RFR: 7903644: typedef of anonymous struct generates a redundant class

[Jorn Vernee]

On Thu, 25 Jan 2024 17:25:59 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> This PR tweaks jextract so that typedefs of anonymous structs only generate one class (that of the struct).
>> 
>> This required some changes in both `NameMangler` (to make sure that the special naming rule was applied), and then in `OutputFactory`, to make sure that in such case the typedef class is not emitted.
>> 
>> I've tweaked a number of tests which now reflect the "less verbose" jextract output - as such I don't think we need to add further tests.
>
> src/main/java/org/openjdk/jextract/impl/NameMangler.java line 211:
> 
>> 209:             // We may potentially generate a class for a typedef. Make sure
>> 210:             // class name is unique in the current nesting context.
>> 211:             javaName = curScope.uniqueNestedClassName(typedef.name());
> 
> This logic is a bit subtle: we have to avoid calling `uniqueNestedClassName` in case there's a struct that will inherit the typedef name - otherwise the mangler will see _two_ attempts to add the typedef name to the current scope, which will result in extra mangling.

This seems a bit ad-hoc... Suggestion: the `Scope` constructor tries to generate a unique nested class name if `parent` is not `null`. That's only the case when calling `newStruct`, which is only called from `visitScoped`. So, I think we can move the logic that computes the nested class name from the `Scope` constructor to `visitScoped` (to the `else` branch this patch adds). Then we can just pass the unmangled name from the `if` branch to `newStruct`, and there should be no need to have this logic here.

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PR Review Comment: https://git.openjdk.org/jextract/pull/195#discussion_r1466931107