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OlegYch opened this issue Oct 10, 2024 · 3 comments · Fixed by #23216
Closed

Incorrect warning with -no-indent #21749

OlegYch opened this issue Oct 10, 2024 · 3 comments · Fixed by #23216
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area:parser itype:bug

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@OlegYch
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OlegYch commented Oct 10, 2024 •
edited by KacperFKorban
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Compiler version

3.3-3.5 with -no-indent option

Minimized code

1 match {
  case 1 =>
    case class Test(name: String)
    Nil
}

Output

4 |      Nil
  |      ^
  |      Line is indented too far to the right, or a `{` or `:` is missing

Expectation

no warning
@OlegYch OlegYch added itype:bug stat:needs triage Every issue needs to have an "area" and "itype" label labels Oct 10, 2024
@KacperFKorban KacperFKorban added area:parser Spree Suitable for a future Spree and removed stat:needs triage Every issue needs to have an "area" and "itype" label labels Oct 13, 2024
@mbovel
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mbovel commented May 19, 2025

Why is this a bug? It seems expected to me that this is not parsable with -no-indent. Why would the braces around the case body not be required?

@mbovel mbovel removed the Spree Suitable for a future Spree label May 19, 2025
@OlegYch
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OlegYch commented May 19, 2025

@mbovel it was always parsable

@mbovel
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mbovel commented May 21, 2025

@mbovel it was always parsable

You're right! The relevant rules of the syntax summary are

MatchClause       ::=  ‘match’ <<< CaseClauses >>>
CaseClauses       ::=  CaseClause { CaseClause }
CaseClause        ::=  ‘case’ Pattern [Guard] ‘=>’ Block
Block             ::=  {BlockStat semi} [BlockResult]
BlockStat         ::=  Import
                    |  {Annotation {nl}} {LocalModifier} Def
                    |  Extension
                    |  Expr1
                    |  EndMarker
Def               ::=  ‘val’ PatDef
                    |  ‘var’ PatDef
                    |  ‘def’ DefDef
                    |  ‘type’ {nl} TypeDef
                    |  TmplDef
TmplDef           ::=  ([‘case’] ‘class’ | ‘trait’) ClassDef
                    |  [‘case’] ‘object’ ObjectDef
                    |  ‘enum’ EnumDef
                    |  'given' (GivenDef | OldGivenDef)
ClassDef          ::=  id ClassConstr [Template]

According to this, the body of a case can start with one or more Defs without requiring braces or indentation. That comes as a surprise to me.

@mbovel mbovel mentioned this issue May 21, 2025
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@mbovel mbovel closed this as completed in 3a2635d May 21, 2025
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Fix incorrect warning with -no-indent dotty-staging/dotty
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@OlegYch @mbovel @KacperFKorban