The report printed a COUNT of traced lines that kcov never listed as
instrumentable. A count cannot be acted on: deciding whether such a line is a
real statement or a function declaration needs the line number. It now lists
them, the way it already lists uncovered lines.
Reading them across every lib with a harness splits them cleanly:
benign dwm_config.sh:27 (`heal_config() {`), transcribe_deps.sh:9
(one-line function declaration), clean_audio_filters.sh:197,200
(`((running++))`) -- correctly not statements
real aw_autostart.sh 68,70,73,79-81,83-84,87-88,94 -- plain echo, local,
if, `sudo -u ... mkdir`, `cat >` heredoc. kcov lists nothing after
the `{ ... } >>"$file"` command group at lines 61-65.
So kcov's LINE SET is incomplete too, not just its hit counts. This does NOT
inflate anything: a line reaches that list only because the TRACE SAW IT RUN,
so folding all 11 into both halves moves aw_autostart from 80/82 = 97.56% to
91/93 = 97.85% -- up. An off-set line is by construction an executed line, so
it can only ever be a missing COVERED line, never a missing uncovered one.
What it does mean is that such a subject is measured over a subset of its
statements. The percentage is honest about the subset, not the whole file,
which is why the lines are now printed rather than tallied.
Separately: nc_php.sh reports "kcov instrumented no lines" on the PRE-FIX
instrument too -- checked at 078d3463 in a throwaway worktree -- so it is not
a regression from the two-pass change. The 84/85 = 98.82% in earlier notes
does not reproduce and is recorded as unverified.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The instrument, not the tests, was the bottleneck. Coverage is now
(PS4-traced lines | kcov hits) & (kcov line set - continuation lines).
The trace deliberately does NOT supply the denominator. A trace reports only
lines that RAN, so using it for both halves would make every subject 100.00%
and arm a repo-wide gate that checks nothing.
Three measured findings, each of which yields a silently wrong trace:
1. kcov's ptrace and bash's xtrace cannot share a process. Under
SHELLOPTS=xtrace every line kcov recorded as hits="1" comes back hits="0"
-- reproduced A/B on one subject. Hence two passes, two namespaces.
2. SHELLOPTS is readonly inside bash, so `export SHELLOPTS=xtrace` fails and
tracing never turns on; and `set -x` does not reach child processes.
3. Decisive: bash under `unshare --map-root-user` runs PRIVILEGED and
DISCARDS an inherited PS4, falling back to "+ " while still honouring
xtrace. The trace loses its file:line prefix and every subject reads 0%.
Fixed by delivering PS4 and `set -x` through a BASH_ENV file, which also
solves child-process propagation.
A fourth trap, in the report: kcov records filename="dwm_config.sh", a bare
basename. The source path comes from the trace's ${BASH_SOURCE} or a unique
repo search; an ambiguous basename yields no exclusion rather than a guess.
Measured through run_all.sh, nothing down:
dot_resolver_install.sh 39/39 = 100.00% (acceptance, unchanged)
rpi_nc_ca.sh 73/73 = 100.00% (was 72/73 = 98.63%)
dwm_config.sh 65/66 = 98.48% (was 35/73 = 47.95%)
rpi_nc_install.sh 85/88 = 96.59% (was 10/88 = 11.36%)
rpi_nc_ca reaching 100% is the load-bearing check: its missing line 141 was
cross-process contagion, and the trace pass has no kcov in it to contaminate.
dwm_config's remaining line 39 is a `done < <(...)`. Left in the denominator
on purpose -- removing lines inflates coverage, the fail-open direction, so a
second exclusion rule needs per-line justification, not a pattern from one lib.
Both new Python modules hold 100% branch coverage (29 tests).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
