Update from Gnulib

This incorporates:
2020-09-05 verify: avoid __builtin_assume
2020-08-30 strerrorname_np: New module
2020-08-26 include_next, stdint, time_rz: Change configure message
* lib/gnulib.mk.in: Regenerate.
* lib/string.in.h, lib/verify.h, m4/include_next.m4, m4/stdint.m4:
* m4/string_h.m4, m4/time_rz.m4: Copy from Gnulib.

1 files changed, 8 insertions, 37 deletions

diff --git a/lib/verify.h b/lib/verify.h
index ca2a1540736..fa1ed717d0e 100644
--- a/lib/verify.h
+++ b/lib/verify.h
@@ -246,13 +246,6 @@ template <int w>
 
 /* @assert.h omit start@  */
 
-#if defined __has_builtin
-/* <https://clang.llvm.org/docs/LanguageExtensions.html#builtin-functions> */
-# define _GL_HAS_BUILTIN_ASSUME __has_builtin (__builtin_assume)
-#else
-# define _GL_HAS_BUILTIN_ASSUME 0
-#endif
-
 #if 3 < __GNUC__ + (3 < __GNUC_MINOR__ + (4 <= __GNUC_PATCHLEVEL__))
 # define _GL_HAS_BUILTIN_TRAP 1
 #elif defined __has_builtin
@@ -312,36 +305,14 @@ template <int w>
 
    Although assuming R can help a compiler generate better code or
    diagnostics, performance can suffer if R uses hard-to-optimize
-   features such as function calls not inlined by the compiler.  */
-
-/* Use __builtin_assume in preference to __builtin_unreachable, because
-   in clang versions 8.0.x and older, the definition based on
-   __builtin_assume has an effect on optimizations, whereas the definition
-   based on __builtin_unreachable does not.  (GCC so far has only
-   __builtin_unreachable.)  */
-#if _GL_HAS_BUILTIN_ASSUME
-/* Use __builtin_constant_p to help clang's data-flow analysis for the case
-   assume (0).
-   Use a temporary variable, to avoid a clang warning
-   "the argument to '__builtin_assume' has side effects that will be discarded"
-   if R contains invocations of functions not marked as 'const'.
-   The type of the temporary variable can't be __typeof__ (R), because that
-   does not work on bit field expressions.  Use '_Bool' or 'bool' as type
-   instead.  */
-# if defined __cplusplus
-#  define assume(R) \
-     (__builtin_constant_p (R) && !(R) \
-      ? (void) __builtin_unreachable () \
-      : (void) ({ bool _gl_verify_temp = (R); \
-                  __builtin_assume (_gl_verify_temp); }))
-# else
-#  define assume(R) \
-     (__builtin_constant_p (R) && !(R) \
-      ? (void) __builtin_unreachable () \
-      : (void) ({ _Bool _gl_verify_temp = (R); \
-                  __builtin_assume (_gl_verify_temp); }))
-# endif
-#elif _GL_HAS_BUILTIN_UNREACHABLE
+   features such as function calls not inlined by the compiler.
+
+   Avoid Clang's __builtin_assume, as it breaks GNU Emacs master
+   as of 2020-08-23T21:09:49Z!eggert@cs.ucla.edu; see
+   <https://bugs.gnu.org/43152#71>.  It's not known whether this breakage
+   is a Clang bug or an Emacs bug; play it safe for now.  */
+
+#if _GL_HAS_BUILTIN_UNREACHABLE
 # define assume(R) ((R) ? (void) 0 : __builtin_unreachable ())
 #elif 1200 <= _MSC_VER
 # define assume(R) __assume (R)