proven_c_lib-v0.4.0

A MINOR release: nothing public removed. The whole test suite now runs natively on Windows
(./nob build -no-run, a mingw-w64 build for x86-64 and i686), and its first run found six
Windows defects, all fixed - an empty directory could not be removed, pread/pwrite moved the file
position, positioned calls on a pipe were not refused, and the end of a pipe read as an I/O error
(B-035). Float parsing is faster than glibc at every length measured (B-043), and 32-bit targets
use the Eisel-Lemire fast path (B-042). MSVC and clang-cl are stated as not supported. Behaviour
changes only where it was wrong: proven_fs_remove on an empty directory on Windows, and the
Windows pipe and position cases above.

Added

• The full test suite runs on Windows (B-035). ./nob build -no-run builds every test
  executable and runs none; the build driver asks the compiler for its target, so a mingw-w64
  cross compiler produces static .exe tests (with -lbcrypt, without -ldl).
  win11kd-full-suite.sh and win11kd-run-suite.ps1 build both word sizes and
  run them natively, reporting PASS / FAIL / SKIP / TIMEOUT per test. First run on the Windows 11
  test VM found the six defects below. Three tests that skipped on Windows now run there
  (test_unit_sysio_streams, test_regression_scanner_short_read,
  test_regression_scanner_float_split). x86-64 and i686 each pass 214 with 0 failures; 7
  fixtures whose subject is POSIX skip.

Changed

• Float parsing is faster than glibc at every length measured (B-043). Three changes, each
  exact: a direct Eisel-Lemire layer (Lemire 2021) proves most results from a 64x128-bit product
  with a truncated power of five, where the staged layer validated every candidate with big-
  integer arithmetic; a significand past 19 digits is bounded by its first 19 digits and the same
  plus one, instead of going to the exact path; and one pass reads the digits, where a digit-by-
  digit builder kept pending-zero bookkeeping. test_bench_float_host, x86-64, against glibc
  strtod: %.6g 83 -> 81 ns (0.58x), ~16 digits 186 -> 145 ns (0.72x), %.17g 224 -> 152 ns
  (0.75x, was 1.13x), 25 digits ~640 -> 197 ns (0.86x, a new corpus). Results are unchanged:
  every row is checked against strtod in the same run, and 60 million generated inputs - random
  significands and exponents, %.15g-%.40g of random doubles, integers above 2^53, subnormal
  and overflow edges - matched strtod bit for bit, with and without 128-bit integers. The
  cached powers come from scripts/generate_float_decimal_tables.py, which checks its exponent
  estimate against exact integer arithmetic.
• The Eisel-Lemire float-parsing fast path is used on 32-bit targets too (B-042). It was
  compiled only where the compiler has unsigned __int128, although the code needs none - it
  goes through the portable 64x64 multiply. Without it a 32-bit target sent every decimal past
  the Clinger path to the exact big-integer path. Measured with 128-bit integers disabled on
  x86-64 (test_bench_float_host, release): 16-digit parsing 287 -> 183 ns, 17-digit 473 -> 222 ns;
  the results are checked against the host strtod in the same run, and the Windows i686 run
  passes the differential corpora and expects the fast path in test_unit_float_parse_api.
• MSVC and clang-cl are not supported (owner decision; possibly later). Their C23 support is
  incomplete. The manual used to say recent MSVC worked, which was never verified; it now names
  what is: GCC 13+, Clang 16+, and on Windows mingw-w64 GCC (x86-64 and i686).

Fixed

• Windows: proven_fs_remove deletes an empty directory, as POSIX remove() does. It called
  DeleteFileW only, which refuses a directory, and reported PERMISSION.
• Windows: proven_fs_pread and proven_fs_pwrite no longer move the file position. A
  positioned ReadFile/WriteFile on a synchronous handle leaves the pointer after the bytes;
  the position is now restored.
• Windows: positioned calls on a pipe are UNSUPPORTED. proven_fs_seek, pread and pwrite
  used SetFilePointerEx / an OVERLAPPED offset on a pipe, which Windows does not support, and
  proven_sysio_scan_chunk therefore accepted a pipe it must refuse. The handle type is now
  checked first (FILE_TYPE_DISK), matching POSIX ESPIPE.
• Windows: the end of a pipe is EOF. ReadFile reports a closed writer as ERROR_BROKEN_PIPE,
  which came back as PROVEN_ERR_IO - so producer | program ended in an error. Both read paths
  now map it to PROVEN_ERR_EOF, as read(2) returning 0 does.
• Tests and examples that assumed POSIX or a 64-bit target. Permission checks compare with the
  mode read back after chmod (Windows keeps only the owner-write bit); the durable-write example
  accepts sync_dir's documented UNSUPPORTED on Windows; test_unit_u128_mul and
  test_unit_float_bigint_divmod have references without __int128; a float comparison
  uses a stored double, not a literal that x87 evaluates in long double; a fixture no longer
  needs a build/ directory.
• scripts/release.sh builds a release's PDFs with one date. The site is built at the release
  commit and again by --publish at the site commit; both now take the date of the commit that
  last set the version, so the uploaded PDFs equal the committed ones without a re-publish.