Add warn_unused_result attribute for memory-related functions in libiberty.

2019-06-10  Martin Liska  <mliska@suse.cz>

	* ansidecl.h (ATTRIBUTE_WARN_UNUSED_RESULT): New macro.
	* libiberty.h (xmalloc): Use it.
	(xrealloc): Likewise.
	(xcalloc): Likewise.
	(xstrdup): Likewise.
	(xstrndup): Likewise.
	(xmemdup): Likewise.

From-SVN: r272110

include/ChangeLog

 2019-06-10  Martin Liska  <mliska@suse.cz>
 
+	* ansidecl.h (ATTRIBUTE_WARN_UNUSED_RESULT): New macro.
+	* libiberty.h (xmalloc): Use it.
+	(xrealloc): Likewise.
+	(xcalloc): Likewise.
+	(xstrdup): Likewise.
+	(xstrndup): Likewise.
+	(xmemdup): Likewise.
+
+2019-06-10  Martin Liska  <mliska@suse.cz>
+
 	* ansidecl.h:
 	(ATTRIBUTE_RESULT_SIZE_1): Define new macro.
 	(ATTRIBUTE_RESULT_SIZE_2): Likewise.

include/ansidecl.h

@@ -317,6 +317,15 @@ So instead we use the macro below and test it against specific values.  */
 #endif
 #endif
 
+/* Attribute `warn_unused_result' was valid as of gcc 3.3.  */
+#ifndef ATTRIBUTE_WARN_UNUSED_RESULT
+# if GCC_VERSION >= 3003
+#  define ATTRIBUTE_WARN_UNUSED_RESULT __attribute__ ((warn_unused_result))
+# else
+#  define ATTRIBUTE_WARN_UNUSED_RESULT
+# endif
+#endif
+
 /* We use __extension__ in some places to suppress -pedantic warnings
    about GCC extensions.  This feature didn't work properly before
    gcc 2.8.  */

include/libiberty.h

@@ -310,30 +310,30 @@ extern void xmalloc_failed (size_t) ATTRIBUTE_NORETURN;
    message to stderr (using the name set by xmalloc_set_program_name,
    if any) and then call xexit.  */
 
-extern void *xmalloc (size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_RESULT_SIZE_1;
+extern void *xmalloc (size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_RESULT_SIZE_1 ATTRIBUTE_WARN_UNUSED_RESULT;
 
 /* Reallocate memory without fail.  This works like xmalloc.  Note,
    realloc type functions are not suitable for attribute malloc since
    they may return the same address across multiple calls. */
 
-extern void *xrealloc (void *, size_t) ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_RESULT_SIZE_2;
+extern void *xrealloc (void *, size_t) ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_RESULT_SIZE_2 ATTRIBUTE_WARN_UNUSED_RESULT;
 
 /* Allocate memory without fail and set it to zero.  This works like
    xmalloc.  */
 
-extern void *xcalloc (size_t, size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_RESULT_SIZE_1_2;
+extern void *xcalloc (size_t, size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_RESULT_SIZE_1_2 ATTRIBUTE_WARN_UNUSED_RESULT;
 
 /* Copy a string into a memory buffer without fail.  */
 
-extern char *xstrdup (const char *) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL;
+extern char *xstrdup (const char *) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_WARN_UNUSED_RESULT;
 
 /* Copy at most N characters from string into a buffer without fail.  */
 
-extern char *xstrndup (const char *, size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL;
+extern char *xstrndup (const char *, size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_WARN_UNUSED_RESULT;
 
 /* Copy an existing memory buffer to a new memory buffer without fail.  */
 
-extern void *xmemdup (const void *, size_t, size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL;
+extern void *xmemdup (const void *, size_t, size_t) ATTRIBUTE_MALLOC ATTRIBUTE_RETURNS_NONNULL ATTRIBUTE_WARN_UNUSED_RESULT;
 
 /* Physical memory routines.  Return values are in BYTES.  */
 extern double physmem_total (void);