modules/qt: Allow Generated sources in compile_resources

docs/markdown/_include_qt_base.md

@@ -8,8 +8,9 @@ It takes no positional arguments, and the following keyword arguments:
   - `name` (string | empty): if provided a single .cpp file will be generated,
     and the output of all qrc files will be combined in this file, otherwise
     each qrc file be written to it's own cpp file.
-  - `sources` (File | string)[]: A list of sources to be transpiled. Required,
-    must have at least one source
+  - `sources` (File | string | custom_target | custom_target index | generator_output)[]:
+    A list of sources to be transpiled. Required, must have at least one source
+    *New in 0.60.0*: support for custom_target, custom_target_index, and generator_output.
   - `extra_args` string[]: Extra arguments to pass directly to `qt-rcc`
   - `method` string: The method to use to detect qt, see `dependency()` for more
     information.

mesonbuild/modules/qt.py

@@ -44,7 +44,7 @@ if T.TYPE_CHECKING:
         """Keyword arguments for the Resource Compiler method."""
 
         name: T.Optional[str]
-        sources: T.List[FileOrString]
+        sources: T.Sequence[T.Union[FileOrString, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]]
         extra_args: T.List[str]
         method: str
 
@@ -209,9 +209,17 @@ class QtBaseModule(ExtensionModule):
         except Exception:
             raise MesonException(f'Unable to parse resource file {abspath}')
 
-    def _parse_qrc_deps(self, state: 'ModuleState', rcc_file: 'FileOrString') -> T.List[File]:
-        rcc_dirname, nodes = self._qrc_nodes(state, rcc_file)
+    def _parse_qrc_deps(self, state: 'ModuleState',
+                        rcc_file_: T.Union['FileOrString', build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]) -> T.List[File]:
         result: T.List[File] = []
+        inputs: T.Sequence['FileOrString'] = []
+        if isinstance(rcc_file_, (str, File)):
+            inputs = [rcc_file_]
+        else:
+            inputs = rcc_file_.get_outputs()
+
+        for rcc_file in inputs:
+            rcc_dirname, nodes = self._qrc_nodes(state, rcc_file)
             for resource_path in nodes:
                 # We need to guess if the pointed resource is:
                 #   a) in build directory -> implies a generated file
@@ -267,7 +275,12 @@ class QtBaseModule(ExtensionModule):
     @typed_kwargs(
         'qt.compile_resources',
         KwargInfo('name', str),
-        KwargInfo('sources', ContainerTypeInfo(list, (File, str), allow_empty=False), listify=True, required=True),
+        KwargInfo(
+            'sources',
+            ContainerTypeInfo(list, (File, str, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList), allow_empty=False),
+            listify=True,
+            required=True,
+        ),
         KwargInfo('extra_args', ContainerTypeInfo(list, str), listify=True, default=[]),
         KwargInfo('method', str, default='auto')
     )
@@ -276,6 +289,8 @@ class QtBaseModule(ExtensionModule):
 
         Uses CustomTargets to generate .cpp files from .qrc files.
         """
+        if any(isinstance(s, (build.CustomTarget, build.CustomTargetIndex, build.GeneratedList)) for s in kwargs['sources']):
+            FeatureNew.single_use('qt.compile_resources: custom_target or generator for "sources" keyword argument', '0.60.0', state.subproject)
         out = self._compile_resources_impl(state, kwargs)
         return ModuleReturnValue(out, [out])
 
@@ -294,7 +309,12 @@ class QtBaseModule(ExtensionModule):
         DEPFILE_ARGS: T.List[str] = ['--depfile', '@DEPFILE@'] if self._rcc_supports_depfiles else []
 
         name = kwargs['name']
-        sources = kwargs['sources']
+        sources: T.List['FileOrString'] = []
+        for s in kwargs['sources']:
+            if isinstance(s, (str, File)):
+                sources.append(s)
+            else:
+                sources.extend(s.get_outputs())
         extra_args = kwargs['extra_args']
 
         # If a name was set generate a single .cpp file from all of the qrc