SONARJAVA-1606 uses subtypeOf for typeVar to not lose method resolutions

Author: Wohops

java-frontend/src/main/java/org/sonar/java/resolve/Types.java

@@ -67,6 +67,7 @@ public boolean isSubtype(JavaType t, JavaType s) {
           break;
         case JavaType.CLASS:
         case JavaType.WILDCARD:
+        case JavaType.TYPEVAR:
           result = t.isSubtypeOf(s);
           break;
         case JavaType.BOT:

java-frontend/src/test/files/sym/Generics.java

@@ -74,4 +74,23 @@ interface MyInterface<T> {
 }
 
 class C<T> {
-}
+}
+
+class TypeParameterUsedInMethods<T, U> {
+  Function<? super T, ? extends U> getter;
+
+  void foo(T val, U wantedValue) {
+    getter.apply(val);
+    // these 2 calls do not compile but methods are resolved, as argument matching is based on erasure
+    getter.apply(new Object());
+    getter.apply(wantedValue);
+    // not valid call with different erasure, not resolved
+    getter.apply("hello");
+  }
+
+  static class Function<X, Y> {
+    Y apply(X from) {
+      return null;
+    }
+  }
+}

java-frontend/src/test/java/org/sonar/java/resolve/SymbolTableTest.java

@@ -95,6 +95,10 @@ public void Generics() {
     //Inner class referenced as type parameter in super class/interface
     assertThat(result.reference(68,53)).isSameAs(result.symbol("B", 69));
 
+    JavaSymbol applyMethod = result.symbol("apply");
+    assertThat(result.reference(83, 12)).isSameAs(applyMethod);
+    // FIXME SONARJAVA-1606 should be 1, subtyping of type variable is wrong
+    assertThat(applyMethod.usages()).hasSize(3);
   }
 
   @Test