Fix function parameters autocomplete in calls for new solver

In new solver, the parameters are typed as 'unknown' if they don't have an explicit type annotation.

getParameterExtents treats 'unknown' as an optional type. But note that the new solver would still emit a type error due to mismatching arg counts (see LuauArityMismatchOnUndersaturatedUnknownArguments flag).

Let's manually increment the minimum parameter count when we encounter 'unknown' and treat it as a required type, similar to what this flag does.

Author: JohnnyMorganz

CHANGELOG.md

@@ -22,6 +22,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Autocomplete now properly respects Luau's ParenthesesRecommendation and puts the cursor inside of the parentheses when
   autocompleting a function call where the arguments are all optional / any (e.g., `require()` or
   `wait()`) ([#317](https://github.com/JohnnyMorganz/luau-lsp/issues/317))
+- Fixed autocomplete of function calls in new solver not inserting parameter names if the parameters do not have a type
+  annotation
 
 ## [1.52.1] - 2025-07-12
 

src/operations/Completion.cpp

@@ -357,6 +357,11 @@ static std::pair<std::string, std::string> computeLabelDetailsForFunction(const
 
     auto [minCount, _] = Luau::getParameterExtents(Luau::TxnLog::empty(), ftv->argTypes, true);
 
+    // Include 'unknown' arguments as required types
+    for (auto arg : ftv->argTypes)
+        if (Luau::get<Luau::UnknownType>(follow(arg)))
+            minCount += 1;
+
     auto it = Luau::begin(ftv->argTypes);
     for (; it != Luau::end(ftv->argTypes); ++it, ++argIndex)
     {