Merged in jwalden/mypy/unary-plus (pull request #1)

Add support for modeling unary plus, including with respect to a custom __pos__

mypy/checkexpr.py

@@ -850,7 +850,7 @@ def check_list_multiply(self, e: OpExpr) -> Type:
         return result
 
     def visit_unary_expr(self, e: UnaryExpr) -> Type:
-        """Type check an unary operation ('not', '-' or '~')."""
+        """Type check an unary operation ('not', '-', '+' or '~')."""
         operand_type = self.accept(e.expr)
         op = e.op
         if op == 'not':
@@ -861,7 +861,13 @@ def visit_unary_expr(self, e: UnaryExpr) -> Type:
                                                               operand_type, e)
             result, method_type = self.check_call(method_type, [], [], e)
             e.method_type = method_type
-        elif op == '~':
+        elif op == '+':
+            method_type = self.analyse_external_member_access('__pos__',
+                                                              operand_type, e)
+            result, method_type = self.check_call(method_type, [], [], e)
+            e.method_type = method_type
+        else:
+            assert op == '~', "unhandled unary operator"
             method_type = self.analyse_external_member_access('__invert__',
                                                               operand_type, e)
             result, method_type = self.check_call(method_type, [], [], e)

mypy/icode.py

@@ -639,10 +639,12 @@ def visit_unary_expr(self, e: UnaryExpr) -> int:
         else:
             if e.op == '-':
                 method = '__neg__'
+            elif e.op == '+':
+                method = '__pos__'
             elif e.op == '~':
                 method = '__invert__'
             else:
-                raise NotImplementedError()
+                raise NotImplementedError("unhandled op: " + e.op)
             inst = cast(Instance, operand_type) # TODO more flexible
             self.add(CallMethod(target, operand, method, inst.type, []))
         return target

mypy/messages.py

@@ -230,6 +230,9 @@ def has_no_attr(self, typ: Type, member: str, context: Context) -> Type:
         elif member == '__neg__':
             self.fail('Unsupported operand type for unary - ({})'.format(
                 self.format(typ)), context)
+        elif member == '__pos__':
+            self.fail('Unsupported operand type for unary + ({})'.format(
+                self.format(typ)), context)
         elif member == '__invert__':
             self.fail('Unsupported operand type for ~ ({})'.format(
                 self.format(typ)), context)

mypy/test/data/check-expressions.test

@@ -554,6 +554,22 @@ class B:
 main, line 3: Incompatible types in assignment
 main, line 4: Unsupported operand type for unary - ("B")
 
+[case testUnaryPlus]
+from typing import Undefined
+a, b = Undefined, Undefined # type: (A, B)
+a = +a   # Fail
+b = +b   # Fail
+b = +a
+
+class A:
+    def __pos__(self) -> 'B':
+        pass
+class B:
+    pass
+[out]
+main, line 3: Incompatible types in assignment
+main, line 4: Unsupported operand type for unary + ("B")
+
 [case testUnaryNot]
 from typing import Undefined
 a, b = Undefined, Undefined # type: (A, bool)

mypy/test/data/dyncheck-trans-basic.test

@@ -1321,7 +1321,7 @@ x = x in a
 a: A = Undefined
 x = {Any <= int {A x} in a}
 
-[case testUnaryOperator]
+[case testUnaryMinusOperator]
 from typing import Undefined, Any
 class A:
     def __neg__(self) -> bool: pass
@@ -1334,6 +1334,19 @@ x = -a
 a: A = Undefined
 x = {Any <= bool -a}
 
+[case testUnaryPlusOperator]
+from typing import Undefined, Any
+class A:
+    def __pos__(self) -> bool: pass
+x = Undefined # type: Any
+a = Undefined # type: A
+x = +a
+[builtins fixtures/ops.py]
+[out]
+...
+a: A = Undefined
+x = {Any <= bool +a}
+
 [case testTransformBinaryOpOperands]
 from typing import Any, Undefined
 class A:
@@ -1358,7 +1371,7 @@ a[f(1)]
 a: A = Undefined
 a[f({Any <= int 1})]
 
-[case testTransformUnaryOperand]
+[case testTransformUnaryMinusOperand]
 from typing import Any
 class A:
     def __neg__(self) -> int: pass
@@ -1367,3 +1380,13 @@ def f(x: Any) -> A: pass
 [out]
 ...
 -f({Any <= int 1})
+
+[case testTransformUnaryPlusOperand]
+from typing import Any
+class A:
+    def __pos__(self) -> int: pass
+def f(x: Any) -> A: pass
++f(1)
+[out]
+...
++f({Any <= int 1})

mypy/test/data/fixtures/icodegen.py

@@ -19,6 +19,7 @@ def __add__(self, n: int) -> int: pass
     def __sub__(self, n: int) -> int: pass
     def __mul__(self, n: int) -> int: pass
     def __neg__(self) -> int: pass
+    def __pos__(self) -> int: pass
     def __eq__(self, n: int) -> bool: pass
     def __ne__(self, n: int) -> bool: pass
     def __lt__(self, n: int) -> bool: pass

mypy/test/data/fixtures/ops.py

@@ -22,6 +22,7 @@ def __sub__(self, x: 'int') -> 'int': pass
     def __mul__(self, x: 'int') -> 'int': pass
     def __mod__(self, x: 'int') -> 'int': pass
     def __floordiv__(self, x: 'int') -> 'int': pass
+    def __pos__(self) -> 'int': pass
     def __neg__(self) -> 'int': pass
     def __eq__(self, x: object) -> bool: pass
     def __ne__(self, x: object) -> bool: pass

mypy/test/data/icode-basic.test

@@ -531,15 +531,21 @@ def f:
 import typing
 class A:
     def __neg__(self) -> int: pass
+    def __pos__(self) -> int: pass
     def __invert__(self) -> int: pass
 def f(a: A) -> int:
     return -a
 def g(a: A) -> int:
+    return +a
+def h(a: A) -> int:
     return ~a
 [out]
 def f:
     r1 = r0.__neg__() [A]
     return r1
 def g:
+    r1 = r0.__pos__() [A]
+    return r1
+def h:
     r1 = r0.__invert__() [A]
     return r1

stubs/2.7/builtins.py

@@ -101,6 +101,7 @@ def __rlshift__(self, n: int) -> int: pass
     def __rrshift__(self, n: int) -> int: pass
 
     def __neg__(self) -> int: pass
+    def __pos__(self) -> int: pass
     def __invert__(self) -> int: pass
 
     def __eq__(self, x: object) -> bool: pass
@@ -159,6 +160,7 @@ def __le__(self, x: float) -> bool: pass
     def __gt__(self, x: float) -> bool: pass
     def __ge__(self, x: float) -> bool: pass
     def __neg__(self) -> float: pass
+    def __pos__(self) -> float: pass
 
     def __str__(self) -> str: pass
     def __int__(self) -> int: pass

stubs/3.2/builtins.py

@@ -114,6 +114,7 @@ def __rlshift__(self, n: int) -> int: pass
     def __rrshift__(self, n: int) -> int: pass
 
     def __neg__(self) -> int: pass
+    def __pos__(self) -> int: pass
     def __invert__(self) -> int: pass
 
     def __eq__(self, x: object) -> bool: pass
@@ -179,6 +180,7 @@ def __le__(self, x: float) -> bool: pass
     def __gt__(self, x: float) -> bool: pass
     def __ge__(self, x: float) -> bool: pass
     def __neg__(self) -> float: pass
+    def __pos__(self) -> float: pass
 
     def __str__(self) -> str: pass
     def __int__(self) -> int: pass