From 09143a5586ec8f968dcca1fe5041f378dac527e0 Mon Sep 17 00:00:00 2001
From: kerams <kerams@users.noreply.github.com>
Date: Tue, 18 Jul 2023 12:43:12 +0200
Subject: [PATCH] Fix recovery of `member _` (#15540)

* Fix recovery of member with wildcard this

* Update CheckExpressions.fs

* Refactor
---
 src/Compiler/Checking/CheckDeclarations.fs    |  1 +
 src/Compiler/Checking/CheckExpressions.fs     |  2 +-
 .../data/SyntaxTree/Member/Member 10.fs       |  6 +++
 .../data/SyntaxTree/Member/Member 10.fs.bsl   | 48 +++++++++++++++++++
 .../data/SyntaxTree/Member/Member 11.fs       |  6 +++
 .../data/SyntaxTree/Member/Member 11.fs.bsl   | 48 +++++++++++++++++++
 6 files changed, 110 insertions(+), 1 deletion(-)
 create mode 100644 tests/service/data/SyntaxTree/Member/Member 10.fs
 create mode 100644 tests/service/data/SyntaxTree/Member/Member 10.fs.bsl
 create mode 100644 tests/service/data/SyntaxTree/Member/Member 11.fs
 create mode 100644 tests/service/data/SyntaxTree/Member/Member 11.fs.bsl

diff --git a/src/Compiler/Checking/CheckDeclarations.fs b/src/Compiler/Checking/CheckDeclarations.fs
index 47606b18751..58bd39d1cdc 100644
--- a/src/Compiler/Checking/CheckDeclarations.fs
+++ b/src/Compiler/Checking/CheckDeclarations.fs
@@ -915,6 +915,7 @@ module MutRecBindingChecking =
                             let innerState = (incrClassCtorLhsOpt, envForTycon, tpenv, recBindIdx, uncheckedBindsRev)     
                             [Phase2AIncrClassBindings (tcref, letBinds, isStatic, isRec, m)], innerState
 
+                        | SynMemberDefn.Member(SynBinding(headPat = SynPat.Wild _; expr = SynExpr.ArbitraryAfterError _), _), _
                         | SynMemberDefn.Member(SynBinding(headPat = SynPat.FromParseError(SynPat.Wild _, _)), _), _ ->
                             [], innerState
 
diff --git a/src/Compiler/Checking/CheckExpressions.fs b/src/Compiler/Checking/CheckExpressions.fs
index 92c93b5a623..32f9a4de039 100644
--- a/src/Compiler/Checking/CheckExpressions.fs
+++ b/src/Compiler/Checking/CheckExpressions.fs
@@ -3930,7 +3930,7 @@ let GetInstanceMemberThisVariable (vspec: Val, expr) =
     // Skip over LAM tps. Choose 'a.
     if vspec.IsInstanceMember then
         let rec firstArg e =
-          match stripDebugPoints e with
+            match stripDebugPoints e with
             | Expr.TyLambda (_, _, b, _, _) -> firstArg b
             | Expr.TyChoose (_, b, _) -> firstArg b
             | Expr.Lambda (_, _, _, [v], _, _, _) -> Some v
diff --git a/tests/service/data/SyntaxTree/Member/Member 10.fs b/tests/service/data/SyntaxTree/Member/Member 10.fs
new file mode 100644
index 00000000000..f9ed788c6e4
--- /dev/null
+++ b/tests/service/data/SyntaxTree/Member/Member 10.fs	
@@ -0,0 +1,6 @@
+module Module
+
+type U =
+    | A
+
+    member _
diff --git a/tests/service/data/SyntaxTree/Member/Member 10.fs.bsl b/tests/service/data/SyntaxTree/Member/Member 10.fs.bsl
new file mode 100644
index 00000000000..5749df6a18b
--- /dev/null
+++ b/tests/service/data/SyntaxTree/Member/Member 10.fs.bsl	
@@ -0,0 +1,48 @@
+ImplFile
+  (ParsedImplFileInput
+     ("/root/Member/Member 10.fs", false, QualifiedNameOfFile Module, [], [],
+      [SynModuleOrNamespace
+         ([Module], false, NamedModule,
+          [Types
+             ([SynTypeDefn
+                 (SynComponentInfo
+                    ([], None, [], [U],
+                     PreXmlDoc ((3,0), FSharp.Compiler.Xml.XmlDocCollector),
+                     false, None, (3,5--3,6)),
+                  Simple
+                    (Union
+                       (None,
+                        [SynUnionCase
+                           ([], SynIdent (A, None), Fields [],
+                            PreXmlDoc ((4,4), FSharp.Compiler.Xml.XmlDocCollector),
+                            None, (4,6--4,7), { BarRange = Some (4,4--4,5) })],
+                        (4,4--4,7)), (4,4--4,7)),
+                  [Member
+                     (SynBinding
+                        (None, Normal, false, false, [],
+                         PreXmlDoc ((6,4), FSharp.Compiler.Xml.XmlDocCollector),
+                         SynValData
+                           (Some { IsInstance = true
+                                   IsDispatchSlot = false
+                                   IsOverrideOrExplicitImpl = false
+                                   IsFinal = false
+                                   GetterOrSetterIsCompilerGenerated = false
+                                   MemberKind = Member },
+                            SynValInfo
+                              ([[SynArgInfo ([], false, None)]; []],
+                               SynArgInfo ([], false, None)), None),
+                         Wild (6,11--6,12), None,
+                         ArbitraryAfterError ("memberCore2", (6,12--6,12)),
+                         (6,11--6,12), NoneAtInvisible,
+                         { LeadingKeyword = Member (6,4--6,10)
+                           InlineKeyword = None
+                           EqualsRange = None }), (6,4--6,12))], None,
+                  (3,5--6,12), { LeadingKeyword = Type (3,0--3,4)
+                                 EqualsRange = Some (3,7--3,8)
+                                 WithKeyword = None })], (3,0--6,12))],
+          PreXmlDoc ((1,0), FSharp.Compiler.Xml.XmlDocCollector), [], None,
+          (1,0--6,12), { LeadingKeyword = Module (1,0--1,6) })], (true, true),
+      { ConditionalDirectives = []
+        CodeComments = [] }, set []))
+
+(7,0)-(7,0) parse error Incomplete structured construct at or before this point in member definition. Expected 'with', '=' or other token.
diff --git a/tests/service/data/SyntaxTree/Member/Member 11.fs b/tests/service/data/SyntaxTree/Member/Member 11.fs
new file mode 100644
index 00000000000..390f2e0d57d
--- /dev/null
+++ b/tests/service/data/SyntaxTree/Member/Member 11.fs	
@@ -0,0 +1,6 @@
+module Module
+
+type U =
+    | A
+
+    member _.
diff --git a/tests/service/data/SyntaxTree/Member/Member 11.fs.bsl b/tests/service/data/SyntaxTree/Member/Member 11.fs.bsl
new file mode 100644
index 00000000000..a4d4b985c40
--- /dev/null
+++ b/tests/service/data/SyntaxTree/Member/Member 11.fs.bsl	
@@ -0,0 +1,48 @@
+ImplFile
+  (ParsedImplFileInput
+     ("/root/Member/Member 11.fs", false, QualifiedNameOfFile Module, [], [],
+      [SynModuleOrNamespace
+         ([Module], false, NamedModule,
+          [Types
+             ([SynTypeDefn
+                 (SynComponentInfo
+                    ([], None, [], [U],
+                     PreXmlDoc ((3,0), FSharp.Compiler.Xml.XmlDocCollector),
+                     false, None, (3,5--3,6)),
+                  Simple
+                    (Union
+                       (None,
+                        [SynUnionCase
+                           ([], SynIdent (A, None), Fields [],
+                            PreXmlDoc ((4,4), FSharp.Compiler.Xml.XmlDocCollector),
+                            None, (4,6--4,7), { BarRange = Some (4,4--4,5) })],
+                        (4,4--4,7)), (4,4--4,7)),
+                  [Member
+                     (SynBinding
+                        (None, Normal, false, false, [],
+                         PreXmlDoc ((6,4), FSharp.Compiler.Xml.XmlDocCollector),
+                         SynValData
+                           (Some { IsInstance = true
+                                   IsDispatchSlot = false
+                                   IsOverrideOrExplicitImpl = false
+                                   IsFinal = false
+                                   GetterOrSetterIsCompilerGenerated = false
+                                   MemberKind = Member },
+                            SynValInfo
+                              ([[SynArgInfo ([], false, None)]; []],
+                               SynArgInfo ([], false, None)), None),
+                         FromParseError (Wild (6,10--6,10), (6,10--6,10)), None,
+                         ArbitraryAfterError ("classDefnMember1", (6,10--6,10)),
+                         (6,4--6,10), NoneAtInvisible,
+                         { LeadingKeyword = Member (6,4--6,10)
+                           InlineKeyword = None
+                           EqualsRange = None }), (6,4--6,10))], None,
+                  (3,5--6,10), { LeadingKeyword = Type (3,0--3,4)
+                                 EqualsRange = Some (3,7--3,8)
+                                 WithKeyword = None })], (3,0--6,10))],
+          PreXmlDoc ((1,0), FSharp.Compiler.Xml.XmlDocCollector), [], None,
+          (1,0--6,10), { LeadingKeyword = Module (1,0--1,6) })], (true, true),
+      { ConditionalDirectives = []
+        CodeComments = [] }, set []))
+
+(7,0)-(7,0) parse error Incomplete structured construct at or before this point in member definition. Expected identifier, '(', '(*)' or other token.