From f2b844307d84d34a65c8e527ff9b94bc0d7972bb Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Sun, 25 May 2025 02:25:59 +0200
Subject: [PATCH] Fix test for .symver asm directive support in configure

We need to use it with the correct, i.e. existing, symbol name, which
means the mangled name actually used by the linker and not just the name
of the function as it appears in the source.

Fix the test to actually detect lack of support for .symver when using
clang with -flto.

Closes #25438.
---
 configure        | 38 +++++++++++++++++++++++++++++++++-----
 configure.in     | 14 +++++++++++---
 docs/changes.txt |  1 +
 3 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/configure b/configure
index 57a04db1f8..ff442b5c9f 100755
--- a/configure
+++ b/configure
@@ -33873,18 +33873,26 @@ if ${wx_cv_elf_symver_multiple+:} false; then :
 else
 
                     echo "lib_new {}; lib_old { *; };" >conftest.sym
+                    ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
                     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
                             #include "wx/private/elfversion.h"
-                            wxELF_SYMVER("foo","foo@lib_old")
-                            wxELF_SYMVER("foo","foo@@lib_new")
+                            extern "C" {
+                            wxELF_SYMVER("_foo","_foo@lib_old")
+                            wxELF_SYMVER("_foo","_foo@@lib_new")
                             void foo() {}
+                            }
                             int main() { return 0; }
 
 _ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
+if ac_fn_cxx_try_link "$LINENO"; then :
   wx_cv_elf_symver_multiple=yes
 else
   wx_cv_elf_symver_multiple=no
@@ -33892,6 +33900,12 @@ else
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
+                    ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
                     rm -f conftest.sym
 
 
@@ -33909,17 +33923,25 @@ if ${wx_cv_elf_symver+:} false; then :
 else
 
                         echo "lib_new {}; lib_old { *; };" >conftest.sym
+                        ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
                         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
                                 #include "wx/private/elfversion.h"
-                                wxELF_SYMVER("foo","foo@@lib_new")
+                                extern "C" {
+                                wxELF_SYMVER("_foo","_foo@@lib_new")
                                 void foo() {}
+                                }
                                 int main() { return 0; }
 
 _ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
+if ac_fn_cxx_try_link "$LINENO"; then :
   wx_cv_elf_symver=yes
 else
   wx_cv_elf_symver=no
@@ -33927,6 +33949,12 @@ else
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
+                        ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
                         rm -f conftest.sym
 
 
diff --git a/configure.in b/configure.in
index 610a440a0c..9e119382a8 100644
--- a/configure.in
+++ b/configure.in
@@ -4025,17 +4025,21 @@ if test "$wxUSE_SHARED" = "yes"; then
                 wx_cv_elf_symver_multiple,
                 [
                     echo "lib_new {}; lib_old { *; };" >conftest.sym
+                    AC_LANG_PUSH(C++)
                     AC_LINK_IFELSE([
                         AC_LANG_SOURCE([
                             #include "wx/private/elfversion.h"
-                            wxELF_SYMVER("foo","foo@lib_old")
-                            wxELF_SYMVER("foo","foo@@lib_new")
+                            extern "C" {
+                            wxELF_SYMVER("_foo","_foo@lib_old")
+                            wxELF_SYMVER("_foo","_foo@@lib_new")
                             void foo() {}
+                            }
                             int main() { return 0; }
                         ])],
                         wx_cv_elf_symver_multiple=yes,
                         wx_cv_elf_symver_multiple=no
                     )
+                    AC_LANG_POP()
                     rm -f conftest.sym
                 ]
             )
@@ -4047,16 +4051,20 @@ if test "$wxUSE_SHARED" = "yes"; then
                     wx_cv_elf_symver,
                     [
                         echo "lib_new {}; lib_old { *; };" >conftest.sym
+                        AC_LANG_PUSH(C++)
                         AC_LINK_IFELSE([
                             AC_LANG_SOURCE([
                                 #include "wx/private/elfversion.h"
-                                wxELF_SYMVER("foo","foo@@lib_new")
+                                extern "C" {
+                                wxELF_SYMVER("_foo","_foo@@lib_new")
                                 void foo() {}
+                                }
                                 int main() { return 0; }
                             ])],
                             wx_cv_elf_symver=yes,
                             wx_cv_elf_symver=no
                         )
+                        AC_LANG_POP()
                         rm -f conftest.sym
                     ]
                 )
diff --git a/docs/changes.txt b/docs/changes.txt
index efa569222b..f76a70f491 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -255,6 +255,7 @@ Changes in behaviour which may result in build errors
 All (Unix):
 
 - Fix configure build with --with-flavour option broken in 3.2.8 (#25436).
+- Fix configure build with clang and LTO broken in 3.2.8 (#25438).
 
 wxGTK: