Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Retry constraint.replace after constraint.updateEntry #20399

Merged
merged 4 commits into from
May 16, 2024
Merged

Retry constraint.replace after constraint.updateEntry #20399

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
49940ee
Retry `constraint.replace` after `constraint.updateEntry`
EugeneFlesselle Apr 17, 2024
97ed37e
Fix: don't use oldBounds to re-tryReplace
EugeneFlesselle May 15, 2024
14a6cac
Do tryReplace using narrowedBounds instead of legalBound
EugeneFlesselle May 15, 2024
b1d7735
Fix doc position
EugeneFlesselle May 16, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
56 changes: 33 additions & 23 deletions compiler/src/dotty/tools/dotc/core/ConstraintHandling.scala
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -120,7 +120,7 @@ trait ConstraintHandling {
*/
private var myTrustBounds = true

inline def withUntrustedBounds(op: => Type): Type =
transparent inline def withUntrustedBounds(op: => Type): Type =
val saved = myTrustBounds
myTrustBounds = false
try op finally myTrustBounds = saved
Expand Down Expand Up @@ -301,34 +301,44 @@ trait ConstraintHandling {
// so we shouldn't allow them as constraints either.
false
else
val bound = legalBound(param, rawBound, isUpper)
val oldBounds @ TypeBounds(lo, hi) = constraint.nonParamBounds(param)
val equalBounds = (if isUpper then lo else hi) eq bound
if equalBounds && !bound.existsPart(_ eq param, StopAt.Static) then
// The narrowed bounds are equal and not recursive,
// so we can remove `param` from the constraint.
constraint = constraint.replace(param, bound)
true
else
// Narrow one of the bounds of type parameter `param`
// If `isUpper` is true, ensure that `param <: `bound`, otherwise ensure
// that `param >: bound`.
val narrowedBounds =
val saved = homogenizeArgs
homogenizeArgs = Config.alignArgsInAnd
try
withUntrustedBounds(
if isUpper then oldBounds.derivedTypeBounds(lo, hi & bound)
else oldBounds.derivedTypeBounds(lo | bound, hi))
finally
homogenizeArgs = saved

// Narrow one of the bounds of type parameter `param`
// If `isUpper` is true, ensure that `param <: `bound`,
// otherwise ensure that `param >: bound`.
val narrowedBounds: TypeBounds =
val bound = legalBound(param, rawBound, isUpper)
val oldBounds @ TypeBounds(lo, hi) = constraint.nonParamBounds(param)

val saved = homogenizeArgs
homogenizeArgs = Config.alignArgsInAnd
try
withUntrustedBounds(
if isUpper then oldBounds.derivedTypeBounds(lo, hi & bound)
else oldBounds.derivedTypeBounds(lo | bound, hi))
finally
homogenizeArgs = saved
end narrowedBounds

// If the narrowed bounds are equal and not recursive,
// we can remove `param` from the constraint.
def tryReplace(newBounds: TypeBounds): Boolean =
val TypeBounds(lo, hi) = newBounds
val canReplace = (lo eq hi) && !newBounds.existsPart(_ eq param, StopAt.Static)
if canReplace then constraint = constraint.replace(param, lo)
canReplace

tryReplace(narrowedBounds) || locally:
//println(i"narrow bounds for $param from $oldBounds to $narrowedBounds")
val c1 = constraint.updateEntry(param, narrowedBounds)
(c1 eq constraint)
|| {
constraint = c1
val TypeBounds(lo, hi) = constraint.entry(param): @unchecked
isSub(lo, hi)
val isSat = isSub(lo, hi)
if isSat then
// isSub may have narrowed the bounds further
tryReplace(constraint.nonParamBounds(param))
isSat
}
end addOneBound

Expand Down
Loading