[rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature

 [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature

…=petrochenkov,mejrs,Urgau

 [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature

Fixes rust-lang#103300.

After long last, this PR finally allows the derive proc-macro `cfg_attr` cfg predicates information to be kept so rustdoc can use it for its `doc_cfg` feature (cc rust-lang#43781).

It works as follows: for `impl` generated by macro expansion, we then look for the attributes on the type for which the `impl` block is implemented. Then, to know which `cfg_attr` attribute we want to look at, we use `expn_that_defined` on the impl's `DefId` which returns the `Span` where the macro was expanded. If it's part of a `cfg_attr`, then the `cfg_attr`'s `Span` will contain the derive's, so from then, we just need to add the `cfg` information.

This PR also adds the cfg predicates into the `AttributeKind::CfgAttrTrace` variant so it can be reused by rustdoc (hence the `compiler/*` changes).

Thanks a lot @petrochenkov for the pointers here!

r? @petrochenkov

…=petrochenkov,mejrs,Urgau

 [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature

Fixes rust-lang#103300.

After long last, this PR finally allows the derive proc-macro `cfg_attr` cfg predicates information to be kept so rustdoc can use it for its `doc_cfg` feature (cc rust-lang#43781).

It works as follows: for `impl` generated by macro expansion, we then look for the attributes on the type for which the `impl` block is implemented. Then, to know which `cfg_attr` attribute we want to look at, we use `expn_that_defined` on the impl's `DefId` which returns the `Span` where the macro was expanded. If it's part of a `cfg_attr`, then the `cfg_attr`'s `Span` will contain the derive's, so from then, we just need to add the `cfg` information.

This PR also adds the cfg predicates into the `AttributeKind::CfgAttrTrace` variant so it can be reused by rustdoc (hence the `compiler/*` changes).

Thanks a lot @petrochenkov for the pointers here!

r? @petrochenkov

…=petrochenkov,mejrs,Urgau

 [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature

Fixes rust-lang#103300.

After long last, this PR finally allows the derive proc-macro `cfg_attr` cfg predicates information to be kept so rustdoc can use it for its `doc_cfg` feature (cc rust-lang#43781).

It works as follows: for `impl` generated by macro expansion, we then look for the attributes on the type for which the `impl` block is implemented. Then, to know which `cfg_attr` attribute we want to look at, we use `expn_that_defined` on the impl's `DefId` which returns the `Span` where the macro was expanded. If it's part of a `cfg_attr`, then the `cfg_attr`'s `Span` will contain the derive's, so from then, we just need to add the `cfg` information.

This PR also adds the cfg predicates into the `AttributeKind::CfgAttrTrace` variant so it can be reused by rustdoc (hence the `compiler/*` changes).

Thanks a lot @petrochenkov for the pointers here!

r? @petrochenkov

Rollup of 12 pull requests

Successful merges:

 - #159765 (Avoid spurious rebuilds of JSON docs in bootstrap)
 - #159781 (Update bootstrap to use -Zembed-metadata=no instead of -Zno-embed-metadata)
 - #158362 (trait solver: account for universes from replace_bound_vars)
 - #159173 (Add allowed list check on EII implementations attributes)
 - #159718 (Make `DocLinkResMap` an `FxIndexMap`)
 - #159722 ( [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature)
 - #155795 (constify `vec![1, 2, 3]` macro)
 - #157776 (ci: Enable autodiff tests on x86_64 linux)
 - #158766 (Promote riscv64-unknown-linux-musl to tier 2 with host tools)
 - #159271 (str: add ASCII fast path to word_to_titlecase)
 - #159666 (fix(ld64.lld): route version mismatch warnings to linker_info on macOS)
 - #159667 (Make some parser structured suggestions verbose and tweak their wording)

Rollup of 14 pull requests

Successful merges:

 - #159765 (Avoid spurious rebuilds of JSON docs in bootstrap)
 - #159781 (Update bootstrap to use -Zembed-metadata=no instead of -Zno-embed-metadata)
 - #158362 (trait solver: account for universes from replace_bound_vars)
 - #158372 (rustfmt: Discover modules via `cfg_select!`)
 - #159173 (Add allowed list check on EII implementations attributes)
 - #159718 (Make `DocLinkResMap` an `FxIndexMap`)
 - #159722 ( [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature)
 - #159731 (std: Implement futex on wasip3 targets, update target spec)
 - #159755 (Improve consistency of attribute error messages)
 - #155795 (constify `vec![1, 2, 3]` macro)
 - #157776 (ci: Enable autodiff tests on x86_64 linux)
 - #158766 (Promote riscv64-unknown-linux-musl to tier 2 with host tools)
 - #159271 (str: add ASCII fast path to word_to_titlecase)
 - #159667 (Make some parser structured suggestions verbose and tweak their wording)

Rollup merge of #159722 - GuillaumeGomez:cfg_attr-doc_cfg, r=petrochenkov,mejrs,Urgau

 [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature

Fixes #103300.

After long last, this PR finally allows the derive proc-macro `cfg_attr` cfg predicates information to be kept so rustdoc can use it for its `doc_cfg` feature (cc #43781).

It works as follows: for `impl` generated by macro expansion, we then look for the attributes on the type for which the `impl` block is implemented. Then, to know which `cfg_attr` attribute we want to look at, we use `expn_that_defined` on the impl's `DefId` which returns the `Span` where the macro was expanded. If it's part of a `cfg_attr`, then the `cfg_attr`'s `Span` will contain the derive's, so from then, we just need to add the `cfg` information.

This PR also adds the cfg predicates into the `AttributeKind::CfgAttrTrace` variant so it can be reused by rustdoc (hence the `compiler/*` changes).

Thanks a lot @petrochenkov for the pointers here!

r? @petrochenkov

Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#159765 (Avoid spurious rebuilds of JSON docs in bootstrap)
 - rust-lang/rust#159781 (Update bootstrap to use -Zembed-metadata=no instead of -Zno-embed-metadata)
 - rust-lang/rust#158362 (trait solver: account for universes from replace_bound_vars)
 - rust-lang/rust#158372 (rustfmt: Discover modules via `cfg_select!`)
 - rust-lang/rust#159173 (Add allowed list check on EII implementations attributes)
 - rust-lang/rust#159718 (Make `DocLinkResMap` an `FxIndexMap`)
 - rust-lang/rust#159722 ( [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature)
 - rust-lang/rust#159731 (std: Implement futex on wasip3 targets, update target spec)
 - rust-lang/rust#159755 (Improve consistency of attribute error messages)
 - rust-lang/rust#155795 (constify `vec![1, 2, 3]` macro)
 - rust-lang/rust#157776 (ci: Enable autodiff tests on x86_64 linux)
 - rust-lang/rust#158766 (Promote riscv64-unknown-linux-musl to tier 2 with host tools)
 - rust-lang/rust#159271 (str: add ASCII fast path to word_to_titlecase)
 - rust-lang/rust#159667 (Make some parser structured suggestions verbose and tweak their wording)

Minor `rustc_ast::ast` doc cleanups

`P` is an outdated reference.

`CfgAttrTrace` was updated in rust-lang#159722

Docs were formatted so that the entire paragraph doesn't show up on the module level docs (pet peeve of mine).

r? @nnethercote

Minor `rustc_ast::ast` doc cleanups

`P` is an outdated reference.

`CfgAttrTrace` was updated in rust-lang#159722

Docs were formatted so that the entire paragraph doesn't show up on the module level docs (pet peeve of mine).

r? @nnethercote

Minor `rustc_ast::ast` doc cleanups

`P` is an outdated reference.

`CfgAttrTrace` was updated in rust-lang#159722

Docs were formatted so that the entire paragraph doesn't show up on the module level docs (pet peeve of mine).

r? @nnethercote

Minor `rustc_ast::ast` doc cleanups

`P` is an outdated reference.

`CfgAttrTrace` was updated in rust-lang#159722

Docs were formatted so that the entire paragraph doesn't show up on the module level docs (pet peeve of mine).

r? @nnethercote

Minor `rustc_ast::ast` doc cleanups

`P` is an outdated reference.

`CfgAttrTrace` was updated in rust-lang#159722

Docs were formatted so that the entire paragraph doesn't show up on the module level docs (pet peeve of mine).

r? @nnethercote

Minor `rustc_ast::ast` doc cleanups

`P` is an outdated reference.

`CfgAttrTrace` was updated in rust-lang#159722

Docs were formatted so that the entire paragraph doesn't show up on the module level docs (pet peeve of mine).

r? @nnethercote