Remove ql/implicit-this restriction to files with explicit this

Author: kaspersv

ql/ql/src/codeql_ql/style/ImplicitThisQuery.qll

@@ -1,20 +1,10 @@
 import ql
 
-MemberCall explicitThisCallInFile(File f) {
-  result.getLocation().getFile() = f and
-  result.getBase() instanceof ThisAccess and
-  // Exclude `this.(Type).whatever(...)`, as some files have that as their only instance of `this`.
-  not result = any(InlineCast c).getBase()
-}
-
 PredicateCall implicitThisCallInFile(File f) {
   result.getLocation().getFile() = f and
   exists(result.getTarget().getDeclaringType().getASuperType()) and
   // Exclude `SomeModule::whatever(...)`
   not exists(result.getQualifier())
 }
 
-PredicateCall confusingImplicitThisCall(File f) {
-  result = implicitThisCallInFile(f) and
-  exists(explicitThisCallInFile(f))
-}
+PredicateCall confusingImplicitThisCall(File f) { result = implicitThisCallInFile(f) }

ql/ql/test/queries/style/ImplicitThis/Bad2.qll

@@ -0,0 +1,9 @@
+import ql
+
+class Foo extends string {
+  Foo() { this = "hello" }
+
+  string getBar() { result = "bar" }
+
+  string getBarWithoutThis() { result = getBar() }
+}

ql/ql/test/queries/style/ImplicitThis/ImplicitThis.expected

@@ -1 +1,2 @@
+| Bad2.qll:8:41:8:48 | PredicateCall | Use of implicit `this`. |
 | Bad.qll:10:41:10:48 | PredicateCall | Use of implicit `this`. |

ql/ql/test/queries/style/ImplicitThis/Okay.qll

@@ -5,9 +5,6 @@ class Foo extends string {
 
   string getBar() { result = "bar" }
 
-  /* Okay, because we don't write `this.some_method` anywhere */
-  string getBarWithoutThis() { result = getBar() }
-
   /* Okay, because this is the only way to cast `this`. */
   string useThisWithInlineCast() { result = this.(string).toUpperCase() }
 }