Merge branch 'master' into iade

Author: ilevkivskyi

mypy/expandtype.py

@@ -251,9 +251,9 @@ def visit_type_var(self, t: TypeVarType) -> Type:
             if (tvar_id := repl.id) in self.recursive_tvar_guard:
                 return self.recursive_tvar_guard[tvar_id] or repl
             self.recursive_tvar_guard[tvar_id] = None
-            repl = repl.accept(self)
-            if isinstance(repl, TypeVarType):
-                repl.default = repl.default.accept(self)
+            repl.default = repl.default.accept(self)
+            expanded = repl.accept(self)  # Note: `expanded is repl` may be true.
+            repl = repl if isinstance(expanded, TypeVarType) else expanded
             self.recursive_tvar_guard[tvar_id] = repl
         return repl
 

mypy/report.py

@@ -141,12 +141,9 @@ def should_skip_path(path: str) -> bool:
 
 def iterate_python_lines(path: str) -> Iterator[tuple[int, str]]:
     """Return an iterator over (line number, line text) from a Python file."""
-    try:
+    if not os.path.isdir(path):  # can happen with namespace packages
         with tokenize.open(path) as input_file:
             yield from enumerate(input_file, 1)
-    except IsADirectoryError:
-        # can happen with namespace packages
-        pass
 
 
 class FuncCounterVisitor(TraverserVisitor):

test-data/unit/check-typevar-defaults.test

@@ -416,6 +416,38 @@ def func_c4(
     reveal_type(m)  # N: Revealed type is "__main__.ClassC4[builtins.int, builtins.float]"
 [builtins fixtures/tuple.pyi]
 
+[case testTypeVarDefaultsSwap]
+from typing import TypeVar, Generic
+
+T = TypeVar("T")
+X = TypeVar("X", default=object)
+Y = TypeVar("Y", default=object)
+
+
+class Foo(Generic[T, Y]):
+    def test(self) -> None:
+        reveal_type( Foo[Y, T]() )  # N: Revealed type is "__main__.Foo[Y`2 = builtins.object, T`1]"
+
+
+class Bar(Generic[X, Y]):
+    def test(self) -> None:
+        reveal_type( Bar[Y, X]() )  # N: Revealed type is "__main__.Bar[Y`2 = builtins.object, X`1 = builtins.object]"
+
+
+[case testTypeVarDefaultsSwap2]
+from typing import TypeVar, Generic
+
+X = TypeVar("X", default=object)
+Y = TypeVar("Y", default=object)
+U = TypeVar("U", default=object)
+V = TypeVar("V", default=object)
+
+class Transform(Generic[X, Y]):
+    def invert(self) -> "Transform[Y, X]": ...
+
+class Foo(Transform[U, V], Generic[U, V]):
+    def invert(self) -> "Foo[V, U]": ...
+
 [case testTypeVarDefaultsClassRecursive1]
 # flags: --disallow-any-generics
 from typing import Generic, TypeVar, List

test-data/unit/reports.test

@@ -555,3 +555,37 @@ namespace_packages = True
 [file folder/subfolder/something.py]
 class Something:
     pass
+
+[case testReportCoberturaCrashOnNamespacePackages]
+# cmd: mypy --cobertura-xml-report report -p folder
+-- Regression test for https://github.com/python/mypy/issues/19843
+[file folder/subfolder/something.py]
+-- This output is not important, but due to the way tests are run we need to check it.
+[outfile report/cobertura.xml]
+<coverage timestamp="$TIMESTAMP" version="$VERSION" line-rate="1.0" branch-rate="0" lines-covered="0" lines-valid="0">
+  <sources>
+    <source>$PWD</source>
+  </sources>
+  <packages>
+    <package complexity="1.0" name="folder" branch-rate="0" line-rate="1.0">
+      <classes>
+        <class complexity="1.0" filename="folder" name="folder" branch-rate="0" line-rate="1.0">
+          <methods/>
+          <lines/>
+        </class>
+        <class complexity="1.0" filename="folder/subfolder" name="subfolder" branch-rate="0" line-rate="1.0">
+          <methods/>
+          <lines/>
+        </class>
+      </classes>
+    </package>
+    <package complexity="1.0" name="folder.subfolder" branch-rate="0" line-rate="1.0">
+      <classes>
+        <class complexity="1.0" filename="folder/subfolder/something.py" name="something.py" branch-rate="0" line-rate="1.0">
+          <methods/>
+          <lines/>
+        </class>
+      </classes>
+    </package>
+  </packages>
+</coverage>