[foreign-jextract] RFR: 8249536: jextract throw IllegalStateException for bitfields in nested anonymous structs

[Paul Sandoz]

On Wed, 15 Jul 2020 20:30:39 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> What happens for the following?
>> struct Foo {
>>     struct {
>>         int a : 7;
>>         int b : 25;
>>     };
>>     struct Bar {
>> 	int a : 12;
>>     } bar;
>> };
>
>> 
>> 
>> What happens for the following?
>> 
>> ```c
>> struct Foo {
>>     struct {
>>         int a : 7;
>>         int b : 25;
>>     };
>>     struct Bar {
>> 	int a : 12;
>>     } bar;
>> };
>> ```
> 
> In that case there is no problem since the `bar` struct is not anonymous.
> 
> You get the following tree (On Windows):
> 
> Scoped: TOPLEVEL <toplevel>
>     Scoped: STRUCT Foo layout =
>     [b32[contents=[b7(a)[layout/name=a]b25(b)[layout/name=b]],abi/windows/class=INTEGER][b32[contents=[b12(a)[layout/name=a]x20],abi/windows/class=INTEGER]](bar)[layout/name=bar]](Foo)[layout/name=Foo]
>         Scoped: STRUCT  layout = [b32[contents=[b7(a)[layout/name=a]b25(b)[layout/name=b]],abi/windows/class=INTEGER]]
>             Scoped: BITFIELDS  layout = [b7(a)[layout/name=a]b25(b)[layout/name=b]]
>                 Variable: BITFIELD a type = Int(layout = b32[abi/windows/class=INTEGER]), layout = Optional[b7]
>                 Variable: BITFIELD b type = Int(layout = b32[abi/windows/class=INTEGER]), layout = Optional[b25]
>         Scoped: STRUCT Bar layout = [b32[contents=[b12(a)[layout/name=a]x20],abi/windows/class=INTEGER]](Bar)[layout/name=Bar]
>             Scoped: BITFIELDS  layout = [b12(a)[layout/name=a]x20]
>                 Variable: BITFIELD a type = Int(layout = b32[abi/windows/class=INTEGER]), layout = Optional[b12]
>         Variable: FIELD bar type =
>         Declared([b32[contents=[b12(a)[layout/name=a]x20],abi/windows/class=INTEGER]](Bar)[layout/name=Bar]), layout =
>         Optional[[b32[contents=[b12(a)[layout/name=a]x20],abi/windows/class=INTEGER]](Bar)[layout/name=Bar]]

Will the bit fields named "a" in the anonymous and named nested structs clash. so processing "a" in struct Bar will get
filtered out because "a" is added to the `nestedBitfieldNames` set?

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PR: https://git.openjdk.java.net/panama-foreign/pull/246