Re: Speedup configure and build with system.h

[Michael Matz <matz@suse.de>]

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Hi,

On Mon, 25 Jan 2016, Uros Bizjak wrote:

> This patch caused bootstrap failure on non-c++11 bootstrap compiler
> [1], e.g. CentOS 5.11.
> 
> The problem is with std::swap, which was defined in header <algorithm>
> until c++11 [2].
> 
> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69464
> [2] http://en.cppreference.com/w/cpp/algorithm/swap

Meh.  Can you try the attached patch with a configure test (it includes 
the generated files)?  It works for me with 4.3.4, and should make your 
build include <algorithm> always.


Ciao,
Michael.

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Index: configure.ac
===================================================================
--- configure.ac	(revision 232675)
+++ configure.ac	(working copy)
@@ -416,6 +416,15 @@ struct X<long long> { typedef long long
 ]], [[X<int64_t>::t x;]])],[],[AC_MSG_ERROR([error verifying int64_t uses long long])])
 fi
 
+AC_CACHE_CHECK(for std::swap in <utility>, ac_cv_std_swap_in_utility, [
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#include <utility>
+]], [[int a, b; std::swap(a,b);]])],[ac_cv_std_swap_in_utility=yes],[ac_cv_std_swap_in_utility=no])])
+if test $ac_cv_std_swap_in_utility = yes; then
+  AC_DEFINE(HAVE_SWAP_IN_UTILITY, 1,
+  [Define if <utility> defines std::swap.])
+fi
+
 # Check whether compiler is affected by placement new aliasing bug (PR 29286).
 # If the host compiler is affected by the bug, and we build with optimization
 # enabled (which happens e.g. when cross-compiling), the pool allocator may
Index: system.h
===================================================================
--- system.h	(revision 232736)
+++ system.h	(working copy)
@@ -217,7 +217,7 @@ extern int errno;
 #endif
 
 #ifdef __cplusplus
-#ifdef INCLUDE_ALGORITHM
+#if defined (INCLUDE_ALGORITHM) || !defined (HAVE_SWAP_IN_UTILITY)
 # include <algorithm>
 #endif
 # include <cstring>
Index: configure
===================================================================
--- configure	(revision 232675)
+++ configure	(working copy)
@@ -6534,6 +6534,40 @@ fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for std::swap in <utility>" >&5
+$as_echo_n "checking for std::swap in <utility>... " >&6; }
+if test "${ac_cv_std_swap_in_utility+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <utility>
+
+int
+main ()
+{
+int a, b; std::swap(a,b);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_std_swap_in_utility=yes
+else
+  ac_cv_std_swap_in_utility=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_std_swap_in_utility" >&5
+$as_echo "$ac_cv_std_swap_in_utility" >&6; }
+if test $ac_cv_std_swap_in_utility = yes; then
+
+$as_echo "#define HAVE_SWAP_IN_UTILITY 1" >>confdefs.h
+
+fi
+
 # Check whether compiler is affected by placement new aliasing bug (PR 29286).
 # If the host compiler is affected by the bug, and we build with optimization
 # enabled (which happens e.g. when cross-compiling), the pool allocator may
@@ -18419,7 +18453,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18422 "configure"
+#line 18456 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -18525,7 +18559,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18528 "configure"
+#line 18562 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
Index: config.in
===================================================================
--- config.in	(revision 232675)
+++ config.in	(working copy)
@@ -1705,6 +1705,12 @@
 #endif
 
 
+/* Define if <utility> defines std::swap. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_SWAP_IN_UTILITY
+#endif
+
+
 /* Define to 1 if you have the `sysconf' function. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_SYSCONF
@@ -1865,7 +1871,8 @@
 #endif
 
 
-/* Define if your assembler supports .dwsect 0xB0000 */
+/* Define if your assembler supports AIX debug frame section label reference.
+   */
 #ifndef USED_FOR_TARGET
 #undef HAVE_XCOFF_DWARF_EXTRAS
 #endif