Add derived flag to item

[sakupan102]

To distinguish between items that are automatically generated by #[derive()] and those that aren't, I added a derived flag to Item.

• GCC development requires copyright assignment or the Developer's Certificate of Origin sign-off, see https://gcc.gnu.org/contribute.html or https://gcc.gnu.org/dco.html
• Read contributing guidlines
• make check-rust passes locally
• Run clang-format

[philberty]

This LGTM but lets see what @P-E-P and @CohenArthur say.

Another option to avoid changing the HIR could be to make a std::map<NodeId, bool AST::Item&

in the rust-mappings.h and during hir lowering you can look that up to determine if an ITEM was derived.

But yeah see what the guys think.

[powerboat9]

Why distinguish? Producing better errors for derive-generated code?

[P-E-P]

This LGTM but lets see what @P-E-P and @CohenArthur say.

Another option to avoid changing the HIR could be to make a std::map<NodeId, bool AST::Item&

in the rust-mappings.h and during hir lowering you can look that up to determine if an ITEM was derived.

But yeah see what the guys think.

A set instead of a map<NodeId, bool> would probably be better but I agree, this kind of informations should probably be kept outside of the AST.

[philberty]

yeah sounds like if you need this flag then follow @P-E-P advice

[philberty]

change this to use a map and loop instead

[CohenArthur]

rustc adds the #[automatically_derived] attribute to the impls it creates, which is something we can consider as well. I'm not sure if the attribute is used for other things

[sakupan102]

I will close this PR and create a new issue because the implementation is entirely different.