Detect files with trailing space

On Windows, if you accidently add a space at the end of a file name, like
`files('myfile.txt ')`, the file is not reported as missing, because of
the normalization performed by the OS. However, ninja will reference it
with the trailing space, and will fail because the file does not exist.

See python/cpython#115104 for reference.

mesonbuild/interpreter/interpreter.py

@@ -664,6 +664,9 @@ def func_import(self, node: mparser.BaseNode, args: T.Tuple[str],
     @typed_pos_args('files', varargs=str)
     @noKwargs
     def func_files(self, node: mparser.FunctionNode, args: T.Tuple[T.List[str]], kwargs: 'TYPE_kwargs') -> T.List[mesonlib.File]:
+        for filename in args[0]:
+            if filename.endswith(' '):
+                raise MesonException(f'{filename!r} ends with a space. This is probably an error.', file=node.filename, lineno=node.lineno, colno=node.colno)
         return self.source_strings_to_files(args[0])
 
     @noPosargs

mesonbuild/utils/universal.py

@@ -398,7 +398,7 @@ def __repr__(self) -> str:
 
     @staticmethod
     @lru_cache(maxsize=None)
-    def from_source_file(source_root: str, subdir: str, fname: str) -> 'File':
+    def from_source_file(source_root: str, subdir: str, fname: str) -> File:
         if not os.path.isfile(os.path.join(source_root, subdir, fname)):
             raise MesonException(f'File {fname} does not exist.')
         return File(False, subdir, fname)