (it is
+ * a single statement).
+ *
+ * NULL is any pointer type, and doesn't need to be cast, so use
+ * NULL instead of (struct foo *)0 or (struct foo *)NULL. Also,
+ * test pointers against NULL because it indicates the type of the
+ * expression to the user. I.e. use:
*
* (p = f()) == NULL
* not:
