Further clarifications of the #ifdef/#if/#elif/#endif style information,

largely submitted by bde.  Return our exemption of the #ifdef lint
comments since the exemption is intended to handle a particularly
common current case without mandating change.  Improve language and
spelling, and slightly clarify the notions associated specifically
with #elif.

Obtained from:	bde

1 files changed, 16 insertions, 13 deletions

diff --git a/share/man/man9/style.9 b/share/man/man9/style.9
index e5e2061..d669b3b 100644
--- a/share/man/man9/style.9
+++ b/share/man/man9/style.9
@@ -82,7 +82,7 @@ in front of foreign VCS IDs if the file is renamed.
 #if 0
 #ifndef lint
 static char sccsid[] = "@(#)style	1.14 (Berkeley) 4/28/95";
-#endif /* !lint */
+#endif /* not lint */
 #endif
 
 #include <sys/cdefs.h>
@@ -180,7 +180,7 @@ for pretty-printers and editors.
 } while (0)
 .Ed
 .Pp
-When code blocks are conditionally defined using
+When code is conditionally compiled using
 .Ic #ifdef
 or
 .Ic #if ,
@@ -188,34 +188,37 @@ a comment may be added following the matching
 .Ic #endif
 or
 .Ic #else
-to permit the reader to easily discern where conditionally defined code
+to permit the reader to easily discern where conditionally compiled code
 regions end.
 This comment should be used only for (subjectively) long regions, regions
 greater than 20 lines, or where a series of nested
 .Ic #ifdef 's
 may be confusing to the reader.
-Exceptions may be made for cases where code is contionally undefined for
-the purposes of lint, even though the undefined region may be small.
-The comment shall be seperated from the
+Exceptions may be made for cases where code is conditionally not compiled for
+the purposes of lint, even though the uncompiled region may be small.
+The comment should be separated from the
 .Ic #endif
 or
 .Ic #else
 by a single space.
-For short conditionally defined regions, a closing comment should not be
+For short conditionally compiled regions, a closing comment should not be
 used.
 .Pp
 The comment for
 .Ic #endif
-should match the expression used in
+should match the expression used in the corresponding
 .Ic #if
 or
 .Ic #ifdef .
 The comment for
 .Ic #else
-should be the inverse of the expression used in the previous
+and
+.Ic #elif
+should match the inverse of the expression(s) used in the preceding
 .Ic #if
-or
-.Ic #elsif .
+and/or
+.Ic #elif
+statements.
 In the comments, the subexpression
 .Dq Li defined(FOO)
 is abbreviated as
@@ -230,13 +233,13 @@ is treated as
 #endif
 
 #ifdef COMPAT_43
-/* A long block here, or other conditional code. */
+/* A large region here, or other conditional code. */
 #else /* !COMPAT_43 */
 /* Or here. */
 #endif /* COMPAT_43 */
 
 #ifndef COMPAT_43
-/* Yet another long block here, or other conditional code. */
+/* Yet another large region here, or other conditional code. */
 #else /* COMPAT_43 */
 /* Or here. */
 #endif /* !COMPAT_43*/