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coverage: Be more strict about what counts as a "visible macro" #118595

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Merged
merged 2 commits into from
Dec 6, 2023
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coverage: Be more strict about what counts as a "visible macro" #118595

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ff3af59
coverage: Clean up `maybe_push_macro_name_span`
Zalathar Dec 4, 2023
242bff3
coverage: Be more strict about what counts as a "visible macro"
Zalathar Dec 4, 2023
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38 changes: 20 additions & 18 deletions compiler/rustc_mir_transform/src/coverage/spans.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -129,16 +129,14 @@ impl CoverageSpan {
/// If the span is part of a macro, and the macro is visible (expands directly to the given
/// body_span), returns the macro name symbol.
pub fn visible_macro(&self, body_span: Span) -> Option<Symbol> {
if let Some(current_macro) = self.current_macro()
&& self
.expn_span
.parent_callsite()
.unwrap_or_else(|| bug!("macro must have a parent"))
.eq_ctxt(body_span)
{
return Some(current_macro);
}
None
let current_macro = self.current_macro()?;
let parent_callsite = self.expn_span.parent_callsite()?;

// In addition to matching the context of the body span, the parent callsite
// must also be the source callsite, i.e. the parent must have no parent.
let is_visible_macro =
parent_callsite.parent_callsite().is_none() && parent_callsite.eq_ctxt(body_span);
is_visible_macro.then_some(current_macro)
}

pub fn is_macro_expansion(&self) -> bool {
Expand Down Expand Up @@ -379,18 +377,22 @@ impl<'a> CoverageSpansGenerator<'a> {
return;
}

let merged_prefix_len = self.curr_original_span.lo() - curr.span.lo();
let after_macro_bang = merged_prefix_len + BytePos(visible_macro.as_str().len() as u32 + 1);
if self.curr().span.lo() + after_macro_bang > self.curr().span.hi() {
// The split point is relative to `curr_original_span`,
// because `curr.span` may have been merged with preceding spans.
let split_point_after_macro_bang = self.curr_original_span.lo()
+ BytePos(visible_macro.as_str().len() as u32)
+ BytePos(1); // add 1 for the `!`
debug_assert!(split_point_after_macro_bang <= curr.span.hi());
if split_point_after_macro_bang > curr.span.hi() {
// Something is wrong with the macro name span;
// return now to avoid emitting malformed mappings.
// FIXME(#117788): Track down why this happens.
// return now to avoid emitting malformed mappings (e.g. #117788).
return;
}

let mut macro_name_cov = curr.clone();
self.curr_mut().span = curr.span.with_lo(curr.span.lo() + after_macro_bang);
macro_name_cov.span =
macro_name_cov.span.with_hi(macro_name_cov.span.lo() + after_macro_bang);
macro_name_cov.span = macro_name_cov.span.with_hi(split_point_after_macro_bang);
self.curr_mut().span = curr.span.with_lo(split_point_after_macro_bang);

debug!(
" and curr starts a new macro expansion, so add a new span just for \
the macro `{visible_macro}!`, new span={macro_name_cov:?}",
Expand Down