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Auto merge of #120227 - nnethercote:further-improve-space_between, r=petrochenkov

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Further improve `space_between`

`space_between` is used by `print_tts` to decide when spaces should be put between  tokens. This PR improves it in two ways:
- avoid unnecessary spaces before semicolons, and
- don't omit some necessary spaces before/after some punctuation symbols.

r? `@petrochenkov`
This commit is contained in:
bors 2024-01-31 02:01:43 +00:00
commit 80deabd098
28 changed files with 100 additions and 107 deletions
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47
compiler/rustc_ast_pretty/src/pprust/state.rs
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@ -160,6 +160,10 @@ fn space_between(tt1: &TokenTree, tt2: &TokenTree) -> bool {
use TokenTree::Delimited as Del;
use TokenTree::Token as Tok;
fn is_punct(tt: &TokenTree) -> bool {
matches!(tt, TokenTree::Token(tok, _) if tok.is_punct())
}
// Each match arm has one or more examples in comments. The default is to
// insert space between adjacent tokens, except for the cases listed in
// this match.
@ -167,24 +171,35 @@ fn space_between(tt1: &TokenTree, tt2: &TokenTree) -> bool {
// No space after line doc comments.
(Tok(Token { kind: DocComment(CommentKind::Line, ..), .. }, _), _) => false,
// `.` + ANYTHING: `x.y`, `tup.0`
// `$` + ANYTHING: `$e`
(Tok(Token { kind: Dot | Dollar, .. }, _), _) => false,
// `.` + NON-PUNCT: `x.y`, `tup.0`
(Tok(Token { kind: Dot, .. }, _), tt2) if !is_punct(tt2) => false,
// ANYTHING + `,`: `foo,`
// ANYTHING + `.`: `x.y`, `tup.0`
// ANYTHING + `!`: `foo! { ... }`
//
// FIXME: Incorrect cases:
// - Logical not: `x =! y`, `if! x { f(); }`
// - Never type: `Fn() ->!`
(_, Tok(Token { kind: Comma | Dot | Not, .. }, _)) => false,
// `$` + IDENT: `$e`
(Tok(Token { kind: Dollar, .. }, _), Tok(Token { kind: Ident(..), .. }, _)) => false,
// IDENT + `(`: `f(3)`
//
// FIXME: Incorrect cases:
// - Let: `let(a, b) = (1, 2)`
(Tok(Token { kind: Ident(..), .. }, _), Del(_, _, Parenthesis, _)) => false,
// NON-PUNCT + `,`: `foo,`
// NON-PUNCT + `;`: `x = 3;`, `[T; 3]`
// NON-PUNCT + `.`: `x.y`, `tup.0`
(tt1, Tok(Token { kind: Comma | Semi | Dot, .. }, _)) if !is_punct(tt1) => false,
// IDENT + `!`: `println!()`, but `if !x { ... }` needs a space after the `if`
(Tok(Token { kind: Ident(sym, is_raw), span }, _), Tok(Token { kind: Not, .. }, _))
if !Ident::new(*sym, *span).is_reserved() || *is_raw =>
{
false
}
// IDENT|`fn`|`Self`|`pub` + `(`: `f(3)`, `fn(x: u8)`, `Self()`, `pub(crate)`,
// but `let (a, b) = (1, 2)` needs a space after the `let`
(Tok(Token { kind: Ident(sym, is_raw), span }, _), Del(_, _, Parenthesis, _))
if !Ident::new(*sym, *span).is_reserved()
|| *sym == kw::Fn
|| *sym == kw::SelfUpper
|| *sym == kw::Pub
|| *is_raw =>
{
false
}
// `#` + `[`: `#[attr]`
(Tok(Token { kind: Pound, .. }, _), Del(_, _, Bracket, _)) => false,