Always use baseType when constraining patternTp with scrutineeTp #20032
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In the following example: ``` type Cond[B <: Boolean] <: Tuple2[String, String] = B match ... type Decoded[B <: Boolean] = Cond[B] match case (h1, _) => Int ``` When constraining the `(h1, _)` pattern with `Cond[B]`, we incorrectly assumed we could constrain h1 with B, because `Cond[B]` is an applied type of which the baseType is Tuple2. The issue can be fixed in constrainSimplePatternType by obtaining the baseType for both the patternTp and scrutineeTp, with the most general base of the two. So in the above example, we wound constrain `B` with String by obtaining `(String, String)` from `Cond[B]`.
smarter
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Apr 6, 2024
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In the following example:
When constraining the
(h1, _)pattern withCond[B], we incorrectly assumed we could constrain h1 with B, becauseCond[B]is an applied type of which the baseType is Tuple2.The issue can be fixed in constrainSimplePatternType by obtaining the baseType for both the patternTp and scrutineeTp, with the most general base of the two.
So in the above example, we wound constrain B with String by obtaining
(String, String)fromCond[B].Fixes #19706