WIP: Attempt to fix TestSignatureHelpWithTriggers02 - still failing

The logic now returns the first call found if any call contains the position, falling back to the innermost call. However, TestSignatureHelpWithTriggers02 still fails because the applicable span for bar() with empty arguments doesn't include the position right after inserting '('.

The issue appears to be in getApplicableSpanForArguments when argumentList is nil - the span calculation may not correctly include positions inside empty parentheses.

Co-authored-by: jakebailey <[email protected]>

Author: Copilot

internal/ls/signaturehelp.go

@@ -750,7 +750,7 @@ func containsPrecedingToken(startingToken *ast.Node, sourceFile *ast.SourceFile,
 }
 
 func getContainingArgumentInfo(node *ast.Node, sourceFile *ast.SourceFile, checker *checker.Checker, isManuallyInvoked bool, position int) *argumentListInfo {
-	var lastArgumentInfo *argumentListInfo
+	var firstArgumentInfo *argumentListInfo
 	for n := node; !ast.IsSourceFile(n) && (isManuallyInvoked || !ast.IsBlock(n)); n = n.Parent {
 		// If the node is not a subspan of its parent, this is a big problem.
 		// There have been crashes that might be caused by this violation.
@@ -765,22 +765,23 @@ func getContainingArgumentInfo(node *ast.Node, sourceFile *ast.SourceFile, check
 				return argumentInfo
 			}
 
-			// For regular call expressions, check if the position is actually within the applicable span.
-			// This ensures that for nested calls, the outer call takes precedence
-			// when the position is outside the inner call's argument list.
+			// Remember the first (innermost) argument info we find
+			if firstArgumentInfo == nil {
+				firstArgumentInfo = argumentInfo
+			}
+			
+			// If any call's span contains the position, return it.
+			// We walk from inner to outer, so this naturally prefers the innermost call
+			// when multiple calls contain the position.
 			if argumentInfo.argumentsSpan.Contains(position) {
 				return argumentInfo
 			}
-			// Remember this argument info in case we don't find an outer call
-			if lastArgumentInfo == nil {
-				lastArgumentInfo = argumentInfo
-			}
-			// Continue looking for an outer call if position is outside this call's applicable span
 		}
 	}
-	// If we didn't find a call that contains the position, return the last call we found.
-	// This handles cases where the cursor is at the edge of a call (e.g., right after a parameter).
-	return lastArgumentInfo
+	
+	// No call's span contains the position. Return the innermost call as fallback.
+	// This handles cases like foo(bar(|)) where bar's span might be empty.
+	return firstArgumentInfo
 }
 
 func getImmediatelyContainingArgumentOrContextualParameterInfo(node *ast.Node, position int, sourceFile *ast.SourceFile, checker *checker.Checker) *argumentListInfo {