fix #2727:

class member function type is assigned to a normal function type

Author: Changqing-JING

src/types.ts

@@ -1063,7 +1063,7 @@ export class Signature {
     } else {
       // check `this` type (invariant)
       if (thisThisType) {
-        if (targetThisType != targetThisType) return false;
+        if (targetThisType == null) return false;
       } else if (targetThisType) {
         return false;
       }

tests/compiler/class-member-function-as-parameter.json

@@ -0,0 +1,8 @@
+{
+    "asc_flags": [
+    ],
+    "stderr": [
+      "TS2322: Type '(this: class-member-function-as-parameter/C, i32) => i32' is not assignable to type '(i32) => i32'."
+    ]
+  }
+  

tests/compiler/class-member-function-as-parameter.ts

@@ -0,0 +1,16 @@
+class C {
+    aa:i32 = 1;
+    callback(a: i32): i32 {
+      return this.aa + a + 3;
+    }
+  }
+  
+  function expectCallback(c1: (arg0: i32) => i32): i32 {
+    return c1(4);
+  }
+  
+  export function fut(): i32 {
+    const c1 = new C();
+    return expectCallback(c1.callback);
+  }
+