Warn on use of inferred quote type variable bounds #16932
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We also need #16942 for this message to make sense in type patterns. |
nicolasstucki
commented
Feb 17, 2023
| @@ -159,6 +159,8 @@ trait QuotesAndSplices { | |||
| case _ => TypeBounds.empty | |||
| val typeSym = newSymbol(spliceOwner(ctx), name, EmptyFlags, typeSymInfo, NoSymbol, tree.span) | |||
| typeSym.addAnnotation(Annotation(New(ref(defn.QuotedRuntimePatterns_patternTypeAnnot.typeRef)).withSpan(tree.span))) | |||
| if !(typeSymInfo =:= TypeBounds.empty) then | |||
| report.warning(em"Type variable `$tree` has partially inferred bounds$pt.\n\nConsider defining bounds explicitly `'{ $typeSym$pt; ... }`", tree.srcPos) | |||
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We should write '[ type t <: T; ... ] for type patterns once we support #16942
This kind of inference is not reliable in general. We can only consider the bounds from type constructor where the type variable is defined but any other constraints are ignored. Therefore it is not possible to properly infer the type bounds of the type variable. The solution is simple, write the bounds explicitly and just check that those bounds conform to the use site of the type variable.
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This kind of inference is not reliable in general. We can only consider the bounds from type constructor where the type variable is defined but any other constraints are ignored. Therefore it is not possible to properly infer the type bounds of the type variable.
The solution is simple, write the bounds explicitly and just check that those bounds conform to the use site of the type variable.