Commit 0abda558 authored by Paul Eggert's avatar Paul Eggert

Port configure.ac to future Gnulib

Rewrite an ancient Alpha ELF check to port to a future Gnulib
version that may require AC_CHECK_DECL to be set up properly as
per the ‘Expanded Before Required’ section of the Autoconf manual
Autoconf doesn’t guarantee that AC_CHECK_DECL will work properly
if called conditionally (e.g., inside a shell ‘case’ statement)
and the condition is false.  Problem reported by Bruno Haible in:
https://lists.gnu.org/r/bug-gnulib/2020-01/msg00088.html
* configure.ac (LD_SWITCH_MACHINE): Migrate ELF check later,
when AC_CHECK_DECL is properly set up.
parent 6100f9a1
......@@ -1508,6 +1508,7 @@ case "$opsys" in
UNEXEC_OBJ=unexelf.o
;;
esac
AC_SUBST(UNEXEC_OBJ)
LD_SWITCH_SYSTEM=
test "$with_unexec" = no || case "$opsys" in
......@@ -1561,8 +1562,6 @@ C_SWITCH_MACHINE=
test $with_unexec = yes &&
case $canonical in
alpha*)
AC_CHECK_DECL([__ELF__])
if test "$ac_cv_have_decl___ELF__" = "yes"; then
## With ELF, make sure that all common symbols get allocated to in the
## data section. Otherwise, the dump of temacs may miss variables in
## the shared library that have been initialized. For example, with
......@@ -1573,18 +1572,10 @@ case $canonical in
else
AC_MSG_ERROR([Non-GCC compilers are not supported.])
fi
else
dnl This was the unexalpha.c case. Removed in 24.1, 2010-07-24,
dnl albeit under the mistaken assumption that said file
dnl was no longer used.
AC_MSG_ERROR([Non-ELF systems are not supported since Emacs 24.1.])
fi
;;
esac
AC_SUBST(C_SWITCH_MACHINE)
AC_SUBST(UNEXEC_OBJ)
C_SWITCH_SYSTEM=
## Some programs in src produce warnings saying certain subprograms
## are too complex and need a MAXMEM value greater than 2000 for
......@@ -4216,6 +4207,12 @@ dnl No need to check for posix_memalign if aligned_alloc works.
AC_CHECK_FUNCS([aligned_alloc posix_memalign], [break])
AC_CHECK_DECLS([aligned_alloc], [], [], [[#include <stdlib.h>]])
case $with_unexec,$canonical in
yes,alpha*)
AC_CHECK_DECL([__ELF__], [],
[AC_MSG_ERROR([Non-ELF systems are not supported on this platform.])]);;
esac
# Dump loading
AC_CHECK_FUNCS([posix_madvise])
......
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