Fix -Wempty-body warnings in glibc.

One group of warnings seen building glibc with -Wextra is -Wempty-body
warnings about an 'if' body (or in one case an 'else' body) that is
just a semicolon, "warning: suggest braces around empty body in an
'if' statement [-Wempty-body]" - I think the point of the warning
being to make it more visible whether an 'if' body is actually present
or not.

This patch fixes such warnings in glibc.  There's one place, with a
semicolon at the end of a comment, where this is clearly making the
presence of an 'else' body more visible.  The other cases involve
macro definitions expanding to nothing.  While there's no issue there
with visibility at the call sites, I think it's still cleaner to have
a macro that expands to something nonempty appropriate for the context
- so do {} while (0) if it's only intended to be usable as a
statement, or ((void) 0) where the macro definition is an alternative
to a call to a function returning void, so this patch makes those
changes.

Tested for x86_64.

	* catgets/gencat.c (normalize_line): Use braces around empty
	'else' body.
	* include/stap-probe.h [!USE_STAP_PROBE && !__ASSEMBLER__]
	(STAP_PROBE0): Use do {} while (0) for do-nothing definition.
	[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE1): Likewise.
	[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE2): Likewise.
	[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE3): Likewise.
	[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE4): Likewise.
	* libio/libio.h (_IO_funlockfile): Use ((void) 0) for do-nothing
	definition.

diff --git a/ChangeLog b/ChangeLog
index 4279eeedb3e0827f945f29bb5bdcf4bff8978da4..f8210cdb418679b57130ddfc59d23898480a41bc 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,16 @@
 2019-02-13  Joseph Myers  <joseph@codesourcery.com>
 
+       * catgets/gencat.c (normalize_line): Use braces around empty
+       'else' body.
+       * include/stap-probe.h [!USE_STAP_PROBE && !__ASSEMBLER__]
+       (STAP_PROBE0): Use do {} while (0) for do-nothing definition.
+       [!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE1): Likewise.
+       [!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE2): Likewise.
+       [!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE3): Likewise.
+       [!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE4): Likewise.
+       * libio/libio.h (_IO_funlockfile): Use ((void) 0) for do-nothing
+       definition.
+
        * support/test-container.c (recursive_remove): Use FAIL_EXIT1 if
        execlp returns.
 

diff --git a/catgets/gencat.c b/catgets/gencat.c
index 9d6db7017e9c2a514003dac60856a5a86cd257f3..51fd2a724edb0d737a15dc02789de09b3277d4af 100644 (file)
--- a/catgets/gencat.c
+++ b/catgets/gencat.c
@@ -1196,7 +1196,9 @@ normalize_line (const char *fname, size_t line, iconv_t cd, wchar_t *string,
                  ++rp;
                }
              else
-               /* Simply ignore the backslash character.  */;
+               {
+                 /* Simply ignore the backslash character.  */
+               }
              break;
            }
       }

diff --git a/include/stap-probe.h b/include/stap-probe.h
index 8c26292edd4d5180db3de19a24f94c2252c4fbf2..85f41c9162fc2d0c84f40351f60ae08acd4c06e0 100644 (file)
--- a/include/stap-probe.h
+++ b/include/stap-probe.h
@@ -60,11 +60,11 @@
 /* Evaluate all the arguments and verify that N matches their number.  */
 #  define LIBC_PROBE(name, n, ...) STAP_PROBE##n (__VA_ARGS__)
 
-#  define STAP_PROBE0()
-#  define STAP_PROBE1(a1)
-#  define STAP_PROBE2(a1, a2)
-#  define STAP_PROBE3(a1, a2, a3)
-#  define STAP_PROBE4(a1, a2, a3, a4)
+#  define STAP_PROBE0()                                do {} while (0)
+#  define STAP_PROBE1(a1)                      do {} while (0)
+#  define STAP_PROBE2(a1, a2)                  do {} while (0)
+#  define STAP_PROBE3(a1, a2, a3)              do {} while (0)
+#  define STAP_PROBE4(a1, a2, a3, a4)          do {} while (0)
 
 # else
 #  define LIBC_PROBE(name, n, ...)             /* Nothing.  */

diff --git a/libio/libio.h b/libio/libio.h
index d21162aab057108e00b7729818cce29452475440..9c08c7eba162c643ef638128fa5fa57b19beccea 100644 (file)
--- a/libio/libio.h
+++ b/libio/libio.h
@@ -240,7 +240,7 @@ extern int _IO_ftrylockfile (FILE *) __THROW;
 
 #define _IO_peekc(_fp) _IO_peekc_unlocked (_fp)
 #define _IO_flockfile(_fp) /**/
-#define _IO_funlockfile(_fp) /**/
+#define _IO_funlockfile(_fp) ((void) 0)
 #define _IO_ftrylockfile(_fp) /**/
 #ifndef _IO_cleanup_region_start
 #define _IO_cleanup_region_start(_fct, _fp) /**/