Fix crash related to legacy method decorators and signatures with rest

src/compiler/checker.ts

@@ -36280,7 +36280,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             case SyntaxKind.GetAccessor:
             case SyntaxKind.SetAccessor:
                 // For decorators with only two parameters we supply only two arguments
-                return signature.parameters.length <= 2 ? 2 : 3;
+                return getParameterCount(signature) <= 2 ? 2 : 3;
             case SyntaxKind.Parameter:
                 return 3;
             default:

tests/baselines/reference/decoratorRestNoCrash1.errors.txt

@@ -0,0 +1,15 @@
+decoratorRestNoCrash1.ts(4,29): error TS2339: Property 'greeting' does not exist on type 'Greeter'.
+
+
+==== decoratorRestNoCrash1.ts (1 errors) ====
+    class Greeter {
+      @deco
+      greet1() {
+        return "Hello, " + this.greeting;
+                                ~~~~~~~~
+!!! error TS2339: Property 'greeting' does not exist on type 'Greeter'.
+      }
+    }
+
+    declare function deco(...args: [any, any, any]): any;
+

tests/baselines/reference/decoratorRestNoCrash1.symbols

@@ -0,0 +1,21 @@
+//// [tests/cases/compiler/decoratorRestNoCrash1.ts] ////
+
+=== decoratorRestNoCrash1.ts ===
+class Greeter {
+>Greeter : Symbol(Greeter, Decl(decoratorRestNoCrash1.ts, 0, 0))
+
+  @deco
+>deco : Symbol(deco, Decl(decoratorRestNoCrash1.ts, 5, 1))
+
+  greet1() {
+>greet1 : Symbol(Greeter.greet1, Decl(decoratorRestNoCrash1.ts, 0, 15))
+
+    return "Hello, " + this.greeting;
+>this : Symbol(Greeter, Decl(decoratorRestNoCrash1.ts, 0, 0))
+  }
+}
+
+declare function deco(...args: [any, any, any]): any;
+>deco : Symbol(deco, Decl(decoratorRestNoCrash1.ts, 5, 1))
+>args : Symbol(args, Decl(decoratorRestNoCrash1.ts, 7, 22))
+

tests/baselines/reference/decoratorRestNoCrash1.types

@@ -0,0 +1,35 @@
+//// [tests/cases/compiler/decoratorRestNoCrash1.ts] ////
+
+=== decoratorRestNoCrash1.ts ===
+class Greeter {
+>Greeter : Greeter
+>        : ^^^^^^^
+
+  @deco
+>deco : (args_0: any, args_1: any, args_2: any) => any
+>     : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^   
+
+  greet1() {
+>greet1 : () => string
+>       : ^^^^^^^^^^^^
+
+    return "Hello, " + this.greeting;
+>"Hello, " + this.greeting : string
+>                          : ^^^^^^
+>"Hello, " : "Hello, "
+>          : ^^^^^^^^^
+>this.greeting : any
+>              : ^^^
+>this : this
+>     : ^^^^
+>greeting : any
+>         : ^^^
+  }
+}
+
+declare function deco(...args: [any, any, any]): any;
+>deco : (args_0: any, args_1: any, args_2: any) => any
+>     : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^   
+>args : [any, any, any]
+>     : ^^^^^^^^^^^^^^^
+

tests/cases/compiler/decoratorRestNoCrash1.ts

@@ -0,0 +1,12 @@
+// @strict: true
+// @noEmit: true
+// @experimentalDecorators: true
+
+class Greeter {
+  @deco
+  greet1() {
+    return "Hello, " + this.greeting;
+  }
+}
+
+declare function deco(...args: [any, any, any]): any;