From 9f473b70cb7aa124cc095b83c912f777045e913b Mon Sep 17 00:00:00 2001
From: Mike Fleetwood <mike.fleetwood@googlemail.com>
Date: Wed, 30 Aug 2023 19:01:40 +0100
Subject: [PATCH] Always require C++11 compilation (!117)

All the oldest supported distributions now have versions of GTK C++
libraries which require C++11 compilation, therefore forcing GParted to
require C++11 compilation [1][2][3].  Fragment of existing ./configure
output which lists the library versions requiring C++11 compilation:

    $ ./configure
    ...
    checking for glibmm >= 2.45.40 which requires C++11 compilation... yes
    checking for libsigc++ >= 2.5.1 which requires C++11 compilation... yes
    checking for gtkmm >= 3.18.0 which requires C++11 compilation... yes
    checking whether g++ supports C++11 features with -std=gnu++11... yes

The oldest supported distributions and their versions of GTK C++
libraries and GCC compiler:

    Distribution        gtkmm    glibmm   libsigc++   gcc

    Debian 10           3.24.0   2.58.0   2.10.1      4.8.3
    RHEL / CentOS 7.9   3.22.2   2.56.0   2.10.0      4.8.5
    SLES 12 SP5         3.20.1   2.48.1   2.8.0       4.8
    Ubuntu 20.04 LTS    3.24.2   2.64.2   2.10.2      9.3.0

Technically GCC didn't have full C++11 support until GCC 4.8.1 [6] and
SLES 12 SP5 only has GCC 4.8 (as well as many later versions of GCC).
However which ever version of the GCC compiler is being used to compile
the GTK C++ libraries it must have all the features needed to compile
those libraries.

Simplify the configure script and just always require a C++11 capable
compiler.  This also allows the use of C++11 features in the GParted
code.

[1] commit cc0740148e6ba0da9e30608deea2aa13078c2584
    port-to-gtk3: Switch to Gtkmm3 (#7)
[2] commit 707bae6fed6783e84600c6143f0f4bfd7989f56f
    Enable C++11 compilation when using libsigc++ 2.5.1 and later (#758545)
[3] commit d6d7cb2bbf2fc381b890f63bbbf626eacfc8cdf8
    Enable C++11 compilation when using glibmm 2.45.40 and later (#756035)
[4] SUSE Product Support Lifecycle, SUSE Linux Enterprise Server 12
    https://www.suse.com/lifecycle/#suse-linux-enterprise-server-12
[5] SUSE package search
    https://scc.suse.com/packages?name=SUSE%20Linux%20Enterprise%20Server&version=12.5&arch=x86_64&query=&module=
[6] C++ Standards Support in GCC, C++11 Support in GCC
    https://gcc.gnu.org/projects/cxx-status.html#cxx11

Closes !117 - Require C++11 compilation
---
 configure.ac | 34 ++--------------------------------
 1 file changed, 2 insertions(+), 32 deletions(-)

diff --git a/configure.ac b/configure.ac
index b7fd0655..038fab48 100644
--- a/configure.ac
+++ b/configure.ac
@@ -209,38 +209,8 @@ dnl Check for glibmm minimum required version.
 PKG_CHECK_MODULES([GLIBMM], [glibmm-2.4 >= 2.32.0])
 
 
-need_cxx_compile_stdcxx_11=no
-dnl Check for glibmm >= 2.45.40 which requires C++11 compilation.
-AC_MSG_CHECKING([for glibmm >= 2.45.40 which requires C++11 compilation])
-PKG_CHECK_EXISTS(
-	[glibmm-2.4 >= 2.45.40],
-	[need_cxx_compile_stdcxx_11=yes
-	 AC_MSG_RESULT([yes])
-	],
-	[AC_MSG_RESULT([no])]
-)
-dnl Check for libsigc++ >= 2.5.1 which requires C++11 compilation.
-AC_MSG_CHECKING([for libsigc++ >= 2.5.1 which requires C++11 compilation])
-PKG_CHECK_EXISTS(
-	[sigc++-2.0 >= 2.5.1],
-	[need_cxx_compile_stdcxx_11=yes
-	 AC_MSG_RESULT([yes])
-	],
-	[AC_MSG_RESULT([no])]
-)
-dnl Check for gtkmm >= 3.18.0 which requires C++11 compilation.
-AC_MSG_CHECKING([for gtkmm >= 3.18.0 which requires C++11 compilation])
-PKG_CHECK_EXISTS(
-	[gtkmm-3.0 >= 3.18.0],
-	[need_cxx_compile_stdcxx_11=yes
-	 AC_MSG_RESULT([yes])
-	],
-	[AC_MSG_RESULT([no])]
-)
-dnl Enable C++11 compilation only if required.
-if test "x$need_cxx_compile_stdcxx_11" = xyes; then
-	AX_CXX_COMPILE_STDCXX_11()
-fi
+dnl Require C++11 compilation.
+AX_CXX_COMPILE_STDCXX_11()
 
 
 dnl Check for gtkmm >= 3.16 to determine availability of Gtk::Label::set_xalign().