Fix #1757: Be more careful about positions of type variable binders #1764
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
We interpolate a type variable if the current tree contains the type variables binding tree. Previously, this was the application owning the variable. However, sometimes this tree is transformed so that the containment test fails, and type variables are instantiated too late (in the case of scala#1757 this was never). We fix this by - setting the binding tree to the type tree that first contains the type variable - making sure that tree is never copied literally anywhere else. It's a tricky dance, but I believe we got it right now.
smarter
reviewed
Dec 1, 2016
| // Note: It is important that the type arguments `targs` are passed in new trees | ||
| // instead of being spliced in literally. Otherwise, a type argument to a default | ||
| // method could be constructed as the definition site of the type variable for | ||
| // that default constructor. This would interpolate type variables too early, |
There was a problem hiding this comment.
I'm having trouble following this explanation, could you illustrate it with an example?
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
We interpolate a type variable if the current tree contains the type variable's
binding tree. Previously, this was the application owning the variable. However,
sometimes that tree is transformed so that the containment test fails, and
type variables are instantiated too late (in the case of #1757 this was never).
We fix this by
It's a tricky dance, but I believe we got it right now.
Fixes #1757. Review by @smarter ?