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Auto merge of #108471 - clubby789:unbox-the-syntax, r=Nilstrieb,est31

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Remove `box_syntax`

r? `@Nilstrieb`

This removes the feature `box_syntax`, which allows the use of `box <expr>` to create a Box, and finalises removing use of the feature from the compiler. `box_patterns` (allowing the use of `box <pat>` in a pattern) is unaffected.
It also removes `ast::ExprKind::Box` - the only way to create a 'box' expression now is with the rustc-internal `#[rustc_box]` attribute.
As a temporary measure to help users move away, `box <expr>` now parses the inner expression, and emits a `MachineApplicable` lint to replace it with `Box::new`

Closes #49733
This commit is contained in:
bors 2023-03-13 10:41:50 +00:00
commit f1b1ed7e18
110 changed files with 990 additions and 1065 deletions
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24
compiler/rustc_parse/src/parser/expr.rs
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@ -8,6 +8,7 @@ use super::{
use crate::errors;
use crate::maybe_recover_from_interpolated_ty_qpath;
use ast::{Path, PathSegment};
use core::mem;
use rustc_ast::ptr::P;
use rustc_ast::token::{self, Delimiter, Token, TokenKind};
@ -29,6 +30,7 @@ use rustc_session::errors::{report_lit_error, ExprParenthesesNeeded};
use rustc_session::lint::builtin::BREAK_WITH_LABEL_AND_LOOP;
use rustc_session::lint::BuiltinLintDiagnostics;
use rustc_span::source_map::{self, Span, Spanned};
use rustc_span::symbol::kw::PathRoot;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{BytePos, Pos};
use thin_vec::{thin_vec, ThinVec};
@ -636,11 +638,27 @@ impl<'a> Parser<'a> {
self.parse_expr_unary(lo, UnOp::Not)
}
/// Parse `box expr`.
/// Parse `box expr` - this syntax has been removed, but we still parse this
/// for now to provide an automated way to fix usages of it
fn parse_expr_box(&mut self, lo: Span) -> PResult<'a, (Span, ExprKind)> {
let (span, expr) = self.parse_expr_prefix_common(lo)?;
self.sess.gated_spans.gate(sym::box_syntax, span);
Ok((span, ExprKind::Box(expr)))
let code = self.sess.source_map().span_to_snippet(span.with_lo(lo.hi())).unwrap();
self.sess.emit_err(errors::BoxSyntaxRemoved { span, code: code.trim() });
// So typechecking works, parse `box <expr>` as `::std::boxed::Box::new(expr)`
let path = Path {
span,
segments: [
PathSegment::from_ident(Ident::with_dummy_span(PathRoot)),
PathSegment::from_ident(Ident::with_dummy_span(sym::std)),
PathSegment::from_ident(Ident::from_str("boxed")),
PathSegment::from_ident(Ident::from_str("Box")),
PathSegment::from_ident(Ident::with_dummy_span(sym::new)),
]
.into(),
tokens: None,
};
let path = self.mk_expr(span, ExprKind::Path(None, path));
Ok((span, self.mk_call(path, ThinVec::from([expr]))))
}
fn is_mistaken_not_ident_negation(&self) -> bool {