Fix merge file using an array. Closes #4424.

mesonbuild/modules/i18n.py

@@ -85,6 +85,10 @@ class I18nModule(ExtensionModule):
         if hasattr(inputfile, 'held_object'):
             ct = build.CustomTarget(kwargs['output'] + '_merge', state.subdir, state.subproject, kwargs)
         else:
+            if isinstance(inputfile, list):
+                # We only use this input file to create a name of the custom target.
+                # Thus we can ignore the other entries.
+                inputfile = inputfile[0]
             if isinstance(inputfile, str):
                 inputfile = mesonlib.File.from_source_file(state.environment.source_dir,
                                                            state.subdir, inputfile)

test cases/frameworks/6 gettext/data/meson.build

@@ -10,7 +10,7 @@ i18n.merge_file(
 
 # Use filename substitution for another file
 i18n.merge_file(
-  input: 'test2.desktop.in',
+  input: files('test2.desktop.in'),
   output: '@BASENAME@',
   type: 'desktop',
   po_dir: '../po',