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2026-07-30 13:22:50 -04:00
# TODO
Working notes for `libakerror`. Outstanding items only.
## 1. The test suite has no sanitizer run
Mutation testing caught an out-of-bounds probe in the status-name hash table
that the suite could not: the failure mode was a write into adjacent BSS, which
does not crash, so every test still passed. Sharpening one test closed that
instance, but ASan would have caught the whole class directly and independently
of how sharp the assertions are.
Add a `-fsanitize=address,undefined` build to `.gitea/workflows/ci.yaml`, or a
CMake option alongside `AKERR_COVERAGE`. This is the highest-value item here: it
covers the whole library, not just the registry, and the library's fixed pools
and manual buffer arithmetic are exactly what it is good at.
## 2. `HANDLE`-level status aliasing is still undetectable
Two components can compile the same integer into a `case` label without ever
reserving a range or registering a name, and nothing sees it. Ownership
enforcement covers *naming*, which is the part the library mediates; the `case`
label never reaches it.
Closing this needs the `if`/`else if` handler ladder — rewriting
`PROCESS`/`HANDLE`/`HANDLE_GROUP`/`HANDLE_DEFAULT`/`FINISH` so status matching
is not restricted to integer constant expressions. That would also allow
matching on ranges or predicates, and would let a handler resolve a code through
its owner. It touches the most load-bearing code in the library and every
consumer's error handling at once, so it wants its own change.
Note it would *not* by itself fix the "don't use `CATCH` or `FAIL_*_BREAK`
inside a loop" hazard: that comes from exiting via `break`, not from `switch`.
## 3. No registry introspection
There is no way to ask who owns a status, or to enumerate reservations. The
Raise errors from the status registry instead of returning codes akerr_reserve_status_range() and akerr_register_status_name() returned private int enumerations, which was the one place in the library where a failure was not an akerr_ErrorContext *. They now return one like everything else: NULL on success, and on refusal an error whose status is a real code in the library's reserved band, so it can be CATCH-ed, HANDLE-d, PASS-ed, or left to propagate into a stack trace. Both are marked AKERR_NOIGNORE, so discarding the result warns at compile time. AKERR_STATUS_RANGE_OK and AKERR_STATUS_NAME_OK are gone; the remaining seven codes move into the AKERR_* offset span and get registered names. AKERR_LAST_LIBRARY_STATUS replaces AKERR_BADEXC as the top of that span in the reserved-band static assert and the exhaustiveness sweep. The refusal detail that used to go straight to akerr_log_method now travels in the error message, so a caller that handles the error decides whether it is reported. The two-argument akerr_name_for_status() set path is the exception: it returns a name and cannot raise, so it logs and releases. akerr_init() likewise has no caller to raise into, so failing to reserve its own band or name its own codes is logged and fatal -- that can only happen on a misconfigured build, and continuing would degrade every later stack trace to "Unknown Error". Move the 1.0.0 upgrade notice out of README.md into UPGRADING.md and rewrite its return-code tables in terms of the statuses now raised. Tests: ctest 29/29, coverage 97.5% line / 64.5% branch, mutation 77.5% (was 77.6%; the new survivors are the fatal init path, which needs a library built with an undersized name table -- TODO item 7). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 20:58:47 -04:00
"coordinate ranges at the dependency-stack level" advice in UPGRADING.md
therefore has no tooling behind it.
A read-only accessor plus a dump through `akerr_log_method` would let a startup
self-check or a CI job print the whole map for a linked stack. Cheap, additive,
and the natural next step for multi-component adoption.
## 4. No way to release a reservation
A plugin host that `dlopen`s many distinct plugins over a process lifetime
accumulates ranges until the table fills. Reloading the *same* plugin is fine —
an identical repeat by the same owner is idempotent.
## 5. The registry is not thread safe
Global mutable state, no locking, and `akerr_status_name_count++` is not atomic.
Currently documented as an initialization-time-only API rather than enforced. If
components start initializing on separate threads this needs either a lock or a
documented once-per-process init barrier.
## 6. Deprecate the two-argument name-registration path
`akerr_name_for_status(status, name)` cannot identify its caller, so it can only
check that *some* reservation covers the status, not that the caller owns it. It
exists for migration. Once consumers have moved to
`akerr_register_status_name()`, make the set path a no-op or remove it and leave
`akerr_name_for_status()` as pure lookup.
Enforce status-code ownership and harden the name registry Reservations were advisory bookkeeping: any component could name any status, so the registry only detected declared-range overlap between components that both opted in. Naming a status now requires a reservation. akerr_register_status_name() checks that the range belongs to the caller, and the legacy two-argument akerr_name_for_status() set path, which cannot identify its caller, requires that some reservation covers the status. Every refusal is logged and names the real owner, because a name that fails to register degrades that code to "Unknown Error" in every later stack trace. Fix a reservation made before the first PREPARE_ERROR being silently discarded. akerr_init() clears the tables, so whichever component first triggered it wiped an earlier reservation and the next component to claim the same range was told it was free, producing exactly the undetected aliasing the registry exists to prevent. Every registry entry point now calls akerr_init(), which sets its guard before doing any work so those calls do not recurse. Replace the linear-scan name array with an open-addressed hash table, taking lookup from O(n) to O(1) and raising usable capacity from 512 entries (366 free to consumers after errno registration) to 3072 (~2900 free). Both table sizes are build-time overridable and applied PRIVATE: they live entirely in src/error.c, so raising them cannot desynchronize a library from its consumers the way AKERR_MAX_ERR_VALUE could. Exhausting either table is now logged and returned to the caller rather than silently dropping the entry. No dynamic allocation is introduced; both tables remain file-scope arrays, and the library's undefined-symbol set gains only strcmp and strlen. Register names for AKERR_EOF, AKERR_ITERATOR_BREAK and AKERR_NOT_IMPLEMENTED, which had none and rendered as "Unknown Error" in every stack trace carrying them. err_error_names.c now sweeps the whole AKERR_* offset span so a code added without a name fails there instead of in production traces. Add static assertions that the slot count is a power of two and that AKERR_BADEXC stays inside the library's own 0-255 band, the latter guarding against a host errno space large enough to push library codes into the range consumers are told to allocate from. Set a project version and soname (1.0.0 / libakerror.so.1) so a stale installed library can no longer be silently paired with newer headers, and so akerror.pc ships a real Version field instead of an empty one. Mutation testing surfaced an out-of-bounds probe in the new table that the suite did not catch: masking with SLOTS rather than SLOTS-1 indexes past the array, and err_maxval.c asserted only that some names registered before the table filled, which a collapsed probe sequence still satisfies. It now requires a substantial entry count and reads every entry back by its own distinct name. Tests: 28/28 pass. Coverage 99.4% line / 86.8% branch. Mutation score for src/error.c 74% -> 77.3%. Compatibility: source and ABI break. AKERR_MAX_ERR_VALUE and the __AKERR_ERROR_NAMES data symbol are gone, custom codes must move out of 0-255, and names must be registered against a reserved range. README.md carries the migration steps. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 18:19:25 -04:00
Use the library's own error idioms inside the library Four things in src/error.c did by hand what the macros already do, or skipped checks the library would have caught for a consumer. akerr_copy_string() returned void and validated only its capacity, while writing through a caller-supplied pointer for a caller-supplied length. It is now __akerr_copy_string() and raises: AKERR_NULLPOINTER for a NULL destination or source, AKERR_VALUE for a capacity with no room for a terminator. Both call sites PASS it, and the owner copy in akerr_reserve_status_range() now gates the commit, so a failed copy cannot leave a range claimed under an empty owner. It is exported under the internal prefix rather than static so tests/err_copy_string.c can drive those guards; nothing else can reach them. __akerr_name_library_status() and the band reservation in akerr_init() hand-rolled the log/handler/release sequence. Both now use ATTEMPT/CATCH/PROCESS/FINISH_NORETURN. PASS does not fit: both sites are void and have no caller to propagate to, so the terminal form of the same idiom is the right one -- an unhandled failure prints its stack trace and goes to akerr_handler_unhandled_error, which terminates, exactly as before but without the bespoke plumbing. The legacy set path in akerr_name_for_status() had the same shape and now handles its refusal with HANDLE_DEFAULT, converting it to the "Unknown Error" sentinel. Every remaining `if (x) { FAIL_RETURN }` in the registry is now FAIL_ZERO_RETURN or FAIL_NONZERO_RETURN, and akerr_register_status_name() checks both owner and name before passing either down -- akerr_store_status_name() reads a NULL owner as "caller did not identify itself" for the legacy path, so a NULL arriving through the owned entry point would have skipped the ownership check entirely. New tests: err_copy_string (the guards above), err_library_status_fatal (WILL_FAIL -- proves a refused library-status registration terminates). Tests: ctest 31/31, mutation 80.7% (was 77.5%), line coverage 98.9%. Branch coverage on src/error.c drops 64.5% -> 50.4%, just over its gate: each FAIL_* site carries ~6 branch outcomes of error-construction machinery that only run when that failure fires, and each PASS around a call that cannot fail carries ~25, so added validation lowers the ratio by construction. Recorded in TODO.md item 7. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 21:53:33 -04:00
## 7. `akerr_init()`'s own reservation failure is untested
Raise errors from the status registry instead of returning codes akerr_reserve_status_range() and akerr_register_status_name() returned private int enumerations, which was the one place in the library where a failure was not an akerr_ErrorContext *. They now return one like everything else: NULL on success, and on refusal an error whose status is a real code in the library's reserved band, so it can be CATCH-ed, HANDLE-d, PASS-ed, or left to propagate into a stack trace. Both are marked AKERR_NOIGNORE, so discarding the result warns at compile time. AKERR_STATUS_RANGE_OK and AKERR_STATUS_NAME_OK are gone; the remaining seven codes move into the AKERR_* offset span and get registered names. AKERR_LAST_LIBRARY_STATUS replaces AKERR_BADEXC as the top of that span in the reserved-band static assert and the exhaustiveness sweep. The refusal detail that used to go straight to akerr_log_method now travels in the error message, so a caller that handles the error decides whether it is reported. The two-argument akerr_name_for_status() set path is the exception: it returns a name and cannot raise, so it logs and releases. akerr_init() likewise has no caller to raise into, so failing to reserve its own band or name its own codes is logged and fatal -- that can only happen on a misconfigured build, and continuing would degrade every later stack trace to "Unknown Error". Move the 1.0.0 upgrade notice out of README.md into UPGRADING.md and rewrite its return-code tables in terms of the statuses now raised. Tests: ctest 29/29, coverage 97.5% line / 64.5% branch, mutation 77.5% (was 77.6%; the new survivors are the fatal init path, which needs a library built with an undersized name table -- TODO item 7). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 20:58:47 -04:00
Use the library's own error idioms inside the library Four things in src/error.c did by hand what the macros already do, or skipped checks the library would have caught for a consumer. akerr_copy_string() returned void and validated only its capacity, while writing through a caller-supplied pointer for a caller-supplied length. It is now __akerr_copy_string() and raises: AKERR_NULLPOINTER for a NULL destination or source, AKERR_VALUE for a capacity with no room for a terminator. Both call sites PASS it, and the owner copy in akerr_reserve_status_range() now gates the commit, so a failed copy cannot leave a range claimed under an empty owner. It is exported under the internal prefix rather than static so tests/err_copy_string.c can drive those guards; nothing else can reach them. __akerr_name_library_status() and the band reservation in akerr_init() hand-rolled the log/handler/release sequence. Both now use ATTEMPT/CATCH/PROCESS/FINISH_NORETURN. PASS does not fit: both sites are void and have no caller to propagate to, so the terminal form of the same idiom is the right one -- an unhandled failure prints its stack trace and goes to akerr_handler_unhandled_error, which terminates, exactly as before but without the bespoke plumbing. The legacy set path in akerr_name_for_status() had the same shape and now handles its refusal with HANDLE_DEFAULT, converting it to the "Unknown Error" sentinel. Every remaining `if (x) { FAIL_RETURN }` in the registry is now FAIL_ZERO_RETURN or FAIL_NONZERO_RETURN, and akerr_register_status_name() checks both owner and name before passing either down -- akerr_store_status_name() reads a NULL owner as "caller did not identify itself" for the legacy path, so a NULL arriving through the owned entry point would have skipped the ownership check entirely. New tests: err_copy_string (the guards above), err_library_status_fatal (WILL_FAIL -- proves a refused library-status registration terminates). Tests: ctest 31/31, mutation 80.7% (was 77.5%), line coverage 98.9%. Branch coverage on src/error.c drops 64.5% -> 50.4%, just over its gate: each FAIL_* site carries ~6 branch outcomes of error-construction machinery that only run when that failure fires, and each PASS around a call that cannot fail carries ~25, so added validation lowers the ratio by construction. Recorded in TODO.md item 7. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 21:53:33 -04:00
`tests/err_library_status_fatal.c` covers the terminal path in
`__akerr_name_library_status()` by naming a status the library does not own. The
band reservation in `akerr_init()` has no such handle: it can only fail in a
build whose tables are too small for the library's own entries, and both sizes
are `PRIVATE` to the library target, so a test executable cannot set them.
Raise errors from the status registry instead of returning codes akerr_reserve_status_range() and akerr_register_status_name() returned private int enumerations, which was the one place in the library where a failure was not an akerr_ErrorContext *. They now return one like everything else: NULL on success, and on refusal an error whose status is a real code in the library's reserved band, so it can be CATCH-ed, HANDLE-d, PASS-ed, or left to propagate into a stack trace. Both are marked AKERR_NOIGNORE, so discarding the result warns at compile time. AKERR_STATUS_RANGE_OK and AKERR_STATUS_NAME_OK are gone; the remaining seven codes move into the AKERR_* offset span and get registered names. AKERR_LAST_LIBRARY_STATUS replaces AKERR_BADEXC as the top of that span in the reserved-band static assert and the exhaustiveness sweep. The refusal detail that used to go straight to akerr_log_method now travels in the error message, so a caller that handles the error decides whether it is reported. The two-argument akerr_name_for_status() set path is the exception: it returns a name and cannot raise, so it logs and releases. akerr_init() likewise has no caller to raise into, so failing to reserve its own band or name its own codes is logged and fatal -- that can only happen on a misconfigured build, and continuing would degrade every later stack trace to "Unknown Error". Move the 1.0.0 upgrade notice out of README.md into UPGRADING.md and rewrite its return-code tables in terms of the statuses now raised. Tests: ctest 29/29, coverage 97.5% line / 64.5% branch, mutation 77.5% (was 77.6%; the new survivors are the fatal init path, which needs a library built with an undersized name table -- TODO item 7). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 20:58:47 -04:00
Use the library's own error idioms inside the library Four things in src/error.c did by hand what the macros already do, or skipped checks the library would have caught for a consumer. akerr_copy_string() returned void and validated only its capacity, while writing through a caller-supplied pointer for a caller-supplied length. It is now __akerr_copy_string() and raises: AKERR_NULLPOINTER for a NULL destination or source, AKERR_VALUE for a capacity with no room for a terminator. Both call sites PASS it, and the owner copy in akerr_reserve_status_range() now gates the commit, so a failed copy cannot leave a range claimed under an empty owner. It is exported under the internal prefix rather than static so tests/err_copy_string.c can drive those guards; nothing else can reach them. __akerr_name_library_status() and the band reservation in akerr_init() hand-rolled the log/handler/release sequence. Both now use ATTEMPT/CATCH/PROCESS/FINISH_NORETURN. PASS does not fit: both sites are void and have no caller to propagate to, so the terminal form of the same idiom is the right one -- an unhandled failure prints its stack trace and goes to akerr_handler_unhandled_error, which terminates, exactly as before but without the bespoke plumbing. The legacy set path in akerr_name_for_status() had the same shape and now handles its refusal with HANDLE_DEFAULT, converting it to the "Unknown Error" sentinel. Every remaining `if (x) { FAIL_RETURN }` in the registry is now FAIL_ZERO_RETURN or FAIL_NONZERO_RETURN, and akerr_register_status_name() checks both owner and name before passing either down -- akerr_store_status_name() reads a NULL owner as "caller did not identify itself" for the legacy path, so a NULL arriving through the owned entry point would have skipped the ownership check entirely. New tests: err_copy_string (the guards above), err_library_status_fatal (WILL_FAIL -- proves a refused library-status registration terminates). Tests: ctest 31/31, mutation 80.7% (was 77.5%), line coverage 98.9%. Branch coverage on src/error.c drops 64.5% -> 50.4%, just over its gate: each FAIL_* site carries ~6 branch outcomes of error-construction machinery that only run when that failure fires, and each PASS around a call that cannot fail carries ~25, so added validation lowers the ratio by construction. Recorded in TODO.md item 7. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 21:53:33 -04:00
Closing it means a second library target built with tiny tables plus a
Raise errors from the status registry instead of returning codes akerr_reserve_status_range() and akerr_register_status_name() returned private int enumerations, which was the one place in the library where a failure was not an akerr_ErrorContext *. They now return one like everything else: NULL on success, and on refusal an error whose status is a real code in the library's reserved band, so it can be CATCH-ed, HANDLE-d, PASS-ed, or left to propagate into a stack trace. Both are marked AKERR_NOIGNORE, so discarding the result warns at compile time. AKERR_STATUS_RANGE_OK and AKERR_STATUS_NAME_OK are gone; the remaining seven codes move into the AKERR_* offset span and get registered names. AKERR_LAST_LIBRARY_STATUS replaces AKERR_BADEXC as the top of that span in the reserved-band static assert and the exhaustiveness sweep. The refusal detail that used to go straight to akerr_log_method now travels in the error message, so a caller that handles the error decides whether it is reported. The two-argument akerr_name_for_status() set path is the exception: it returns a name and cannot raise, so it logs and releases. akerr_init() likewise has no caller to raise into, so failing to reserve its own band or name its own codes is logged and fatal -- that can only happen on a misconfigured build, and continuing would degrade every later stack trace to "Unknown Error". Move the 1.0.0 upgrade notice out of README.md into UPGRADING.md and rewrite its return-code tables in terms of the statuses now raised. Tests: ctest 29/29, coverage 97.5% line / 64.5% branch, mutation 77.5% (was 77.6%; the new survivors are the fatal init path, which needs a library built with an undersized name table -- TODO item 7). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 20:58:47 -04:00
`WILL_FAIL` test linked against it — worth doing when the CMake gains a
sanitizer variant (item 1), since that adds the same machinery.
Use the library's own error idioms inside the library Four things in src/error.c did by hand what the macros already do, or skipped checks the library would have caught for a consumer. akerr_copy_string() returned void and validated only its capacity, while writing through a caller-supplied pointer for a caller-supplied length. It is now __akerr_copy_string() and raises: AKERR_NULLPOINTER for a NULL destination or source, AKERR_VALUE for a capacity with no room for a terminator. Both call sites PASS it, and the owner copy in akerr_reserve_status_range() now gates the commit, so a failed copy cannot leave a range claimed under an empty owner. It is exported under the internal prefix rather than static so tests/err_copy_string.c can drive those guards; nothing else can reach them. __akerr_name_library_status() and the band reservation in akerr_init() hand-rolled the log/handler/release sequence. Both now use ATTEMPT/CATCH/PROCESS/FINISH_NORETURN. PASS does not fit: both sites are void and have no caller to propagate to, so the terminal form of the same idiom is the right one -- an unhandled failure prints its stack trace and goes to akerr_handler_unhandled_error, which terminates, exactly as before but without the bespoke plumbing. The legacy set path in akerr_name_for_status() had the same shape and now handles its refusal with HANDLE_DEFAULT, converting it to the "Unknown Error" sentinel. Every remaining `if (x) { FAIL_RETURN }` in the registry is now FAIL_ZERO_RETURN or FAIL_NONZERO_RETURN, and akerr_register_status_name() checks both owner and name before passing either down -- akerr_store_status_name() reads a NULL owner as "caller did not identify itself" for the legacy path, so a NULL arriving through the owned entry point would have skipped the ownership check entirely. New tests: err_copy_string (the guards above), err_library_status_fatal (WILL_FAIL -- proves a refused library-status registration terminates). Tests: ctest 31/31, mutation 80.7% (was 77.5%), line coverage 98.9%. Branch coverage on src/error.c drops 64.5% -> 50.4%, just over its gate: each FAIL_* site carries ~6 branch outcomes of error-construction machinery that only run when that failure fires, and each PASS around a call that cannot fail carries ~25, so added validation lowers the ratio by construction. Recorded in TODO.md item 7. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 21:53:33 -04:00
Related: branch coverage on `src/error.c` now sits just above its 50% gate.
Every `FAIL_*` site carries about six branch outcomes of error-construction
machinery (`ENSURE_ERROR_READY`, `AKERR_STACKTRACE_APPEND`) that only run when
that specific failure fires, and every `PASS` site around a call that cannot
fail carries about twenty-five. Validating more inputs therefore lowers the
ratio by construction. Before adding defensive checks, expect to add a test that
drives them, as `tests/err_copy_string.c` does.
Enforce status-code ownership and harden the name registry Reservations were advisory bookkeeping: any component could name any status, so the registry only detected declared-range overlap between components that both opted in. Naming a status now requires a reservation. akerr_register_status_name() checks that the range belongs to the caller, and the legacy two-argument akerr_name_for_status() set path, which cannot identify its caller, requires that some reservation covers the status. Every refusal is logged and names the real owner, because a name that fails to register degrades that code to "Unknown Error" in every later stack trace. Fix a reservation made before the first PREPARE_ERROR being silently discarded. akerr_init() clears the tables, so whichever component first triggered it wiped an earlier reservation and the next component to claim the same range was told it was free, producing exactly the undetected aliasing the registry exists to prevent. Every registry entry point now calls akerr_init(), which sets its guard before doing any work so those calls do not recurse. Replace the linear-scan name array with an open-addressed hash table, taking lookup from O(n) to O(1) and raising usable capacity from 512 entries (366 free to consumers after errno registration) to 3072 (~2900 free). Both table sizes are build-time overridable and applied PRIVATE: they live entirely in src/error.c, so raising them cannot desynchronize a library from its consumers the way AKERR_MAX_ERR_VALUE could. Exhausting either table is now logged and returned to the caller rather than silently dropping the entry. No dynamic allocation is introduced; both tables remain file-scope arrays, and the library's undefined-symbol set gains only strcmp and strlen. Register names for AKERR_EOF, AKERR_ITERATOR_BREAK and AKERR_NOT_IMPLEMENTED, which had none and rendered as "Unknown Error" in every stack trace carrying them. err_error_names.c now sweeps the whole AKERR_* offset span so a code added without a name fails there instead of in production traces. Add static assertions that the slot count is a power of two and that AKERR_BADEXC stays inside the library's own 0-255 band, the latter guarding against a host errno space large enough to push library codes into the range consumers are told to allocate from. Set a project version and soname (1.0.0 / libakerror.so.1) so a stale installed library can no longer be silently paired with newer headers, and so akerror.pc ships a real Version field instead of an empty one. Mutation testing surfaced an out-of-bounds probe in the new table that the suite did not catch: masking with SLOTS rather than SLOTS-1 indexes past the array, and err_maxval.c asserted only that some names registered before the table filled, which a collapsed probe sequence still satisfies. It now requires a substantial entry count and reads every entry back by its own distinct name. Tests: 28/28 pass. Coverage 99.4% line / 86.8% branch. Mutation score for src/error.c 74% -> 77.3%. Compatibility: source and ABI break. AKERR_MAX_ERR_VALUE and the __AKERR_ERROR_NAMES data symbol are gone, custom codes must move out of 0-255, and names must be registered against a reserved range. README.md carries the migration steps. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 18:19:25 -04:00
## Unrelated pre-existing issues
- The `AKERR_USE_STDLIB=OFF` build does not compile at all: `bool`, `PATH_MAX`
and `NULL` are used unconditionally but only included under the stdlib branch.
The README's dependency list states what a replacement must provide, but the
header still needs its includes untangled for that configuration to work.
- `CMakeLists.txt` sets `main_lib_dest` from `MY_LIBRARY_VERSION`, which is never
defined and never read. Dead line.