RFR: 8357653: Inner classes of type parameters emitted as raw types in signatures [v18]

[Maurizio Cimadamore]

On Mon, 14 Jul 2025 12:34:30 GMT, Aggelos Biboudis <abimpoudis at openjdk.org> wrote:

>> There are various occasions that the qualifier of an _inner type_ needs to be normalized. 
>> 
>> Briefly:
>> 
>> - This occurs when there is an explicit type application in the signature of the method or a type application operation or when type checking an expression operation (e.g., `G.Getter` in the first example, `M.B<?>` in the second example). 
>> - The reference to an inner type may not be explicitly qualified (e.g., `B<?>` which is not qualified but its type needs be calculated as seen from `A<String>.B<?>`).
>> 
>> Semi-formally: 
>> 
>> - A type reference is simple name `R`:
>> 
>>   - `R` is a non-inner class type, nothing to do
>>   - `R` is an inner class type, we need to find an implicit type qualifier `S<T>.R`, where `S` is the class in which `R` is enclosed
>>   - `R` is an array type `A[]`, repeat the analysis for the simple type name `A`, and then use the implicit type qualifier to rewrite the array
>> 
>> - A type reference is a qualified name `Q.R`
>>   
>>   - find the supertype of `Q`, namely `S<T>`, where `S` is the class in which `R` is enclosed
>> 
>> 
>> 
>> // example 1
>> static class Usage1<T, G extends Getters<T>> {
>>   public T test(G.Getter getter) {
>>       return getter.get();
>>   }
>> }
>> 
>> // example 2
>> class A<T> {
>>   protected class B<V> {}
>> 
>>   public static <T, M extends A<T>> void f(Object g) {
>>     @SuppressWarnings("unchecked")
>>     M.B<?> mapping = (M.B<?>) g;
>>   }
>> }
>> 
>> // example 3
>> class A<T> {
>>     class B<W> {
>>         public T rett() { return null; }
>>     }
>> }
>> 
>> class C extends A<String> {
>>     static class D {
>>         {
>>             B<?> b = null;
>>             String s = b.rett();
>>         }
>>     }
>> }
>
> Aggelos Biboudis has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reduce comments

Looks very good, I left two optional minor doc changes

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java line 2248:

> 2246:      *        class I {
> 2247:      *          void test() {
> 2248:      *              String f2 = f; // Sup<String>

Suggestion:

     *              String f2 = f; // Sup<String>::f

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java line 2278:

> 2276:      * class C extends A<String> {
> 2277:      *   static class D {
> 2278:      *      B b; // qualifier is A<String>.B

Suggestion:

     *      B b; // A<String>.B

-------------

Marked as reviewed by mcimadamore (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25451#pullrequestreview-3017839826
PR Review Comment: https://git.openjdk.org/jdk/pull/25451#discussion_r2205825684
PR Review Comment: https://git.openjdk.org/jdk/pull/25451#discussion_r2205826160