Symbol Signature text API

src/Compiler/Symbols/Symbols.fs

@@ -2355,6 +2355,33 @@ type FSharpMemberOrFunctionOrValue(cenv, d:FSharpMemberOrValData, item) =
             |> LayoutRender.toArray
             |> Some
 
+    member x.GetValSignatureText (displayContext: FSharpDisplayContext, m: range) =
+        checkIsResolved()
+        let stringValOfMethInfo methInfo =
+            match methInfo with
+            | FSMeth(valRef = vref) -> NicePrint.stringValOrMember (displayContext.Contents cenv.g) cenv.infoReader vref
+            | _ -> NicePrint.stringOfMethInfo cenv.infoReader m (displayContext.Contents cenv.g) methInfo
+
+        let stringValOfPropInfo (p: PropInfo) =
+            let t = p.GetPropertyType(cenv.amap, m ) |> NicePrint.layoutType (displayContext.Contents cenv.g) |> LayoutRender.showL
+            let withGetSet =
+                if p.HasGetter && p.HasSetter then "with get, set"
+                elif p.HasGetter then "with get"
+                elif p.HasSetter then "with set"
+                else ""
+
+            $"member val %s{p.DisplayName}: %s{t} %s{withGetSet}"
+
+        match d with
+        | E _ -> None
+        | V v ->
+            NicePrint.stringValOrMember (displayContext.Contents cenv.g) cenv.infoReader v
+            |> Some
+        | C methInfo
+        | M methInfo -> stringValOfMethInfo methInfo |> Some
+        | P p -> stringValOfPropInfo p |> Some
+
+
     member x.GetWitnessPassingInfo() = 
         let witnessInfos = 
             match d with 

src/Compiler/Symbols/Symbols.fsi

@@ -966,6 +966,9 @@ type FSharpMemberOrFunctionOrValue =
     /// Format the type using the rules of the given display context
     member GetReturnTypeLayout: displayContext: FSharpDisplayContext -> TaggedText[] option
 
+    /// Get the signature text to include this Symbol into an existing signature file.
+    member GetValSignatureText: displayContext: FSharpDisplayContext * m: range -> string option
+
     /// Check if this method has an entrpoint that accepts witness arguments and if so return
     /// the name of that entrypoint and information about the additional witness arguments
     member GetWitnessPassingInfo: unit -> (string * IList<FSharpParameter>) option

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

@@ -4959,6 +4959,7 @@ FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSh
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.Object] LiteralValue
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.Object] get_LiteralValue()
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.String[]] TryGetFullCompiledOperatorNameIdents()
+FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.String] GetValSignatureText(FSharp.Compiler.Symbols.FSharpDisplayContext, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.String] TryGetFullDisplayName()
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.Tuple`2[System.String,System.Collections.Generic.IList`1[FSharp.Compiler.Symbols.FSharpParameter]]] GetWitnessPassingInfo()
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: System.Collections.Generic.IList`1[FSharp.Compiler.Symbols.FSharpAbstractSignature] ImplementedAbstractSignatures

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

@@ -4959,6 +4959,7 @@ FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSh
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.Object] LiteralValue
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.Object] get_LiteralValue()
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.String[]] TryGetFullCompiledOperatorNameIdents()
+FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.String] GetValSignatureText(FSharp.Compiler.Symbols.FSharpDisplayContext, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.String] TryGetFullDisplayName()
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: Microsoft.FSharp.Core.FSharpOption`1[System.Tuple`2[System.String,System.Collections.Generic.IList`1[FSharp.Compiler.Symbols.FSharpParameter]]] GetWitnessPassingInfo()
 FSharp.Compiler.Symbols.FSharpMemberOrFunctionOrValue: System.Collections.Generic.IList`1[FSharp.Compiler.Symbols.FSharpAbstractSignature] ImplementedAbstractSignatures

tests/service/Symbols.fs

@@ -614,4 +614,35 @@ match Unchecked.defaultof<R> with
 """
         getSymbolUses checkResults
         |> Seq.exists (fun symbolUse -> symbolUse.IsFromUse && symbolUse.Symbol.DisplayName = "F2")
-        |> shouldEqual true
+        |> shouldEqual true
+
+module GetValSignatureText =
+    let private assertSignature (expected:string) source (lineNumber, column, line, identifier) =
+        let _, checkResults = getParseAndCheckResults source
+        let symbolUseOpt = checkResults.GetSymbolUseAtLocation(lineNumber, column, line, [ identifier ])
+        match symbolUseOpt with
+        | None -> Assert.Fail "Expected symbol"
+        | Some symbolUse ->
+            match symbolUse.Symbol with
+            | :? FSharpMemberOrFunctionOrValue as mfv ->
+                let expected = expected.Replace("\r", "")
+                let signature = mfv.GetValSignatureText(symbolUse.DisplayContext, symbolUse.Range)
+                Assert.AreEqual(expected, signature.Value)
+            | symbol -> Assert.Fail $"Expected FSharpMemberOrFunctionOrValue, got %A{symbol}"
+
+    [<Test>]
+    let ``Signature text for let binding`` () =
+        assertSignature
+            "val a: b: int -> c: int -> int"
+            "let a b c = b + c"
+            (1, 4, "let a b c = b + c", "a")
+
+    [<Test>]
+    let ``Signature text for member binding`` () =
+        assertSignature
+            "member Bar: a: int -> b: int -> int"
+            """
+type Foo() =
+    member this.Bar (a:int) (b:int) : int = 0
+"""
+            (3, 19, "    member this.Bar (a:int) (b:int) : int = 0", "Bar")