libstdc++: Use GCC_TRY_COMPILE_OR_LINK for getentropy, arc4random

Since r12-5056-g3439657b0286, there has been a regression in
test results; an additional 100 FAILs running the g++ and
libstdc++ testsuite on cris-elf, a newlib target.  The
failures are linker errors, not finding a definition for
getentropy.  It appears newlib has since 2017-12-03
declarations of getentropy and arc4random, and provides an
implementation of arc4random using getentropy, but provides no
definition of getentropy, not even a stub yielding ENOSYS.
This is similar to what it does for many other functions too.

While fixing newlib (like adding said stub) would likely help,
it still leaves older newlib releases hanging.  Thankfully,
the libstdc++ configury test can be improved to try linking
where possible; using the bespoke GCC_TRY_COMPILE_OR_LINK
instead of AC_TRY_COMPILE.  BTW, I see a lack of consistency;
some tests use AC_TRY_COMPILE and some GCC_TRY_COMPILE_OR_LINK
for no apparent reason, but this commit just amends
r12-5056-g3439657b0286.

libstdc++-v3:
	PR libstdc++/103166
	* acinclude.m4 (GLIBCXX_CHECK_GETENTROPY, GLIBCXX_CHECK_ARC4RANDOM):
	Use GCC_TRY_COMPILE_OR_LINK instead of AC_TRY_COMPILE.
	* configure: Regenerate.

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 4adfdf646acbcb63c9c8bb5199d17ac5c9970366..30bd92d37f236ee0fbec757df75004e02df197eb 100644 (file)
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -4839,7 +4839,7 @@ AC_DEFUN([GLIBCXX_CHECK_GETENTROPY], [
   AC_LANG_CPLUSPLUS
   AC_MSG_CHECKING([for getentropy])
   AC_CACHE_VAL(glibcxx_cv_getentropy, [
-      AC_TRY_COMPILE(
+      GCC_TRY_COMPILE_OR_LINK(
        [#include <unistd.h>],
        [unsigned i;
         ::getentropy(&i, sizeof(i));],
@@ -4862,7 +4862,7 @@ AC_DEFUN([GLIBCXX_CHECK_ARC4RANDOM], [
   AC_LANG_CPLUSPLUS
   AC_MSG_CHECKING([for arc4random])
   AC_CACHE_VAL(glibcxx_cv_arc4random, [
-      AC_TRY_COMPILE(
+      GCC_TRY_COMPILE_OR_LINK(
        [#include <stdlib.h>],
        [unsigned i = ::arc4random();],
        [glibcxx_cv_arc4random=yes], [glibcxx_cv_arc4random=no])

diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 3a572475546f1d8eab8b7b2629eeb33d8bb22134..3eb391f409f269cfcd16cdc02957a1bbb20dd73f 100755 (executable)
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -75445,7 +75445,8 @@ $as_echo_n "checking for getentropy... " >&6; }
   $as_echo_n "(cached) " >&6
 else
 
-      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+      if test x$gcc_no_link = xyes; then
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <unistd.h>
 int
@@ -75463,6 +75464,30 @@ else
   glibcxx_cv_getentropy=no
 fi
 rm -f core conftest.err conftest.$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.$ac_ext
+/* end confdefs.h.  */
+#include <unistd.h>
+int
+main ()
+{
+unsigned i;
+        ::getentropy(&i, sizeof(i));
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  glibcxx_cv_getentropy=yes
+else
+  glibcxx_cv_getentropy=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
 
 fi
 
@@ -75496,7 +75521,8 @@ $as_echo_n "checking for arc4random... " >&6; }
   $as_echo_n "(cached) " >&6
 else
 
-      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+      if test x$gcc_no_link = xyes; then
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <stdlib.h>
 int
@@ -75513,6 +75539,29 @@ else
   glibcxx_cv_arc4random=no
 fi
 rm -f core conftest.err conftest.$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.$ac_ext
+/* end confdefs.h.  */
+#include <stdlib.h>
+int
+main ()
+{
+unsigned i = ::arc4random();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  glibcxx_cv_arc4random=yes
+else
+  glibcxx_cv_arc4random=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
 
 fi