The change was "Show invisible delimiters (within comments) when pretty
printing". It's useful to show these delimiters, but is a breaking
change for some proc macros.
Fixes#97608.
Reduce the amount of unstable features used in libproc_macro
This makes it easier to adapt the source for stable when copying it into rust-analyzer to load rustc compiled proc macros.
This updates the standard library's documentation to use the new syntax. The
documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.
A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).
This feature is aimed at giving proc macros access to powers similar to
those used by builtin macros such as `format_args!` or `concat!`. These
macros are able to accept macros in place of string literal parameters,
such as the format string, as they perform recursive macro expansion
while being expanded.
This can be especially useful in many cases thanks to helper macros like
`concat!`, `stringify!` and `include_str!` which are often used to
construct string literals at compile-time in user code.
For now, this method only allows expanding macros which produce
literals, although more expresisons will be supported before the method
is stabilized.
Add proc_macro::Span::{before, after}.
This adds `proc_macro::Span::before()` and `proc_macro::Span::after()` to get a zero width span at the start or end of the span.
These are equivalent to rustc's `Span::shrink_to_lo()` and `Span::shrink_to_hi()` but with a less cryptic name. They are useful when generating diagnostlics like "missing \<thing\> after \<thing\>".
E.g.
```rust
syn::Error::new(ident.span().after(), "missing `:` after field name").into_compile_error()
```
add `track_path::path` fn for usage in `proc_macro`s
Adds a way to declare a dependency on external files without including them, to either re-trigger the build of a file as well as covering the use case of including dependencies within the `rustc` invocation, such that tools like `sccache`/`cachepot` are able to handle references to external files which are not included.
Ref #73921
Due to the std/alloc split, it is not possible to make
`alloc::collections::TryReserveError::AllocError` non-exhaustive without
having an unstable, doc-hidden method to construct (which negates the
benefits from `#[non_exhaustive]`.
