Don't always infer unions for conditional expressions #5095
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Use a join for type of a conditional expression unless the type context is a union type. A recent change (#5041) modified the type to always use a union, but this caused many problems in internal Dropbox repos that we aren't ready to fix yet.
gvanrossum
approved these changes
May 22, 2018
mypy/checkexpr.py
Outdated
| @@ -2357,7 +2357,14 @@ def visit_conditional_expr(self, e: ConditionalExpr) -> Type: | |||
| # branch's type. | |||
| else_type = self.analyze_cond_branch(else_map, e.else_expr, context=if_type) | |||
|
|
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| res = UnionType.make_simplified_union([if_type, else_type]) | |||
| # Only create a union type if the type context is a union to be mostly | |||
|
Merging this, though I'd like to revert it at some point. |
JelleZijlstra
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to JelleZijlstra/mypy
that referenced
this pull request
Mar 21, 2022
Undoes python#5095. Part of python#12056. This fails a few tests but I want to see the mypy-primer output before I spend time fixing them.
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Use a join for type of a conditional expression unless the type context
is a union type.
A recent change (#5041) modified the type to always use a union, but this
caused many problems in internal Dropbox repos that we aren't ready to
fix yet.