Guard backtick-escaped names in overload error range narrowing

Skip narrowing for method names that need backtick escaping, since
the logical name length differs from the source text width. Also adds
tests for backtick-escaped methods and multiline method access.

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

Author: T-Gro

src/Compiler/Checking/Expressions/CheckExpressions.fs

@@ -10427,7 +10427,11 @@ and TcMethodApplication
                     // 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
+                    if
+                        mItem.StartLine = mItem.EndLine
+                        && methodName.Length < itemWidth
+                        && not (DoesIdentifierNeedBackticks methodName)
+                    then
                         let startPos = mkPos mItem.EndLine (mItem.EndColumn - methodName.Length)
                         withStart startPos mItem
                     else

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

@@ -97,3 +97,47 @@ 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") ]
+
+// Verify that backtick-escaped method names fall back to the full mItem range
+// (methodName.Length doesn't account for backtick delimiters in source text)
+[<Fact>]
+let ``Issue 14284 - backtick-escaped method name falls back to full range`` () =
+    FSharp
+        """
+type T() =
+    static member Instance = T()
+
+    member _.``My Method``(_: double) = ()
+    member _.``My Method``(_: int) = ()
+
+T.Instance.``My Method``("")
+        """
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics
+        [ (Error 41, Line 8, Col 1, Line 8, Col 25, "No overloads match for method 'My Method'.
+
+Known type of argument: string
+
+Available overloads:
+ - member T.``My Method`` : double -> unit // Argument at index 1 doesn't match
+ - member T.``My Method`` : int -> unit // Argument at index 1 doesn't match") ]
+
+// Verify multiline method access falls back to mItem range
+[<Fact>]
+let ``Issue 14284 - multiline method access falls back to mItem`` () =
+    FSharp
+        """
+type T() =
+    static member Instance = T()
+
+    member _.Method(_: double) = ()
+    member _.Method(_: int) = ()
+
+T
+  .Instance
+  .Method("")
+        """
+    |> typecheck
+    |> shouldFail
+    |> withErrorCode 41