Extend lint_source.py to catch stop/error stop, integer(wp), and signed d-exponent literals

[sbryngelson]

toolchain/mfc/lint_source.py is the CI source linter. Current checks include: check_raw_directives (raw !$acc/!$omp), check_double_precision (dsqrt/…, real(8)/real(4)/double precision, and [0-9]d0 literals), check_junk_code, check_false_integers (bare 2_wp), check_junk_comments, check_fypp_list_duplicates, check_duplicate_lines, check_hardcoded_byte_size.

Gaps that let convention violations recur:

1. No stop/error stop check. Nothing flags Fortran stop/error stop. Proposed check_stop_statements: flag stop/error stop in src/ .fpp/.f90, on non-comment/non-#: lines (so Fypp #:stop is exempt), excluding syscheck/ and the #ifndef MFC_MPI fallback in m_mpi_common.fpp (allowlist that file/routine).

2. No integer(wp) check. Add a regex \binteger\s*\(\s*wp\s*\) → suggest plain integer.

3. The d-literal regex is too narrow. check_double_precision uses [0-9]d0, which only matches a d0 exponent. Signed/multi-digit exponents like 5.0d-11, 2.5d+3, 1.0d12 are not caught. Broaden to [0-9]\.?[0-9]*[dD][-+]?[0-9]+ (case-insensitive, on the code portion only). This single fix would have caught m_bubbles_EL.fpp:1345.

Why it matters: these conventions are otherwise enforced only by review; real violations exist today that review missed. Closing the linter gaps makes them CI-gated.

Scope note: catching bare-real-literal-missing-_wp in general is much harder (huge false-positive surface — array indices, loop bounds, (/1,0,0/) are all integers-by-design). Recommend scoping this issue to (1)–(3) only, which are unambiguous.

This pairs with the stop→s_mpi_abort and forbidden-literal cleanup issues.

---

_{Filed from a repo-wide code-cleanliness review; verified against master @ 40dde5e.}

Code references

• toolchain/mfc/lint_source.py — linter to extend

[BakaOverflow]

Hello @sbryngelson, CodePath AI301 student here, I'd like to tackle this issue and handle the convention violations mentioned:

1. Add check_stop_statements to flag stop / error stop in src/ .fpp / .f90 on code lines only (skipping comments and Fypp #: lines so #:stop is exempt), with the allowlist for syscheck/ and the #ifndef MFC_MPI fallback in m_mpi_common.fpp.
2. Add an integer(wp) check (\binteger\s*\(\s*wp\s*\)), since wp in, integer(wp) should just be plain integer.
3. Broaden check_double_precision d-literal regex from [0-9]d0 to [0-9]\.?[0-9]*[dD][-+]?[0-9]+ to catch the signed/multi-digit exponent cases (e.g. 5.0d-11).