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Rollup merge of #119062 - compiler-errors:asm-in-let-else, r=davidtwc…
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…o,est31

Deny braced macro invocations in let-else

Fixes #119057

Pending T-lang decision

cc `@dtolnay`
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matthiaskrgr authored Jan 19, 2024
2 parents 2d828cd + ec263df commit 2e4c6fc
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Showing 7 changed files with 98 additions and 21 deletions.
10 changes: 7 additions & 3 deletions compiler/rustc_ast/src/util/classify.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@

// Predicates on exprs and stmts that the pretty-printer and parser use

use crate::ast;
use crate::{ast, token::Delimiter};

/// Does this expression require a semicolon to be treated
/// as a statement? The negation of this: 'can this expression
Expand Down Expand Up @@ -59,8 +59,12 @@ pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> {
| While(..)
| ConstBlock(_) => break Some(expr),

// FIXME: These can end in `}`, but changing these would break stable code.
InlineAsm(_) | OffsetOf(_, _) | MacCall(_) | IncludedBytes(_) | FormatArgs(_) => {
MacCall(mac) => {
break (mac.args.delim == Delimiter::Brace).then_some(expr);
}

InlineAsm(_) | OffsetOf(_, _) | IncludedBytes(_) | FormatArgs(_) => {
// These should have been denied pre-expansion.
break None;
}

Expand Down
2 changes: 2 additions & 0 deletions compiler/rustc_parse/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -724,6 +724,8 @@ parse_sugg_turbofish_syntax = use `::<...>` instead of `<...>` to specify lifeti
parse_sugg_wrap_expression_in_parentheses = wrap the expression in parentheses
parse_sugg_wrap_macro_in_parentheses = use parentheses instead of braces for this macro
parse_sugg_wrap_pattern_in_parens = wrap the pattern in parentheses
parse_switch_mut_let_order =
Expand Down
37 changes: 25 additions & 12 deletions compiler/rustc_parse/src/errors.rs
Original file line number Diff line number Diff line change
Expand Up @@ -722,19 +722,32 @@ pub(crate) struct LabeledLoopInBreak {
#[primary_span]
pub span: Span,
#[subdiagnostic]
pub sub: WrapExpressionInParentheses,
pub sub: WrapInParentheses,
}

#[derive(Subdiagnostic)]
#[multipart_suggestion(
parse_sugg_wrap_expression_in_parentheses,
applicability = "machine-applicable"
)]
pub(crate) struct WrapExpressionInParentheses {
#[suggestion_part(code = "(")]
pub left: Span,
#[suggestion_part(code = ")")]
pub right: Span,

pub(crate) enum WrapInParentheses {
#[multipart_suggestion(
parse_sugg_wrap_expression_in_parentheses,
applicability = "machine-applicable"
)]
Expression {
#[suggestion_part(code = "(")]
left: Span,
#[suggestion_part(code = ")")]
right: Span,
},
#[multipart_suggestion(
parse_sugg_wrap_macro_in_parentheses,
applicability = "machine-applicable"
)]
MacroArgs {
#[suggestion_part(code = "(")]
left: Span,
#[suggestion_part(code = ")")]
right: Span,
},
}

#[derive(Diagnostic)]
Expand Down Expand Up @@ -936,7 +949,7 @@ pub(crate) struct InvalidExpressionInLetElse {
pub span: Span,
pub operator: &'static str,
#[subdiagnostic]
pub sugg: WrapExpressionInParentheses,
pub sugg: WrapInParentheses,
}

#[derive(Diagnostic)]
Expand All @@ -945,7 +958,7 @@ pub(crate) struct InvalidCurlyInLetElse {
#[primary_span]
pub span: Span,
#[subdiagnostic]
pub sugg: WrapExpressionInParentheses,
pub sugg: WrapInParentheses,
}

#[derive(Diagnostic)]
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_parse/src/parser/expr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1844,7 +1844,7 @@ impl<'a> Parser<'a> {
let lexpr = self.parse_expr_labeled(label, true)?;
self.dcx().emit_err(errors::LabeledLoopInBreak {
span: lexpr.span,
sub: errors::WrapExpressionInParentheses {
sub: errors::WrapInParentheses::Expression {
left: lexpr.span.shrink_to_lo(),
right: lexpr.span.shrink_to_hi(),
},
Expand Down
15 changes: 11 additions & 4 deletions compiler/rustc_parse/src/parser/stmt.rs
Original file line number Diff line number Diff line change
Expand Up @@ -389,7 +389,7 @@ impl<'a> Parser<'a> {
self.dcx().emit_err(errors::InvalidExpressionInLetElse {
span: init.span,
operator: op.node.as_str(),
sugg: errors::WrapExpressionInParentheses {
sugg: errors::WrapInParentheses::Expression {
left: init.span.shrink_to_lo(),
right: init.span.shrink_to_hi(),
},
Expand All @@ -400,12 +400,19 @@ impl<'a> Parser<'a> {

fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) {
if let Some(trailing) = classify::expr_trailing_brace(init) {
self.dcx().emit_err(errors::InvalidCurlyInLetElse {
span: trailing.span.with_lo(trailing.span.hi() - BytePos(1)),
sugg: errors::WrapExpressionInParentheses {
let sugg = match &trailing.kind {
ExprKind::MacCall(mac) => errors::WrapInParentheses::MacroArgs {
left: mac.args.dspan.open,
right: mac.args.dspan.close,
},
_ => errors::WrapInParentheses::Expression {
left: trailing.span.shrink_to_lo(),
right: trailing.span.shrink_to_hi(),
},
};
self.dcx().emit_err(errors::InvalidCurlyInLetElse {
span: trailing.span.with_lo(trailing.span.hi() - BytePos(1)),
sugg,
});
}
}
Expand Down
25 changes: 25 additions & 0 deletions tests/ui/parser/bad-let-else-statement.rs
Original file line number Diff line number Diff line change
Expand Up @@ -161,4 +161,29 @@ fn q() {
};
}

fn r() {
let ok = format_args!("") else { return; };

let bad = format_args! {""} else { return; };
//~^ ERROR right curly brace `}` before `else` in a `let...else` statement not allowed
}

fn s() {
macro_rules! a {
() => { {} }
}

macro_rules! b {
(1) => {
let x = a!() else { return; };
};
(2) => {
let x = a! {} else { return; };
//~^ ERROR right curly brace `}` before `else` in a `let...else` statement not allowed
};
}

b!(1); b!(2);
}

fn main() {}
28 changes: 27 additions & 1 deletion tests/ui/parser/bad-let-else-statement.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -228,5 +228,31 @@ LL | x
LL ~ }) else {
|

error: aborting due to 17 previous errors
error: right curly brace `}` before `else` in a `let...else` statement not allowed
--> $DIR/bad-let-else-statement.rs:167:31
|
LL | let bad = format_args! {""} else { return; };
| ^
|
help: use parentheses instead of braces for this macro
|
LL | let bad = format_args! ("") else { return; };
| ~ ~

error: right curly brace `}` before `else` in a `let...else` statement not allowed
--> $DIR/bad-let-else-statement.rs:181:25
|
LL | let x = a! {} else { return; };
| ^
...
LL | b!(1); b!(2);
| ----- in this macro invocation
|
= note: this error originates in the macro `b` (in Nightly builds, run with -Z macro-backtrace for more info)
help: use parentheses instead of braces for this macro
|
LL | let x = a! () else { return; };
| ~~

error: aborting due to 19 previous errors

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