Fix local function variables being suggested in parameter defaults

package.json

@@ -68,7 +68,7 @@
         "fast-xml-parser": "^4.5.2",
         "glob": "^10.4.5",
         "globals": "^15.15.0",
-        "hereby": "^1.10.0",
+        "hereby": "^1.11.0",
         "jsonc-parser": "^3.3.1",
         "knip": "^5.44.4",
         "minimist": "^1.2.8",

src/services/completions.ts

@@ -2805,12 +2805,25 @@ export function getCompletionEntriesFromSymbols(
             return !!(allFlags & SymbolFlags.Namespace);
         }
 
-        if (isTypeOnlyLocation) {
-            // It's a type, but you can reach it by namespace.type as well
-            return symbolCanBeReferencedAtTypeLocation(symbol, typeChecker);
-        }
-
-        // expressions are value space (which includes the value namespaces)
+        if (isTypeOnlyLocation) {
+            // It's a type, but you can reach it by namespace.type as well
+            return symbolCanBeReferencedAtTypeLocation(symbol, typeChecker);
+        }
+
+        // Filter out function body variables from parameter defaults
+        // `function f(a = /* no function body variables here */) { var x; }`
+        if (closestSymbolDeclaration && isParameter(closestSymbolDeclaration) && symbolDeclaration && isInParameterDefault(contextToken)) {
+            const functionNode = closestSymbolDeclaration.parent;
+            if (isFunctionLike(functionNode) && "body" in functionNode) {
+                const functionBody = functionNode.body;
+                if (functionBody && symbolDeclaration.pos > functionBody.pos && symbolDeclaration.pos < functionBody.end) {
+                    // This symbol is declared inside the function body, exclude it
+                    return false;
+                }
+            }
+        }
+
+        // expressions are value space (which includes the value namespaces)
         return !!(allFlags & SymbolFlags.Value);
     }
 
@@ -4037,8 +4050,8 @@ function getCompletionData(
                     symbolToOriginInfoMap[i] = origin;
                 }
             }
-        }
-
+        }
+
         // Need to insert 'this.' before properties of `this` type, so only do that if `includeInsertTextCompletions`
         if (preferences.includeCompletionsWithInsertText && scopeNode.kind !== SyntaxKind.SourceFile) {
             const thisType = typeChecker.tryGetThisTypeAt(scopeNode, /*includeGlobalThis*/ false, isClassLike(scopeNode.parent) ? scopeNode as ThisContainer : undefined);
@@ -6044,9 +6057,29 @@ function isInTypeParameterDefault(contextToken: Node | undefined) {
         parent = parent.parent;
     }
 
-    return false;
-}
-
+    return false;
+}
+
+function isInParameterDefault(contextToken: Node | undefined) {
+    if (!contextToken) {
+        return false;
+    }
+
+    let node = contextToken;
+    while (node) {
+        if (isParameter(node.parent)) {
+            const param = node.parent;
+            // Check if we're in the initializer part after the equals sign
+            return param.initializer === node || 
+                   (param.initializer && node.pos >= param.initializer.pos && node.pos < param.initializer.end);
+        }
+        node = node.parent;
+        if (!node) break;
+    }
+
+    return false;
+}
+
 function isArrowFunctionBody(node: Node) {
     return node.parent && isArrowFunction(node.parent) &&
         (node.parent.body === node ||

tests/cases/fourslash/noCompletionsForLocalVariablesInDefaults.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+//// function test1(a: string, b = /*marker*/) {
+////   var hoisted
+////   let mutable  
+////   const readonly = 1
+//// }
+
+// Check that parameter 'a' is included but local variables are excluded
+verify.completions({
+    marker: "marker",
+    includes: ["a"],
+    excludes: ["hoisted", "mutable", "readonly"],
+});