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

[Copilot]

The "No overloads match for method" error (Error 41) previously covered the entire expression including object access chains and arguments. For example, T.Instance.Method("") would underline everything from T to "). This is especially problematic on larger expressions where the wide error range hides other errors and warnings.

Changes Made

• src/Compiler/Checking/Expressions/CheckExpressions.fs: After ResolveOverloadingForCall returns, intercept UnresolvedOverloading errors and narrow the range from the whole expression (mMethExpr) to just the method name identifier. The method-name-only range is computed from mItem.End and methodName.Length.

• tests/FSharp.Compiler.ComponentTests/ErrorMessages/OverloadResolutionErrorRangeTests.fs: Added 4 regression tests verifying the error range covers only the method name for:

  • Instance method calls (T.Instance.Method(""))
  • Static method calls (T.Method(""))
  • Chained expressions (T.Instance.Next.Next.Method(""))
  • Lambda arguments (T.Instance.Method(fun () -> ""))

Before

Error underlines the entire T.Instance.Method("") expression.

After

Error underlines only Method, leaving the rest of the expression clean for other diagnostics.

---

📱 Kick off Copilot coding agent tasks wherever you are with GitHub Mobile, available on iOS and Android.

[T-Gro]

@copilot : Try again

[T-Gro]

@copilot : Try again.

[abonie]

@copilot Try again

[Copilot]

@copilot Try again

Implemented the fix in commit aa4c1a9. The UnresolvedOverloading error range is now narrowed from the whole expression (mMethExpr) to just the method name identifier by computing the method-name-only range from mItem.End and methodName.Length in TcMethodApplication.

For T.Instance.Method(""), the error now covers only Method (Col 12-18) instead of the entire T.Instance.Method("") expression (Col 1-22). Added 4 regression tests covering instance calls, static calls, chained expressions, and lambda arguments. Tests and compiler build pass. Release notes and full test suite validation still pending.