diff options
| -rw-r--r-- | src/librustc_mir_build/lints.rs | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/librustc_mir_build/lints.rs b/src/librustc_mir_build/lints.rs index 3e0028a66d4..74ab6025415 100644 --- a/src/librustc_mir_build/lints.rs +++ b/src/librustc_mir_build/lints.rs @@ -28,7 +28,12 @@ fn check_fn_for_unconditional_recursion<'tcx>( def_id: DefId, ) { let self_calls = find_blocks_calling_self(tcx, &body, def_id); + + // Stores a list of `Span`s for every basic block. Those are the spans of `Call` terminators + // where we know that one of them will definitely be reached. let mut results = IndexVec::from_elem_n(vec![], body.basic_blocks().len()); + + // We start the analysis at the self calls and work backwards. let mut queue: VecDeque<_> = self_calls.iter().collect(); while let Some(bb) = queue.pop_front() { @@ -39,6 +44,8 @@ fn check_fn_for_unconditional_recursion<'tcx>( let locations = if self_calls.contains(bb) { // `bb` *is* a self-call. + // We don't look at successors here because they are irrelevant here and we don't want + // to lint them (eg. `f(); f()` should only lint the first call). vec![bb] } else { // If *all* successors of `bb` lead to a self-call, emit notes at all of their @@ -69,12 +76,16 @@ fn check_fn_for_unconditional_recursion<'tcx>( } }; + // If all our successors are known to lead to self-calls, then we do too. let all_are_self_calls = relevant_successors.clone().all(|&succ| !results[succ].is_empty()); if all_are_self_calls { + // We'll definitely lead to a self-call. Merge all call locations of the successors + // for linting them later. relevant_successors.flat_map(|&succ| results[succ].iter().copied()).collect() } else { + // At least 1 successor does not always lead to a self-call, so we also don't. vec![] } }; |