Suppress errors from semantic analysis in dynamic (unannotated) functions. (#1415)

* Suppress errors from semantic analysis in dynamic (unannotated) functions. Fix #1334.

* Don't suppress 'continue/break' outside loop.

* Rough and tumble fix to make tests pass. Not sure all these are right. Please review.

* Clean up SemanticAnalyzer.__init__().

Author: gvanrossum

mypy/build.py

@@ -368,16 +368,18 @@ def __init__(self, data_dir: str,
         self.custom_typing_module = custom_typing_module
         self.source_set = source_set
         self.reports = reports
+        check_untyped_defs = CHECK_UNTYPED_DEFS in self.flags
         self.semantic_analyzer = SemanticAnalyzer(lib_path, self.errors,
-                                                  pyversion=pyversion)
+                                                  pyversion=pyversion,
+                                                  check_untyped_defs=check_untyped_defs)
         self.modules = self.semantic_analyzer.modules
         self.semantic_analyzer_pass3 = ThirdPass(self.modules, self.errors)
         self.type_checker = TypeChecker(self.errors,
                                         self.modules,
                                         self.pyversion,
                                         DISALLOW_UNTYPED_CALLS in self.flags,
                                         DISALLOW_UNTYPED_DEFS in self.flags,
-                                        CHECK_UNTYPED_DEFS in self.flags)
+                                        check_untyped_defs)
         self.missing_modules = set()  # type: Set[str]
 
     def all_imported_modules_in_file(self,

mypy/semanal.py

@@ -190,8 +190,11 @@ class SemanticAnalyzer(NodeVisitor):
     imports = None  # type: Set[str]  # Imported modules (during phase 2 analysis)
     errors = None  # type: Errors     # Keeps track of generated errors
 
-    def __init__(self, lib_path: List[str], errors: Errors,
-                 pyversion: Tuple[int, int] = defaults.PYTHON3_VERSION) -> None:
+    def __init__(self,
+                 lib_path: List[str],
+                 errors: Errors,
+                 pyversion: Tuple[int, int],
+                 check_untyped_defs: bool) -> None:
         """Construct semantic analyzer.
 
         Use lib_path to search for modules, and report analysis errors
@@ -211,6 +214,7 @@ def __init__(self, lib_path: List[str], errors: Errors,
         self.errors = errors
         self.modules = {}
         self.pyversion = pyversion
+        self.check_untyped_defs = check_untyped_defs
         self.postpone_nested_functions_stack = [FUNCTION_BOTH_PHASES]
         self.postponed_functions_stack = []
 
@@ -244,10 +248,12 @@ def visit_file(self, file_node: MypyFile, fnam: str) -> None:
     def visit_func_def(self, defn: FuncDef) -> None:
         phase_info = self.postpone_nested_functions_stack[-1]
         if phase_info != FUNCTION_SECOND_PHASE:
+            self.function_stack.append(defn)
             # First phase of analysis for function.
             self.errors.push_function(defn.name())
             self.update_function_type_variables(defn)
             self.errors.pop_function()
+            self.function_stack.pop()
 
             defn.is_conditional = self.block_depth[-1] > 0
 
@@ -1630,11 +1636,11 @@ def visit_for_stmt(self, s: ForStmt) -> None:
 
     def visit_break_stmt(self, s: BreakStmt) -> None:
         if self.loop_depth == 0:
-            self.fail("'break' outside loop", s)
+            self.fail("'break' outside loop", s, True)
 
     def visit_continue_stmt(self, s: ContinueStmt) -> None:
         if self.loop_depth == 0:
-            self.fail("'continue' outside loop", s)
+            self.fail("'continue' outside loop", s, True)
 
     def visit_if_stmt(self, s: IfStmt) -> None:
         infer_reachability_of_if_statement(s, pyversion=self.pyversion)
@@ -2203,10 +2209,19 @@ def name_not_defined(self, name: str, ctx: Context) -> None:
     def name_already_defined(self, name: str, ctx: Context) -> None:
         self.fail("Name '{}' already defined".format(name), ctx)
 
-    def fail(self, msg: str, ctx: Context) -> None:
+    def fail(self, msg: str, ctx: Context, serious: bool = False) -> None:
+        if (not serious and
+                not self.check_untyped_defs and
+                self.function_stack and
+                self.function_stack[-1].is_dynamic()):
+            return
         self.errors.report(ctx.get_line(), msg)
 
     def note(self, msg: str, ctx: Context) -> None:
+        if (not self.check_untyped_defs and
+                self.function_stack and
+                self.function_stack[-1].is_dynamic()):
+            return
         self.errors.report(ctx.get_line(), msg, severity='note')
 
     def undefined_name_extra_info(self, fullname: str) -> Optional[str]:

mypy/test/data/check-weak-typing.test

@@ -123,14 +123,6 @@ def f():
     1 + 'a' # E: Unsupported left operand type for + ("int")
 [out]
 main: note: In function "f":
-[case testNonWeakFunction]
-def f():
-    if y:      # E: Name 'y' is not defined
-        x = 1
-    else:
-        x = 'a'
-[out]
-main: note: In function "f":
 [case testWeakFunctionCall]
 # mypy: weak=global
 def f(a: str) -> None: pass

mypy/test/data/semanal-errors.test

@@ -17,7 +17,7 @@ main:3: error: Name 'y' is not defined
 
 [case testUndefinedVariableWithinFunctionContext]
 import typing
-def f():
+def f() -> None:
   x
 y
 [out]
@@ -39,7 +39,7 @@ import typing
 class A:
   def f(self): pass
 class B:
-  def g(self):
+  def g(self) -> None:
     f # error
     g # error
 [out]
@@ -178,7 +178,7 @@ main:4: error: Name 'x' already defined
 [case testLocalVarRedefinition]
 import typing
 class A: pass
-def f():
+def f() -> None:
   x = 0 # type: A
   x = 0 # type: A
 [out]
@@ -523,7 +523,7 @@ main:4: error: Invalid type "__main__.t"
 from typing import TypeVar, Generic
 t = TypeVar('t')
 class c(Generic[t]):
-    def f(self): x = t
+    def f(self) -> None: x = t
 def f(y: t): x = t
 [out]
 main: note: In function "f":
@@ -546,7 +546,7 @@ main:2: error: Name 'B' is not defined
 [case testSuperOutsideClass]
 class A: pass
 super().x
-def f(): super().y
+def f() -> None: super().y
 [out]
 main:2: error: "super" used outside class
 main: note: In function "f":
@@ -572,7 +572,7 @@ main:5: error: Name 'f' already defined
 
 [case testInvalidGlobalDecl]
 import typing
-def f():
+def f() -> None:
     global x
     x = None
 [out]
@@ -582,7 +582,7 @@ main:4: error: Name 'x' is not defined
 [case testInvalidNonlocalDecl]
 import typing
 def f():
-    def g():
+    def g() -> None:
        nonlocal x
        x = None
 [out]
@@ -593,7 +593,7 @@ main:5: error: Name 'x' is not defined
 [case testNonlocalDeclNotMatchingGlobal]
 import typing
 x = None
-def f():
+def f() -> None:
     nonlocal x
     x = None
 [out]
@@ -605,7 +605,7 @@ main:5: error: Name 'x' is not defined
 import typing
 def g():
     x = None
-    def f(x):
+    def f(x) -> None:
         nonlocal x
         x = None
 [out]
@@ -623,7 +623,7 @@ import typing
 x = 1
 def f():
     x = 1
-    def g():
+    def g() -> None:
        global x
        nonlocal x
        x = None
@@ -636,7 +636,7 @@ import typing
 x = 1
 def f():
     x = 1
-    def g():
+    def g() -> None:
        nonlocal x
        global x
        x = None
@@ -646,7 +646,7 @@ main:7: error: Name 'x' is nonlocal and global
 
 [case testNestedFunctionAndScoping]
 import typing
-def f(x):
+def f(x) -> None:
     def g(y):
         z = x
     z
@@ -659,7 +659,7 @@ main:6: error: Name 'y' is not defined
 
 [case testMultipleNestedFunctionDef]
 import typing
-def f(x):
+def f(x) -> None:
     def g(): pass
     x = 1
     def g(): pass
@@ -669,7 +669,7 @@ main:5: error: Name 'g' already defined
 
 [case testRedefinedOverloadedFunction]
 from typing import overload, Any
-def f():
+def f() -> None:
     @overload
     def p(o: object) -> None: pass # no error
     @overload
@@ -683,8 +683,8 @@ main:8: error: Name 'p' already defined
 [case testNestedFunctionInMethod]
 import typing
 class A:
-   def f(self):
-       def g():
+   def f(self) -> None:
+       def g() -> None:
            x
        y
 [out]
@@ -861,7 +861,7 @@ main:3: error: 'abstractmethod' used with a non-method
 [case testAbstractNestedFunction]
 import typing
 from abc import abstractmethod
-def g():
+def g() -> None:
   @abstractmethod
   def foo(): pass
 [out]
@@ -1133,7 +1133,7 @@ import typing
 @staticmethod
 def f(): pass
 class A:
-  def g(self):
+  def g(self) -> None:
     @staticmethod
     def h(): pass
 [builtins fixtures/staticmethod.py]
@@ -1147,7 +1147,7 @@ import typing
 @classmethod
 def f(): pass
 class A:
-  def g(self):
+  def g(self) -> None:
     @classmethod
     def h(): pass
 [builtins fixtures/classmethod.py]

mypy/test/data/semanal-statements.test

@@ -534,7 +534,7 @@ MypyFile:1(
             IntExpr(0)))))))
 
 [case testDelMultipleThingsInvalid]
-def f(x, y):
+def f(x, y) -> None:
     del x, y + 1
 [out]
 main: note: In function "f":