[libgnome-volume-control/wip/inigomartinez/meson: 6/8] build: Make use of assert function

[Iñigo Martínez <inigomartinez src gnome org>]

commit 7a83f0caa6bbac71ceaf2bba8e0565dedfeca037
Author: Iñigo Martínez <inigomartinez gmail com>
Date:   Sat Jan 27 09:45:58 2018 +0100

    build: Make use of assert function
    
    meson has support for `assert` function, which halts meson's
    execution showing a given message when a given condition is false.
    
    This patch takes advantage of this function to slightly improve
    meson's build file readibility.
    
    It also removes a duplicated check for `pkglibdir` being set when
    introspection is also set, because this check is already done when
    a shared library is being created, that is a precondition for
    introspection generation.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=792948

 meson.build |   19 ++++---------------
 1 files changed, 4 insertions(+), 15 deletions(-)
---
diff --git a/meson.build b/meson.build
index a9b223a..0d16eea 100644
--- a/meson.build
+++ b/meson.build
@@ -3,9 +3,7 @@ project('gvc', 'c',
   default_options: 'default_library=static'
 )
 
-if not meson.is_subproject()
-  error('This project is only intended to be used as a subproject!')
-endif
+assert(meson.is_subproject(), 'This project is only intended to be used as a subproject!')
 
 gnome = import('gnome')
 
@@ -68,13 +66,7 @@ cdata.set('HAVE_ALSA', enable_alsa)
 static = get_option('default_library') == 'static'
 enable_introspection = get_option('introspection')
 
-if not static and pkglibdir == ''
-  error('Installing shared library, but pkglibdir is unset!')
-endif
-
-if static and enable_introspection
-  error('Currently meson requires a shared library for building girs.')
-endif
+assert(static or pkglibdir != '', 'Installing shared library, but pkglibdir is unset!')
 
 c_args = ['-DG_LOG_DOMAIN="Gvc"']
 
@@ -93,11 +85,8 @@ libgvc = library('gvc',
 )
 
 if enable_introspection
-  if pkgdatadir == ''
-    error('Installing introspection, but pkgdatadir is unset!')
-  elif (pkglibdir == '')
-    error('Installing introspection, but pkglibdir is unset!')
-  endif
+  assert(not static, 'Currently meson requires a shared library for building girs.')
+  assert(pkgdatadir != '', 'Installing introspection, but pkgdatadir is unset!')
 
   libgvc_gir = gnome.generate_gir(libgvc,
     sources: libgvc_gir_sources + libgvc_gir_headers,