reporting unnamed fields in an FCS helper function

src/Compiler/Service/ServiceAnalysis.fs

@@ -451,3 +451,74 @@ module UnusedDeclarations =
             let unusedRanges = getUnusedDeclarationRanges allSymbolUsesInFile isScriptFile
             return unusedRanges
         }
+
+module public Naming =
+
+    type UnnamedFieldsLocations =
+        | InDiscriminatedUnionCases
+        | InExceptions
+
+    let defaultOptions = Set.ofArray [|InDiscriminatedUnionCases; InExceptions|]
+
+    let fieldNotOk (field: FSharpField) =
+        field.IsNameGenerated 
+        || isNull field.Name 
+        || System.String.Empty = field.Name
+
+    [<TailCall>]
+    let rec checkDeclaration (options: Set<UnnamedFieldsLocations>) declaration =
+        match declaration with
+        | FSharpImplementationFileDeclaration.MemberOrFunctionOrValue _ -> Seq.empty
+        | FSharpImplementationFileDeclaration.InitAction _ -> Seq.empty
+        | FSharpImplementationFileDeclaration.Entity(entity, _declarations) ->
+            seq {
+                if options.Contains InDiscriminatedUnionCases then
+                    for case in entity.UnionCases do
+                        // lenient on non public members
+                        if not case.Accessibility.IsPublic then () else
+                        // lenient on single field cases
+                        if case.Fields.Count <= 1 then () else
+                        for field in case.Fields do
+                            if fieldNotOk field then
+                                field.DeclarationLocation
+                                match field.ImplementationLocation with
+                                | None -> ()
+                                | Some range -> range
+                                match field.SignatureLocation with
+                                | None -> ()
+                                | Some range -> range
+                if options.Contains InExceptions then
+                    if entity.IsFSharpExceptionDeclaration then
+                        // lenient on non public members
+                        if not entity.Accessibility.IsPublic then () else
+                        // lenient on single field cases
+                        if entity.FSharpFields.Count <= 1 then () else
+                        for field in entity.FSharpFields do
+                            if fieldNotOk field then
+                                field.DeclarationLocation
+                                match field.ImplementationLocation with
+                                | None -> ()
+                                | Some range -> range
+                                match field.SignatureLocation with
+                                | None -> ()
+                                | Some range -> range
+                for declaration in _declarations do
+                    yield! checkDeclaration options declaration
+            }
+
+    let getUnnamedDiscriminatedUnionAndExceptionFields (checkFileResults: FSharpCheckFileResults, isScriptFile: bool) =
+        async {
+            let options = defaultOptions
+            // be lenient in case of script
+            if isScriptFile then return Seq.empty else
+            match checkFileResults.ImplementationFile with
+            | None -> return Seq.empty
+            | Some checkResults ->
+                return (seq {
+                    for d in checkResults.Declarations do
+                        yield! checkDeclaration options d
+                }
+                |> Seq.distinct // not comparable but distinct works :)
+                //|> Seq.sort // not comparable
+                )
+        }

src/Compiler/Service/ServiceAnalysis.fsi

@@ -31,3 +31,7 @@ module public UnusedDeclarations =
 
     /// Get all unused declarations in a file
     val getUnusedDeclarations: checkFileResults: FSharpCheckFileResults * isScriptFile: bool -> Async<seq<range>>
+
+
+module public Naming =
+    val getUnnamedDiscriminatedUnionAndExceptionFields : checkFileResults: FSharpCheckFileResults * isScriptFile : bool -> Async<seq<range>>

tests/service/ProjectAnalysisTests.fs

@@ -5765,3 +5765,41 @@ let ``References from #r nuget are included in script project options`` () =
         |> Seq.distinct
     printfn "%s" (assemblyNames |> String.concat "\n")
     assemblyNames |> should contain "Dapper.dll"
+
+
+[<Test>]
+let ``detects unnamed fields in DU and exceptions`` () =
+    let file = __SOURCE_DIRECTORY__ + "/data/analysis/unammed-fields/unnamed.members.diagnostics.fsx"
+    let baseline = System.IO.Path.ChangeExtension(file, ".bsl")
+    let input = 
+        file
+        |> System.IO.File.ReadAllText
+        |> SourceText.ofString 
+    let checker = FSharpChecker.Create(keepAssemblyContents=true)
+
+    let projOptions, diagnostics = 
+        checker.GetProjectOptionsFromScript(file, input)
+        |> Async.RunSynchronously
+
+    let parseResults, checkFileAnswer = 
+        checker.ParseAndCheckFileInProject(file, 0, input, projOptions)
+        |> Async.RunSynchronously
+
+    match checkFileAnswer with
+    | FSharpCheckFileAnswer.Aborted -> failwith $"unexpected check file results for {file}"
+    | FSharpCheckFileAnswer.Succeeded results -> 
+        let warns = 
+            Naming.getUnnamedDiscriminatedUnionAndExceptionFields(results, false)
+            |> Async.RunSynchronously
+            |> Seq.toArray
+            |> Seq.map string
+            |> String.concat "\n"
+        let expected = System.IO.File.ReadAllText baseline
+        if expected <> warns then
+            let postmortem = System.IO.Path.ChangeExtension(file, ".err")
+            System.IO.File.WriteAllText(postmortem, warns)
+            let message =
+                $"expected:\n{expected}\ngot:\n{warns}\n"
+                + $"please compare\n{baseline}\nwith\n{postmortem}"
+            failwith message
+

tests/service/data/analysis/unammed-fields/unnamed.members.diagnostics.bsl

@@ -0,0 +1,5 @@
+(4,19--4,22)
+(10,13--10,16)
+(14,26--14,29)
+(20,20--20,23)
+(24,33--24,36)

tests/service/data/analysis/unammed-fields/unnamed.members.diagnostics.fsx

@@ -0,0 +1,27 @@
+type TopLevelDU =
+| TopLevelCase1 of int
+| TopLevelCase2 of ok: int * okok: string
+| TopLevelCase3 of int * noOkCase: string
+
+module Outer =
+  type DU =
+  | Case1 of int
+  | Case2 of ok: int * okok: string
+  | Case3 of int * noOkCase: string
+
+  exception Exception1 of int
+  exception Exception2 of ok: int * okok: string
+  exception Exception3 of int * noOkCase: string  
+
+  module Inner =
+    type InnerDU =
+    | InnerCase1 of int
+    | InnerCase2 of ok: int * okok: string
+    | InnerCase3 of int * noOkCase: string
+
+    exception InnerException1 of int
+    exception InnerException2 of ok: int * okok: string
+    exception InnerException3 of int * noOkCase: string
+
+    type PrivateDU = private PrivateCase1 of int * string
+    exception private PrivateException of int * string