Bug#1015713: zam-plugins: ftbfs with LTO (link time optimization) enabled

[Matthias Klose <doko@debian.org>]

Package: src:zam-plugins
Version: 3.14~repack3-1
Severity: minor
Tags: sid bookworm
User: debian-gcc@lists.debian.org
Usertags: ftbfs-lto

This package currently fails to build (at least on the amd64
architecture) with link time optimizations enabled.  For a background
for LTO please see

https://wiki.debian.org/ToolChain/LTO

The goal is to enable this optimization by default in an upcoming
Debian release in dpkg-buildflags for 64bit architectures.  The goal
is to get this package to build with link time optimizations, or to
explicitly disable link time optimizations for this package build.

To reproduce the build failure, enable the lto optimization in
testing/unstable by adding "optimize=+lto" to DEB_BUILD_MAINT_OPTIONS
in the debian/rules file, or if this macro is unset, just set it:

export DEB_BUILD_MAINT_OPTIONS = optimize=+lto

Please try to fix the build with lto enabled, fixing the packaging or
forwarding the issue upstream. If the issue cannot be fixed,
explicitly disallow building the package with lto by adding to your
rules file:

export DEB_BUILD_MAINT_OPTIONS = optimize=-lto

or adding that string to your existing setting of DEB_BUILD_MAINT_OPTIONS.

The full build log can be found at:
http://qa-logs.debian.net/2022/06/09/dpkglto/zam-plugins_3.14~repack3-1_unstable_dpkglto.log
The last lines of the build log are at the end of this report.

[...]
dh clean
   dh_clean
 debian/rules binary
dh binary
   dh_update_autotools_config
   dh_autoreconf
   dh_auto_configure
   debian/rules override_dh_auto_build
make[1]: Entering directory '/<<PKGBUILDDIR>>'
/usr/bin/make \
	PREFIX=/usr \
	NOOPT=false
make[2]: Entering directory '/<<PKGBUILDDIR>>'
/usr/bin/make -C dpf/dgl
make[3]: Entering directory '/<<PKGBUILDDIR>>/dpf/dgl'
Compiling src/Application.cpp
Compiling src/Color.cpp
Compiling src/Geometry.cpp
Compiling src/ImageBase.cpp
Compiling src/Resources.cpp
Compiling src/Widget.cpp
Compiling src/OpenGL.cpp (OpenGL variant)
Compiling src/Image.cpp (OpenGL variant)
Compiling src/ImageWidgets.cpp (OpenGL variant)
Compiling src/NanoVG.cpp (OpenGL variant)
Compiling src/WidgetPrivateData.cpp (OpenGL variant)
Compiling src/Window.cpp (OpenGL variant)
Creating libdgl-opengl.a
Symlinking libdgl.a
make[3]: Leaving directory '/<<PKGBUILDDIR>>/dpf/dgl'
/usr/bin/make -C plugins/ZamComp
make[3]: Entering directory '/<<PKGBUILDDIR>>/plugins/ZamComp'
Compiling ZamCompPlugin.cpp
Compiling ZamCompArtwork.cpp
Compiling ZamCompUI.cpp
ZamCompUI.cpp: In member function ‘virtual void DISTRHO::ZamCompUI::onDisplay()’:
ZamCompUI.cpp:278:5: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation]
  278 |     for (int i=numRedLeds; i>0; --i)
      |     ^~~
ZamCompUI.cpp:281:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘for’
  281 |         if (fLedYellowValue >= 20.f)
      |         ^~
Compiling DistrhoPluginMain.cpp (JACK)
Compiling DistrhoUIMain.cpp (JACK)
Creating JACK standalone for ZamComp
In function ‘fons__freeFont’,
    inlined from ‘fonsAddFontMem’ at ../../dpf/dgl/src/nanovg/fontstash.h:919:16,
    inlined from ‘nvgCreateFontMem’ at ../../dpf/dgl/src/nanovg/nanovg.c:2164:23,
    inlined from ‘loadSharedResources’ at ../../dpf/dgl/src/NanoVG.cpp:925:21:
../../dpf/dgl/src/nanovg/fontstash.h:821:47: warning: ‘free’ called on unallocated object ‘temp1’ [-Wfree-nonheap-object]
  821 |         if (font->freeData && font->data) free((void*)font->data);
      |                                               ^
../../dpf/dgl/src/nanovg/fontstash.h: In member function ‘loadSharedResources’:
../../dpf/dgl/src/Resources.cpp:5:28: note: declared here
    5 | static const unsigned char temp1[] = {0,1,0,0,0,19,1,0,0,4,0,48,70,70,84,77,102,9,29,176,0,0,1,60,0,0,0,28,71,68,69,70,144,48,138,184,0,0,1,88,
      |                            ^
/usr/bin/ld: /tmp/cc99AiZl.ltrans0.ltrans.o: in function `DGL::ZamKnob::onDisplay()':
./plugins/ZamComp/../../dpf/dgl/src/Geometry.cpp:906: undefined reference to `DGL::Rectangle<int>::_draw(bool)'
/usr/bin/ld: ./plugins/ZamComp/../../dpf/dgl/src/Geometry.cpp:906: undefined reference to `DGL::Rectangle<int>::_draw(bool)'
/usr/bin/ld: /tmp/cc99AiZl.ltrans1.ltrans.o: in function `DGL::Image::_drawAt(DGL::Point<int> const&)':
./plugins/ZamComp/../../dpf/dgl/src/Geometry.cpp:906: undefined reference to `DGL::Rectangle<int>::_draw(bool)'
collect2: error: ld returned 1 exit status
make[3]: *** [../../dpf/Makefile.plugins.mk:174: ../../bin/ZamComp] Error 1
make[3]: Leaving directory '/<<PKGBUILDDIR>>/plugins/ZamComp'
make[2]: *** [Makefile:32: ZamComp] Error 2
make[2]: Leaving directory '/<<PKGBUILDDIR>>'
make[1]: *** [debian/rules:16: override_dh_auto_build] Error 2
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:11: binary] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2