gdbus-codegen: Add --glib-max-allowed argument

This complements the `--glib-min-required` argument, just like the
`GLIB_MIN_REQUIRED` and `GLIB_MAX_ALLOWED` preprocessor defines which
control access to APIs in C.

Currently, it doesn’t affect code generation at all. When we next change
code generation, we will need to gate any new API usage on this
argument.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Fixes: #1993

docs/reference/gio/gdbus-codegen.xml

@@ -51,6 +51,7 @@
       </arg>
     </group>
     <arg><option>--glib-min-required</option> <replaceable>VERSION</replaceable></arg>
+    <arg><option>--glib-max-allowed</option> <replaceable>VERSION</replaceable></arg>
     <arg choice="plain">FILE</arg>
     <arg>
       <arg choice="plain" rep="repeat">FILE</arg>
@@ -460,6 +461,27 @@ gdbus-codegen --c-namespace MyApp                           \
       </listitem>
     </varlistentry>
 
+    <varlistentry>
+      <term><option>--glib-max-allowed</option> <replaceable>VERSION</replaceable></term>
+      <listitem>
+        <para>
+          Specifies the maximum version of GLib which the code generated by
+          <command>gdbus-codegen</command> can depend on. This may be used to
+          ensure that code generated by <command>gdbus-codegen</command> is
+          compilable with specific older versions of GLib that your software has
+          to support.
+        </para>
+        <para>
+          The version number must be of the form
+          <literal><replaceable>MAJOR</replaceable>.<replaceable>MINOR</replaceable>.<replaceable>MICRO</replaceable></literal>,
+          where all parts are integers. <replaceable>MINOR</replaceable> and
+          <replaceable>MICRO</replaceable> are optional. The version number must
+          be greater than or equal to that passed to <option>--glib-min-required</option>.
+          It defaults to the version of GLib which provides this <command>gdbus-codegen</command>.
+        </para>
+      </listitem>
+    </varlistentry>
+
   </variablelist>
 </refsect1>
 

gio/gdbus-2.0/codegen/codegen_main.py

@@ -169,6 +169,8 @@ def codegen_main():
                             help='Add annotation (may be used several times)')
     arg_parser.add_argument('--glib-min-required', metavar='VERSION',
                             help='Minimum version of GLib to be supported by the outputted code (default: 2.30)')
+    arg_parser.add_argument('--glib-max-allowed', metavar='VERSION',
+                            help='Maximum version of GLib to be used by the outputted code (default: current GLib version)')
 
     group = arg_parser.add_mutually_exclusive_group()
     group.add_argument('--generate-c-code', metavar='OUTFILES',
@@ -256,6 +258,28 @@ def codegen_main():
     else:
         glib_min_required = (2, 30)
 
+    # And the maximum GLib version.
+    if args.glib_max_allowed:
+        try:
+            parts = args.glib_max_allowed.split('.', 3)
+            glib_max_allowed = (int(parts[0]),
+                                int(parts[1] if len(parts) > 1 else 0))
+            # Ignore micro component, but still validate it:
+            _ = int(parts[2] if len(parts) > 2 else 0)
+        except (ValueError, IndexError):
+            print_error('Unrecognized --glib-max-allowed string ‘{}’'.format(
+                args.glib_max_allowed))
+    else:
+        glib_max_allowed = (config.MAJOR_VERSION, config.MINOR_VERSION)
+
+    # Round --glib-max-allowed up to the next stable release.
+    glib_max_allowed = \
+        (glib_max_allowed[0], glib_max_allowed[1] + (glib_max_allowed[1] % 2))
+
+    if glib_max_allowed < glib_min_required:
+        print_error('Invalid versions: --glib-min-required ({}) must be '
+                    'less than or equal to --glib-max-allowed ({})'.format(glib_min_required, glib_max_allowed))
+
     glib_min_required_is_2_64 = (glib_min_required[0] > 2 or
                                  (glib_min_required[0] == 2 and
                                   glib_min_required[1] >= 64))

gio/gdbus-2.0/codegen/config.py.in

@@ -20,3 +20,5 @@
 # Author: David Zeuthen <davidz@redhat.com>
 
 VERSION = "@VERSION@"
+MAJOR_VERSION = @MAJOR_VERSION@
+MINOR_VERSION = @MINOR_VERSION@

gio/gdbus-2.0/codegen/meson.build

@@ -10,6 +10,8 @@ gdbus_codegen_files = [
 
 gdbus_codegen_conf = configuration_data()
 gdbus_codegen_conf.set('VERSION', glib_version)
+gdbus_codegen_conf.set('MAJOR_VERSION', major_version)
+gdbus_codegen_conf.set('MINOR_VERSION', minor_version)
 gdbus_codegen_conf.set('PYTHON', python_name)
 gdbus_codegen_conf.set('DATADIR', glib_datadir)
 

gio/tests/codegen.py

@@ -384,7 +384,8 @@ G_END_DECLS
         result = self.runCodegenWithInterface('',
                                               '--output', '/dev/stdout',
                                               '--header',
-                                              '--glib-min-required', '3')
+                                              '--glib-min-required', '3',
+                                              '--glib-max-allowed', '3.2')
         self.assertEqual('', result.err)
         self.assertNotEqual('', result.out.strip())
 
@@ -397,6 +398,55 @@ G_END_DECLS
         self.assertEqual('', result.err)
         self.assertNotEqual('', result.out.strip())
 
+    def test_glib_max_allowed_too_low(self):
+        """Test running with a --glib-max-allowed which is too low (and hence
+        probably a typo)."""
+        with self.assertRaises(subprocess.CalledProcessError):
+            self.runCodegenWithInterface('',
+                                         '--output', '/dev/stdout',
+                                         '--body',
+                                         '--glib-max-allowed', '2.6')
+
+    def test_glib_max_allowed_major_only(self):
+        """Test running with a --glib-max-allowed which contains only a major version."""
+        result = self.runCodegenWithInterface('',
+                                              '--output', '/dev/stdout',
+                                              '--header',
+                                              '--glib-max-allowed', '3')
+        self.assertEqual('', result.err)
+        self.assertNotEqual('', result.out.strip())
+
+    def test_glib_max_allowed_with_micro(self):
+        """Test running with a --glib-max-allowed which contains a micro version."""
+        result = self.runCodegenWithInterface('',
+                                              '--output', '/dev/stdout',
+                                              '--header',
+                                              '--glib-max-allowed', '2.46.2')
+        self.assertEqual('', result.err)
+        self.assertNotEqual('', result.out.strip())
+
+    def test_glib_max_allowed_unstable(self):
+        """Test running with a --glib-max-allowed which is unstable. It should
+        be rounded up to the next stable version number, and hence should not
+        end up less than --glib-min-required."""
+        result = self.runCodegenWithInterface('',
+                                              '--output', '/dev/stdout',
+                                              '--header',
+                                              '--glib-max-allowed', '2.63',
+                                              '--glib-min-required', '2.64')
+        self.assertEqual('', result.err)
+        self.assertNotEqual('', result.out.strip())
+
+    def test_glib_max_allowed_less_than_min_required(self):
+        """Test running with a --glib-max-allowed which is less than
+        --glib-min-required."""
+        with self.assertRaises(subprocess.CalledProcessError):
+            self.runCodegenWithInterface('',
+                                         '--output', '/dev/stdout',
+                                         '--body',
+                                         '--glib-max-allowed', '2.62',
+                                         '--glib-min-required', '2.64')
+
     def test_unix_fd_types_and_annotations(self):
         """Test an interface with `h` arguments, no annotation, and GLib < 2.64.