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Merged
merged 5 commits into from
Nov 9, 2018
Merged

Tailrec improvements #5399

merged 5 commits into from
Nov 9, 2018

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allanrenucci
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@allanrenucci allanrenucci mentioned this pull request Nov 6, 2018
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sjrd
sjrd requested changes Nov 6, 2018
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sjrd commented Nov 7, 2018

The optimization is incorrect. It is possible to re-enter a tail-pos context even from some places where we are in a non-tail-pos context. The most important example is when finding a return[label] expr where the label: { ... } block was in tail position, but the return was not. In that case, expr must be considered to be in tail position. This is critical for tail-recursive calls in the cases of a pattern match.

@allanrenucci allanrenucci force-pushed the fix-5163-bis branch 5 times, most recently from 3eca547 to f8f2b4e Compare November 8, 2018 13:36
@allanrenucci allanrenucci changed the title Fix #5163: Report tailrec failures on recursive call targeting supertype Tailrec improvements Nov 8, 2018
@allanrenucci allanrenucci requested a review from sjrd November 9, 2018 15:54
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sjrd approved these changes Nov 9, 2018
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Optimise the Tailrec phase
d47ead5 
We can stop traversing a tree in Tailrec as soon as we are not in tail
position anymore and we are not within a labeled block in tail position.
We keep traversing the tree however if the method is @tailrec annotated
to report errors on eventual recursive calls.
@allanrenucci
Improve error reporting for Tailrec
a129cbd
@allanrenucci allanrenucci merged commit a9029dc into scala:master Nov 9, 2018
@allanrenucci allanrenucci deleted the fix-5163-bis branch November 9, 2018 17:10
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