rust/tests/ui/macros/syntax-extension-source-utils.rs
Nicholas Nethercote 925f7fad57 Improve print_tts by changing tokenstream::Spacing.
`tokenstream::Spacing` appears on all `TokenTree::Token` instances,
both punct and non-punct. Its current usage:
- `Joint` means "can join with the next token *and* that token is a
  punct".
- `Alone` means "cannot join with the next token *or* can join with the
  next token but that token is not a punct".

The fact that `Alone` is used for two different cases is awkward.
This commit augments `tokenstream::Spacing` with a new variant
`JointHidden`, resulting in:
- `Joint` means "can join with the next token *and* that token is a
  punct".
- `JointHidden` means "can join with the next token *and* that token is a
  not a punct".
- `Alone` means "cannot join with the next token".

This *drastically* improves the output of `print_tts`. For example,
this:
```
stringify!(let a: Vec<u32> = vec![];)
```
currently produces this string:
```
let a : Vec < u32 > = vec! [] ;
```
With this PR, it now produces this string:
```
let a: Vec<u32> = vec![] ;
```
(The space after the `]` is because `TokenTree::Delimited` currently
doesn't have spacing information. The subsequent commit fixes this.)

The new `print_tts` doesn't replicate original code perfectly. E.g.
multiple space characters will be condensed into a single space
character. But it's much improved.

`print_tts` still produces the old, uglier output for code produced by
proc macros. Because we have to translate the generated code from
`proc_macro::Spacing` to the more expressive `token::Spacing`, which
results in too much `proc_macro::Along` usage and no
`proc_macro::JointHidden` usage. So `space_between` still exists and
is used by `print_tts` in conjunction with the `Spacing` field.

This change will also help with the removal of `Token::Interpolated`.
Currently interpolated tokens are pretty-printed nicely via AST pretty
printing. `Token::Interpolated` removal will mean they get printed with
`print_tts`. Without this change, that would result in much uglier
output for code produced by decl macro expansions. With this change, AST
pretty printing and `print_tts` produce similar results.

The commit also tweaks the comments on `proc_macro::Spacing`. In
particular, it refers to "compound tokens" rather than "multi-char
operators" because lifetimes aren't operators.
2023-12-11 09:19:09 +11:00

37 lines
1.1 KiB
Rust

// run-pass
#![allow(stable_features)]
pub mod m1 {
pub mod m2 {
pub fn where_am_i() -> String {
(module_path!()).to_string()
}
}
}
macro_rules! indirect_line { () => ( line!() ) }
pub fn main() {
assert_eq!(line!(), 16);
assert_eq!(column!(), 16);
assert_eq!(indirect_line!(), 18);
assert!((file!().ends_with("syntax-extension-source-utils.rs")));
assert_eq!(stringify!((2*3) + 5).to_string(), "(2*3) + 5".to_string());
assert!(include!("syntax-extension-source-utils-files/includeme.\
fragment").to_string()
== "victory robot 6".to_string());
assert!(
include_str!("syntax-extension-source-utils-files/includeme.\
fragment").to_string()
.starts_with("/* this is for "));
assert!(
include_bytes!("syntax-extension-source-utils-files/includeme.fragment")
[1] == (42 as u8)); // '*'
// The Windows tests are wrapped in an extra module for some reason
assert!((m1::m2::where_am_i().ends_with("m1::m2")));
assert_eq!((35, "(2*3) + 5"), (line!(), stringify!((2*3) + 5)));
}