bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Rollup merge of #103521 - chenyukang:yukang/fix-103451-avoid-hang, r=jackh726,wesleywiser

Browse source 
Avoid possible infinite  loop when next_point reaching the end of file

Fixes #103451
If we return a span with `lo` = `hi`, `span_to_snippet` will always get `Ok("")`, which may introduce infinite loop if we don't care.

This PR make `find_width_of_character_at_span` return `width` with 1, so that `span_to_snippet` will get an `Err`.
This commit is contained in:
Manish Goregaokar 2022-11-08 21:03:53 -05:00 • committed by GitHub
commit 75c239402c
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
4 changed files with 46 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

8
compiler/rustc_span/src/source_map.rs
View file

@ -855,7 +855,8 @@ impl SourceMap {
/// Returns a new span representing the next character after the end-point of this span.
/// Special cases:
/// - if span is a dummy one, returns the same span
/// - if next_point reached the end of source, return span with lo = hi
/// - if next_point reached the end of source, return a span exceeding the end of source,
/// which means sm.span_to_snippet(next_point) will get `Err`
/// - respect multi-byte characters
pub fn next_point(&self, sp: Span) -> Span {
if sp.is_dummy() {
@ -864,9 +865,6 @@ impl SourceMap {
let start_of_next_point = sp.hi().0;
let width = self.find_width_of_character_at_span(sp, true);
if width == 0 {
return Span::new(sp.hi(), sp.hi(), sp.ctxt(), None);
}
// If the width is 1, then the next span should only contain the next char besides current ending.
// However, in the case of a multibyte character, where the width != 1, the next span should
// span multiple bytes to include the whole character.
@ -938,7 +936,7 @@ impl SourceMap {
// Ensure indexes are also not malformed.
if start_index > end_index || end_index > source_len - 1 {
debug!("find_width_of_character_at_span: source indexes are malformed");
return 0;
return 1;
}
let src = local_begin.sf.external_src.borrow();

11
compiler/rustc_span/src/source_map/tests.rs
View file

@ -511,16 +511,17 @@ fn test_next_point() {
assert_eq!(span.lo().0, 4);
assert_eq!(span.hi().0, 5);
// A non-empty span at the last byte should advance to create an empty
// span pointing at the end of the file.
// Reaching to the end of file, return a span that will get error with `span_to_snippet`
let span = Span::with_root_ctxt(BytePos(4), BytePos(5));
let span = sm.next_point(span);
assert_eq!(span.lo().0, 5);
assert_eq!(span.hi().0, 5);
assert_eq!(span.hi().0, 6);
assert!(sm.span_to_snippet(span).is_err());
// Empty span pointing just past the last byte.
// Reaching to the end of file, return a span that will get error with `span_to_snippet`
let span = Span::with_root_ctxt(BytePos(5), BytePos(5));
let span = sm.next_point(span);
assert_eq!(span.lo().0, 5);
assert_eq!(span.hi().0, 5);
assert_eq!(span.hi().0, 6);
assert!(sm.span_to_snippet(span).is_err());
}