New analyzer: reverse order of modules within SCC (#7163)

This brings the new semantic analyzer closer to the old one and 
slightly helps performance.

Author: JukkaL

mypy/newsemanal/semanal_main.py

@@ -66,6 +66,9 @@ def semantic_analysis_for_scc(graph: 'Graph', scc: List[str], errors: Errors) ->
     """Perform semantic analysis for all modules in a SCC (import cycle).
 
     Assume that reachability analysis has already been performed.
+
+    The scc will be processed roughly in the order the modules are included
+    in the list.
     """
     patches = []  # type: Patches
     # Note that functions can't define new module-level attributes
@@ -152,6 +155,10 @@ def restore_saved_attrs(saved_attrs: SavedAttributes) -> None:
 def process_top_levels(graph: 'Graph', scc: List[str], patches: Patches) -> None:
     # Process top levels until everything has been bound.
 
+    # Reverse order of the scc so the first modules in the original list will be
+    # be processed first. This helps with performance.
+    scc = list(reversed(scc))
+
     # Initialize ASTs and symbol tables.
     for id in scc:
         state = graph[id]

test-data/unit/check-attr.test

@@ -1156,7 +1156,9 @@ C(0).total = 1  # E: Property "total" defined in "C" is read-only
 import lib
 [file lib.py]
 import attr
-from other import *
+MYPY = False
+if MYPY:  # Force deferral
+    from other import *
 
 @attr.s
 class C:

test-data/unit/check-classes.test

@@ -5925,3 +5925,49 @@ class B:
 
 class C(A, B): pass
 [out]
+
+[case testAttributeDefOrder1]
+import a
+
+[file a.py]
+from b import C
+
+class D(C):
+    def g(self) -> None:
+        self.x = '' # E: Incompatible types in assignment (expression has type "str", variable has type "int")
+
+    def f(self) -> None:
+        reveal_type(self.x) # N: Revealed type is 'builtins.int'
+
+
+[file b.py]
+import a
+
+class C:
+    def __init__(self) -> None:
+        self.x = 0
+
+[targets b, a, b.C.__init__, a.D.g, a.D.f, __main__]
+
+[case testAttributeDefOrder2]
+class D(C):
+    def g(self) -> None:
+        self.x = ''
+
+    def f(self) -> None:
+        # https://github.com/python/mypy/issues/7162
+        reveal_type(self.x) # N: Revealed type is 'builtins.str'
+
+
+class C:
+    def __init__(self) -> None:
+        self.x = 0
+
+class E(C):
+    def g(self) -> None:
+        self.x = '' # E: Incompatible types in assignment (expression has type "str", variable has type "int")
+
+    def f(self) -> None:
+        reveal_type(self.x) # N: Revealed type is 'builtins.int'
+
+[targets __main__, __main__, __main__.D.g, __main__.D.f, __main__.C.__init__, __main__.E.g, __main__.E.f]

test-data/unit/check-dataclasses.test

@@ -670,7 +670,9 @@ c.x = 1  # E: Property "x" defined in "C" is read-only
 import lib
 [file lib.py]
 from dataclasses import dataclass
-from other import *
+MYPY = False
+if MYPY:  # Force deferral
+    from other import *
 
 @dataclass
 class C:

test-data/unit/check-incremental.test

@@ -4521,12 +4521,12 @@ B = List[A]
 
 [builtins fixtures/list.pyi]
 [out]
-tmp/other.pyi:2: error: Module 'lib' has no attribute 'A'
+tmp/lib.pyi:4: error: Module 'other' has no attribute 'B'
 tmp/other.pyi:3: error: Cannot resolve name "B" (possible cyclic definition)
 [out2]
-tmp/other.pyi:2: error: Module 'lib' has no attribute 'A'
+tmp/lib.pyi:4: error: Module 'other' has no attribute 'B'
 tmp/other.pyi:3: error: Cannot resolve name "B" (possible cyclic definition)
-tmp/a.py:3: note: Revealed type is 'builtins.list[builtins.list[Any]]'
+tmp/a.py:3: note: Revealed type is 'builtins.list[Any]'
 
 [case testRecursiveNamedTupleTypedDict]
 # https://github.com/python/mypy/issues/7125

test-data/unit/check-newsemanal.test

@@ -74,10 +74,11 @@ from a import bad2 # E: Module 'a' has no attribute 'bad2'; maybe "bad"?
 [case testNewAnalyzerTypeAnnotationCycle4]
 import b
 [file a.py]
-# TODO: Could we generate an error here as well?
-from b import bad
+from b import bad # E: Module 'b' has no attribute 'bad'
 [file b.py]
-from a import bad # E: Module 'a' has no attribute 'bad'
+# TODO: Could we generate an error here as well?
+from a import bad
+[targets a, b, a, b, a, b, a, b, __main__]
 
 [case testNewAnalyzerExportedValuesInImportAll]
 from m import *
@@ -225,6 +226,8 @@ class A:
 class C(B):
     c: int
 
+[targets b, a, b, a, __main__]
+
 [case testNewAnalyzerTypedDictClass]
 from mypy_extensions import TypedDict
 import a
@@ -298,6 +301,8 @@ from a import x
 
 def f(): pass
 
+[targets a, b, a, a.y, b.f, __main__]
+
 [case testNewAnalyzerRedefinitionAndDeferral1b]
 import a
 
@@ -323,6 +328,8 @@ if MYPY:  # Tweak processing order
 
 def f(): pass
 
+[targets b, a, b, a, b.f, a.y, __main__]
+
 [case testNewAnalyzerRedefinitionAndDeferral2a]
 import a
 
@@ -436,11 +443,11 @@ def main() -> None:
 import b
 [file a.py]
 import b
-x = b.x  # E: Cannot determine type of 'x'
+x = b.x  # E: Cannot resolve attribute "x" (possible cyclic definition) \
+         # E: Module has no attribute "x"
 [file b.py]
 import a
-x = a.x  # E: Cannot resolve attribute "x" (possible cyclic definition) \
-         # E: Module has no attribute "x"
+x = a.x
 [builtins fixtures/module.pyi]
 
 [case testNewAnalyzerMutuallyRecursiveOverloadedFunctions]
@@ -3081,4 +3088,4 @@ class Yes: ...
 import a
 
 def func() -> int: ...
-[targets a, b, a, b.func, a.func, __main__]
+[targets b, a, a, b.func, a.func, __main__]