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Rollup merge of rust-lang#94985 - dtolnay:constattr, r=pnkfelix
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Parse inner attributes on inline const block

According to rust-lang#84414 (comment), inner attributes are intended to be supported *"in all containers for statements (or some subset of statements)"*.

This PR adds inner attribute parsing and pretty-printing for inline const blocks (rust-lang#76001), which contain statements just like an unsafe block or a loop body.

```rust
let _ = const {
    #![allow(...)]

    let x = ();
    x
};
```
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RalfJung authored Apr 15, 2022
2 parents 6718b41 + f427698 commit 0bf9ebb
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Showing 4 changed files with 26 additions and 6 deletions.
2 changes: 1 addition & 1 deletion compiler/rustc_ast_pretty/src/pprust/state.rs
Original file line number Diff line number Diff line change
Expand Up @@ -959,7 +959,7 @@ impl<'a> State<'a> {
self.word_space("=");
match term {
Term::Ty(ty) => self.print_type(ty),
Term::Const(c) => self.print_expr_anon_const(c),
Term::Const(c) => self.print_expr_anon_const(c, &[]),
}
}
ast::AssocConstraintKind::Bound { bounds } => self.print_type_bounds(":", &*bounds),
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17 changes: 14 additions & 3 deletions compiler/rustc_ast_pretty/src/pprust/state/expr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -88,10 +88,21 @@ impl<'a> State<'a> {
self.end();
}

pub(super) fn print_expr_anon_const(&mut self, expr: &ast::AnonConst) {
pub(super) fn print_expr_anon_const(
&mut self,
expr: &ast::AnonConst,
attrs: &[ast::Attribute],
) {
self.ibox(INDENT_UNIT);
self.word("const");
self.print_expr(&expr.value);
self.nbsp();
if let ast::ExprKind::Block(block, None) = &expr.value.kind {
self.cbox(0);
self.ibox(0);
self.print_block_with_attrs(block, attrs);
} else {
self.print_expr(&expr.value);
}
self.end();
}

Expand Down Expand Up @@ -275,7 +286,7 @@ impl<'a> State<'a> {
self.print_expr_vec(exprs);
}
ast::ExprKind::ConstBlock(ref anon_const) => {
self.print_expr_anon_const(anon_const);
self.print_expr_anon_const(anon_const, attrs);
}
ast::ExprKind::Repeat(ref element, ref count) => {
self.print_expr_repeat(element, count);
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4 changes: 2 additions & 2 deletions compiler/rustc_parse/src/parser/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1125,13 +1125,13 @@ impl<'a> Parser<'a> {
self.sess.gated_spans.gate(sym::inline_const, span);
}
self.eat_keyword(kw::Const);
let blk = self.parse_block()?;
let (attrs, blk) = self.parse_inner_attrs_and_block()?;
let anon_const = AnonConst {
id: DUMMY_NODE_ID,
value: self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new()),
};
let blk_span = anon_const.value.span;
Ok(self.mk_expr(span.to(blk_span), ExprKind::ConstBlock(anon_const), AttrVec::new()))
Ok(self.mk_expr(span.to(blk_span), ExprKind::ConstBlock(anon_const), AttrVec::from(attrs)))
}

/// Parses mutability (`mut` or nothing).
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9 changes: 9 additions & 0 deletions src/test/pretty/stmt_expr_attributes.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
// pp-exact

#![feature(box_syntax)]
#![feature(inline_const)]
#![feature(inline_const_pat)]
#![feature(rustc_attrs)]
#![feature(stmt_expr_attributes)]

Expand All @@ -16,6 +18,7 @@ fn _1() {

#[rustc_dummy]
unsafe {
#![rustc_dummy]
// code
}
}
Expand Down Expand Up @@ -206,6 +209,12 @@ fn _11() {
let _ = ();
()
};
let const {
#![rustc_dummy]
} =
#[rustc_dummy] const {
#![rustc_dummy]
};
let mut x = 0;
let _ = #[rustc_dummy] x = 15;
let _ = #[rustc_dummy] x += 15;
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