Allow passing a list of Files to CustomTarget. Closes #1720

docs/markdown/Reference-manual.md

@@ -137,7 +137,7 @@ These are all the supported keyword arguments:
 
 Create a custom top level build target. The only positional argument is the name of this target and the keyword arguments are the following.
 
-- `input` list of source files
+- `input` list of source files. As of 0.41.0 the list will be flattened.
 - `output` list of output files
 - `command` command to run to create outputs from inputs. The command may be strings or the return of `find_program()` or `executable()` (note: always specify commands in array form `['commandname', '-arg1', '-arg2']` rather than as a string `'commandname -arg1 -arg2'` as the latter will *not* work)
 - `install` when true, this target is installed during the install step

mesonbuild/build.py

@@ -1439,8 +1439,7 @@ class CustomTarget(Target):
     def process_kwargs(self, kwargs):
         super().process_kwargs(kwargs)
         self.sources = kwargs.get('input', [])
-        if not isinstance(self.sources, list):
-            self.sources = [self.sources]
+        self.sources = flatten(self.sources)
         if 'output' not in kwargs:
             raise InvalidArguments('Missing keyword argument "output".')
         self.outputs = kwargs['output']

test cases/common/151 list of file sources/foo

@@ -0,0 +1 @@
+some text

test cases/common/151 list of file sources/gen.py

@@ -0,0 +1,7 @@
+import shutil
+import sys
+
+if __name__ == '__main__':
+    if len(sys.argv) != 3:
+        raise Exception('Requires exactly 2 args')
+    shutil.copy2(sys.argv[1], sys.argv[2])

test cases/common/151 list of file sources/meson.build

@@ -0,0 +1,12 @@
+project('test', 'c')
+
+mod_py = import('python3')
+python = mod_py.find_python()
+
+test_target = custom_target(
+  'test_target',
+  input : [files('gen.py'), files('foo')],
+  output : 'bar',
+  command : [python, '@INPUT0@', '@INPUT1@', '@OUTPUT@'],
+  build_by_default : true,
+)