Rollup of 8 pull requests
Successful merges:
- #125205 (Fixup Windows verbatim paths when used with the `include!` macro)
- #131049 (Validate args are correct for `UnevaluatedConst`, `ExistentialTraitRef`/`ExistentialProjection`)
- #131549 (Add a note for `?` on a `impl Future<Output = Result<..>>` in sync function)
- #131731 (add `TestFloatParse` to `tools.rs` for bootstrap)
- #131732 (Add doc(plugins), doc(passes), etc. to INVALID_DOC_ATTRIBUTES)
- #132006 (don't stage-off to previous compiler when CI rustc is available)
- #132022 (Move `cmp_in_dominator_order` out of graph dominator computation)
- #132033 (compiletest: Make `line_directive` return a `DirectiveLine`)
r? `@ghost`
`@rustbot` modify labels: rollup
Fixup Windows verbatim paths when used with the `include!` macro
On Windows, the following code can fail if the `OUT_DIR` environment variable is a [verbatim path](https://doc.rust-lang.org/std/path/enum.Prefix.html) (i.e. begins with `\\?\`):
```rust
include!(concat!(env!("OUT_DIR"), "/src/repro.rs"));
```
This is because verbatim paths treat `/` literally, as if it were just another character in the file name.
The good news is that the standard library already has code to fix this. We can simply use `components` to normalize the path so it works as intended.
Rollup of 9 pull requests
Successful merges:
- #122670 (Fix bug where `option_env!` would return `None` when env var is present but not valid Unicode)
- #131095 (Use environment variables instead of command line arguments for merged doctests)
- #131339 (Expand set_ptr_value / with_metadata_of docs)
- #131652 (Move polarity into `PolyTraitRef` rather than storing it on the side)
- #131675 (Update lint message for ABI not supported)
- #131681 (Fix up-to-date checking for run-make tests)
- #131702 (Suppress import errors for traits that couldve applied for method lookup error)
- #131703 (Resolved python deprecation warning in publish_toolstate.py)
- #131710 (Remove `'apostrophes'` from `rustc_parse_format`)
r? `@ghost`
`@rustbot` modify labels: rollup
Make deprecated_cfg_attr_crate_type_name a hard error
Turns the forward compatibility lint added by #83744 into a hard error, so now, while the `#![crate_name]` and `#![crate_type]` attributes are still allowed in raw form, they are now forbidden to be nested inside a `#![cfg_attr()]` attribute.
The following will now be an error:
```Rust
#![cfg_attr(foo, crate_name = "foobar")]
#![cfg_attr(foo, crate_type = "bin")]
```
This code will continue working and is not deprecated:
```Rust
#![crate_name = "foobar"]
#![crate_type = "lib"]
```
The reasoning for this is explained in #83744: it allows us to not have to cfg-expand in order to determine the crate's type and name.
As of filing the PR, exactly two years have passed since #99784 has been merged, which has turned the lint's default warning level into an error, so there has been ample time to move off the now-forbidden syntax.
cc #91632 - tracking issue for the lint
Implement RFC3695 Allow boolean literals as cfg predicates
This PR implements https://github.com/rust-lang/rfcs/pull/3695: allow boolean literals as cfg predicates, i.e. `cfg(true)` and `cfg(false)`.
r? `@nnethercote` *(or anyone with parser knowledge)*
cc `@clubby789`
rustc_expand: remember module `#[path]`s during expansion
During invocation collection, if a module item parsed from a `#[path]` attribute needed a second pass after parsing, its path wouldn't get added to the file path stack, so cycle detection broke. This checks the `#[path]` in such cases, so that it gets added appropriately. I think it should work identically to the case for external modules that don't need a second pass, but I'm not 100% sure.
Fixes#97589
Stabilize `unsafe_attributes`
# Stabilization report
## Summary
This is a tracking issue for the RFC 3325: unsafe attributes
We are stabilizing `#![feature(unsafe_attributes)]`, which makes certain attributes considered 'unsafe', meaning that they must be surrounded by an `unsafe(...)`, as in `#[unsafe(no_mangle)]`.
RFC: rust-lang/rfcs#3325
Tracking issue: #123757
## What is stabilized
### Summary of stabilization
Certain attributes will now be designated as unsafe attributes, namely, `no_mangle`, `export_name`, and `link_section` (stable only), and these attributes will need to be called by surrounding them in `unsafe(...)` syntax. On editions prior to 2024, this is simply an edition lint, but it will become a hard error in 2024. This also works in `cfg_attr`, but `unsafe` is not allowed for any other attributes, including proc-macros ones.
```rust
#[unsafe(no_mangle)]
fn a() {}
#[cfg_attr(any(), unsafe(export_name = "c"))]
fn b() {}
```
For a table showing the attributes that were considered to be included in the list to require unsafe, and subsequent reasoning about why each such attribute was or was not included, see [this comment here](https://github.com/rust-lang/rust/pull/124214#issuecomment-2124753464)
## Tests
The relevant tests are in `tests/ui/rust-2024/unsafe-attributes` and `tests/ui/attributes/unsafe`.
Use more slice patterns inside the compiler
Nothing super noteworthy. Just replacing the common 'fragile' pattern of "length check followed by indexing or unwrap" with slice patterns for legibility and 'robustness'.
r? ghost
When using `concat!` to join paths, the Unix path separator (`/`) is often used. This breaks on Windows if the base path is a verbatim path (i.e. starts with `\\?\`).
This makes it possible for the `unsafe(...)` syntax to only be
valid at the top level, and the `NestedMetaItem`s will automatically
reject `unsafe(...)`.
Tell users not to file a bug when using internal library features
Actually fixes#97501. I don't think we should suppress the suggestion to add `#![feature(..)]`, though I guess I could be convinced otherwise.
r? `@Nilstrieb` cc `@RalfJung`
Didn't add a test b/c I don't think we test this for lang features either, but I can confirm it does work.
```
warning: the feature `core_intrinsics` is internal to the compiler or standard library
--> /home/michael/test.rs:1:12
|
1 | #![feature(core_intrinsics)]
| ^^^^^^^^^^^^^^^
|
= note: using it is strongly discouraged
= note: `#[warn(internal_features)]` on by default
thread 'rustc' panicked at compiler/rustc_mir_transform/src/validate.rs:94:25:
broken MIR in Item(DefId(0:6 ~ test[42db]::{impl#0}::add)) (after phase change to runtime-optimized) at bb0[0]:
Cannot perform arithmetic Add on type WrapInt8
stack backtrace:
0: begin_panic_handler
at ./library/std/src/panicking.rs:665:5
1: panic_fmt
at ./library/core/src/panicking.rs:74:14
2: fail<alloc::string::String>
at ./compiler/rustc_mir_transform/src/validate.rs:146:9
3: run_pass
at ./compiler/rustc_mir_transform/src/validate.rs:94:13
4: validate_body
at ./compiler/rustc_mir_transform/src/pass_manager.rs:193:5
5: run_passes_inner
at ./compiler/rustc_mir_transform/src/pass_manager.rs:176:13
6: rustc_mir_transform::pass_manager::run_passes
at ./compiler/rustc_mir_transform/src/pass_manager.rs:87:5
7: run_optimization_passes
at ./compiler/rustc_mir_transform/src/lib.rs:561:5
8: inner_optimized_mir
at ./compiler/rustc_mir_transform/src/lib.rs:667:5
9: optimized_mir
at ./compiler/rustc_mir_transform/src/lib.rs:630:21
10: {closure#0}
at ./compiler/rustc_query_impl/src/plumbing.rs:285:13
[... omitted 22 frames ...]
11: query_get_at<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 8]>>>
at ./compiler/rustc_middle/src/query/plumbing.rs:145:17
12: instance_mir
13: collect_items_of_instance
at ./compiler/rustc_monomorphize/src/collector.rs:1203:16
14: {closure#0}
at ./compiler/rustc_monomorphize/src/collector.rs:447:17
15: maybe_grow<(), rustc_monomorphize::collector::collect_items_rec::{closure_env#0}>
at /home/michael/.cargo/registry/src/index.crates.io-6f17d22bba15001f/stacker-0.1.15/src/lib.rs:55:9
16: ensure_sufficient_stack<(), rustc_monomorphize::collector::collect_items_rec::{closure_env#0}>
at ./compiler/rustc_data_structures/src/stack.rs:17:5
17: collect_items_rec
at ./compiler/rustc_monomorphize/src/collector.rs:446:13
18: collect_items_rec
at ./compiler/rustc_monomorphize/src/collector.rs:526:13
19: {closure#0}
at ./compiler/rustc_monomorphize/src/collector.rs:1597:17
20: {closure#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>
at ./compiler/rustc_data_structures/src/sync/parallel.rs:182:34
21: call_once<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#0}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>
at ./library/core/src/panic/unwind_safe.rs:272:9
22: do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#0}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>, ()>
at ./library/std/src/panicking.rs:557:40
23: try<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#0}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>>
at ./library/std/src/panicking.rs:521:19
24: run<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure#1}::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>
at ./compiler/rustc_data_structures/src/sync/parallel.rs:28:9
25: {closure#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>
at ./compiler/rustc_data_structures/src/sync/parallel.rs:186:21
26: {closure#0}<rustc_middle::mir::mono::MonoItem, rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure_env#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>
at ./library/core/src/iter/traits/iterator.rs:815:29
27: fold<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global, (), core::iter::traits::iterator::Iterator::for_each::call::{closure_env#0}<rustc_middle::mir::mono::MonoItem, rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure_env#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>>
at ./library/alloc/src/vec/into_iter.rs:317:25
28: for_each<alloc::vec::into_iter::IntoIter<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure#0}::{closure_env#1}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>
at ./library/core/src/iter/traits/iterator.rs:818:9
29: {closure#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>
at ./compiler/rustc_data_structures/src/sync/parallel.rs:185:17
30: parallel_guard<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in::{closure_env#0}<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>>
at ./compiler/rustc_data_structures/src/sync/parallel.rs:44:15
31: par_for_each_in<rustc_middle::mir::mono::MonoItem, alloc::vec::Vec<rustc_middle::mir::mono::MonoItem, alloc::alloc::Global>, rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure_env#0}>
at ./compiler/rustc_data_structures/src/sync/parallel.rs:178:9
32: {closure#1}
at ./compiler/rustc_monomorphize/src/collector.rs:1595:13
33: run<(), rustc_monomorphize::collector::collect_crate_mono_items::{closure_env#1}>
at ./compiler/rustc_data_structures/src/profiling.rs:754:9
34: time<(), rustc_monomorphize::collector::collect_crate_mono_items::{closure_env#1}>
at ./compiler/rustc_session/src/utils.rs:16:9
35: collect_crate_mono_items
at ./compiler/rustc_monomorphize/src/collector.rs:1594:9
36: collect_and_partition_mono_items
at ./compiler/rustc_monomorphize/src/partitioning.rs:1124:30
37: {closure#0}
at ./compiler/rustc_query_impl/src/plumbing.rs:281:9
[... omitted 22 frames ...]
38: query_get_at<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 24]>>>
at ./compiler/rustc_middle/src/query/plumbing.rs:145:17
39: collect_and_partition_mono_items
at ./compiler/rustc_middle/src/query/plumbing.rs:423:31
40: collect_and_partition_mono_items
at ./compiler/rustc_middle/src/query/plumbing.rs:414:17
41: codegen_crate<rustc_codegen_llvm::LlvmCodegenBackend>
at ./compiler/rustc_codegen_ssa/src/base.rs:596:25
42: codegen_crate
at ./compiler/rustc_codegen_llvm/src/lib.rs:361:18
43: {closure#0}
at ./compiler/rustc_interface/src/passes.rs:1027:9
44: run<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
at ./compiler/rustc_data_structures/src/profiling.rs:754:9
45: time<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
at ./compiler/rustc_session/src/utils.rs:16:9
46: start_codegen
at ./compiler/rustc_interface/src/passes.rs:1026:19
47: codegen_and_build_linker
at ./compiler/rustc_interface/src/queries.rs:128:31
48: {closure#6}
at ./compiler/rustc_driver_impl/src/lib.rs:451:25
49: {closure#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_middle/src/ty/context.rs:1336:37
50: {closure#0}<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_middle/src/ty/context/tls.rs:82:9
51: try_with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
at ./library/std/src/thread/local.rs:283:12
52: with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
at ./library/std/src/thread/local.rs:260:9
53: enter_context<rustc_middle::ty::context::{impl#19}::enter::{closure_env#1}<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_middle/src/ty/context/tls.rs:79:5
54: enter<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure_env#6}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_middle/src/ty/context.rs:1336:9
55: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#6}>
at ./compiler/rustc_interface/src/queries.rs:64:9
56: {closure#1}
at ./compiler/rustc_driver_impl/src/lib.rs:450:13
57: enter<rustc_driver_impl::run_compiler::{closure#0}::{closure_env#1}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_interface/src/queries.rs:209:19
58: {closure#0}
at ./compiler/rustc_driver_impl/src/lib.rs:388:22
59: {closure#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>
at ./compiler/rustc_interface/src/interface.rs:502:27
60: {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_interface/src/util.rs:154:13
61: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_interface/src/util.rs:106:21
62: set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>>
at /home/michael/.cargo/registry/src/index.crates.io-6f17d22bba15001f/scoped-tls-1.0.1/src/lib.rs:137:9
63: create_session_globals_then<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>>>
at ./compiler/rustc_span/src/lib.rs:134:5
64: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure_env#0}>, core::result::Result<(), rustc_span::ErrorGuaranteed>>, core::result::Result<(), rustc_span::ErrorGuaranteed>>
at ./compiler/rustc_interface/src/util.rs:105:17
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
error: the compiler unexpectedly panicked. this is a bug.
note: using internal features is not supported and expected to cause internal compiler errors when used incorrectly
note: rustc 1.82.0-dev running on x86_64-unknown-linux-gnu
query stack during panic:
#0 [optimized_mir] optimizing MIR for `<impl at /home/michael/test.rs:9:1: 9:32>::add`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
```
`missing_fragment_specifier` has been a future compatibility warning
since 2017. Uplifting it to an unconditional hard error was attempted in
2020, but eventually reverted due to fallout.
Make it an error only in edition >= 2024, leaving the lint for older
editions. This change will make it easier to support more macro syntax
that relies on usage of `$`.
Fixes <https://github.com/rust-lang/rust/issues/40107>
Improve spans on evaluated `cfg_attr`s.
When converting something like `#![cfg_attr(cond, attr)]` into `#![attr]`, we currently duplicate the `#` token and the `!` token. But weirdly, there is also this comment:
// We don't really have a good span to use for the synthesized `[]`
// in `#[attr]`, so just use the span of the `#` token.
Maybe that comment used to be true? But now it is false: we can duplicate the existing delimiters (and their spans and spacing), much like we do for the `#` and `!`.
This commit does that, thus removing the incorrect comment, and improving the spans on `Group`s in a few proc-macro tests.
`@petrochenkov`
When converting something like `#![cfg_attr(cond, attr)]` into
`#![attr]`, we currently duplicate the `#` token and the `!` token. But
weirdly, there is also this comment:
// We don't really have a good span to use for the synthesized `[]`
// in `#[attr]`, so just use the span of the `#` token.
Maybe that comment used to be true? But now it is false: we can
duplicate the existing delimiters (and their spans and spacing), much
like we do for the `#` and `!`.
This commit does that, thus removing the incorrect comment, and
improving the spans on `Group`s in a few proc-macro tests.
