dynarray: merge from glibc

This also helps document glibc’s direction in using GCC’s
memory-allocation checking.
* lib/cdefs.h: Omit comments that glibc rejected.
(__returns_nonnull, __attr_access_none, __attr_dealloc)
(__attr_dealloc_free): New macros.
* lib/libc-config.h: Undef the new macros that are defined
unconditionally.
* lib/malloc/dynarray_at_failure.c [_LIBC]: Do not include stdlib.h.
(__libc_dynarray_at_failure) [_LIBC]: Call __libc_fatal,
fixing a bad merge previously.

1 files changed, 28 insertions, 5 deletions

diff --git a/lib/cdefs.h b/lib/cdefs.h
index b883b25666..4dac9d264d 100644
--- a/lib/cdefs.h
+++ b/lib/cdefs.h
@@ -261,10 +261,6 @@
 
 #if __GNUC_PREREQ (2,7) || __glibc_has_attribute (__unused__)
 # define __attribute_maybe_unused__ __attribute__ ((__unused__))
-/* Once the next version of the C standard comes out, we can
-   do something like the following here:
-   #elif defined __STDC_VERSION__ && 202???L <= __STDC_VERSION__
-   # define __attribute_maybe_unused__ [[__maybe_unused__]]   */
 #else
 # define __attribute_maybe_unused__ /* Ignore */
 #endif
@@ -336,6 +332,16 @@
 # define __nonnull(params) __attribute_nonnull__ (params)
 #endif
 
+/* The returns_nonnull function attribute marks the return type of the function
+   as always being non-null.  */
+#ifndef __returns_nonnull
+# if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__returns_nonnull__)
+# define __returns_nonnull __attribute__ ((__returns_nonnull__))
+# else
+# define __returns_nonnull
+# endif
+#endif
+
 /* If fortification mode, we warn about unused results of certain
    function calls which can lead to problems.  */
 #if __GNUC_PREREQ (3,4) || __glibc_has_attribute (__warn_unused_result__)
@@ -598,9 +604,26 @@ _Static_assert (0, "IEEE 128-bits long double requires redirection on this platf
    array according to access mode, or at least one element when
    size-index is not provided:
      access (access-mode, <ref-index> [, <size-index>])  */
-#define __attr_access(x) __attribute__ ((__access__ x))
+#  define __attr_access(x) __attribute__ ((__access__ x))
+#  if __GNUC_PREREQ (11, 0)
+#    define __attr_access_none(argno) __attribute__ ((__access__ (__none__, argno)))
+#  else
+#    define __attr_access_none(argno)
+#  endif
 #else
 #  define __attr_access(x)
+#  define __attr_access_none(argno)
+#endif
+
+#if __GNUC_PREREQ (11, 0)
+/* Designates dealloc as a function to call to deallocate objects
+   allocated by the declared function.  */
+# define __attr_dealloc(dealloc, argno) \
+    __attribute__ ((__malloc__ (dealloc, argno)))
+# define __attr_dealloc_free __attr_dealloc (__builtin_free, 1)
+#else
+# define __attr_dealloc(dealloc, argno)
+# define __attr_dealloc_free
 #endif
 
 /* Specify that a function such as setjmp or vfork may return