As explained in the PR, flockfile and funlockfile are always declared by
newlib and there's no easy way to detect whether they're actually
defined. Ensure that ac_stdio_locking=no gets set for non-cygwin newlib
targets.
libstdc++-v3/ChangeLog:
PR libstdc++/123406
* acinclude.m4 (GLIBCXX_CHECK_STDIO_LOCKING): Override detection
of flockfile for non-cygwin newlib targets.
* configure: Regenerate.
---
Tested x86_64-linux, where this doesn't change the generated c++config.h
file.
Built on cris-elf to verify that the _GLIBCXX_USE_STDIO_LOCKING macro is
no longer defined in c++config.h.
libstdc++-v3/acinclude.m4 | 9 ++++++++-
libstdc++-v3/configure | 7 +++++++
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 103515c000f4..e6723edf880e 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -5822,13 +5822,20 @@ AC_LANG_SAVE
AC_MSG_CHECKING([whether flockfile and putc_unlocked are defined in
<stdio.h>])
AC_TRY_COMPILE([
#include <stdio.h>
+ #if __has_include(<newlib.h>)
+ # ifdef __CYGWIN__
+ // Cygwin has working flockfile
+ # else
+ # error No usable flockfile on most newlib targets
+ # endif
+ #endif
],[
FILE* f = ::fopen("", "");
::flockfile(f);
::putc_unlocked(' ', f);
::funlockfile(f);
::fclose(f);
- ], [ac_stdio_locking=yes], [ac_stdio_locking=no])
+ ],[ac_stdio_locking=yes],[ac_stdio_locking=no])
AC_MSG_RESULT($ac_stdio_locking)
if test "$ac_stdio_locking" = yes; then
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 0469cbe0f59c..3d825a69fa2e 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -55051,6 +55051,13 @@ $as_echo_n "checking whether flockfile and
putc_unlocked are defined in <stdio.h
/* end confdefs.h. */
#include <stdio.h>
+ #if __has_include(<newlib.h>)
+ # ifdef __CYGWIN__
+ // Cygwin has working flockfile
+ # else
+ # error No usable flockfile on most newlib targets
+ # endif
+ #endif
int
main ()
--
2.52.0
