Update from Gnulib

This incorporates:
2020-08-20 sigabbrev_np: New module
2020-08-20 stdalign: Fix 32-bit test failures clang versions < 8
2020-08-17 careadlinkat: speedup for GCC 10 with GCC_LINT
2020-08-17 Assume autoconf >= 2.64
* build-aux/config.guess, build-aux/config.sub, lib/careadlinkat.c:
* lib/stdalign.in.h, lib/string.in.h, m4/std-gnu11.m4, m4/string_h.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

4 files changed, 85 insertions, 48 deletions

diff --git a/lib/careadlinkat.c b/lib/careadlinkat.c
index 1aa04363dac..e43aa42d5c4 100644
--- a/lib/careadlinkat.c
+++ b/lib/careadlinkat.c
@@ -38,66 +38,41 @@
 
 #include "allocator.h"
 
-/* Assuming the current directory is FD, get the symbolic link value
-   of FILENAME as a null-terminated string and put it into a buffer.
-   If FD is AT_FDCWD, FILENAME is interpreted relative to the current
-   working directory, as in openat.
-
-   If the link is small enough to fit into BUFFER put it there.
-   BUFFER's size is BUFFER_SIZE, and BUFFER can be null
-   if BUFFER_SIZE is zero.
-
-   If the link is not small, put it into a dynamically allocated
-   buffer managed by ALLOC.  It is the caller's responsibility to free
-   the returned value if it is nonnull and is not BUFFER.  A null
-   ALLOC stands for the standard allocator.
-
-   The PREADLINKAT function specifies how to read links.  It operates
-   like POSIX readlinkat()
-   <https://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
-   but can assume that its first argument is the same as FD.
-
-   If successful, return the buffer address; otherwise return NULL and
-   set errno.  */
-
-char *
-careadlinkat (int fd, char const *filename,
+enum { STACK_BUF_SIZE = 1024 };
+
+/* Act like careadlinkat (see below), with an additional argument
+   STACK_BUF that can be used as temporary storage.
+
+   If GCC_LINT is defined, do not inline this function with GCC 10.1
+   and later, to avoid creating a pointer to the stack that GCC
+   -Wreturn-local-addr incorrectly complains about.  See:
+   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93644
+   Although the noinline attribute can hurt performance a bit, no better way
+   to pacify GCC is known; even an explicit #pragma does not pacify GCC.
+   When the GCC bug is fixed this workaround should be limited to the
+   broken GCC versions.  */
+#if (defined GCC_LINT || defined lint) && _GL_GNUC_PREREQ (10, 1)
+__attribute__ ((__noinline__))
+#endif
+static char *
+readlink_stk (int fd, char const *filename,
               char *buffer, size_t buffer_size,
               struct allocator const *alloc,
-              ssize_t (*preadlinkat) (int, char const *, char *, size_t))
+              ssize_t (*preadlinkat) (int, char const *, char *, size_t),
+              char stack_buf[STACK_BUF_SIZE])
 {
   char *buf;
   size_t buf_size;
   size_t buf_size_max =
     SSIZE_MAX < SIZE_MAX ? (size_t) SSIZE_MAX + 1 : SIZE_MAX;
-  char stack_buf[1024];
-
-#if (defined GCC_LINT || defined lint) && _GL_GNUC_PREREQ (10, 1)
-  /* Pacify preadlinkat without creating a pointer to the stack
-     that a broken gcc -Wreturn-local-addr would cry wolf about.  See:
-     https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95044
-     This workaround differs from the mainline code, but
-     no other way to pacify GCC 10.1.0 is known; even an explicit
-     #pragma does not pacify GCC.  When the GCC bug is fixed this
-     workaround should be limited to the broken GCC versions.  */
-# define WORK_AROUND_GCC_BUG_95044
-#endif
 
   if (! alloc)
     alloc = &stdlib_allocator;
 
   if (!buffer)
     {
-#ifdef WORK_AROUND_GCC_BUG_95044
-      buffer = alloc->allocate (sizeof stack_buf);
-#else
-      /* Allocate the initial buffer on the stack.  This way, in the
-         common case of a symlink of small size, we get away with a
-         single small malloc() instead of a big malloc() followed by a
-         shrinking realloc().  */
       buffer = stack_buf;
-#endif
-      buffer_size = sizeof stack_buf;
+      buffer_size = STACK_BUF_SIZE;
     }
 
   buf = buffer;
@@ -172,3 +147,44 @@ careadlinkat (int fd, char const *filename,
   errno = ENOMEM;
   return NULL;
 }
+
+
+/* Assuming the current directory is FD, get the symbolic link value
+   of FILENAME as a null-terminated string and put it into a buffer.
+   If FD is AT_FDCWD, FILENAME is interpreted relative to the current
+   working directory, as in openat.
+
+   If the link is small enough to fit into BUFFER put it there.
+   BUFFER's size is BUFFER_SIZE, and BUFFER can be null
+   if BUFFER_SIZE is zero.
+
+   If the link is not small, put it into a dynamically allocated
+   buffer managed by ALLOC.  It is the caller's responsibility to free
+   the returned value if it is nonnull and is not BUFFER.  A null
+   ALLOC stands for the standard allocator.
+
+   The PREADLINKAT function specifies how to read links.  It operates
+   like POSIX readlinkat()
+   <https://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
+   but can assume that its first argument is the same as FD.
+
+   If successful, return the buffer address; otherwise return NULL and
+   set errno.  */
+
+char *
+careadlinkat (int fd, char const *filename,
+              char *buffer, size_t buffer_size,
+              struct allocator const *alloc,
+              ssize_t (*preadlinkat) (int, char const *, char *, size_t))
+{
+  /* Allocate the initial buffer on the stack.  This way, in the
+     common case of a symlink of small size, we get away with a
+     single small malloc instead of a big malloc followed by a
+     shrinking realloc.
+
+     If GCC -Wreturn-local-addr warns about this buffer, the warning
+     is bogus; see readlink_stk.  */
+  char stack_buf[STACK_BUF_SIZE];
+  return readlink_stk (fd, filename, buffer, buffer_size, alloc,
+                       preadlinkat, stack_buf);
+}
diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index 7b4fc74219f..78b4542d80a 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -424,6 +424,7 @@ GNULIB_SECURE_GETENV = @GNULIB_SECURE_GETENV@
 GNULIB_SELECT = @GNULIB_SELECT@
 GNULIB_SETENV = @GNULIB_SETENV@
 GNULIB_SETHOSTNAME = @GNULIB_SETHOSTNAME@
+GNULIB_SIGABBREV_NP = @GNULIB_SIGABBREV_NP@
 GNULIB_SIGACTION = @GNULIB_SIGACTION@
 GNULIB_SIGNAL_H_SIGPIPE = @GNULIB_SIGNAL_H_SIGPIPE@
 GNULIB_SIGPROCMASK = @GNULIB_SIGPROCMASK@
@@ -644,6 +645,7 @@ HAVE_SECURE_GETENV = @HAVE_SECURE_GETENV@
 HAVE_SETENV = @HAVE_SETENV@
 HAVE_SETHOSTNAME = @HAVE_SETHOSTNAME@
 HAVE_SETSTATE = @HAVE_SETSTATE@
+HAVE_SIGABBREV_NP = @HAVE_SIGABBREV_NP@
 HAVE_SIGACTION = @HAVE_SIGACTION@
 HAVE_SIGHANDLER_T = @HAVE_SIGHANDLER_T@
 HAVE_SIGINFO_T = @HAVE_SIGINFO_T@
@@ -2843,6 +2845,7 @@ string.h: string.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H
 	      -e 's/@''GNULIB_STRTOK_R''@/$(GNULIB_STRTOK_R)/g' \
 	      -e 's/@''GNULIB_STRERROR''@/$(GNULIB_STRERROR)/g' \
 	      -e 's/@''GNULIB_STRERROR_R''@/$(GNULIB_STRERROR_R)/g' \
+	      -e 's/@''GNULIB_SIGABBREV_NP''@/$(GNULIB_SIGABBREV_NP)/g' \
 	      -e 's/@''GNULIB_STRSIGNAL''@/$(GNULIB_STRSIGNAL)/g' \
 	      -e 's/@''GNULIB_STRVERSCMP''@/$(GNULIB_STRVERSCMP)/g' \
 	      < $(srcdir)/string.in.h | \
@@ -2865,6 +2868,7 @@ string.h: string.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H
 	      -e 's|@''HAVE_STRCASESTR''@|$(HAVE_STRCASESTR)|g' \
 	      -e 's|@''HAVE_DECL_STRTOK_R''@|$(HAVE_DECL_STRTOK_R)|g' \
 	      -e 's|@''HAVE_DECL_STRERROR_R''@|$(HAVE_DECL_STRERROR_R)|g' \
+	      -e 's|@''HAVE_SIGABBREV_NP''@|$(HAVE_SIGABBREV_NP)|g' \
 	      -e 's|@''HAVE_DECL_STRSIGNAL''@|$(HAVE_DECL_STRSIGNAL)|g' \
 	      -e 's|@''HAVE_STRVERSCMP''@|$(HAVE_STRVERSCMP)|g' \
 	      -e 's|@''REPLACE_MEMCHR''@|$(REPLACE_MEMCHR)|g' \
diff --git a/lib/stdalign.in.h b/lib/stdalign.in.h
index e4809b401f7..b5b63e53f12 100644
--- a/lib/stdalign.in.h
+++ b/lib/stdalign.in.h
@@ -54,10 +54,12 @@
 #undef _Alignof
 
 /* GCC releases before GCC 4.9 had a bug in _Alignof.  See GCC bug 52023
-   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>.  */
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>.
+   clang versions < 8.0.0 have the same bug.  */
 #if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \
      || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \
-         && !defined __clang__))
+         && !defined __clang__) \
+     || (defined __clang__ && __clang_major__ < 8))
 # ifdef __cplusplus
 #  if 201103 <= __cplusplus
 #   define _Alignof(type) alignof (type)
diff --git a/lib/string.in.h b/lib/string.in.h
index 7d83668f6ec..5134e11289d 100644
--- a/lib/string.in.h
+++ b/lib/string.in.h
@@ -1045,6 +1045,21 @@ _GL_WARN_ON_USE (strerror_r, "strerror_r is unportable - "
 # endif
 #endif
 
+/* Return an abbreviation string for the signal number SIG.  */
+#if @GNULIB_SIGABBREV_NP@
+# if ! @HAVE_SIGABBREV_NP@
+_GL_FUNCDECL_SYS (sigabbrev_np, const char *, (int sig));
+# endif
+_GL_CXXALIAS_SYS (sigabbrev_np, const char *, (int sig));
+_GL_CXXALIASWARN (sigabbrev_np);
+#elif defined GNULIB_POSIXCHECK
+# undef sigabbrev_np
+# if HAVE_RAW_DECL_SIGABBREV_NP
+_GL_WARN_ON_USE (sigabbrev_np, "sigabbrev_np is unportable - "
+                 "use gnulib module sigabbrev_np for portability");
+# endif
+#endif
+
 #if @GNULIB_STRSIGNAL@
 # if @REPLACE_STRSIGNAL@
 #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)