Narrow 'No matching overload' error range to method name only

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

@@ -1,5 +1,6 @@
 ### Fixed
 
+* Narrow 'No overloads match for method' error range to method name only instead of covering the entire expression. ([Issue #14284](https://github.com/dotnet/fsharp/issues/14284), [PR #19505](https://github.com/dotnet/fsharp/pull/19505))
 * Fix DU case names matching IWSAM member names no longer cause duplicate property entries. (Issue [#14321](https://github.com/dotnet/fsharp/issues/14321), [PR #19341](https://github.com/dotnet/fsharp/pull/19341))
 * Fix DefaultAugmentation(false) duplicate entry in method table. (Issue [#16565](https://github.com/dotnet/fsharp/issues/16565), [PR #19341](https://github.com/dotnet/fsharp/pull/19341))
 * Fix abstract event accessors now have SpecialName flag. (Issue [#5834](https://github.com/dotnet/fsharp/issues/5834), [PR #19341](https://github.com/dotnet/fsharp/pull/19341))

src/Compiler/Checking/Expressions/CheckExpressions.fs

@@ -10401,6 +10401,26 @@ and TcMethodApplication
 
         let result, errors = ResolveOverloadingForCall denv cenv.css mMethExpr methodName callerArgs ad postArgumentTypeCheckingCalledMethGroup true returnTy
 
+        // Narrow the error range for unresolved overloading from the whole expression (mMethExpr)
+        // to just the method name. For instance calls like T.Instance.Method(""), mItem covers
+        // the entire "T.Instance.Method" range, so we compute the method-name-only range from
+        // the end of mItem and the method name length. See https://github.com/dotnet/fsharp/issues/14284.
+        let errors =
+            match errors with
+            | ErrorResult(warns, UnresolvedOverloading(denvErr, callerArgsErr, failure, _mWide)) ->
+                let mMethodName =
+                    let itemWidth = mItem.EndColumn - mItem.StartColumn
+                    // Only narrow when the range is single-line and the method name fits within it.
+                    // Generic constructors may have internal names longer than the source text
+                    // (e.g., "ImmutableStack`1" vs source "ImmutableStack").
+                    if mItem.StartLine = mItem.EndLine && methodName.Length < itemWidth then
+                        let startPos = mkPos mItem.EndLine (mItem.EndColumn - methodName.Length)
+                        withStart startPos mItem
+                    else
+                        mItem
+                ErrorResult(warns, UnresolvedOverloading(denvErr, callerArgsErr, failure, mMethodName))
+            | other -> other
+
         match afterResolution, result with
         | AfterResolution.DoNothing, _ -> ()
 

tests/FSharp.Compiler.ComponentTests/ConstraintSolver/neg_invalid_constructor.fs.err.bsl

@@ -1,18 +1,18 @@
-neg_invalid_constructor.fs (3,29)-(3,56) typecheck error A unique overload for method 'ImmutableStack`1' could not be determined based on type information prior to this program point. A type annotation may be needed.
+neg_invalid_constructor.fs (3,29)-(3,43) typecheck error A unique overload for method 'ImmutableStack`1' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'a list
 
 Candidates:
  - new: col: 'b -> ImmutableStack<'a>
  - private new: items: 'a list -> ImmutableStack<'a>
-neg_invalid_constructor.fs (4,93)-(4,111) typecheck error A unique overload for method 'ImmutableStack`1' could not be determined based on type information prior to this program point. A type annotation may be needed.
+neg_invalid_constructor.fs (4,93)-(4,107) typecheck error A unique overload for method 'ImmutableStack`1' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'a list
 
 Candidates:
  - new: col: 'b -> ImmutableStack<'a>
  - private new: items: 'a list -> ImmutableStack<'a>
-neg_invalid_constructor.fs (7,30)-(7,60) typecheck error A unique overload for method 'ImmutableStack`1' could not be determined based on type information prior to this program point. A type annotation may be needed.
+neg_invalid_constructor.fs (7,30)-(7,44) typecheck error A unique overload for method 'ImmutableStack`1' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'a list
 

tests/FSharp.Compiler.ComponentTests/ErrorMessages/OverloadResolutionErrorRangeTests.fs

@@ -0,0 +1,99 @@
+module ErrorMessages.OverloadResolutionErrorRangeTests
+
+open Xunit
+open FSharp.Test.Compiler
+
+// https://github.com/dotnet/fsharp/issues/14284
+[<Fact>]
+let ``Issue 14284 - overload error should cover only method name, not full expression`` () =
+    FSharp
+        """
+type T() =
+    static member Instance = T()
+
+    member _.Method(_: double) = ()
+    member _.Method(_: int) = ()
+
+T.Instance.Method("")
+        """
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics
+        [ (Error 41, Line 8, Col 12, Line 8, Col 18, "No overloads match for method 'Method'.
+
+Known type of argument: string
+
+Available overloads:
+ - member T.Method: double -> unit // Argument at index 1 doesn't match
+ - member T.Method: int -> unit // Argument at index 1 doesn't match") ]
+
+// Verify that the error range is narrow also for simple direct method calls
+[<Fact>]
+let ``Issue 14284 - overload error for simple static method`` () =
+    FSharp
+        """
+type T() =
+    static member Method(_: double) = ()
+    static member Method(_: int) = ()
+
+T.Method("")
+        """
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics
+        [ (Error 41, Line 6, Col 3, Line 6, Col 9, "No overloads match for method 'Method'.
+
+Known type of argument: string
+
+Available overloads:
+ - static member T.Method: double -> unit // Argument at index 1 doesn't match
+ - static member T.Method: int -> unit // Argument at index 1 doesn't match") ]
+
+// Verify that a long expression before the method doesn't widen the error range
+[<Fact>]
+let ``Issue 14284 - overload error on chained expression`` () =
+    FSharp
+        """
+type T() =
+    static member Instance = T()
+
+    member _.Next = T()
+    member _.Method(_: double) = ()
+    member _.Method(_: int) = ()
+
+T.Instance.Next.Next.Method("")
+        """
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics
+        [ (Error 41, Line 9, Col 22, Line 9, Col 28, "No overloads match for method 'Method'.
+
+Known type of argument: string
+
+Available overloads:
+ - member T.Method: double -> unit // Argument at index 1 doesn't match
+ - member T.Method: int -> unit // Argument at index 1 doesn't match") ]
+
+// Verify error range with lambda argument
+[<Fact>]
+let ``Issue 14284 - overload error with lambda argument`` () =
+    FSharp
+        """
+type T() =
+    static member Instance = T()
+
+    member _.Method(_: double) = ()
+    member _.Method(_: int) = ()
+
+T.Instance.Method(fun () -> "")
+        """
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics
+        [ (Error 41, Line 8, Col 12, Line 8, Col 18, "No overloads match for method 'Method'.
+
+Known type of argument: (unit -> string)
+
+Available overloads:
+ - member T.Method: double -> unit // Argument at index 1 doesn't match
+ - member T.Method: int -> unit // Argument at index 1 doesn't match") ]

tests/FSharp.Compiler.ComponentTests/FSharp.Compiler.ComponentTests.fsproj

@@ -302,6 +302,7 @@
     <Compile Include="ErrorMessages\MissingExpressionTests.fs" />
     <Compile Include="ErrorMessages\ModuleTests.fs" />
     <Compile Include="ErrorMessages\DiagnosticRegressionTests.fs" />
+    <Compile Include="ErrorMessages\OverloadResolutionErrorRangeTests.fs" />
     <Compile Include="ErrorMessages\NameResolutionTests.fs" />
     <Compile Include="ErrorMessages\SuggestionsTests.fs" />
     <Compile Include="ErrorMessages\TypeMismatchTests.fs" />

tests/FSharp.Compiler.Service.Tests/TypeChecker/TypeCheckerRecoveryTests.fs

@@ -39,7 +39,7 @@ Math.Max(a,)
     dumpDiagnosticNumbers checkResults |> shouldEqual [
         "(4,10--4,11)", 3100
         "(4,9--4,10)", 39
-        "(4,0--4,12)", 41
+        "(4,5--4,8)", 41
     ]
 
     assertHasSymbolUsages ["Max"] checkResults

tests/fsharp/Compiler/Language/TypeDirectedConversionTests.fs

@@ -329,7 +329,7 @@ let test2(x: 'T) =
          [|
              (FSharpDiagnosticSeverity.Error,
              41,
-             (11, 5, 11, 11),
+             (11, 7, 11, 8),
              """A unique overload for method 'A' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'T
@@ -341,7 +341,7 @@ Candidates:
  - static member M.A: n: int -> unit""")
              (FSharpDiagnosticSeverity.Error,
              41,
-             (19, 5, 19, 12),
+             (19, 8, 19, 9),
              """A unique overload for method 'A' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'T
@@ -368,7 +368,7 @@ let test(x: 'T) =
 """
          FSharpDiagnosticSeverity.Error
          41
-         (10, 5, 10, 11)
+         (10, 7, 10, 8)
          """A unique overload for method 'A' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'T
@@ -495,7 +495,7 @@ let test() = M.A(System.DateTime.UtcNow, 1)
         """
              FSharpDiagnosticSeverity.Error
              41
-             (6, 14, 6, 44)
+             (6, 16, 6, 17)
              """A unique overload for method 'A' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: System.DateTime * int

tests/fsharp/conformance/expressions/syntacticsugar/E_Slices01.bsl

@@ -1,5 +1,5 @@
 
-E_Slices01.fsx(15,9,15,19): typecheck error FS0041: A unique overload for method 'GetSlice' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_Slices01.fsx(15,11,15,19): typecheck error FS0041: A unique overload for method 'GetSlice' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: int * int option * 'a option
 
@@ -15,7 +15,7 @@ Candidates:
  - member Foo.GetSlice: x: int * y1: int option * y2: float option -> unit
  - member Foo.GetSlice: x: int * y1: int option * y2: int option -> unit
 
-E_Slices01.fsx(17,9,17,19): typecheck error FS0041: A unique overload for method 'GetSlice' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_Slices01.fsx(17,11,17,19): typecheck error FS0041: A unique overload for method 'GetSlice' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a option * int option * int
 

tests/fsharp/conformance/expressions/type-relatedexpressions/E_RigidTypeAnnotation03.bsl

@@ -4,7 +4,7 @@ E_RigidTypeAnnotation03.fsx(17,13,17,16): typecheck error FS0001: This expressio
 but here has type
     'byte'    
 
-E_RigidTypeAnnotation03.fsx(17,9,17,25): typecheck error FS0041: No overloads match for method 'M'.
+E_RigidTypeAnnotation03.fsx(17,11,17,12): typecheck error FS0041: No overloads match for method 'M'.
 
 Known type of argument: sbyte
 
@@ -20,7 +20,7 @@ E_RigidTypeAnnotation03.fsx(18,13,18,19): typecheck error FS0001: This expressio
 but here has type
     'float<'u>'    
 
-E_RigidTypeAnnotation03.fsx(18,9,18,30): typecheck error FS0041: No overloads match for method 'M'.
+E_RigidTypeAnnotation03.fsx(18,11,18,12): typecheck error FS0041: No overloads match for method 'M'.
 
 Known type of argument: float32
 
@@ -42,7 +42,7 @@ but given a
     'decimal<Kg>'    
 The unit of measure 'N s ^ 2' does not match the unit of measure 'Kg'
 
-E_RigidTypeAnnotation03.fsx(20,9,20,39): typecheck error FS0041: No overloads match for method 'M'.
+E_RigidTypeAnnotation03.fsx(20,11,20,12): typecheck error FS0041: No overloads match for method 'M'.
 
 Known type of argument: decimal<N s ^ 2>
 
@@ -58,7 +58,7 @@ E_RigidTypeAnnotation03.fsx(21,14,21,18): typecheck error FS0001: This expressio
 but here has type
     'string'    
 
-E_RigidTypeAnnotation03.fsx(21,9,21,27): typecheck error FS0041: No overloads match for method 'M'.
+E_RigidTypeAnnotation03.fsx(21,11,21,12): typecheck error FS0041: No overloads match for method 'M'.
 
 Known type of argument: char
 

tests/fsharp/conformance/inference/E_LeftToRightOverloadResolution01.bsl

@@ -1,5 +1,5 @@
 
-E_LeftToRightOverloadResolution01.fsx(7,23,7,51): typecheck error FS0041: A unique overload for method 'WriteLine' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_LeftToRightOverloadResolution01.fsx(7,38,7,47): typecheck error FS0041: A unique overload for method 'WriteLine' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'a
 
@@ -18,7 +18,7 @@ Candidates:
  - System.Console.WriteLine(value: uint32) : unit
  - System.Console.WriteLine(value: uint64) : unit
 
-E_LeftToRightOverloadResolution01.fsx(9,23,9,51): typecheck error FS0041: A unique overload for method 'WriteLine' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_LeftToRightOverloadResolution01.fsx(9,38,9,47): typecheck error FS0041: A unique overload for method 'WriteLine' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known type of argument: 'a
 

tests/fsharp/conformance/inference/E_OneTypeVariable03.bsl

@@ -1,13 +1,13 @@
 
-E_OneTypeVariable03.fsx(60,34,60,44): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_OneTypeVariable03.fsx(60,38,60,39): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * int
 
 Candidates:
  - static member C23.M: x: 'a * y: 'b -> Two
  - static member C23.M: x: 'a * y: int -> Three
 
-E_OneTypeVariable03.fsx(61,34,61,45): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_OneTypeVariable03.fsx(61,39,61,40): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * int
 

tests/fsharp/conformance/inference/E_OneTypeVariable03rec.bsl

@@ -1,13 +1,13 @@
 
-E_OneTypeVariable03rec.fsx(60,38,60,48): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_OneTypeVariable03rec.fsx(60,42,60,43): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * int
 
 Candidates:
  - static member C23.M: x: 'a * y: 'b -> Two
  - static member C23.M: x: 'a * y: int -> Three
 
-E_OneTypeVariable03rec.fsx(61,38,61,49): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_OneTypeVariable03rec.fsx(61,43,61,44): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * int
 

tests/fsharp/conformance/inference/E_TwoDifferentTypeVariables01.bsl

@@ -1,29 +1,29 @@
 
-E_TwoDifferentTypeVariables01.fsx(61,33,61,43): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01.fsx(61,37,61,38): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b
 
 Candidates:
  - static member C13.M: x: 'a * y: 'a -> One
  - static member C13.M: x: 'a * y: int -> Three
 
-E_TwoDifferentTypeVariables01.fsx(62,33,62,43): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01.fsx(62,37,62,38): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b
 
 Candidates:
  - static member C24.M: x: 'a * y: 'b -> Two
  - static member C24.M: x: 'a * y: C -> Four
 
-E_TwoDifferentTypeVariables01.fsx(63,33,63,47): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01.fsx(63,37,63,38): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b
 
 Candidates:
  - static member C13.M: x: 'a * y: 'a -> One
  - static member C13.M: x: 'a * y: int -> Three
 
-E_TwoDifferentTypeVariables01.fsx(64,33,64,46): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01.fsx(64,37,64,38): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b
 

tests/fsharp/conformance/inference/E_TwoDifferentTypeVariables01rec.bsl

@@ -1,29 +1,29 @@
 
-E_TwoDifferentTypeVariables01rec.fsx(60,37,60,47): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01rec.fsx(60,41,60,42): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b
 
 Candidates:
  - static member C13.M: x: 'a * y: 'a -> One
  - static member C13.M: x: 'a * y: int -> Three
 
-E_TwoDifferentTypeVariables01rec.fsx(61,37,61,47): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01rec.fsx(61,41,61,42): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b
 
 Candidates:
  - static member C24.M: x: 'a * y: 'b -> Two
  - static member C24.M: x: 'a * y: C -> Four
 
-E_TwoDifferentTypeVariables01rec.fsx(62,37,62,51): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01rec.fsx(62,41,62,42): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b
 
 Candidates:
  - static member C13.M: x: 'a * y: 'a -> One
  - static member C13.M: x: 'a * y: int -> Three
 
-E_TwoDifferentTypeVariables01rec.fsx(63,37,63,50): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
+E_TwoDifferentTypeVariables01rec.fsx(63,41,63,42): typecheck error FS0041: A unique overload for method 'M' could not be determined based on type information prior to this program point. A type annotation may be needed.
 
 Known types of arguments: 'a * 'b