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Fix ICE when handling malformed cfgd tail expressions #118582

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Fix ICE when handling malformed cfgd tail expressions #118582

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87 changes: 53 additions & 34 deletions compiler/rustc_parse/src/parser/diagnostics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -772,45 +772,64 @@ impl<'a> Parser<'a> {
&& let [segment] = &attr_kind.item.path.segments[..]
&& segment.ident.name == sym::cfg
&& let Some(args_span) = attr_kind.item.args.span()
&& let Ok(next_attr) = snapshot.parse_attribute(InnerAttrPolicy::Forbidden(None))
&& let ast::AttrKind::Normal(next_attr_kind) = next_attr.kind
&& let Some(next_attr_args_span) = next_attr_kind.item.args.span()
&& let [next_segment] = &next_attr_kind.item.path.segments[..]
&& segment.ident.name == sym::cfg
&& let Ok(next_expr) = snapshot.parse_expr()
{
// We have for sure
// #[cfg(..)]
// expr
// #[cfg(..)]
// other_expr
// So we suggest using `if cfg!(..) { expr } else if cfg!(..) { other_expr }`.
let margin = self.sess.source_map().span_to_margin(next_expr.span).unwrap_or(0);
let sugg = vec![
(attr.span.with_hi(segment.span().hi()), "if cfg!".to_string()),
(args_span.shrink_to_hi().with_hi(attr.span.hi()), " {".to_string()),
(expr.span.shrink_to_lo(), " ".to_string()),
(
next_attr.span.with_hi(next_segment.span().hi()),
"} else if cfg!".to_string(),
),
(
next_attr_args_span.shrink_to_hi().with_hi(next_attr.span.hi()),
" {".to_string(),
),
(next_expr.span.shrink_to_lo(), " ".to_string()),
(next_expr.span.shrink_to_hi(), format!("\n{}}}", " ".repeat(margin))),
];
err.multipart_suggestion(
"it seems like you are trying to provide different expressions depending on \
`cfg`, consider using `if cfg!(..)`",
sugg,
Applicability::MachineApplicable,
);
let next_attr = match snapshot.parse_attribute(InnerAttrPolicy::Forbidden(None)) {
Ok(next_attr) => next_attr,
Err(mut perr) => {
// Handle cases like #118575, where the attribute is malformed
err.cancel();
perr.emit();
return;
}
};
if let ast::AttrKind::Normal(next_attr_kind) = next_attr.kind
&& let Some(next_attr_args_span) = next_attr_kind.item.args.span()
&& let [next_segment] = &next_attr_kind.item.path.segments[..]
&& segment.ident.name == sym::cfg
{
let next_expr = match snapshot.parse_expr() {
Ok(next_expr) => next_expr,
Err(mut perr) => {
// Handle cases like #118575, where the expression is malformed
err.cancel();
perr.emit();
return;
}
};
// We have for sure
// #[cfg(..)]
// expr
// #[cfg(..)]
// other_expr
// So we suggest using `if cfg!(..) { expr } else if cfg!(..) { other_expr }`.
let margin = self.sess.source_map().span_to_margin(next_expr.span).unwrap_or(0);
let sugg = vec![
(attr.span.with_hi(segment.span().hi()), "if cfg!".to_string()),
(args_span.shrink_to_hi().with_hi(attr.span.hi()), " {".to_string()),
(expr.span.shrink_to_lo(), " ".to_string()),
(
next_attr.span.with_hi(next_segment.span().hi()),
"} else if cfg!".to_string(),
),
(
next_attr_args_span.shrink_to_hi().with_hi(next_attr.span.hi()),
" {".to_string(),
),
(next_expr.span.shrink_to_lo(), " ".to_string()),
(next_expr.span.shrink_to_hi(), format!("\n{}}}", " ".repeat(margin))),
];
err.multipart_suggestion(
"it seems like you are trying to provide different expressions depending on \
`cfg`, consider using `if cfg!(..)`",
sugg,
Applicability::MachineApplicable,
);
}
}
}
err.emit();
}

fn check_too_many_raw_str_terminators(&mut self, err: &mut Diagnostic) -> bool {
let sm = self.sess.source_map();
match (&self.prev_token.kind, &self.token.kind) {
Expand Down
17 changes: 17 additions & 0 deletions tests/ui/parser/attribute/multiple-tail-expr-behind-cfg.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,23 @@ fn bar() -> String {
String::new()
}

fn baz() -> String {
// Issue #118575: Don't ICE when encountering malformed attributes
#[cfg(feature = "validation")]
"foo".into()
#[]
//~^ ERROR expected identifier, found `]`
//~| ERROR expected identifier, found `]`
"bar".into()
}

fn qux() -> String {
// Issue #118575: Don't ICE when encountering malformed tail expressions
#[cfg(feature = "validation")]
"foo".into()
#[cfg(not(feature = "validation"))] //~ ERROR expected statement after outer attribute
} //~ ERROR expected expression, found `}`

fn main() {
println!("{}", foo());
}
28 changes: 27 additions & 1 deletion tests/ui/parser/attribute/multiple-tail-expr-behind-cfg.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -44,11 +44,37 @@ help: alternatively, consider surrounding the expression with a block
LL | { [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>() }
| + +

error: expected identifier, found `]`
--> $DIR/multiple-tail-expr-behind-cfg.rs:21:7
|
LL | #[]
| ^ expected identifier

error: expected identifier, found `]`
--> $DIR/multiple-tail-expr-behind-cfg.rs:21:7
|
LL | #[]
| ^ expected identifier
|
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: expected expression, found `}`
--> $DIR/multiple-tail-expr-behind-cfg.rs:32:1
|
LL | }
| ^ expected expression

error: expected statement after outer attribute
--> $DIR/multiple-tail-expr-behind-cfg.rs:31:5
|
LL | #[cfg(not(feature = "validation"))]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: cannot find attribute `attr` in this scope
--> $DIR/multiple-tail-expr-behind-cfg.rs:13:7
|
LL | #[attr]
| ^^^^

error: aborting due to 3 previous errors
error: aborting due to 7 previous errors