Add parser recovery for incomplete named pat pair. (#14985)

* Add parser recovery for incomplete named pat pair.

* Remove newly added parser error.

* Update baseline

src/Compiler/SyntaxTree/SyntaxTree.fs

@@ -881,7 +881,7 @@ type SynSimplePats =
 type SynArgPats =
     | Pats of pats: SynPat list
 
-    | NamePatPairs of pats: (Ident * range * SynPat) list * range: range * trivia: SynArgPatsNamePatPairsTrivia
+    | NamePatPairs of pats: (Ident * range option * SynPat) list * range: range * trivia: SynArgPatsNamePatPairsTrivia
 
     member x.Patterns =
         match x with

src/Compiler/SyntaxTree/SyntaxTree.fsi

@@ -1025,7 +1025,7 @@ type SynSimplePats =
 type SynArgPats =
     | Pats of pats: SynPat list
 
-    | NamePatPairs of pats: (Ident * range * SynPat) list * range: range * trivia: SynArgPatsNamePatPairsTrivia
+    | NamePatPairs of pats: (Ident * range option * SynPat) list * range: range * trivia: SynArgPatsNamePatPairsTrivia
 
     member Patterns: SynPat list
 

src/Compiler/pars.fsy

@@ -3133,7 +3133,12 @@ namePatPairs:
 namePatPair:
    | ident EQUALS parenPattern
      { let mEquals = rhs parseState 2
-       ($1, mEquals, $3) }
+       ($1, Some mEquals, $3) }
+   | ident EQUALS recover
+     { let mEquals = rhs parseState 2
+       ($1, Some mEquals, patFromParseError (SynPat.Wild mEquals.EndRange)) }
+   | ident recover
+     { ($1, None, patFromParseError (SynPat.Wild $1.idRange.EndRange)) }
 
 constrPattern:
   | atomicPatternLongIdent explicitValTyparDecls

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl

@@ -5770,8 +5770,8 @@ FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.SyntaxTrivia.Syn
 FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.SyntaxTrivia.SynArgPatsNamePatPairsTrivia trivia
 FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.Text.Range range
-FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,FSharp.Compiler.Text.Range,FSharp.Compiler.Syntax.SynPat]] get_pats()
-FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,FSharp.Compiler.Text.Range,FSharp.Compiler.Syntax.SynPat]] pats
+FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range],FSharp.Compiler.Syntax.SynPat]] get_pats()
+FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range],FSharp.Compiler.Syntax.SynPat]] pats
 FSharp.Compiler.Syntax.SynArgPats+Pats: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynPat] get_pats()
 FSharp.Compiler.Syntax.SynArgPats+Pats: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynPat] pats
 FSharp.Compiler.Syntax.SynArgPats+Tags: Int32 NamePatPairs
@@ -5780,7 +5780,7 @@ FSharp.Compiler.Syntax.SynArgPats: Boolean IsNamePatPairs
 FSharp.Compiler.Syntax.SynArgPats: Boolean IsPats
 FSharp.Compiler.Syntax.SynArgPats: Boolean get_IsNamePatPairs()
 FSharp.Compiler.Syntax.SynArgPats: Boolean get_IsPats()
-FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats NewNamePatPairs(Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,FSharp.Compiler.Text.Range,FSharp.Compiler.Syntax.SynPat]], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynArgPatsNamePatPairsTrivia)
+FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats NewNamePatPairs(Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range],FSharp.Compiler.Syntax.SynPat]], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynArgPatsNamePatPairsTrivia)
 FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats NewPats(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynPat])
 FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats+NamePatPairs
 FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats+Pats

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl

@@ -5770,8 +5770,8 @@ FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.SyntaxTrivia.Syn
 FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.SyntaxTrivia.SynArgPatsNamePatPairsTrivia trivia
 FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: FSharp.Compiler.Text.Range range
-FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,FSharp.Compiler.Text.Range,FSharp.Compiler.Syntax.SynPat]] get_pats()
-FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,FSharp.Compiler.Text.Range,FSharp.Compiler.Syntax.SynPat]] pats
+FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range],FSharp.Compiler.Syntax.SynPat]] get_pats()
+FSharp.Compiler.Syntax.SynArgPats+NamePatPairs: Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range],FSharp.Compiler.Syntax.SynPat]] pats
 FSharp.Compiler.Syntax.SynArgPats+Pats: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynPat] get_pats()
 FSharp.Compiler.Syntax.SynArgPats+Pats: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynPat] pats
 FSharp.Compiler.Syntax.SynArgPats+Tags: Int32 NamePatPairs
@@ -5780,7 +5780,7 @@ FSharp.Compiler.Syntax.SynArgPats: Boolean IsNamePatPairs
 FSharp.Compiler.Syntax.SynArgPats: Boolean IsPats
 FSharp.Compiler.Syntax.SynArgPats: Boolean get_IsNamePatPairs()
 FSharp.Compiler.Syntax.SynArgPats: Boolean get_IsPats()
-FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats NewNamePatPairs(Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,FSharp.Compiler.Text.Range,FSharp.Compiler.Syntax.SynPat]], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynArgPatsNamePatPairsTrivia)
+FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats NewNamePatPairs(Microsoft.FSharp.Collections.FSharpList`1[System.Tuple`3[FSharp.Compiler.Syntax.Ident,Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range],FSharp.Compiler.Syntax.SynPat]], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynArgPatsNamePatPairsTrivia)
 FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats NewPats(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynPat])
 FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats+NamePatPairs
 FSharp.Compiler.Syntax.SynArgPats: FSharp.Compiler.Syntax.SynArgPats+Pats

tests/service/data/SyntaxTree/Pattern/NamedPatPairRecoverAfterEquals.fs

+match x with
+| Y(z = ) -> ()

tests/service/data/SyntaxTree/Pattern/NamedPatPairRecoverAfterEquals.fs.bsl

+ImplFile
+  (ParsedImplFileInput
+     ("/root/Pattern/NamedPatPairRecoverAfterEquals.fs", false,
+      QualifiedNameOfFile NamedPatPairRecoverAfterEquals, [], [],
+      [SynModuleOrNamespace
+         ([NamedPatPairRecoverAfterEquals], false, AnonModule,
+          [Expr
+             (Match
+                (Yes (1,0--1,12), Ident x,
+                 [SynMatchClause
+                    (LongIdent
+                       (SynLongIdent ([Y], [], [None]), None, None,
+                        NamePatPairs
+                          ([(z, Some (2,6--2,7),
+                             FromParseError (Wild (2,7--2,7), (2,7--2,7)))],
+                           (2,4--2,9), { ParenRange = (2,3--2,9) }), None,
+                        (2,2--2,9)), None, Const (Unit, (2,13--2,15)),
+                     (2,2--2,15), Yes, { ArrowRange = Some (2,10--2,12)
+                                         BarRange = Some (2,0--2,1) })],
+                 (1,0--2,15), { MatchKeyword = (1,0--1,5)
+                                WithKeyword = (1,8--1,12) }), (1,0--2,15))],
+          PreXmlDocEmpty, [], None, (1,0--3,0), { LeadingKeyword = None })],
+      (true, true), { ConditionalDirectives = []
+                      CodeComments = [] }, set []))
+
+(2,8)-(2,9) parse error Unexpected symbol ')' in pattern

tests/service/data/SyntaxTree/Pattern/NamedPatPairRecoverAfterIdentifier.fs

+match x with
+| Y(a = 1; b = 2; c) -> ()

tests/service/data/SyntaxTree/Pattern/NamedPatPairRecoverAfterIdentifier.fs.bsl

+ImplFile
+  (ParsedImplFileInput
+     ("/root/Pattern/NamedPatPairRecoverAfterIdentifier.fs", false,
+      QualifiedNameOfFile NamedPatPairRecoverAfterIdentifier, [], [],
+      [SynModuleOrNamespace
+         ([NamedPatPairRecoverAfterIdentifier], false, AnonModule,
+          [Expr
+             (Match
+                (Yes (1,0--1,12), Ident x,
+                 [SynMatchClause
+                    (LongIdent
+                       (SynLongIdent ([Y], [], [None]), None, None,
+                        NamePatPairs
+                          ([(a, Some (2,6--2,7), Const (Int32 1, (2,8--2,9)));
+                            (b, Some (2,13--2,14), Const (Int32 2, (2,15--2,16)));
+                            (c, None,
+                             FromParseError (Wild (2,19--2,19), (2,19--2,19)))],
+                           (2,4--2,20), { ParenRange = (2,3--2,20) }), None,
+                        (2,2--2,20)), None, Const (Unit, (2,24--2,26)),
+                     (2,2--2,26), Yes, { ArrowRange = Some (2,21--2,23)
+                                         BarRange = Some (2,0--2,1) })],
+                 (1,0--2,26), { MatchKeyword = (1,0--1,5)
+                                WithKeyword = (1,8--1,12) }), (1,0--2,26))],
+          PreXmlDocEmpty, [], None, (1,0--3,0), { LeadingKeyword = None })],
+      (true, true), { ConditionalDirectives = []
+                      CodeComments = [] }, set []))
+
+(2,19)-(2,20) parse error Unexpected symbol ')' in pattern. Expected '=' or other token.

tests/service/data/SyntaxTree/Pattern/ParenthesesOfSynArgPatsNamePatPairs.fs.bsl

@@ -11,7 +11,7 @@ ImplFile
                     (LongIdent
                        (SynLongIdent ([OnePartData], [], [None]), None, None,
                         NamePatPairs
-                          ([(part1, (4,10--4,11),
+                          ([(part1, Some (4,10--4,11),
                              Named
                                (SynIdent (p1, None), false, None, (4,12--4,14)))],
                            (4,4--5,13), { ParenRange = (3,13--5,13) }), None,

tests/service/data/SyntaxTree/Pattern/SynArgPatsNamePatPairsContainsTheRangeOfTheEqualsSign.fs.bsl

@@ -14,7 +14,7 @@ ImplFile
                     (LongIdent
                        (SynLongIdent ([X], [], [None]), None, None,
                         NamePatPairs
-                          ([(Y, (3,7--3,8),
+                          ([(Y, Some (3,7--3,8),
                              Named
                                (SynIdent (y, None), false, None, (3,9--3,10)))],
                            (3,4--3,11), { ParenRange = (3,3--3,11) }), None,