gdbus_codegen: Return 2 targets when docbook is disabled

Also document this behaviour, test it, and fix the return value from
the module -- we create one target and return it thrice to the build
file

docs/markdown/Gnome-module.md

@@ -242,11 +242,14 @@ files and the second specifies the XML file name.
   bundle depending on previous options
 * `install_header`: (*Added 0.46.0*) if true, install the header file
 
-If gdbus-codegen version is greater than 2.55.2 it will return at
-most three targets, one for the souce code, one for the header and
-another one for the files generated with docbook. Otherwise, it
-returns an opaque object containing the source files. Add it to a
-top level target's source list.
+Starting *0.46.0*, this function returns a list of at least two custom targets
+(in order): one for the source code and one for the header. The list will
+contain a third custom target for the generated docbook files if that keyword
+argument is passed.
+
+Earlier versions return a single custom target representing all the outputs.
+Generally, you should just add this list of targets to a top level target's
+source list.
 
 Example:
 

mesonbuild/modules/gnome.py

@@ -873,10 +873,9 @@ This will become a hard error in the future.''')
     def gdbus_codegen(self, state, args, kwargs):
         if len(args) != 2:
             raise MesonException('Gdbus_codegen takes two arguments, name and xml file.')
-        namebase = args[0]
+        namebase = args[0] + '-gdbus'
         xml_file = args[1]
-        target_name = namebase + '-gdbus'
-        cmd = [find_program('gdbus-codegen', target_name)]
+        cmd = [find_program('gdbus-codegen', namebase)]
         if 'interface_prefix' in kwargs:
             cmd += ['--interface-prefix', kwargs.pop('interface_prefix')]
         if 'namespace' in kwargs:
@@ -922,7 +921,7 @@ This will become a hard error in the future.''')
             targets.append(build.CustomTarget(output, state.subdir, state.subproject, custom_kwargs))
 
             if 'docbook' in kwargs:
-                docbook = kwargs.pop('docbook')
+                docbook = kwargs['docbook']
                 if not isinstance(docbook, str):
                     raise MesonException('docbook value must be a string.')
 
@@ -937,7 +936,7 @@ This will become a hard error in the future.''')
                 targets.append(build.CustomTarget(output, state.subdir, state.subproject, custom_kwargs))
         else:
             if 'docbook' in kwargs:
-                docbook = kwargs.pop('docbook')
+                docbook = kwargs['docbook']
                 if not isinstance(docbook, str):
                     raise MesonException('docbook value must be a string.')
 
@@ -955,9 +954,13 @@ This will become a hard error in the future.''')
                              'command': cmd,
                              'build_by_default': build_by_default
                              }
-            ct = build.CustomTarget(target_name, state.subdir, state.subproject, custom_kwargs)
-            targets = [ct, ct, ct]
-        return ModuleReturnValue(targets, targets)
+            ct = build.CustomTarget(namebase, state.subdir, state.subproject, custom_kwargs)
+            # Ensure that the same number (and order) of arguments are returned
+            # regardless of the gdbus-codegen (glib) version being used
+            targets = [ct, ct]
+            if 'docbook' in kwargs:
+                targets.append(ct)
+        return ModuleReturnValue(targets, [ct])
 
     @permittedKwargs({'sources', 'c_template', 'h_template', 'install_header', 'install_dir',
                       'comments', 'identifier_prefix', 'symbol_prefix', 'eprod', 'vprod',

test cases/frameworks/7 gnome/gdbus/meson.build

@@ -1,3 +1,12 @@
+gdbus_src = gnome.gdbus_codegen('generated-gdbus-no-docbook', 'com.example.Sample.xml',
+  interface_prefix : 'com.example.',
+  namespace : 'Sample',
+  annotations : [
+    ['com.example.Hello()', 'org.freedesktop.DBus.Deprecated', 'true']
+  ],
+)
+assert(gdbus_src.length() == 2, 'expected 2 targets')
+
 gdbus_src = gnome.gdbus_codegen('generated-gdbus', 'com.example.Sample.xml',
   interface_prefix : 'com.example.',
   namespace : 'Sample',
@@ -6,6 +15,7 @@ gdbus_src = gnome.gdbus_codegen('generated-gdbus', 'com.example.Sample.xml',
   ],
   docbook : 'generated-gdbus-doc'
 )
+assert(gdbus_src.length() == 3, 'expected 3 targets')
 
 gdbus_exe = executable('gdbus-test', 'gdbusprog.c',
   gdbus_src,