Remove special handling of box expressions from parser

Author: clubby789

compiler/rustc_ast/src/token.rs

@@ -191,7 +191,6 @@ pub fn ident_can_begin_expr(name: Symbol, span: Span, is_raw: bool) -> bool {
         || [
             kw::Async,
             kw::Do,
-            kw::Box,
             kw::Break,
             kw::Const,
             kw::Continue,

compiler/rustc_parse/src/parser/expr.rs

@@ -33,7 +33,6 @@ 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, Spanned};
-use rustc_span::symbol::kw::PathRoot;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, Pos, Span};
 use thin_vec::{thin_vec, ThinVec};
@@ -612,9 +611,6 @@ impl<'a> Parser<'a> {
                 let operand_expr = this.parse_expr_dot_or_call(Default::default())?;
                 this.recover_from_prefix_increment(operand_expr, pre_span, starts_stmt)
             }
-            token::Ident(..) if this.token.is_keyword(kw::Box) => {
-                make_it!(this, attrs, |this, _| this.parse_expr_box(lo))
-            }
             token::Ident(..) if this.may_recover() && this.is_mistaken_not_ident_negation() => {
                 make_it!(this, attrs, |this, _| this.recover_not_expr(lo))
             }
@@ -641,29 +637,6 @@ impl<'a> Parser<'a> {
         self.parse_expr_unary(lo, UnOp::Not)
     }
 
-    /// 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)?;
-        let code = self.sess.source_map().span_to_snippet(span.with_lo(lo.hi())).unwrap();
-        self.dcx().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 {
         let token_cannot_continue_expr = |t: &Token| match t.uninterpolate().kind {
             // These tokens can start an expression after `!`, but

tests/ui/parser/removed-syntax-box.fixed

@@ -1,14 +1,3 @@
-// run-rustfix
-
 fn main() {
-    #[allow(dead_code)]
-    struct T {
-        a: u8,
-        b: u8,
-    }
-    let _ = box (); //~ ERROR `box_syntax` has been removed
-    let _ = box 1; //~ ERROR `box_syntax` has been removed
-    let _ = box T { a: 12, b: 18 }; //~ ERROR `box_syntax` has been removed
-    let _ = box [5; 30]; //~ ERROR `box_syntax` has been removed
-    let _: Box<()> = box (); //~ ERROR `box_syntax` has been removed
+    let _ = box (); //~ ERROR expected expression, found reserved keyword `box`
 }

tests/ui/parser/removed-syntax-box.rs

@@ -1,57 +1,8 @@
-error: `box_syntax` has been removed
-  --> $DIR/removed-syntax-box.rs:9:13
+error: expected expression, found reserved keyword `box`
+  --> $DIR/removed-syntax-box.rs:2:13
    |
 LL |     let _ = box ();
-   |             ^^^^^^
-   |
-help: use `Box::new()` instead
-   |
-LL |     let _ = Box::new(());
-   |             ~~~~~~~~~~~~
-
-error: `box_syntax` has been removed
-  --> $DIR/removed-syntax-box.rs:10:13
-   |
-LL |     let _ = box 1;
-   |             ^^^^^
-   |
-help: use `Box::new()` instead
-   |
-LL |     let _ = Box::new(1);
-   |             ~~~~~~~~~~~
-
-error: `box_syntax` has been removed
-  --> $DIR/removed-syntax-box.rs:11:13
-   |
-LL |     let _ = box T { a: 12, b: 18 };
-   |             ^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: use `Box::new()` instead
-   |
-LL |     let _ = Box::new(T { a: 12, b: 18 });
-   |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-error: `box_syntax` has been removed
-  --> $DIR/removed-syntax-box.rs:12:13
-   |
-LL |     let _ = box [5; 30];
-   |             ^^^^^^^^^^^
-   |
-help: use `Box::new()` instead
-   |
-LL |     let _ = Box::new([5; 30]);
-   |             ~~~~~~~~~~~~~~~~~
-
-error: `box_syntax` has been removed
-  --> $DIR/removed-syntax-box.rs:13:22
-   |
-LL |     let _: Box<()> = box ();
-   |                      ^^^^^^
-   |
-help: use `Box::new()` instead
-   |
-LL |     let _: Box<()> = Box::new(());
-   |                      ~~~~~~~~~~~~
+   |             ^^^ expected expression
 
-error: aborting due to 5 previous errors
+error: aborting due to 1 previous error
 

tests/ui/parser/removed-syntax-box.stderr

@@ -1,3 +1,3 @@
 fn main() {
-    let a_box = box mut 42; //~ ERROR expected expression, found keyword `mut`
+    let a_box = box mut 42; //~ ERROR expected expression, found reserved keyword `box`
 }

tests/ui/parser/removed-syntax-uniq-mut-expr.rs

@@ -1,8 +1,8 @@
-error: expected expression, found keyword `mut`
-  --> $DIR/removed-syntax-uniq-mut-expr.rs:2:21
+error: expected expression, found reserved keyword `box`
+  --> $DIR/removed-syntax-uniq-mut-expr.rs:2:17
    |
 LL |     let a_box = box mut 42;
-   |                     ^^^ expected expression
+   |                 ^^^ expected expression
 
 error: aborting due to 1 previous error