[PATCH v2] Detect if symbol versioning is supported (was "Disable symbol versioning if .symver doesn't work")

[PATCH v2] Detect if symbol versioning is supported (was "Disable symbol versioning if .symver doesn't work")

[Ulf Hermann]

If not, throw an error unless symbol versioning was explicitly
disabled.

Signed-off-by: Ulf Hermann <ulf.hermann@qt.io>
---
 ChangeLog    |  4 ++++
 configure.ac | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 01f88f3..22c46c6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2017-05-03  Ulf Hermann  <ulf.hermann@qt.io>
+
+	* configure.ac: Test if symbol versioning is supported.
+
 2017-04-27  Ulf Hermann  <ulf.hermann@qt.io>
 
 	* configure.ac: Check if the compiler supports
diff --git a/configure.ac b/configure.ac
index 0266a36..48b06de 100644
--- a/configure.ac
+++ b/configure.ac
@@ -376,6 +376,21 @@ AS_IF([test "x$enable_textrelcheck" != "xno"],
 AC_ARG_ENABLE([symbol-versioning],
 AS_HELP_STRING([--disable-symbol-versioning],
                [Disable symbol versioning in shared objects]))
+
+AC_CACHE_CHECK([whether symbol versioning is supported], ac_cv_symbol_versioning, [dnl
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([dnl
+#define NEW_VERSION(name, version) \
+  asm (".symver " #name "," #name "@@@" #version);
+int foo(int x) { return x + 1; }
+NEW_VERSION (foo, ELFUTILS_12.12)
+])], ac_cv_symbol_versioning=yes, ac_cv_symbol_versioning=no)])
+if test "$ac_cv_symbol_versioning" = "no"; then
+    if test "x$enable_symbol_versioning" != "xno"; then
+        AC_MSG_ERROR([Symbol versioning is not supported.
+                      Use --disable-symbol-versioning to build without.])
+    fi
+fi
+
 AM_CONDITIONAL(SYMBOL_VERSIONING, [test "x$enable_symbol_versioning" != "xno"])
 AS_IF([test "x$enable_symbol_versioning" = "xno"],
       [AC_MSG_WARN([Disabling symbol versioning breaks ABI compatibility.])
-- 
2.1.4