Parser: recover on missing interface members

docs/release-notes/.FSharp.Compiler.Service/11.0.100.md

@@ -108,12 +108,10 @@
 * Fix signature conformance: overloaded member with unit parameter `M(())` now matches sig `member M: unit -> unit`. ([Issue #19596](https://github.com/dotnet/fsharp/issues/19596), [PR #19615](https://github.com/dotnet/fsharp/pull/19615))
 * Fix `--quiet` not suppressing NuGet restore output on stdout in F# Interactive ([Issue #18086](https://github.com/dotnet/fsharp/issues/18086))
 * Reference assembly MVIDs are now deterministic across compiler invocations. Previously, `--refout` / `<ProduceReferenceAssembly>true</ProduceReferenceAssembly>` produced a different MVID every build because the implied signature hash used .NET's randomized `String.GetHashCode()`. ([Issue #19751](https://github.com/dotnet/fsharp/issues/19751), [PR #19801](https://github.com/dotnet/fsharp/pull/19801))
-* Parser: recover on unfinished if and binary expressions
-([PR #19724](https://github.com/dotnet/fsharp/pull/19724))
+* Parser: recover on unfinished if and binary expressions ([PR #19724](https://github.com/dotnet/fsharp/pull/19724))
 * Fix `SynExpr.shouldBeParenthesizedInContext` to report parentheses as required around `SynExpr.Sequential` expressions used as record or anonymous-record field values, so the IDE "remove unnecessary parentheses" analyzer no longer breaks code like `{| A = ((); B = 3) |}`. ([Issue #17826](https://github.com/dotnet/fsharp/issues/17826), [PR #19850](https://github.com/dotnet/fsharp/pull/19850))
 * Fix semantic classification of `IDisposable` and other interface types in type-occurrence positions being incorrectly classified as `DisposableType` instead of `Interface`. ([Issue #16268](https://github.com/dotnet/fsharp/issues/16268), [PR #19809](https://github.com/dotnet/fsharp/pull/19809))
 * Fix missing semantic classification on second and later type qualifiers in nested copy-and-update expressions like `{ p with Person.Info.X = 1; Person.Info.Y = 2 }`. ([Issue #17428](https://github.com/dotnet/fsharp/issues/17428), [PR #19878](https://github.com/dotnet/fsharp/pull/19878))
-* Parser: recover on unfinished if and binary expressions ([PR #19724](https://github.com/dotnet/fsharp/pull/19724))
 * Fix QuickInfo / `GetAllUsesOfAllSymbolsInFile` for overloaded CE `[<CustomOperation>]` keywords to report the actually-resolved overload instead of the first-registered one. ([Issue #11612](https://github.com/dotnet/fsharp/issues/11612), [Issue #15206](https://github.com/dotnet/fsharp/issues/15206), [PR #19865](https://github.com/dotnet/fsharp/pull/19865))
 * Fix `open` declaration insertion in `.fsx`/`.fsscript` scripts being placed before `#r`/`#load` directives, producing invalid script files. ([Issue #16271](https://github.com/dotnet/fsharp/issues/16271), [PR #19879](https://github.com/dotnet/fsharp/pull/19879))
 * Warn FS3888 when a compiler-semantic attribute on a value/member or type/module is present in the `.fs` but missing from the `.fsi`. Such attributes were previously ignored at the consumer side. Under the `ErrorOnMissingSignatureAttribute` preview language feature, FS3888 is an error. ([Issue #19560](https://github.com/dotnet/fsharp/issues/19560), [PR #19880](https://github.com/dotnet/fsharp/pull/19880))
@@ -129,6 +127,7 @@
 * Fix dot-completion after indexed expressions (`a.[0].Data.`, `a[0].Data.`, `[1;2].Length.`) returning unrelated global completions instead of expression-typings members. ([Issue #4966](https://github.com/dotnet/fsharp/issues/4966), [PR #19934](https://github.com/dotnet/fsharp/pull/19934))
 * Quotations of `match s with "" -> _` no longer leak the `s <> null && s.Length = 0` lowering; the empty-string optimization moved from pattern-match compilation to the optimizer so quoted expressions keep `op_Equality(s, "")`. ([Issue #19873](https://github.com/dotnet/fsharp/issues/19873))
 * Fix #5795: Allow attributes defined in a `module rec` / `namespace rec` scope to be used on union cases, record fields, and generic type parameters of types in the same recursive scope. ([Issue #5795](https://github.com/dotnet/fsharp/issues/5795), [PR #19744](https://github.com/dotnet/fsharp/pull/19744))
+* Parser: recover on missing interface members ([PR #20105](https://github.com/dotnet/fsharp/pull/20105))
 
 ### Added
 

src/Compiler/FSComp.txt

@@ -1828,3 +1828,4 @@ featureErrorOnMissingSignatureAttribute,"error (rather than warning) when an enf
 featureNotNullIfNotNull,"honor the 'NotNullIfNotNull' attribute on a method's return value"
 featureAccessProtectedBaseFieldFromClosure,"Access a protected base-class field from a closure inside a member"
 featureImprovedImpliedArgumentNamesPartTwo,"Improved implied argument names with partial application"
+3892,parsExpectingMember,"Expecting member"

src/Compiler/pars.fsy

@@ -2310,6 +2310,11 @@ opt_interfaceImplDefn:
        Some(mWithKwd, members, m) }
 
   | WITH
+     { let mWithKwd = rhs parseState 1
+       reportParseErrorAt mWithKwd (FSComp.SR.parsExpectingMember ())
+       Some(mWithKwd, [], mWithKwd) }
+
+  | OWITH recover
      { let mWithKwd = rhs parseState 1
        Some(mWithKwd, [], mWithKwd) }
 

tests/service/data/SyntaxTree/Member/Interface 02.fs.bsl

@@ -47,5 +47,6 @@ ImplFile
         WarnDirectives = []
         CodeComments = [] }, set []))
 
+(4,16)-(4,20) parse error Expecting member
 (6,4)-(6,21) parse error Unexpected syntax or possible incorrect indentation: this token is offside of context started at position (4:5). Try indenting this further.
 To continue using non-conforming indentation, pass the '--strict-indentation-' flag to the compiler, or set the language version to F# 7.

tests/service/data/SyntaxTree/Member/Interface 03.fs.bsl

@@ -22,3 +22,5 @@ ImplFile
       { ConditionalDirectives = []
         WarnDirectives = []
         CodeComments = [] }, set []))
+
+(4,16)-(4,20) parse error Expecting member

tests/service/data/SyntaxTree/Member/Interface 04.fs.bsl

@@ -35,3 +35,5 @@ ImplFile
       { ConditionalDirectives = []
         WarnDirectives = []
         CodeComments = [] }, set []))
+
+(4,16)-(4,20) parse error Expecting member

tests/service/data/SyntaxTree/Member/Interface 05.fs.bsl

@@ -35,3 +35,5 @@ ImplFile
       { ConditionalDirectives = []
         WarnDirectives = []
         CodeComments = [] }, set []))
+
+(4,16)-(4,20) parse error Expecting member

tests/service/data/SyntaxTree/Member/Interface 06.fs.bsl

@@ -37,5 +37,6 @@ ImplFile
         WarnDirectives = []
         CodeComments = [] }, set []))
 
+(4,16)-(4,20) parse error Expecting member
 (6,4)-(6,14) parse error Unexpected syntax or possible incorrect indentation: this token is offside of context started at position (4:5). Try indenting this further.
 To continue using non-conforming indentation, pass the '--strict-indentation-' flag to the compiler, or set the language version to F# 7.

tests/service/data/SyntaxTree/Member/Interface 11.fs

@@ -0,0 +1,6 @@
+module Module
+
+type T =
+    interface I with
+
+()

tests/service/data/SyntaxTree/Member/Interface 11.fs.bsl

@@ -0,0 +1,27 @@
+ImplFile
+  (ParsedImplFileInput
+     ("/root/Member/Interface 11.fs", false, QualifiedNameOfFile Module, [],
+      [SynModuleOrNamespace
+         ([Module], false, NamedModule,
+          [Types
+             ([SynTypeDefn
+                 (SynComponentInfo
+                    ([], None, [], [T],
+                     PreXmlDoc ((3,0), FSharp.Compiler.Xml.XmlDocCollector),
+                     false, None, (3,5--3,6)),
+                  ObjectModel
+                    (Unspecified,
+                     [Interface
+                        (LongIdent (SynLongIdent ([I], [], [None])),
+                         Some (4,16--4,20), Some [], (4,4--4,20))], (4,4--4,20)),
+                  [], None, (3,5--4,20), { LeadingKeyword = Type (3,0--3,4)
+                                           EqualsRange = Some (3,7--3,8)
+                                           WithKeyword = None })], (3,0--4,20));
+           Expr (Const (Unit, (6,0--6,2)), (6,0--6,2))],
+          PreXmlDoc ((1,0), FSharp.Compiler.Xml.XmlDocCollector), [], None,
+          (1,0--6,2), { LeadingKeyword = Module (1,0--1,6) })], (true, true),
+      { ConditionalDirectives = []
+        WarnDirectives = []
+        CodeComments = [] }, set []))
+
+(4,16)-(4,20) parse error Expecting member

tests/service/data/SyntaxTree/Member/Interface 12.fs

@@ -0,0 +1,6 @@
+module Module
+
+type T =
+    interface I with
+
+M

tests/service/data/SyntaxTree/Member/Interface 12.fs.bsl

@@ -0,0 +1,29 @@
+ImplFile
+  (ParsedImplFileInput
+     ("/root/Member/Interface 12.fs", false, QualifiedNameOfFile Module, [],
+      [SynModuleOrNamespace
+         ([Module], false, NamedModule,
+          [Types
+             ([SynTypeDefn
+                 (SynComponentInfo
+                    ([], None, [], [T],
+                     PreXmlDoc ((3,0), FSharp.Compiler.Xml.XmlDocCollector),
+                     false, None, (3,5--3,6)),
+                  ObjectModel
+                    (Unspecified,
+                     [Interface
+                        (LongIdent (SynLongIdent ([I], [], [None])),
+                         Some (4,16--4,20), Some [], (4,4--4,20))], (4,4--4,20)),
+                  [], None, (3,5--4,20), { LeadingKeyword = Type (3,0--3,4)
+                                           EqualsRange = Some (3,7--3,8)
+                                           WithKeyword = None })], (3,0--4,20));
+           Expr (Ident M, (6,0--6,1))],
+          PreXmlDoc ((1,0), FSharp.Compiler.Xml.XmlDocCollector), [], None,
+          (1,0--6,1), { LeadingKeyword = Module (1,0--1,6) })], (true, true),
+      { ConditionalDirectives = []
+        WarnDirectives = []
+        CodeComments = [] }, set []))
+
+(4,16)-(4,20) parse error Unexpected syntax or possible incorrect indentation: this token is offside of context started at position (4:5). Try indenting this further.
+To continue using non-conforming indentation, pass the '--strict-indentation-' flag to the compiler, or set the language version to F# 7.
+(6,0)-(6,1) parse error Incomplete structured construct at or before this point in member definition