Allow to redeclare parameters multiple times in nested scopes (#5276)

src/ast/scopes/BlockScope.ts

@@ -22,7 +22,10 @@ export default class BlockScope extends ChildScope {
 			const existingVariable =
 				this.hoistedVariables?.get(name) || (this.variables.get(name) as LocalVariable | undefined);
 			if (existingVariable) {
-				if (existingVariable.kind === VariableKind.var) {
+				if (
+					existingVariable.kind === VariableKind.var ||
+					(kind === VariableKind.var && existingVariable.kind === VariableKind.parameter)
+				) {
 					existingVariable.addDeclaration(identifier, init);
 					return existingVariable;
 				}

test/function/samples/ast-validations/redeclare-var-parameter-nested/_config.js

@@ -0,0 +1,3 @@
+module.exports = defineTest({
+	description: 'allows to redeclare parameters with multiple nested vars'
+});

test/function/samples/ast-validations/redeclare-var-parameter-nested/main.js

@@ -0,0 +1,21 @@
+export function f(val) {
+	{
+		var val = 1;
+		var val = 2;
+	}
+	assert.equal(val, 2);
+}
+f(0);
+
+export function g(val) {
+	{
+		{
+			var val = 1;
+		}
+		{
+			var val = 2;
+		}
+	}
+	assert.equal(val, 2);
+}
+g(0);