GTK not really optional
Using 0cfc3d79 + !2 (merged), the build fails for me when I do not have gtk3 available, even though it is supposed to be optional (configure does not complain about its absence):
CC dpapview.o
dpapview.c:28:10: fatal error: gtk/gtk.h: No such file or directory
28 | #include <gtk/gtk.h>
| ^~~~~~~~~~~
compilation terminated.
make[3]: *** [Makefile:659: dpapview.o] Error 1
make[3]: Leaving directory '/build/libdmapsharing/tests'
make[2]: *** [Makefile:560: all] Error 2
make[2]: Leaving directory '/build/libdmapsharing/tests'
make[1]: *** [Makefile:523: all-recursive] Error 1
make[1]: Leaving directory '/build/libdmapsharing'
make: *** [Makefile:430: all] Error 2
configure output:
configure flags: --disable-static --disable-dependency-tracking --prefix=/nix/store/xkf0lcxyy2bkcmzjwyr7z71nydk6dm1l-libdmapsharing-3.9.8 --bindir=/nix/store/ly29pp8c8awm7cs3mw35c5pyc1bzvdlm-libdmapsharing-3.9.8-dev/bin --sbindir=/nix/store/ly29pp8c8awm7cs3mw35c5pyc1bzvdlm-libdmapsharing-3.9.8-dev/sbin --includedir=/nix/store/ly29pp8c8awm7cs3mw35c5pyc1bzvdlm-libdmapsharing-3.9.8-dev/include --oldincludedir=/nix/store/ly29pp8c8awm7cs3mw35c5pyc1bzvdlm-libdmapsharing-3.9.8-dev/include --mandir=/nix/store/ly29pp8c8awm7cs3mw35c5pyc1bzvdlm-libdmapsharing-3.9.8-dev/share/man --infodir=/nix/store/ly29pp8c8awm7cs3mw35c5pyc1bzvdlm-libdmapsharing-3.9.8-dev/share/info --docdir=/nix/store/xkf0lcxyy2bkcmzjwyr7z71nydk6dm1l-libdmapsharing-3.9.8/share/doc/libdmapsharing --libdir=/nix/store/xkf0lcxyy2bkcmzjwyr7z71nydk6dm1l-libdmapsharing-3.9.8/lib --libexecdir=/nix/store/xkf0lcxyy2bkcmzjwyr7z71nydk6dm1l-libdmapsharing-3.9.8/libexec --localedir=/nix/store/xkf0lcxyy2bkcmzjwyr7z71nydk6dm1l-libdmapsharing-3.9.8/share/locale --enable-gtk-doc
configure: configuring libdmapsharing for development with nano LIBDMAPSHARING_CVS=no
checking whether make supports nested variables... yes
checking for a BSD-compatible install... /nix/store/3k8lm51wqhl7nyr55l9cn9w2glqbdw7n-coreutils-8.31/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /nix/store/3k8lm51wqhl7nyr55l9cn9w2glqbdw7n-coreutils-8.31/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether to enable maintainer-specific portions of Makefiles... no
checking whether make supports the include directive... yes (GNU style)
checking for gcc... gcc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking whether gcc understands -c and -o together... yes
checking dependency style of gcc... none
checking to see if compiler understands -Wall... yes
checking for gcc... (cached) gcc
checking whether we are using the GNU C compiler... (cached) yes
checking whether gcc accepts -g... (cached) yes
checking for gcc option to accept ISO C89... (cached) none needed
checking whether gcc understands -c and -o together... (cached) yes
checking dependency style of gcc... (cached) none
checking how to run the C preprocessor... gcc -E
checking for gcc... (cached) gcc
checking whether we are using the GNU C compiler... (cached) yes
checking whether gcc accepts -g... (cached) yes
checking for gcc option to accept ISO C89... (cached) none needed
checking whether gcc understands -c and -o together... (cached) yes
checking dependency style of gcc... (cached) none
checking for grep that handles long lines and -e... /nix/store/fpmxrgczd54b2b0kspdi3c44m6hpxbzi-gnugrep-3.4/bin/grep
checking for egrep... /nix/store/fpmxrgczd54b2b0kspdi3c44m6hpxbzi-gnugrep-3.4/bin/grep -E
checking for ANSI C header files... yes
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking how to print strings... printf
checking for a sed that does not truncate output... /nix/store/abrakd4qy9py5s1mys72583r08mamkgc-gnused-4.8/bin/sed
checking for fgrep... /nix/store/fpmxrgczd54b2b0kspdi3c44m6hpxbzi-gnugrep-3.4/bin/grep -F
checking for ld used by gcc... ld
checking if the linker (ld) is GNU ld... yes
checking for BSD- or MS-compatible name lister (nm)... nm
checking the name lister (nm) interface... BSD nm
checking whether ln -s works... yes
checking the maximum length of command line arguments... 1572864
checking how to convert x86_64-pc-linux-gnu file names to x86_64-pc-linux-gnu format... func_convert_file_noop
checking how to convert x86_64-pc-linux-gnu file names to toolchain format... func_convert_file_noop
checking for ld option to reload object files... -r
checking for objdump... objdump
checking how to recognize dependent libraries... pass_all
checking for dlltool... no
checking how to associate runtime and link libraries... printf %s\n
checking for archiver @FILE support... @
checking for strip... strip
checking for ranlib... ranlib
checking command to parse nm output from gcc object... ok
checking for sysroot... no
checking for a working dd... /nix/store/3k8lm51wqhl7nyr55l9cn9w2glqbdw7n-coreutils-8.31/bin/dd
checking how to truncate binary pipes... /nix/store/3k8lm51wqhl7nyr55l9cn9w2glqbdw7n-coreutils-8.31/bin/dd bs=4096 count=1
./configure: line 8608: /usr/bin/file: No such file or directory
checking for mt... no
checking if : is a manifest tool... no
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking for dlfcn.h... yes
checking for objdir... .libs
checking if gcc supports -fno-rtti -fno-exceptions... no
checking for gcc option to produce PIC... -fPIC -DPIC
checking if gcc PIC flag -fPIC -DPIC works... yes
checking if gcc static flag -static works... no
checking if gcc supports -c -o file.o... yes
checking if gcc supports -c -o file.o... (cached) yes
checking whether the gcc linker (ld) supports shared libraries... yes
checking whether -lc should be explicitly linked in... no
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking if libtool supports shared libraries... yes
checking whether to build shared libraries... yes
checking whether to build static libraries... no
checking pkg-config is at least version 0.9.0... yes
checking for gobject-introspection... yes
checking for gtk-doc... yes
checking for gtkdoc-check... gtkdoc-check.test
checking for gtkdoc-check... /nix/store/h47ihnvgh0hvzgs87f3dkgvx4acbadqf-gtk-doc-1.32/bin/gtkdoc-check
checking for gtkdoc-rebase... /nix/store/h47ihnvgh0hvzgs87f3dkgvx4acbadqf-gtk-doc-1.32/bin/gtkdoc-rebase
checking for gtkdoc-mkpdf... /nix/store/h47ihnvgh0hvzgs87f3dkgvx4acbadqf-gtk-doc-1.32/bin/gtkdoc-mkpdf
checking whether to build gtk-doc documentation... yes
checking for glib-2.0 >= 2.10.0 gobject-2.0 >= 2.10.0... yes
checking for check >= 0.9.4... yes
checking for pkg-config... yes
checking for glib-2.0 >= 2.40... yes
checking for gthread-2.0... yes
checking for gobject-2.0... yes
checking for gdk-pixbuf-2.0... yes
checking for avahi-client >= 0.6
avahi-glib >= 0.6... yes
checking for howl... no
checking dns_sd.h usability... no
checking dns_sd.h presence... no
checking for dns_sd.h... no
configure: Detected Avahi; using it for mDNS/DNS-SD
checking for libsoup-2.4 >= 2.48.0... yes
checking for gstreamer-app-1.0
gstreamer-plugins-base-1.0 >= 0.10.23.2... yes
checking for valac... /nix/store/36vh0bldkxk21hq8ghmn9ca4djfciq0b-vala-0.48.1/bin/valac
checking whether /nix/store/36vh0bldkxk21hq8ghmn9ca4djfciq0b-vala-0.48.1/bin/valac is at least version 0.11.4... yes
checking for vala-gen-introspect... /nix/store/36vh0bldkxk21hq8ghmn9ca4djfciq0b-vala-0.48.1/bin/vala-gen-introspect
checking for vapigen... /nix/store/36vh0bldkxk21hq8ghmn9ca4djfciq0b-vala-0.48.1/bin/vapigen
checking for pedansee... no
checking for gtk+-3.0... no
checking for gee-0.8... yes
checking for uncompress in -lz... yes
checking if unaligned memory access works correctly... yes
checking that generated files are newer than configure... done
configure: creating ./config.status
config.status: creating Makefile
config.status: creating doc/Makefile
config.status: creating libdmapsharing-4.0-uninstalled.pc
config.status: creating libdmapsharing-4.0.pc
config.status: creating libdmapsharing/Makefile
config.status: creating libdmapsharing/dmap-config.h
config.status: creating tests/Makefile
config.status: creating m4/Makefile
config.status: creating media/Makefile
config.status: creating vala/Makefile
config.status: creating vala/libdmapsharing-4.0-uninstalled.files
config.status: creating config.h
config.status: executing depfiles commands
config.status: executing libtool commands