typed_kwargs: provide better error messages for wrong container types

Currently, if you pass a `[]string`, but the argument expects
`[]number`, then you get a message like `expected list[str] but got
list`. That isn't helpful. With this patch arrays and dictionaries will
both print messages with the types provided.

3 files changed, 17 insertions, 5 deletions

diff --git a/mesonbuild/interpreterbase/decorators.py b/mesonbuild/interpreterbase/decorators.py
index 16aa7d2..817cb85 100644
--- a/mesonbuild/interpreterbase/decorators.py
+++ b/mesonbuild/interpreterbase/decorators.py
@@ -467,6 +467,18 @@ def typed_kwargs(name: str, *types: KwargInfo) -> T.Callable[..., T.Any]:
             shouldbe += ', '.join(candidates)
             return shouldbe
 
+        def raw_description(t: object) -> str:
+            """describe a raw type (ie, one that is not a ContainerTypeInfo)."""
+            if isinstance(t, list):
+                if t:
+                    return f"list[{' | '.join(sorted(mesonlib.OrderedSet(type(v).__name__ for v in t)))}]"
+                return 'list[]'
+            elif isinstance(t, dict):
+                if t:
+                    return f"dict[{' | '.join(sorted(mesonlib.OrderedSet(type(v).__name__ for v in t.values())))}]"
+                return 'dict[]'
+            return type(t).__name__
+
         def check_value_type(types_tuple: T.Tuple[T.Union[T.Type, ContainerTypeInfo], ...],
                              value: T.Any) -> bool:
             for t in types_tuple:
@@ -503,7 +515,7 @@ def typed_kwargs(name: str, *types: KwargInfo) -> T.Callable[..., T.Any]:
                         kwargs[info.name] = value = mesonlib.listify(value)
                     if not check_value_type(types_tuple, value):
                         shouldbe = types_description(types_tuple)
-                        raise InvalidArguments(f'{name} keyword argument {info.name!r} was of type {type(value).__name__!r} but should have been {shouldbe}')
+                        raise InvalidArguments(f'{name} keyword argument {info.name!r} was of type {raw_description(value)} but should have been {shouldbe}')
 
                     if info.validator is not None:
                         msg = info.validator(value)
diff --git a/test cases/failing/116 run_target in test/test.json b/test cases/failing/116 run_target in test/test.json
index c273a3b..7826ceb 100644
--- a/test cases/failing/116 run_target in test/test.json
+++ b/test cases/failing/116 run_target in test/test.json
@@ -1,7 +1,7 @@
 {
     "stdout": [
         {
-            "line": "test cases/failing/116 run_target in test/meson.build:4:0: ERROR: test keyword argument 'args' was of type 'list' but should have been list[str,File,BuildTarget,CustomTarget]"
+            "line": "test cases/failing/116 run_target in test/meson.build:4:0: ERROR: test keyword argument 'args' was of type list[RunTarget] but should have been list[str,File,BuildTarget,CustomTarget]"
         }
     ]
 }
diff --git a/unittests/internaltests.py b/unittests/internaltests.py
index 207bd37..86c1890 100644
--- a/unittests/internaltests.py
+++ b/unittests/internaltests.py
@@ -1266,7 +1266,7 @@ class InternalTests(unittest.TestCase):
 
         with self.assertRaises(InvalidArguments) as cm:
             _(None, mock.Mock(), [], {'input': {}})
-        self.assertEqual(str(cm.exception), "testfunc keyword argument 'input' was of type 'dict' but should have been list[str]")
+        self.assertEqual(str(cm.exception), "testfunc keyword argument 'input' was of type dict[] but should have been list[str]")
 
     def test_typed_kwarg_contained_invalid(self) -> None:
         @typed_kwargs(
@@ -1278,7 +1278,7 @@ class InternalTests(unittest.TestCase):
 
         with self.assertRaises(InvalidArguments) as cm:
             _(None, mock.Mock(), [], {'input': {'key': 1}})
-        self.assertEqual(str(cm.exception), "testfunc keyword argument 'input' was of type 'dict' but should have been dict[str]")
+        self.assertEqual(str(cm.exception), "testfunc keyword argument 'input' was of type dict[int] but should have been dict[str]")
 
     def test_typed_kwarg_container_listify(self) -> None:
         @typed_kwargs(
@@ -1313,7 +1313,7 @@ class InternalTests(unittest.TestCase):
 
         with self.assertRaises(MesonException) as cm:
             _(None, mock.Mock(), [], {'input': ['a']})
-        self.assertEqual(str(cm.exception), "testfunc keyword argument 'input' was of type 'list' but should have been list[str] that has even size")
+        self.assertEqual(str(cm.exception), "testfunc keyword argument 'input' was of type list[str] but should have been list[str] that has even size")
 
     @mock.patch.dict(mesonbuild.mesonlib.project_meson_versions, {})
     def test_typed_kwarg_since(self) -> None: