Fix #2960: Only allow one inserted apply per tree #2962
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This fix prevents infinite chains of inserted apply's. Fixes scala#2960.
The parameter is never queried in current code, just passed along.
| def tryInsertApplyOrImplicit(tree: Tree, pt: ProtoType)(fallBack: => Tree)(implicit ctx: Context): Tree = { | ||
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| def isSyntheticApply(tree: Tree): Boolean = tree match { | ||
| case tree: Select => tree.getAttachment(InsertedApply).isDefined |
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Why is an attachment needed instead of checking if the tree selects nme.apply ?
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Good question. It depends how we want to specity it:
1st choice: An apply is inserted on any expression in function position unless that expression is already an inserted apply.
2nd choice: An apply is inserted on any expression in function position unless that expression is itself an apply selection or call.
Which way should we go? Here's where it makes a difference. Consider the case where we want to expand to
f.apply(...).apply(...)
If we give only one apply, which one should be the inserted one? According to the PR, it must be the second apply. If we followed 2nd choice, this would be rejected instead.
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One reason to keep the current PR is that the first apply could be macro generated where the macro returns a map, say. Then it would seem sensical to insert the 2nd apply automatically, as for any other map.
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Can this go in now? |
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LGTM, but adding a need-spec tag so we remember to specify this at some point.
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This fix prevents infinite chains of inserted apply's. Fixes #2960.