Parser error recovery discards too much in PNGS.sort((String a, Str1));

[stevemessick]

Full source:

class Foo { int boo = 7; mth() { PNGS.sort((String a, Str1)); }}

This is from a code completion test. The completion point is just before the 1 in Str1. The parser produces an AST for the body of mth() that is equivalent to:

{
  PNGS.sort((String));
}

There's no info about the identifier to be completed, so code completion cannot do anything. Note that two identifiers are lost: a, and Str1.

[jtmcdole]

Verified with --dump_ast_format console. This might be a simple case, so I'll take a quick look.

parserChew.dart:1: Unexpected token 'IDENTIFIER' (note: error marker on a)
     1: class Foo { int boo = 7; mth() { PNGS.sort((String a, Str1)); }}
   DartClass (class Foo)
      DartFieldDefinition
         DartTypeNode
            DartIdentifier (int)
         DartField (boo)
            DartIntegerLiteral (7)
      DartMethodDefinition (mth)
         DartFunction
            DartBlock
               DartExprStmt
                  DartMethodInvocation
                     DartIdentifier (PNGS)
                     DartIdentifier (sort)
                     DartParenthesizedExpression
                        DartIdentifier (String)

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[jtmcdole]

So as I suspected, the parser expects a ')' after String, and eats tokens till it finds it. I'm curious to know what you think the AST should look like in this case? DartNode doesn't have an List<DartNode> errors attached to it, so 'IDENTIFIER a, IDENTIFIER Str1' can't get stuffed on DartParenthesizedExpression.

I assume PNGS is a list and you're calling sort() with the compare closure, in which case this should look more like a function with a missing => or {}.

[stevemessick]

Your assumption is correct. The user (i.e. me) was typing a compare function and tried to complete "Str" expecting "String" to appear in the list. The => would be typed shortly thereafter. I don't care what the AST looks like as long as it has enough information that I can produce a completion list for "Str". Some sort of synthetic error node would be fine -- the completion engine is just a huge set of heuristics, and adding one more won't hurt anything.

[DartBot]

This comment was originally written by zundel@google.com

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[kasperl]

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[bwilkerson]

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[bwilkerson]

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[stevemessick]

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