Fix methods tagged as Member instead of Method in tooltips (#10540)

In NicePrint.fs, the SynMemberKind.Member case unconditionally used tagMember
for all members. Now checks isNil argInfos to use tagMethod for methods vs
tagMember for property-like members.

In TypedTreeOps.fs fullDisplayTextOfValRefAsLayout, checks ValReprInfo.ArgInfos
length to distinguish methods from property-like members (instance >1 arg group,
static >0).

Added 5 regression tests: instance method, method with params, static method,
property-like member, and auto property.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: T-Gro

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

@@ -17,6 +17,7 @@
 * Fix `YieldFromFinal`/`ReturnFromFinal` being incorrectly called in non-tail positions (`for`, `use`, `use!`, `try/with` handler). ([Issue #19402](https://github.com/dotnet/fsharp/issues/19402), [PR #19403](https://github.com/dotnet/fsharp/pull/19403))
 * Fixed how the source ranges of warn directives are reported (as trivia) in the parser output (by not reporting leading spaces). ([Issue #19405](https://github.com/dotnet/fsharp/issues/19405), [PR #19408]((https://github.com/dotnet/fsharp/pull/19408)))
 * Fix UoM value type `ToString()` returning garbage values when `--checknulls+` is enabled, caused by double address-taking in codegen. ([Issue #19435](https://github.com/dotnet/fsharp/issues/19435), [PR #19440](https://github.com/dotnet/fsharp/pull/19440))
+* Fix methods being tagged as `Member` instead of `Method` in tooltips. ([Issue #10540](https://github.com/dotnet/fsharp/issues/10540), [PR #19507](https://github.com/dotnet/fsharp/pull/19507))
 
 ### Added
 

src/Compiler/Checking/NicePrint.fs

@@ -1383,7 +1383,8 @@ module PrintTastMemberOrVals =
                 let resL =
                     if short then tauL
                     else
-                        let nameL = layoutMemberName denv vref niceMethodTypars argInfos tagMember vref.DisplayNameCoreMangled true
+                        let tag = if isNil argInfos then tagMember else tagMethod
+                        let nameL = layoutMemberName denv vref niceMethodTypars argInfos tag vref.DisplayNameCoreMangled true
                         let nameL = if short then nameL else mkInlineL denv vref.Deref nameL
                         stat --- ((nameL  |> addColonL) ^^ tauL)
                 prettyTyparInst, resL

src/Compiler/TypedTree/TypedTreeOps.fs

@@ -3433,7 +3433,14 @@ let fullDisplayTextOfValRefAsLayout (vref: ValRef) =
             | SynMemberKind.PropertyGetSet -> tagProperty vref.DisplayName
             | SynMemberKind.ClassConstructor
             | SynMemberKind.Constructor -> tagMethod vref.DisplayName
-            | SynMemberKind.Member -> tagMember vref.DisplayName
+            | SynMemberKind.Member ->
+                match vref.ValReprInfo with
+                | Some valReprInfo ->
+                    let numArgGroups = valReprInfo.ArgInfos.Length
+                    let isMethod = if memberInfo.MemberFlags.IsInstance then numArgGroups > 1 else numArgGroups > 0
+                    if isMethod then tagMethod vref.DisplayName
+                    else tagMember vref.DisplayName
+                | None -> tagMember vref.DisplayName
     match fullNameOfParentOfValRefAsLayout vref with 
     | ValueNone -> wordL n 
     | ValueSome pathText -> 

tests/FSharp.Compiler.Service.Tests/TooltipTests.fs

@@ -388,6 +388,17 @@ let assertAndGetSingleToolTipText items =
     let text,_xml,_remarks = assertAndExtractTooltip items
     text
 
+let getMainDescriptionTags (ToolTipText(items)) =
+    match items with
+    | ToolTipElement.Group [ singleElement ] :: _ -> singleElement.MainDescription
+    | _ -> failwith $"Expected single group in tooltip, got {items}"
+
+let assertNameTagInTooltip expectedTag expectedName (tooltip: ToolTipText) =
+    let tags = getMainDescriptionTags tooltip
+    let found = tags |> Array.exists (fun t -> t.Tag = expectedTag && t.Text = expectedName)
+    let desc = tags |> Array.map (fun t -> sprintf "(%A, %s)" t.Tag t.Text) |> String.concat ", "
+    Assert.True(found, sprintf "Expected tag %A with text '%s' in tooltip, but found: %s" expectedTag expectedName desc)
+
 let normalize (s: string) = s.Replace("\r\n", "\n").Replace("\n\n", "\n")
 
 [<Fact>]
@@ -602,3 +613,50 @@ let normaliz{caret}e' x = x + 1
 """
 
     testXmlDocFallbackToSigFileWhileInImplFile sigSource implSource "Normalize with a prime"
+
+// https://github.com/dotnet/fsharp/issues/10540
+[<Fact>]
+let ``Instance method should be tagged as Method in tooltip`` () =
+    Checker.getTooltip """
+type T() =
+    member x.Metho{caret}d() = ()
+"""
+    |> assertNameTagInTooltip TextTag.Method "Method"
+
+// https://github.com/dotnet/fsharp/issues/10540
+[<Fact>]
+let ``Instance method with parameters should be tagged as Method in tooltip`` () =
+    Checker.getTooltip """
+type T() =
+    member x.Ad{caret}d(a: int, b: int) = a + b
+"""
+    |> assertNameTagInTooltip TextTag.Method "Add"
+
+// https://github.com/dotnet/fsharp/issues/10540
+[<Fact>]
+let ``Static method should be tagged as Method in tooltip`` () =
+    Checker.getTooltip """
+type T() =
+    static member Creat{caret}e() = T()
+"""
+    |> assertNameTagInTooltip TextTag.Method "Create"
+
+// https://github.com/dotnet/fsharp/issues/10540
+[<Fact>]
+let ``Property-like member should be tagged as Property`` () =
+    Checker.getTooltip """
+type T() =
+    member x.Valu{caret}e = 42
+"""
+    |> assertNameTagInTooltip TextTag.Property "Value"
+
+// https://github.com/dotnet/fsharp/issues/10540
+[<Fact>]
+let ``Auto property should be tagged as Property`` () =
+    Checker.getTooltip """
+namespace Foo
+
+type Bar() =
+    member val Fo{caret}o = "bla" with get, set
+"""
+    |> assertNameTagInTooltip TextTag.Property "Foo"