Fix #5823: better erasure of bottom types #5926
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Change the definition of lub so that:
- lub(C, {Null, Nothing}) = C if C is a reference type
- lub(C, {Null, Nothing}) = Object if C is a value type (as before)
This allows us to generate more efficient code, and it better
matches the user's expectations.
abeln
commented
Feb 14, 2019
| } | ||
| } | ||
| def erasedLub(tp1: Type, tp2: Type)(implicit ctx: Context): Type = { | ||
| // After erasure, C | {Null, Nothing} is just C, if C is a reference type. |
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The diff is misleading: I only added the check at the start, but since the pattern matching expressions is no longer at the top level the whole thing is highlighted.
odersky
approved these changes
Feb 15, 2019
ghost
removed
the
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Change the definition of lub so that:
This allows us to generate more efficient code, and it better
matches the user's expectations.