Adversarial review demonstrated that the previous fix closed one class and
left three, then reintroduced the bug this file's own history is about.
- A ``` fence in a PLAIN `//` comment earned the doctest exemption. rustdoc
runs no test there ("running 0 tests"), so two lines exempted anything after
them. The cheapest bypass yet, and `--list-doctests` in the same file already
had it right: one of the two was wrong and it was this one.
- A block comment opened after code on the same line was invisible, since only
a line STARTING with /* was seen. That is the most natural way to write one.
- Nested block comments closed at the first */ and the rest read as code.
- And the false positive: `in_block` had no reset path, so a /* inside a raw
string swallowed the rest of the file. Latent — no .rs file starts a line
with /* today, so the block fix had zero effect on this repo — but 8 files
hold raw strings and this repo's habit is Rust fixtures inside them. The
first such fixture breaks CI with a diagnosis pointing at a string.
A line-based scanner cannot decide any of these, so `scan()` now walks
characters, tracking nested block comments, strings, raw strings (with hashes)
and char literals. `#![...]` ends a run where `#[...]` stays transparent,
because a crate doc and an item doc separated by an inner attribute are two
blocks a reader does not meet as one. `#[doc = "..."]` counts: it is the one
attribute that is a comment.
The self-test carries all of it: 12 bypasses, 6 shapes that must stay legal.
Each new fix was proved discriminating by injecting it alone.
One of those injections caught a VACUOUS test of my own: with raw-string
handling disabled, a plain-string fallback reached the same verdict, so the
fixture proved nothing. It now contains r#"x"y, which a non-raw parse closes
early — so the fault is visible. That is the defect this repo is named for,
found in the test written to prevent it.
Closes improvise-mbmf, which PR #45 claimed to close and did not.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Edward Langley
a6451363ca