Expand span errorTermTree to include skipped span. #14492
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adampauls
commented
Feb 15, 2022
| @@ -10,7 +10,7 @@ object Test { | |||
| val b = type // error: expression expected (on "type") | |||
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| 1 match { | |||
| case // error: pattern expected // error: cannot compare with Null | |||
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This error leaks the implementation detail that parser errors produce a null.
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cc @som-snytt |
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Feb 15, 2022
| @@ -21,9 +21,7 @@ class DiagnosticsTest { | |||
| | Nil.map(x => x).filter(x$m1 =>$m2)$m3 | |||
| |}""".withSource | |||
| .diagnostics(m1, | |||
| (m2 to m2, "expression expected but ')' found", Error, Some(IllegalStartSimpleExprID)), | |||
| (m1 to m1, """Found: Null | |||
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Another confusing error gone.
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odersky
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Feb 16, 2022
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Friendly ping @nicolasstucki , I think I am waiting on you to review. Thanks! |
nicolasstucki
approved these changes
Feb 21, 2022
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At present, when the parser encounters an error and produces
errorTermTree, it first issues a syntax error, which has the side effect of skipping to the nearest "safe point" (), newline, etc.). This means that theerrorTermTreeconceptually covers the whole skipped span, but only the position right before the safe point token is included in the span of the error.This PR keeps track of the
lastOffsetbefore skipping tokens and includes everything from that offset up to the safe point in the span of the error. So for example, infoo(5, :), previously, theerrorTermTreereturned would not include the:.This reduces the number of (redundant) errors, and in particular removes type-checking errors that arise from the presumably-private implementation detail of producing
Constant(null)as theerrorTermTree.