NetworkManager/config-extra.h.meson

#mesondefine BINDIR
#mesondefine DATADIR
#mesondefine LIBEXECDIR
#mesondefine LOCALSTATEDIR
#mesondefine NMCONFDIR
#mesondefine NMLIBDIR
#mesondefine NMLOCALEDIR
#mesondefine NMPLUGINDIR
#mesondefine NMRUNDIR
#mesondefine NMSTATEDIR
#mesondefine NMVPNDIR
#mesondefine NM_BUILD_BUILDDIR
#mesondefine NM_BUILD_SRCDIR
#mesondefine PPPD_PLUGIN_DIR
#mesondefine PREFIX
#mesondefine RUNSTATEDIR
#mesondefine SYSCONFDIR
build: create "config-extra.h" header instead of passing directory variables via CFLAGS 1) the command line gets shorter. I frequently run `make V=1` to see the command line arguments for the compiler, and there is a lot of noise. 2) define each of these variables at one place. This makes it easy to verify that for all compilation units, a particular define has the same value. Previously that was not obvious or even not the case (see commit e5d1a71396e107d1909744d26ad401f206c0c915 and commit d63cf1ef2faba57595112a82e962b9643cce4718). The point is to avoid redundancy. 3) not all compilation units need all defines. In fact, most modules would only need a few of these defines. We aimed to pass the necessary minium of defines to each compilation unit, but that was non-obvious to get right and often we set a define that wasn't used. See for example "src_settings_plugins_ibft_cppflags" which needlessly had "-DSYSCONFDIR". This question is now entirely avoided by just defining all variables in a header. We don't care to find the minimum, because every component gets anyway all defines from the header. 4) this also avoids the situation, where a module that previously did not use a particular define gets modified to require it. Previously, that would have required to identify the missing define, and add it to the CFLAGS of the complation unit. Since every compilation now includes "config-extra.h", all defines are available everywhere. 5) the fact that each define is now available in all compilation units could be perceived as a downside. But it isn't, because these defines should have a unique name and one specific value. Defining the same name with different values, or refer to the same value by different names is a bug, not a desirable feature. Since these defines should be unique accross the entire tree, there is no problem in providing them to every compilation unit. 6) the reason why we generate "config-extra.h" this way, instead of using AC_DEFINE() in configure.ac, is due to the particular handling of autoconf for directory variables. See [1]. With meson, it would be trivial to put them into "config.h.meson". While that is not easy with autoconf, the "config-extra.h" workaround seems still preferable to me. [1] https://www.gnu.org/software/autoconf/manual/autoconf-2.63/html_node/Installation-Directory-Variables.html 2018-07-12 08:58:23 +00:00			`#mesondefine BINDIR`
			`#mesondefine DATADIR`
			`#mesondefine LIBEXECDIR`
			`#mesondefine LOCALSTATEDIR`
			`#mesondefine NMCONFDIR`
			`#mesondefine NMLIBDIR`
			`#mesondefine NMLOCALEDIR`
			`#mesondefine NMPLUGINDIR`
			`#mesondefine NMRUNDIR`
			`#mesondefine NMSTATEDIR`
			`#mesondefine NMVPNDIR`
			`#mesondefine NM_BUILD_BUILDDIR`
			`#mesondefine NM_BUILD_SRCDIR`
			`#mesondefine PPPD_PLUGIN_DIR`
			`#mesondefine PREFIX`
			`#mesondefine RUNSTATEDIR`
			`#mesondefine SYSCONFDIR`