assert: choose function-var name on non-gnu

Selects __PRETTY_FUNCTION__ or __func__. Linux assumes GNU, and chooses
__PRETTY_FUNCTION__ if gcc/g++ versions are favorable.

This also includes a fix in ax_c_var_func.m4:

AC_TRY_COMPILE will wrap the test in main{}, and then GCC will complain
about nested functions. Just use the original main{} body.

diff --git a/m4/ax_c_var_func.m4 b/m4/ax_c_var_func.m4
index 0ad7d2b..8b57563 100644
--- a/m4/ax_c_var_func.m4
+++ b/m4/ax_c_var_func.m4
@@ -57,9 +57,9 @@ AC_DEFUN([AX_C_VAR_FUNC],
 [AC_REQUIRE([AC_PROG_CC])
 AC_CACHE_CHECK(whether $CC recognizes __func__, ac_cv_c_var_func,
 AC_TRY_COMPILE(,
-[int main() {
+[
 char *s = __func__;
-}],
+],
 AC_DEFINE(HAVE_FUNC,,
 [Define if the C complier supports __func__]) ac_cv_c_var_func=yes,
 ac_cv_c_var_func=no) )

Signed-off-by: Noah Watkins <[email protected]>

configure.ac

@@ -114,6 +114,8 @@ AX_CHECK_COMPILE_FLAG([-fvar-tracking-assignments], [HAS_VTA_SUPPORT=1], [HAS_VT
 AM_CONDITIONAL(COMPILER_HAS_VTA, [test "$HAS_VTA_SUPPORT" = 1])
 
 AX_CXX_STATIC_CAST
+AX_C_VAR_FUNC
+AX_C_PRETTY_FUNC
 
 # Checks for libraries.
 ACX_PTHREAD

m4/ax_c_pretty_func.m4

@@ -0,0 +1,18 @@
+#
+# Test for C compiler support of __PRETTY_FUNCTION__
+#
+#  - Adapted from ax_c_var_func (Noah Watkins)
+#
+
+AU_ALIAS([AC_C_PRETTY_FUNC], [AX_C_PRETTY_FUNC])
+AC_DEFUN([AX_C_PRETTY_FUNC],
+[AC_REQUIRE([AC_PROG_CC])
+AC_CACHE_CHECK(whether $CC recognizes __PRETTY_FUNCTION__, ac_cv_c_pretty_func,
+AC_TRY_COMPILE(,
+[
+char *s = __PRETTY_FUNCTION__;
+],
+AC_DEFINE(HAVE_PRETTY_FUNC,,
+[Define if the C complier supports __PRETTY_FUNCTION__]) ac_cv_c_pretty_func=yes,
+ac_cv_c_pretty_func=no) )
+])dnl

m4/ax_c_var_func.m4

@@ -0,0 +1,66 @@
+# ===========================================================================
+#       http://www.gnu.org/software/autoconf-archive/ax_c_var_func.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_C_VAR_FUNC
+#
+# DESCRIPTION
+#
+#   This macro tests if the C complier supports the C9X standard __func__
+#   indentifier.
+#
+#   The new C9X standard for the C language stipulates that the identifier
+#   __func__ shall be implictly declared by the compiler as if, immediately
+#   following the opening brace of each function definition, the declaration
+#
+#     static const char __func__[] = "function-name";
+#
+#   appeared, where function-name is the name of the function where the
+#   __func__ identifier is used.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Christopher Currie <[email protected]>
+#
+#   This program is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation; either version 2 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 5
+
+AU_ALIAS([AC_C_VAR_FUNC], [AX_C_VAR_FUNC])
+AC_DEFUN([AX_C_VAR_FUNC],
+[AC_REQUIRE([AC_PROG_CC])
+AC_CACHE_CHECK(whether $CC recognizes __func__, ac_cv_c_var_func,
+AC_TRY_COMPILE(,
+[
+char *s = __func__;
+],
+AC_DEFINE(HAVE_FUNC,,
+[Define if the C complier supports __func__]) ac_cv_c_var_func=yes,
+ac_cv_c_var_func=no) )
+])dnl

src/include/assert.h

@@ -33,21 +33,38 @@ struct FailedAssertion {
 # define __CEPH_ASSERT_VOID_CAST (void)
 #endif
 
-/* Version 2.4 and later of GCC define a magical variable `__PRETTY_FUNCTION__'
-   which contains the name of the function currently being defined.
-   This is broken in G++ before version 2.6.
-   C9x has a similar variable called __func__, but prefer the GCC one since
-   it demangles C++ function names.  */
-# if defined __cplusplus ? __GNUC_PREREQ (2, 6) : __GNUC_PREREQ (2, 4)
-#   define __CEPH_ASSERT_FUNCTION	__PRETTY_FUNCTION__
-# else
-#  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
-#   define __CEPH_ASSERT_FUNCTION	__func__
-#  else
-#   define __CEPH_ASSERT_FUNCTION	((__const char *) 0)
-#  endif
+/*
+ * For GNU, test specific version features. Otherwise (e.g. LLVM) we'll use
+ * the defaults selected below.
+ */
+#ifdef __GNUC_PREREQ
+
+/*
+ * Version 2.4 and later of GCC define a magical variable
+ * `__PRETTY_FUNCTION__' which contains the name of the function currently
+ * being defined.  This is broken in G++ before version 2.6.  C9x has a
+ * similar variable called __func__, but prefer the GCC one since it demangles
+ * C++ function names. We define __CEPH_NO_PRETTY_FUNC if we want to avoid
+ * broken versions of G++.
+ */
+# if defined __cplusplus ? !__GNUC_PREREQ (2, 6) : !__GNUC_PREREQ (2, 4)
+#   define __CEPH_NO_PRETTY_FUNC
 # endif
 
+#endif
+
+/*
+ * Select a function-name variable based on compiler tests, and any compiler
+ * specific overrides.
+ */
+#if defined(HAVE_PRETTY_FUNC) && !defined(__CEPH_NO_PRETTY_FUNC)
+# define __CEPH_ASSERT_FUNCTION __PRETTY_FUNCTION__
+#elif defined(HAVE_FUNC)
+# define __CEPH_ASSERT_FUNCTION __func__
+#else
+# define __CEPH_ASSERT_FUNCTION ((__const char *) 0)
+#endif
+
 extern void register_assert_context(CephContext *cct);
 extern void __ceph_assert_fail(const char *assertion, const char *file, int line, const char *function)
   __attribute__ ((__noreturn__));