Bug#959602: gtkmm3.0: FTBFS: gtk-demo/demowindow.cc:54:1: error: ‘demo_columns’ function uses ‘auto’ type specifier without trailing return type

[Gianfranco Costamagna]

control: tags -1 patch

Changing stdc++11 to stdc++14 fixed the build failure

--- gtkmm3.0-3.24.2/debian/patches/series	1970-01-01 00:00:00.000000000 +0000
+++ gtkmm3.0-3.24.2/debian/patches/series	2020-05-07 10:03:05.000000000 +0000
@@ -0,0 +1 @@
+stdc++14.patch
diff -Nru gtkmm3.0-3.24.2/debian/patches/stdc++14.patch gtkmm3.0-3.24.2/debian/patches/stdc++14.patch
--- gtkmm3.0-3.24.2/debian/patches/stdc++14.patch	1970-01-01 00:00:00.000000000 +0000
+++ gtkmm3.0-3.24.2/debian/patches/stdc++14.patch	2020-05-07 10:03:05.000000000 +0000
@@ -0,0 +1,16 @@
+Description:
+   * Use std=c++14 for build, to fix a build failure on i386
+Author: Gianfranco Costamagna <locutusofborg at debian.org>
+Last-Update: 2020-05-07
+
+--- gtkmm3.0-3.24.2.orig/configure.ac
++++ gtkmm3.0-3.24.2/configure.ac
+@@ -45,7 +45,7 @@ MM_CONFIG_DOCTOOL_DIR([docs])
+ AC_SUBST([LIBGTKMM_SO_VERSION], [2:0:1])
+ 
+ AC_PROG_CXX
+-MM_AX_CXX_COMPILE_STDCXX([11], [noext],[mandatory])
++MM_AX_CXX_COMPILE_STDCXX([14], [noext],[mandatory])
+ 
+ AC_DISABLE_STATIC
+ LT_INIT([win32-dll])

On Sun, 3 May 2020 14:37:53 +0200 Lucas Nussbaum <lucas at debian.org> wrote:
> Source: gtkmm3.0
> Version: 3.24.2-1
> Severity: serious
> Justification: FTBFS on amd64
> Tags: bullseye sid ftbfs
> Usertags: ftbfs-20200501 ftbfs-bullseye
> 
> Hi,
> 
> During a rebuild of all packages in sid, your package failed to build
> on amd64.
> 
> Relevant part (hopefully):
> > g++ -std=c++11 -DHAVE_CONFIG_H   -I.. -I../gdk  -I../gtk  -pthread -pthread -I/usr/include/atkmm-1.6 -I/usr/include/giomm-2.4 -I/usr/lib/x86_64-linux-gnu/giomm-2.4/include -I/usr/include/pangomm-1.4 -I/usr/lib/x86_64-linux-gnu/pangomm-1.4/include -I/usr/include/glibmm-2.4 -I/usr/lib/x86_64-linux-gnu/glibmm-2.4/include -I/usr/include/cairomm-1.0 -I/usr/lib/x86_64-linux-gnu/cairomm-1.0/include -I/usr/include/sigc++-2.0 -I/usr/lib/x86_64-linux-gnu/sigc++-2.0/include -I/usr/include/gtk-3.0/unix-print -I/usr/include/gtk-3.0 -I/usr/include/at-spi2-atk/2.0 -I/usr/include/at-spi-2.0 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/gtk-3.0 -I/usr/include/gio-unix-2.0 -I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/fribidi -I/usr/include/harfbuzz -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/uuid -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -DDEMOCODEDIR=\"""\"  -Wdate-time -D_FORTIFY_SOURCE=2 -Wall -DGLIBMM_DISABLE_DEPRECATED -DGIOMM_DISABLE_DEPRECATED -DGTKMM_DISABLE_DEPRECATED -DGDKMM_DISABLE_DEPRECATED -g -O2 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -c -o gtk-demo/gtkmm_demo-example_appwindow.o `test -f 'gtk-demo/example_appwindow.cc' || echo './'`gtk-demo/example_appwindow.cc
> > gtk-demo/demowindow.cc:54:1: error: ‘demo_columns’ function uses ‘auto’ type specifier without trailing return type
> >    54 | const auto& demo_columns()
> >       | ^~~~~
> > gtk-demo/demowindow.cc:54:1: note: deduced return type only available with ‘-std=c++14’ or ‘-std=gnu++14’
> > make[4]: *** [Makefile:733: gtk-demo/gtkmm_demo-demowindow.o] Error 1
> 
> The full build log is available from:
>    http://qa-logs.debian.net/2020/05/01/gtkmm3.0_3.24.2-1_unstable.log
> 
> A list of current common problems and possible solutions is available at
> http://wiki.debian.org/qa.debian.org/FTBFS . You're welcome to contribute!
> 
> About the archive rebuild: The rebuild was done on EC2 VM instances from
> Amazon Web Services, using a clean, minimal and up-to-date chroot. Every
> failed build was retried once to eliminate random failures.
> 
>