Potential errors

Potential errors of the tool, derived from the use cases with the HazOp guide words invalid, changed, more and less applied to inputs, outputs and actions. The dangerous direction for a coverage tool is always more coverage than real: an error in that direction hides a verification gap. Errors towards less coverage cost effort but no safety.

Tool impact is high when the error can make a violated structural-coverage requirement go undetected. Detection before qualification describes what a user could notice without the mitigations; the last column lists the tool requirements and constraints of use that mitigate the error.

Id	Error	Impact	Detection	Mitigation
ERR-01	An in-scope file is silently missing from the report (the scope aspect misses a dependency, a select branch, or visibility hides a target).	high	weak	Transitive in-workspace sou... (tool_req__coverage_scope_transitive), Baseline objects accompany ... (tool_req__coverage_scope_baseline_objects), Untested in-scope files app... (tool_req__coverage_report_baseline_zero), CSTR-02, CSTR-08
ERR-02	A line or branch is reported covered although it was never executed (stale profile data, wrong object, wrong test merged, clashing instrumentation of shared objects).	high	none	Per-test profiles are merge... (tool_req__coverage_merge_profraw), One merged profile for all ... (tool_req__coverage_report_merged_profile), Ground-truth validation (tool_req__coverage_validation_ground_truth), CSTR-05
ERR-03	The gate passes although the threshold is not met (rounding, parsing, unset or malformed threshold, tool failure mistaken for a pass).	high	none	Threshold from the environment (tool_req__coverage_gate_threshold), Unrounded comparison (tool_req__coverage_gate_unrounded), Exit codes (tool_req__coverage_gate_exit_codes), Broken input yields no verdict (tool_req__coverage_gate_no_verdict), CSTR-10
ERR-04	A justification is applied to the wrong lines, to a file with the same name, or a stale marker is counted as covered.	high	weak	In-code markers (tool_req__coverage_just_markers), Unknown marker ids do not j... (tool_req__coverage_just_unknown_id), Stale justifications are re... (tool_req__coverage_eff_stale), Justifications match files ... (tool_req__coverage_eff_path_match), CSTR-07
ERR-05	The effective metric overstates coverage (justified and covered lines double counted, rounding up).	medium	weak	Effective coverage metric (tool_req__coverage_eff_metric), Branch-only justifications (tool_req__coverage_eff_branch_only)
ERR-06	Path normalisation maps two source files onto one record.	medium	weak	Report paths are workspace-... (tool_req__coverage_report_relative_paths), Justifications match files ... (tool_req__coverage_eff_path_match)
ERR-07	A Rust rlib is skipped, so its crate appears complete by absence.	high	none	Baseline archives are reduc... (tool_req__coverage_report_rlib_expansion), Ground-truth validation (tool_req__coverage_validation_ground_truth), CSTR-08
ERR-08	The wrong toolchain wins resolution; gcov data is silently mixed in or dropped.	high	weak	Broken input yields no verdict (tool_req__coverage_gate_no_verdict), CSTR-01, CSTR-03, CSTR-04
ERR-09	The report is regenerated from stale data or unpinned tool versions.	low	good	Artifacts tree (tool_req__coverage_artifacts), CSTR-06, CSTR-09
ERR-10	Coverage is reported too low (false gaps).	none	good	Informational; costs review effort only.
ERR-11	gcov backend: a test’s counters are lost or attributed to the wrong file (transport from the target fails silently, per-test records merged with the wrong semantics, the baseline overwrites test data).	high	weak	gcov backend merges per-tes... (tool_req__coverage_gcov_merge), gcov backend baseline from ... (tool_req__coverage_gcov_baseline), Ground-truth validation (tool_req__coverage_validation_ground_truth), CSTR-11
ERR-12	gcov backend: an in-scope translation unit has no counters and no notes file is found, so it disappears instead of showing 0 %.	high	weak	gcno notes files accompany ... (tool_req__coverage_scope_gcno), gcov backend baseline from ... (tool_req__coverage_gcov_baseline), In-scope files without any ... (tool_req__coverage_report_unmapped), CSTR-08
ERR-13	Both backends: Bazel’s guessed --instrumentation_filter leaves a library outside the instrumented set (its tests live in a test subpackage). The library is compiled without counters, or on the gcov backend its counters are dropped by Bazel’s collector, and the report shows 0 % or no-data instead of the measured coverage.	low (coverage is under-reported, the safe direction; costs review effort and hides the real state on QNX)	good	Instrumentation filter hint (tool_req__coverage_instrumentation_hint), Ground-truth validation (tool_req__coverage_validation_ground_truth), user manual step 4 (the filter line)

Classification

Tool impact: yes. An error in the more coverage than real direction lets a violation of the structural-coverage verification requirement go undetected. Tool error detection before qualification: no for ERR-02, ERR-03 and ERR-07; weak for ERR-11 and ERR-12 (a lost per-test record on QNX is only noticed by comparing against the Linux report); ERR-13 under-reports and is detected by the reporters’ warning and the integration test. The expected tool confidence level is therefore TCL LOW, and the qualification method of the S-CORE process, validation of the software tool, applies. The evaluation itself is recorded in the Tool Verification Report.