[RFC] Avoid spurious isolate-erroneous-paths failures

[OndÅej BÃlka <neleai at seznam dot cz>]

Hi,

a gcc isolate-erroneous-paths switch causes trapping of 
memset (NULL, 0, 0), see
http://gcc.gnu.org/ml/gcc/2013-11/msg00345.html

This could give a isolate-erroneous-paths bad reputation as it will
cause more spurious failures than real problems.

One way how to fix this would be drop nonnull attribute from mem* and
strn* function as patch below does.

On other hand a c standard says that passes pointers must be always
valid. String routines now do extra check for n==0 to avoid
dereferencing pointer. By dropping this check a call could be a cycle
faster.

diff --git a/string/string.h b/string/string.h
index ecc3fef..68e19c6 100644
--- a/string/string.h
+++ b/string/string.h
@@ -40,7 +40,7 @@ __BEGIN_DECLS
 __BEGIN_NAMESPACE_STD
 /* Copy N bytes of SRC to DEST.  */
 extern void *memcpy (void *__restrict __dest, const void *__restrict __src,
-		     size_t __n) __THROW __nonnull ((1, 2));
+		     size_t __n) __THROW;
 /* Copy N bytes of SRC to DEST, guaranteeing
    correct behavior for overlapping strings.  */
 extern void *memmove (void *__dest, const void *__src, size_t __n)
@@ -53,26 +53,26 @@ __END_NAMESPACE_STD
 #if defined __USE_SVID || defined __USE_BSD || defined __USE_XOPEN
 extern void *memccpy (void *__restrict __dest, const void *__restrict __src,
 		      int __c, size_t __n)
-     __THROW __nonnull ((1, 2));
+     __THROW;
 #endif /* SVID.  */
 
 
 __BEGIN_NAMESPACE_STD
 /* Set N bytes of S to C.  */
-extern void *memset (void *__s, int __c, size_t __n) __THROW __nonnull ((1));
+extern void *memset (void *__s, int __c, size_t __n) __THROW;
 
 /* Compare N bytes of S1 and S2.  */
 extern int memcmp (const void *__s1, const void *__s2, size_t __n)
-     __THROW __attribute_pure__ __nonnull ((1, 2));
+     __THROW __attribute_pure__;
 
 /* Search N bytes of S for C.  */
 #ifdef __CORRECT_ISO_CPP_STRING_H_PROTO
 extern "C++"
 {
 extern void *memchr (void *__s, int __c, size_t __n)
-      __THROW __asm ("memchr") __attribute_pure__ __nonnull ((1));
+      __THROW __asm ("memchr") __attribute_pure__;
 extern const void *memchr (const void *__s, int __c, size_t __n)
-      __THROW __asm ("memchr") __attribute_pure__ __nonnull ((1));
+      __THROW __asm ("memchr") __attribute_pure__;
 
 # ifdef __OPTIMIZE__
 __extern_always_inline void *
@@ -90,7 +90,7 @@ memchr (const void *__s, int __c, size_t __n) __THROW
 }
 #else
 extern void *memchr (const void *__s, int __c, size_t __n)
-      __THROW __attribute_pure__ __nonnull ((1));
+      __THROW __attribute_pure__;
 #endif
 __END_NAMESPACE_STD
 
@@ -110,12 +110,12 @@ extern void *rawmemchr (const void *__s, int __c)
 /* Search N bytes of S for the final occurrence of C.  */
 # ifdef __CORRECT_ISO_CPP_STRING_H_PROTO
 extern "C++" void *memrchr (void *__s, int __c, size_t __n)
-      __THROW __asm ("memrchr") __attribute_pure__ __nonnull ((1));
+      __THROW __asm ("memrchr") __attribute_pure__;
 extern "C++" const void *memrchr (const void *__s, int __c, size_t __n)
-      __THROW __asm ("memrchr") __attribute_pure__ __nonnull ((1));
+      __THROW __asm ("memrchr") __attribute_pure__;
 # else
 extern void *memrchr (const void *__s, int __c, size_t __n)
-      __THROW __attribute_pure__ __nonnull ((1));
+      __THROW __attribute_pure__;
 # endif
 #endif
 
@@ -134,14 +134,14 @@ extern char *strcat (char *__restrict __dest, const char *__restrict __src)
      __THROW __nonnull ((1, 2));
 /* Append no more than N characters from SRC onto DEST.  */
 extern char *strncat (char *__restrict __dest, const char *__restrict __src,
-		      size_t __n) __THROW __nonnull ((1, 2));
+		      size_t __n) __THROW __nonnull ((1));
 
 /* Compare S1 and S2.  */
 extern int strcmp (const char *__s1, const char *__s2)
      __THROW __attribute_pure__ __nonnull ((1, 2));
 /* Compare N characters of S1 and S2.  */
 extern int strncmp (const char *__s1, const char *__s2, size_t __n)
-     __THROW __attribute_pure__ __nonnull ((1, 2));
+     __THROW __attribute_pure__;
 
 /* Compare the collated forms of S1 and S2.  */
 extern int strcoll (const char *__s1, const char *__s2)
@@ -163,7 +163,7 @@ extern int strcoll_l (const char *__s1, const char *__s2, __locale_t __l)
      __THROW __attribute_pure__ __nonnull ((1, 2, 3));
 /* Put a transformation of SRC into no more than N bytes of DEST.  */
 extern size_t strxfrm_l (char *__dest, const char *__src, size_t __n,
-			 __locale_t __l) __THROW __nonnull ((2, 4));
+			 __locale_t __l) __THROW __nonnull ((4));
 #endif
 
 #if defined __USE_SVID || defined __USE_BSD || defined __USE_XOPEN_EXTENDED \
@@ -178,7 +178,7 @@ extern char *strdup (const char *__s)
    appears before STRING[N].  */
 #if defined __USE_XOPEN2K8
 extern char *strndup (const char *__string, size_t __n)
-     __THROW __attribute_malloc__ __nonnull ((1));
+     __THROW __attribute_malloc__;
 #endif
 
 #if defined __USE_GNU && defined __GNUC__
@@ -377,16 +377,16 @@ extern char *strcasestr (const char *__haystack, const char *__needle)
    HAYSTACK is HAYSTACKLEN bytes long.  */
 extern void *memmem (const void *__haystack, size_t __haystacklen,
 		     const void *__needle, size_t __needlelen)
-     __THROW __attribute_pure__ __nonnull ((1, 3));
+     __THROW __attribute_pure__;
 
 /* Copy N bytes of SRC to DEST, return pointer to bytes after the
    last written byte.  */
 extern void *__mempcpy (void *__restrict __dest,
 			const void *__restrict __src, size_t __n)
-     __THROW __nonnull ((1, 2));
+     __THROW;
 extern void *mempcpy (void *__restrict __dest,
 		      const void *__restrict __src, size_t __n)
-     __THROW __nonnull ((1, 2));
+     __THROW;
 #endif
 
 
@@ -400,7 +400,7 @@ __END_NAMESPACE_STD
 /* Find the length of STRING, but scan at most MAXLEN characters.
    If no '\0' terminator is found in that many characters, return MAXLEN.  */
 extern size_t strnlen (const char *__string, size_t __maxlen)
-     __THROW __attribute_pure__ __nonnull ((1));
+     __THROW __attribute_pure__;
 #endif
 
 
@@ -444,7 +444,7 @@ extern char *strerror_l (int __errnum, __locale_t __l) __THROW;
 
 /* We define this function always since `bzero' is sometimes needed when
    the namespace rules does not allow this.  */
-extern void __bzero (void *__s, size_t __n) __THROW __nonnull ((1));
+extern void __bzero (void *__s, size_t __n) __THROW;
 
 #ifdef __USE_BSD
 /* Copy N bytes of SRC to DEST (like memmove, but args reversed).  */
@@ -452,11 +452,11 @@ extern void bcopy (const void *__src, void *__dest, size_t __n)
      __THROW __nonnull ((1, 2));
 
 /* Set N bytes of S to 0.  */
-extern void bzero (void *__s, size_t __n) __THROW __nonnull ((1));
+extern void bzero (void *__s, size_t __n) __THROW;
 
 /* Compare N bytes of S1 and S2 (same as memcmp).  */
 extern int bcmp (const void *__s1, const void *__s2, size_t __n)
-     __THROW __attribute_pure__ __nonnull ((1, 2));
+     __THROW __attribute_pure__;
 
 /* Find the first occurrence of C in S (same as strchr).  */
 # ifdef __CORRECT_ISO_CPP_STRING_H_PROTO