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Add some debug logs to macro matching

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These were useful while debugging, so I'll leave them here.
This commit is contained in:
Nilstrieb 2022-10-27 22:03:34 +02:00
parent 5f73eac51b
commit 1e21b3cfa3
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1 changed files with 8 additions and 0 deletions
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8
compiler/rustc_expand/src/mbe/macro_rules.rs
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@ -234,6 +234,7 @@ fn description() -> &'static str {
/// Expands the rules based macro defined by `lhses` and `rhses` for a given
/// input `arg`.
#[instrument(skip(cx, transparency, arg, lhses, rhses))]
fn expand_macro<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
@ -429,6 +430,7 @@ enum CanRetry {
/// Try expanding the macro. Returns the index of the sucessful arm and its named_matches if it was successful,
/// and nothing if it failed. On failure, it's the callers job to use `track` accordingly to record all errors
/// correctly.
#[instrument(level = "debug", skip(sess, arg, lhses, track), fields(tracking = %T::description()))]
fn try_match_macro<'matcher, T: Tracker<'matcher>>(
sess: &ParseSess,
name: Ident,
@ -460,6 +462,8 @@ fn try_match_macro<'matcher, T: Tracker<'matcher>>(
// Try each arm's matchers.
let mut tt_parser = TtParser::new(name);
for (i, lhs) in lhses.iter().enumerate() {
let _tracing_span = trace_span!("Matching arm", %i);
// Take a snapshot of the state of pre-expansion gating at this point.
// This is used so that if a matcher is not `Success(..)`ful,
// then the spans which became gated when parsing the unsuccessful matcher
@ -472,6 +476,7 @@ fn try_match_macro<'matcher, T: Tracker<'matcher>>(
match result {
Success(named_matches) => {
debug!("Parsed arm successfully");
// The matcher was `Success(..)`ful.
// Merge the gated spans from parsing the matcher with the pre-existing ones.
sess.gated_spans.merge(gated_spans_snapshot);
@ -479,13 +484,16 @@ fn try_match_macro<'matcher, T: Tracker<'matcher>>(
return Ok((i, named_matches));
}
Failure(_, _) => {
trace!("Failed to match arm, trying the next one");
// Try the next arm
}
Error(_, _) => {
debug!("Fatal error occurred during matching");
// We haven't emitted an error yet
return Err(CanRetry::Yes);
}
ErrorReported(guarantee) => {
debug!("Fatal error occurred and was reported during matching");
return Err(CanRetry::No(guarantee));
}
}