Fix build for systems without POSIX truncate

Older versions of newlib do not provide truncate so add a configure
check for it, and provide a fallback definition.

There were also some missing exports in the linker script, which went
unnoticed because there are no tests for some functions. A new link-only
test checks that every filesystem operation function is defined by the
library.

	* acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Check for truncate.
	* config.h.in: Regenerate.
	* config/abi/pre/gnu.ver: Order patterns for filesystem operations
	alphabetically and add missing entries for copy_symlink,
	hard_link_count, rename, and resize_file.
	* configure: Regenerate.
	* src/c++17/fs_ops.cc (resize_file): Remove #if so posix::truncate is
	used unconditionally.
	* src/filesystem/ops-common.h (__gnu_posix::truncate)
	[!_GLIBCXX_HAVE_TRUNCATE]: Provide fallback definition that only
	supports truncating to zero length.
	* testsuite/27_io/filesystem/operations/all.cc: New test.
	* testsuite/27_io/filesystem/operations/resize_file.cc: New test.

From-SVN: r267647

1 files changed, 56 insertions, 0 deletions

diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index e01d900..15848e3 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -81038,6 +81038,62 @@ $as_echo "#define HAVE_SYMLINK 1" >>confdefs.h
     fi
     { $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_symlink" >&5
 $as_echo "$glibcxx_cv_symlink" >&6; }
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for truncate" >&5
+$as_echo_n "checking for truncate... " >&6; }
+    if ${glibcxx_cv_truncate+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+        if test x$gcc_no_link = xyes; then
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <unistd.h>
+int
+main ()
+{
+truncate("", 99);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  glibcxx_cv_truncate=yes
+else
+  glibcxx_cv_truncate=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  if test x$gcc_no_link = xyes; then
+  as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <unistd.h>
+int
+main ()
+{
+truncate("", 99);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  glibcxx_cv_truncate=yes
+else
+  glibcxx_cv_truncate=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
+fi
+
+    if test $glibcxx_cv_truncate = yes; then
+
+$as_echo "#define HAVE_TRUNCATE 1" >>confdefs.h
+
+    fi
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_truncate" >&5
+$as_echo "$glibcxx_cv_truncate" >&6; }
     CXXFLAGS="$ac_save_CXXFLAGS"
     ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'