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New analyser: Complain about type variable redefinition only after we decided it is valid #7093

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Merged
merged 1 commit into from
Jun 28, 2019
Merged

New analyser: Complain about type variable redefinition only after we decided it is valid #7093

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18 changes: 8 additions & 10 deletions mypy/newsemanal/semanal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2686,17 +2686,7 @@ def process_typevar_declaration(self, s: AssignmentStmt) -> bool:
self.fail("Cannot declare the type of a type variable", s)
return False

assert isinstance(s.rvalue, CallExpr)
name = lvalue.name
names = self.current_symbol_table()
existing = names.get(name)
if existing and not (isinstance(existing.node, PlaceholderNode) or
# Also give error for another type variable with the same name.
(isinstance(existing.node, TypeVarExpr) and
existing.node is s.rvalue.analyzed)):
self.fail("Cannot redefine '%s' as a type variable" % name, s)
return False

if not self.check_typevar_name(call, name, s):
return False

Expand All @@ -2713,6 +2703,14 @@ def process_typevar_declaration(self, s: AssignmentStmt) -> bool:
return False
variance, upper_bound = res

existing = self.current_symbol_table().get(name)
if existing and not (isinstance(existing.node, PlaceholderNode) or
# Also give error for another type variable with the same name.
(isinstance(existing.node, TypeVarExpr) and
existing.node is call.analyzed)):
self.fail("Cannot redefine '%s' as a type variable" % name, s)
return False

if self.options.disallow_any_unimported:
for idx, constraint in enumerate(values, start=1):
if has_any_from_unimported_type(constraint):
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11 changes: 11 additions & 0 deletions test-data/unit/check-newsemanal.test
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Expand Up @@ -2774,3 +2774,14 @@ def g() -> None:
nonlocal bar
bar = [] # type: typing.List[int] # E: Name 'bar' already defined on line 11
[builtins fixtures/list.pyi]

[case testNewAnalyzerMoreInvalidTypeVarArgumentsDeferred]
from typing import TypeVar, Generic

defer: Yes

S = TypeVar('S', covariant=True, contravariant=True) # E: TypeVar cannot be both covariant and contravariant \
# E: "int" not callable

class Yes: ...
[builtins fixtures/bool.pyi]