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Diffstat (limited to 'src/dotty/tools/dotc/core/ConstraintHandling.scala')
| -rw-r--r-- | src/dotty/tools/dotc/core/ConstraintHandling.scala | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/dotty/tools/dotc/core/ConstraintHandling.scala b/src/dotty/tools/dotc/core/ConstraintHandling.scala index 577b958c8..ff7afe99a 100644 --- a/src/dotty/tools/dotc/core/ConstraintHandling.scala +++ b/src/dotty/tools/dotc/core/ConstraintHandling.scala @@ -232,6 +232,16 @@ trait ConstraintHandling { } } + /** Instantiate `param` to `tp` if the constraint stays satisfiable */ + protected def tryInstantiate(param: PolyParam, tp: Type): Boolean = { + val saved = constraint + constraint = + if (addConstraint(param, tp, fromBelow = true) && + addConstraint(param, tp, fromBelow = false)) constraint.replace(param, tp) + else saved + constraint ne saved + } + /** Check that constraint is fully propagated. See comment in Config.checkConstraintsPropagated */ def checkPropagated(msg: => String)(result: Boolean): Boolean = { if (Config.checkConstraintsPropagated && result && addConstraintInvocations == 0) { |