Parser: recover on missing union case fields

docs/release-notes/.FSharp.Compiler.Service/9.0.100.md

@@ -9,6 +9,7 @@
 ### Added
 
 * Support for nullable reference types ([PR #15181](https://github.com/dotnet/fsharp/pull/15181))
+* Parser: recover on missing union case fields ([#17452](https://github.com/dotnet/fsharp/pull/17452))
 * Sink: report function domain type ([PR #17470](https://github.com/dotnet/fsharp/pull/17470))
 
 ### Changed

src/Compiler/FSComp.txt

@@ -1762,7 +1762,7 @@ featureReuseSameFieldsInStructUnions,"Share underlying fields in a [<Struct>] di
 3860,chkStaticMembersOnObjectExpressions,"Object expressions cannot implement interfaces with static abstract members or declare static members."
 3861,chkTailCallAttrOnNonRec,"The TailCall attribute should only be applied to recursive functions."
 3862,parsStaticMemberImcompleteSyntax,"Incomplete declaration of a static construct. Use 'static let','static do','static member' or 'static val' for declaration."
-3863,parsExpectingField,"Expecting record field"
+3863,parsExpectingRecordField,"Expecting record field"
 3864,tooManyMethodsInDotNetTypeWritingAssembly,"The type '%s' has too many methods. Found: '%d', maximum: '%d'"
 3865,parsOnlySimplePatternsAreAllowedInConstructors,"Only simple patterns are allowed in primary constructors"
 3866,chkStaticAbstractInterfaceMembers,"A static abstract non-virtual interface member should only be called via type parameter (for example: 'T.%s)."
@@ -1775,3 +1775,4 @@ featureParsedHashDirectiveArgumentNonString,"# directives with non-quoted string
 3869,featureParsedHashDirectiveUnexpectedInteger,"Unexpected integer literal '%d'."
 3869,featureParsedHashDirectiveUnexpectedIdentifier,"Unexpected identifier '%s'."
 featureEmptyBodiedComputationExpressions,"Support for computation expressions with empty bodies: builder {{ }}"
+3870,parsExpectingUnionCaseField,"Expecting union case field"

src/Compiler/pars.fsy

@@ -2471,7 +2471,7 @@ braceFieldDeclList:
      { [] }
 
   | LBRACE rbrace
-     { errorR (Error(FSComp.SR.parsExpectingField(), rhs parseState 2))
+     { errorR (Error(FSComp.SR.parsExpectingRecordField (), rhs parseState 2))
        [] }
 
 anonRecdType:
@@ -2711,17 +2711,26 @@ attrUnionCaseDecl:
       { fun (xmlDoc, mBar) -> mkSynUnionCase $1 $2 (SynIdent(mkSynId mBar.EndRange "", None)) (SynUnionCaseKind.Fields []) mBar (xmlDoc, mBar) |> Choice2Of2 }
 
   | opt_attributes opt_access unionCaseName OF unionCaseRepr
-      { mkSynUnionCase $1 $2 $3 (SynUnionCaseKind.Fields $5) (rhs2 parseState 1 5) >> Choice2Of2 }
+      { let mId = rhs parseState 3
+        let fields, mFields = $5
+        let mWhole = unionRanges mId mFields
+        mkSynUnionCase $1 $2 $3 (SynUnionCaseKind.Fields fields) mWhole >> Choice2Of2 }
 
   | opt_attributes opt_access unionCaseName unionCaseRepr
       { errorR (Error(FSComp.SR.parsMissingKeyword("of"), rhs2 parseState 3 4))
-        mkSynUnionCase $1 $2 $3 (SynUnionCaseKind.Fields $4) (rhs2 parseState 1 4) >> Choice2Of2 }
+        let mAttributes = rhs parseState 1
+        let fields, mFields = $4
+        let mWhole = unionRanges mAttributes mFields
+        mkSynUnionCase $1 $2 $3 (SynUnionCaseKind.Fields fields) mWhole >> Choice2Of2 }
 
   | opt_attributes opt_access OF unionCaseRepr
-      { let mOf = rhs parseState 3
+      { let mAttributes = rhs parseState 1
+        let mOf = rhs parseState 3
         let mId = mOf.StartRange
+        let fields, mFields = $4
+        let mWhole = unionRanges mAttributes mFields
         errorR (Error(FSComp.SR.parsMissingUnionCaseName(), mOf))
-        mkSynUnionCase $1 $2 (SynIdent(mkSynId mId "", None)) (SynUnionCaseKind.Fields $4) (rhs2 parseState 1 4) >> Choice2Of2 }
+        mkSynUnionCase $1 $2 (SynIdent(mkSynId mId "", None)) (SynUnionCaseKind.Fields fields) mWhole >> Choice2Of2 }
 
   | opt_attributes opt_access OF recover
       { let mOf = rhs parseState 3
@@ -2733,13 +2742,18 @@ attrUnionCaseDecl:
       { mkSynUnionCase $1 $2 $3 (SynUnionCaseKind.Fields []) (rhs2 parseState 1 4) >> Choice2Of2 }
 
   | opt_attributes opt_access unionCaseName COLON topType
-      { if parseState.LexBuffer.ReportLibraryOnlyFeatures then libraryOnlyWarning(lhs parseState)
-        mkSynUnionCase $1 $2 $3 (SynUnionCaseKind.FullType $5) (rhs2 parseState 1 5) >> Choice2Of2 }
+      { let mAttributes = rhs parseState 1
+        let fullType, _ = $5
+        let mWhole = unionRanges mAttributes fullType.Range
+        if parseState.LexBuffer.ReportLibraryOnlyFeatures then libraryOnlyWarning(lhs parseState)
+        mkSynUnionCase $1 $2 $3 (SynUnionCaseKind.FullType $5) mWhole >> Choice2Of2 }
 
   | opt_attributes opt_access unionCaseName EQUALS atomicExpr
       { if Option.isSome $2 then errorR(Error(FSComp.SR.parsEnumFieldsCannotHaveVisibilityDeclarations(), rhs parseState 2))
         let mEquals = rhs parseState 4
-        let mDecl = rhs2 parseState 1 5
+        let mAttributes = rhs parseState 1
+        let expr, _ = $5
+        let mDecl = unionRanges mAttributes expr.Range
         (fun (xmlDoc, mBar) ->
             let trivia: SynEnumCaseTrivia = { BarRange = Some mBar; EqualsRange = mEquals }
             let mDecl = unionRangeWithXmlDoc xmlDoc mDecl
@@ -2797,16 +2811,20 @@ firstUnionCaseDeclOfMany:
 
 firstUnionCaseDecl:
   | ident OF unionCaseRepr
-      { let trivia: SynUnionCaseTrivia = { BarRange = None }
+      { let fields, mFields = $3
+        let trivia: SynUnionCaseTrivia = { BarRange = None }
         let xmlDoc = grabXmlDoc (parseState, [], 1)
-        let mDecl = rhs2 parseState 1 3 |> unionRangeWithXmlDoc xmlDoc
-        Choice2Of2(SynUnionCase([], SynIdent($1, None), SynUnionCaseKind.Fields $3, xmlDoc, None, mDecl, trivia)) }
+        let mId = rhs parseState 1
+        let mDecl = unionRanges mId mFields |> unionRangeWithXmlDoc xmlDoc
+        Choice2Of2(SynUnionCase([], SynIdent($1, None), SynUnionCaseKind.Fields fields, xmlDoc, None, mDecl, trivia)) }
 
-  | unionCaseName COLON topType 
+  | unionCaseName COLON topType
       { if parseState.LexBuffer.ReportLibraryOnlyFeatures then libraryOnlyWarning(lhs parseState)
         let trivia: SynUnionCaseTrivia = { BarRange = None }
         let xmlDoc = grabXmlDoc (parseState, [], 1)
-        let mDecl = rhs2 parseState 1 3 |> unionRangeWithXmlDoc xmlDoc
+        let mId = rhs parseState 1
+        let fullType, _ = $3
+        let mDecl = unionRanges mId fullType.Range |> unionRangeWithXmlDoc xmlDoc
         Choice2Of2(SynUnionCase([], $1, SynUnionCaseKind.FullType $3, xmlDoc, None, mDecl, trivia)) }
 
   | ident OF recover
@@ -2818,18 +2836,21 @@ firstUnionCaseDecl:
   | OF unionCaseRepr
      { let mOf = rhs parseState 1
        let mId = mOf.StartRange
+       let fields, mFields = $2
        errorR (Error(FSComp.SR.parsMissingUnionCaseName(), mOf))
        let id = SynIdent(mkSynId mId "", None)
        let trivia: SynUnionCaseTrivia = { BarRange = None }
        let xmlDoc = grabXmlDoc (parseState, [], 1)
-       let mDecl = rhs2 parseState 1 2 |> unionRangeWithXmlDoc xmlDoc
-       Choice2Of2(SynUnionCase([], id, SynUnionCaseKind.Fields $2, xmlDoc, None, mDecl, trivia)) }
+       let mDecl = unionRanges mOf mFields |> unionRangeWithXmlDoc xmlDoc
+       Choice2Of2(SynUnionCase([], id, SynUnionCaseKind.Fields fields, xmlDoc, None, mDecl, trivia)) }
 
   | ident EQUALS atomicExpr opt_OBLOCKSEP
-      { let mEquals = rhs parseState 2
+      { let mId = rhs parseState 1
+        let mEquals = rhs parseState 2
         let trivia: SynEnumCaseTrivia = { BarRange = None; EqualsRange = mEquals }
         let xmlDoc = grabXmlDoc (parseState, [], 1)
-        let mDecl = rhs2 parseState 1 3 |> unionRangeWithXmlDoc xmlDoc
+        let expr, _ = $3
+        let mDecl = unionRanges mId expr.Range |> unionRangeWithXmlDoc xmlDoc
         Choice1Of2(SynEnumCase([], SynIdent($1, None), fst $3, xmlDoc, mDecl, trivia)) }
 
   | ident EQUALS recover opt_OBLOCKSEP
@@ -2843,10 +2864,26 @@ firstUnionCaseDecl:
 
 unionCaseReprElements:
   | unionCaseReprElement STAR unionCaseReprElements
-     { $1 :: $3 }
+     { let mField = rhs parseState 1
+       let fields, mFields = $3
+       $1 :: fields, unionRanges mField mFields }
+
+  | unionCaseReprElement STAR recover
+     { let mStar = rhs parseState 2
+       let ty = SynType.FromParseError mStar.EndRange
+       let field = mkSynAnonField (ty, PreXmlDoc.Empty)
+       [$1; field], rhs2 parseState 1 2 }
+
+  | STAR unionCaseReprElements
+     { let mStar = rhs parseState 1
+       errorR (Error(FSComp.SR.parsExpectingUnionCaseField (), rhs parseState 1))
+       let fields, mFields = $2
+       let ty = SynType.FromParseError mStar.StartRange
+       let field = mkSynAnonField (ty, PreXmlDoc.Empty)
+       field :: fields, unionRanges mStar mFields }
 
   | unionCaseReprElement %prec prec_toptuptyptail_prefix
-     { [$1] }
+     { [$1], rhs parseState 1 }
 
 unionCaseReprElement:
   | ident COLON appTypeNullableInParens
@@ -2872,7 +2909,7 @@ unionCaseReprElement:
 unionCaseRepr:
   | braceFieldDeclList
      { errorR(Deprecated(FSComp.SR.parsConsiderUsingSeparateRecordType(), lhs parseState))
-       $1 }
+       $1, rhs parseState 1 }
 
   | unionCaseReprElements
      { $1 }
@@ -2948,7 +2985,8 @@ exconIntro:
       { SynUnionCase([], SynIdent($1, None), SynUnionCaseKind.Fields [], PreXmlDoc.Empty, None, lhs parseState, { BarRange = None }) }
 
   | ident OF unionCaseRepr
-      { SynUnionCase([], SynIdent($1, None), SynUnionCaseKind.Fields $3, PreXmlDoc.Empty, None, lhs parseState, { BarRange = None }) }
+      { let fields, _ = $3
+        SynUnionCase([], SynIdent($1, None), SynUnionCaseKind.Fields fields, PreXmlDoc.Empty, None, lhs parseState, { BarRange = None }) }
 
   | ident OF recover
       { SynUnionCase([], SynIdent($1, None), SynUnionCaseKind.Fields [], PreXmlDoc.Empty, None, lhs parseState, { BarRange = None }) }