[PATCH v4 00/10] parseopt: add subcommand autocorrection

Git currently provides auto-correction for builtins and aliases, but lacks this functionality for subcommands parsed via the parse-options API. Subcommands are also commands, and typos will occur, too. Like:

	git remote add-rul

So, this series introduces subcommand auto-correction.

By default, this implementation enables autocorrection for builtins with mandatory subcommands. However, for those using PARSE_OPT_SUBCOMMAND_OPTIONAL, autocorrection is skipped to avoid misinterpreting legitimate unknown arguments as mistyped subcommands.

To allow builtins with optional subcommands to explicitly opt in, this series adds the PARSE_OPT_SUBCOMMAND_AUTOCORR flag, and enables it for git-remote and git-notes.

Additionally, the existing autocorrection logic is extracted from help.c so subcommand handling can reuse the same config parsing and prompt/delay logic.

Some split string literals are also combined so the full text is easier to grep for.

Changes in v4:
  - Add missing files to Meson build
  - Change API prefix from autocorr to autocorrect
  - Split the commit that moves tty code
  - Add API documentation
  - Use standard Damerau-Levenshtein distance and common practice
    fuzziness thresholds
  - Rename AUTOCORRECT_HINTONLY to AUTOCORRECT_HINT
  - Change commit subject prefix for tests from "help:" to "parseopt:"
  - Fix coding style issues

Note on the autocorrection thresholds: In v3, there was a discussion about why specific thresholds were chosen. While attempting to document the legacy magic penalties (0, 2, 1, 3), I realized those weights exist in a system where prefix matches are completely ignored (due to a historical side-effect). Applying them to subcommands (which do evaluate prefix matches) makes the tolerance overly permissive. Therefore, v4 abandons the legacy weights in favor of a standard Damerau-Levenshtein distance and common practice length-based thresholds.

Changes in v3:
  - Align with the coding guildline
  - Split patch so diffs don't get hidden by code movement
  - Improve commit messages

Changes in v2:
  - Reword the explanation of default autocorrection behavior

Jiamu Sun (10):
  parseopt: extract subcommand handling from parse_options_step()
  help: make autocorrect handling reusable
  help: move tty check for autocorrection to autocorrect.c
  autocorrect: use mode and delay instead of magic numbers
  autocorrect: rename AUTOCORRECT_SHOW to AUTOCORRECT_HINT
  autocorrect: provide config resolution API
  parseopt: autocorrect mistyped subcommands
  parseopt: enable subcommand autocorrection for git-remote and
    git-notes
  parseopt: add tests for subcommand autocorrection
  doc: document autocorrect API

 Makefile                          |   1 +
 autocorrect.c                     |  89 ++++++++++++++++
 autocorrect.h                     |  32 ++++++
 builtin/notes.c                   |  10 +-
 builtin/remote.c                  |  12 +--
 help.c                            | 107 ++++----------------
 meson.build                       |   1 +
 parse-options.c                   | 162 ++++++++++++++++++++++--------
 parse-options.h                   |   1 +
 t/meson.build                     |   1 +
 t/t9004-autocorrect-subcommand.sh |  51 ++++++++++
 11 files changed, 325 insertions(+), 142 deletions(-)
 create mode 100644 autocorrect.c
 create mode 100644 autocorrect.h
 create mode 100755 t/t9004-autocorrect-subcommand.sh

base-commit: 795c338de725e13bd361214c6b768019fc45a2c1