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Use Option to indicate failure in CachingSourceMapView.

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Currently the `cache_entry_index` uses -1 to indicate failure. But this
is Rust, not C! So this commit uses `Option`, making it impossible to
forget to check for failure, and avoiding many `as usize` casts.
This commit is contained in:
Nicholas Nethercote
2026-03-30 16:31:02 +11:00
parent a25435bcf7
commit 0eea36fea4
1 changed files with 25 additions and 24 deletions
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compiler/rustc_span/src/caching_source_map_view.rs
+25 -24
View File
@@ -86,8 +86,8 @@ pub fn byte_pos_to_line_and_col(
// Check if the position is in one of the cached lines
let cache_idx = self.cache_entry_index(pos);
if cache_idx != -1 {
let cache_entry = &mut self.line_cache[cache_idx as usize];
if let Some(cache_idx) = cache_idx {
let cache_entry = &mut self.line_cache[cache_idx];
cache_entry.touch(self.time_stamp);
let col = RelativeBytePos(pos.to_u32() - cache_entry.line.start.to_u32());
@@ -118,23 +118,23 @@ pub fn span_data_to_lines_and_cols(
self.time_stamp += 1;
// Check if lo and hi are in the cached lines.
let lo_cache_idx: isize = self.cache_entry_index(span_data.lo);
let lo_cache_idx = self.cache_entry_index(span_data.lo);
let hi_cache_idx = self.cache_entry_index(span_data.hi);
if lo_cache_idx != -1 && hi_cache_idx != -1 {
if let (Some(lo_cache_idx), Some(hi_cache_idx)) = (lo_cache_idx, hi_cache_idx) {
// Cache hit for span lo and hi. Check if they belong to the same file.
let lo_file_index = self.line_cache[lo_cache_idx as usize].file_index;
let hi_file_index = self.line_cache[hi_cache_idx as usize].file_index;
let lo_file_index = self.line_cache[lo_cache_idx].file_index;
let hi_file_index = self.line_cache[hi_cache_idx].file_index;
if lo_file_index != hi_file_index {
return None;
}
self.line_cache[lo_cache_idx as usize].touch(self.time_stamp);
self.line_cache[hi_cache_idx as usize].touch(self.time_stamp);
self.line_cache[lo_cache_idx].touch(self.time_stamp);
self.line_cache[hi_cache_idx].touch(self.time_stamp);
let lo = &self.line_cache[lo_cache_idx as usize];
let hi = &self.line_cache[hi_cache_idx as usize];
let lo = &self.line_cache[lo_cache_idx];
let hi = &self.line_cache[hi_cache_idx];
return Some((
&lo.file,
lo.line_number,
@@ -145,9 +145,10 @@ pub fn span_data_to_lines_and_cols(
}
// No cache hit or cache hit for only one of span lo and hi.
let oldest = if lo_cache_idx != -1 || hi_cache_idx != -1 {
let avoid_idx = if lo_cache_idx != -1 { lo_cache_idx } else { hi_cache_idx };
self.oldest_cache_entry_index_avoid(avoid_idx as usize)
let oldest = if let Some(lo_cache_idx) = lo_cache_idx {
self.oldest_cache_entry_index_avoid(lo_cache_idx)
} else if let Some(hi_cache_idx) = hi_cache_idx {
self.oldest_cache_entry_index_avoid(hi_cache_idx)
} else {
self.oldest_cache_entry_index()
};
@@ -173,7 +174,7 @@ pub fn span_data_to_lines_and_cols(
// Update the cache entries.
let (lo_idx, hi_idx) = match (lo_cache_idx, hi_cache_idx) {
// Oldest cache entry is for span_data.lo line.
(-1, -1) => {
(None, None) => {
let lo = &mut self.line_cache[oldest];
lo.update(new_file_and_idx, span_data.lo, self.time_stamp);
@@ -188,22 +189,22 @@ pub fn span_data_to_lines_and_cols(
}
}
// Oldest cache entry is for span_data.lo line.
(-1, _) => {
(None, Some(hi_cache_idx)) => {
let lo = &mut self.line_cache[oldest];
lo.update(new_file_and_idx, span_data.lo, self.time_stamp);
let hi = &mut self.line_cache[hi_cache_idx as usize];
let hi = &mut self.line_cache[hi_cache_idx];
hi.touch(self.time_stamp);
(oldest, hi_cache_idx as usize)
(oldest, hi_cache_idx)
}
// Oldest cache entry is for span_data.hi line.
(_, -1) => {
(Some(lo_cache_idx), None) => {
let hi = &mut self.line_cache[oldest];
hi.update(new_file_and_idx, span_data.hi, self.time_stamp);
let lo = &mut self.line_cache[lo_cache_idx as usize];
let lo = &mut self.line_cache[lo_cache_idx];
lo.touch(self.time_stamp);
(lo_cache_idx as usize, oldest)
(lo_cache_idx, oldest)
}
_ => {
(Some(_), Some(_)) => {
panic!(
"the case of neither value being equal to -1 was handled above and the function returns."
);
@@ -232,14 +233,14 @@ pub fn span_data_to_lines_and_cols(
))
}
fn cache_entry_index(&self, pos: BytePos) -> isize {
fn cache_entry_index(&self, pos: BytePos) -> Option<usize> {
for (idx, cache_entry) in self.line_cache.iter().enumerate() {
if cache_entry.line.contains(&pos) {
return idx as isize;
return Some(idx)
}
}
-1
None
}
fn oldest_cache_entry_index(&self) -> usize {