Normalize match types before computing implicit scopes #20081
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We now try to reduce match types before computing their contributions to an implicit scope. This avoids problems where joint and separate compilations gave different results, as in scala#20071 and scala#15183. Background: If a match type is reducible to a type R the compiler is free to replace the match type with R. That should not affect the implicit scope computation. Consequently, we have to try to reduce match types before computing their contributions to an implicit scope. scala#20071 and scala#15183 are really the same problem. Both used to compile in sequence and both gave an implicit not found error when two files were compiled together. In scala#15183 a weird match type was constructed intentionally, in order to avoid an otherwise necessary given import. That exploited a bug in the compiler which this PR fixes.
| duplicate of #20077 |
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We now try to reduce match types before computing their contributions to an implicit scope. This avoids problems where joint and separate compilations gave different results, as in #20071 and #15183.
Background: If a match type is reducible to a type R the compiler is free to replace the match type with R. That should not affect the implicit scope computation. Consequently, we have to try to reduce match types before computing their contributions to an implicit scope.
#20071 and #15183 are really the same problem. Both used to compile in sequence and both gave an implicit not found error when two files were compiled together.
In #15183 a weird match type was constructed intentionally, in order to avoid an otherwise necessary given import. That exploited a bug in the compiler which this PR fixes.
Fixes #20071