feat: Allow specifying the base commit for local (non-CI) diffs #180

ScottNotFound · 2026-01-22T21:03:14Z

Changes in this PR only affect behavior in a non CI or non GitHub environment.

Resolves #179

Previous behavior

If staged files exist, then use diff between HEAD and index (staging).
Otherwise, use the diff between HEAD~1 and HEAD.

New behavior

Previous behavior is unchanged. Options were added to allow:

--diff-base BASE and empty index: diff between BASE and HEAD
--diff-base BASE and populated index: diff between BASE and index
--ignore-index: follows behavior as if the index is empty.

Thus, --diff-base BASE and --ignore-index --> always diff between BASE and HEAD

Summary by CodeRabbit

New Features
- Added --diff-base / -b (accepts integer or string) and --ignore-index flags to the CLI.
Behavior
- Diff resolution now respects an explicit base and whether staged/indexed changes are considered, changing which commits/trees are compared.
Tests
- CLI tests extended for new flags; added tests covering SHA/base resolution.
Documentation
- Release matrix updated to list support for diff_base and ignore_index.

coderabbitai · 2026-01-22T21:11:49Z

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Walkthrough

Adds optional diff selection and index-ignoring flags: diff_base and ignore_index are introduced to the CLI, git utilities, REST/Git clients, and are forwarded through main execution paths; tests and docs updated to exercise parsing and SHA/diff resolution behaviors.

Changes

Cohort / File(s)	Summary
CLI Interface `cpp_linter/cli.py`	Added `Union` import; new `Args` fields `diff_base: Optional[Union[int,str]]` and `ignore_index: bool`; added `-b/--diff-base` and `--ignore-index` parser flags.
Library entry / main `cpp_linter/__init__.py`	`main()` now forwards `diff_base` and `ignore_index` into `GithubApiClient.get_list_of_changed_files(...)` in both execution branches.
Git utilities `cpp_linter/git/...` `cpp_linter/git/__init__.py`	`get_sha()` accepts `parent: Optional[Union[int,str]]`; `get_diff()` signature changed to `parents: Optional[Union[int,str]] = None, ignore_index: bool = False`; diff-base resolution and staged-vs-index logic updated to respect these args and to name/cache diffs accordingly.
REST API client `cpp_linter/rest_api/__init__.py`, `cpp_linter/rest_api/github_api.py`	Added `Union` import; extended `RestApiClient.get_list_of_changed_files()` and `GithubApiClient.get_list_of_changed_files()` signatures with `diff_base` and `ignore_index`; docs updated; non-CI path now calls `get_diff(diff_base, ignore_index)` and parses that diff.
Tests `tests/test_cli_args.py`, `tests/capture_tools_output/test_tools_output.py`	CLI argument tests accept Optional values for `diff-base` (int/str) and `ignore-index`; added/updated `test_get_sha` to validate SHA resolution; typing imports adjusted (Optional, Tuple, Union).
Docs / Config `docs/conf.py`	Added `REQUIRED_VERSIONS["1.12.0"] = ["diff_base", "ignore_index"]`.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

fix: enhance parsing paginated diffs #125 — Modifies GithubApiClient diff handling and parsing; likely related to changes adding diff_base/ignore_index to the client.

Suggested reviewers

shenxianpeng
2bndy5

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: allowing users to specify the base commit for local (non-CI) diffs, which is the core feature added in this PR.
Linked Issues check	✅ Passed	The PR fully addresses issue `#179` by implementing CLI options (--diff-base and --ignore-index) to allow users to explicitly choose the base commit reference for diffs in non-CI environments.
Out of Scope Changes check	✅ Passed	All changes are directly related to implementing the requested feature. The modifications span CLI argument parsing, git operations, REST API client methods, and corresponding tests—all necessary for the feature.
Docstring Coverage	✅ Passed	Docstring coverage is 88.89% which is sufficient. The required threshold is 80.00%.

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codecov · 2026-01-22T21:19:00Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.30%. Comparing base (4dc4d9d) to head (3eb723b).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #180      +/-   ##
==========================================
+ Coverage   98.27%   98.30%   +0.02%     
==========================================
  Files          24       24              
  Lines        1916     1947      +31     
==========================================
+ Hits         1883     1914      +31     
  Misses         33       33

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ScottNotFound · 2026-01-22T22:19:31Z

I did not mean to close this.

- fixed a sphinx formatting issue - changed replaced type with isinstance in get_sha

cpp_linter/git/__init__.py

Co-authored-by: Brendan <2bndy5@gmail.com>

cpp_linter/git/__init__.py

Co-authored-by: Brendan <2bndy5@gmail.com>

2bndy5

This looks great, thanks!

I have some final requests about the docs and --ignore-index CLI parsing.

Also, could you apply the following patch to conf.py:

diff --git a/docs/conf.py b/docs/conf.py
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -238,6 +238,7 @@ REQUIRED_VERSIONS = {
     "1.8.1": ["jobs"],
     "1.9.0": ["ignore_tidy", "ignore_format"],
     "1.10.0": ["passive_reviews"],
+    "1.12.0": ["diff_base", "ignore_index"],
 }
 SUBCOMMAND_VERSIONS = {"version": "1.11.0"}

It will help when generating the CLI doc from the --help output. Currently, it is incorrect:

Yes, I intend to bump the minor version because this is a new feature.

cpp_linter/cli.py

cpp_linter/git/__init__.py

cpp_linter/rest_api/__init__.py

tests/test_cli_args.py

Co-authored-by: Brendan <2bndy5@gmail.com>

csv table in doc for clarity Co-authored-by: Brendan <2bndy5@gmail.com>

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@cpp_linter/rest_api/__init__.py`:
- Around line 171-180: The docstring for parameter diff_base in __init__.py has
the diff ranges reversed; update the CSV table so ranges are "older..newer"
(base → head/index): replace "HEAD..HEAD~1" with "HEAD~1..HEAD" and replace
"index..HEAD" with "HEAD..index" so the examples for diff_base (in the table
under the diff_base param) show the correct base→target ordering.

cpp_linter/rest_api/__init__.py

2bndy5

Small doc revision about CLI option vs switch.

cpp_linter/cli.py

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Resolved

cpp_linter/cli.py

2bndy5

🎉

- ref cpp-linter/cpp-linter#180 - as discussed in cpp-linter/cpp-linter#179

- ref cpp-linter/cpp-linter#180 - as discussed in cpp-linter/cpp-linter#179  ## Summary by CodeRabbit * **New Features** * Added --diff-base and --ignore-index CLI options to control base diffs and staged-file handling. * **Documentation** * Documented new CLI options (minimum version 1.12.0). * Improved CLI argument header formatting to handle missing short names. * **Chores** * Default test filter updated to exclude a specific test. * **Tests** * Tests expanded to cover diff-base and ignore-index behaviors and updated call sites.  --------- Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

In porting #180 to rust (cpp-inter/cpp-linter-rs#260), I found a few spots for improvement. These changes should be more performant when there are staged changes. I also made some typing-related changes to satisfy mypy.

In porting #180 to rust (cpp-linter/cpp-linter-rs#260), I found a few spots for improvement. These changes should be more performant when there are staged changes.

ScottNotFound changed the title ~~Allow command line users to specify the base commit to use and flag to ignore the index for producing diffs~~ feat: Allow command line users to specify the base commit to use and flag to ignore the index for producing diffs Jan 22, 2026

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2bndy5 changed the title ~~feat: Allow command line users to specify the base commit to use and flag to ignore the index for producing diffs~~ feat: Allow specifying the base commit for local (non-CI) diffs Jan 22, 2026

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ScottNotFound closed this Jan 22, 2026

ScottNotFound force-pushed the allow-specify-parent-index branch from c4de8ea to f9b56dc Compare January 22, 2026 22:14

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ScottNotFound added 4 commits January 22, 2026 17:35

add option to specify base commit

a1fae55

rename base commit diff option

c6916be

add option to ignore index

1fb4fb4

fix: doc and type checking

53255bf

- fixed a sphinx formatting issue - changed replaced type with isinstance in get_sha

ScottNotFound reopened this Jan 22, 2026

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2bndy5 reviewed Jan 22, 2026

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Update cpp_linter/git/__init__.py as per ai suggestion

ab7de02

Co-authored-by: Brendan <2bndy5@gmail.com>

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2bndy5 reviewed Jan 23, 2026

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ScottNotFound and others added 3 commits January 23, 2026 10:20

Update tests/test_cli_args.py - fix type mismatch in cli test

8d50a05

Co-authored-by: Brendan <2bndy5@gmail.com>

Update cpp_linter/git/__init__.py fix wrong return type

c25afbe

Co-authored-by: Brendan <2bndy5@gmail.com>

add test for get_sha

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shenxianpeng added the enhancement New feature or request label Jan 28, 2026

ScottNotFound and others added 4 commits February 3, 2026 15:28

Update cpp_linter/git/__init__.py - fix doc auto link

d9d2475

Co-authored-by: Brendan <2bndy5@gmail.com>

Update cpp_linter/rest_api/__init__.py

36a28c2

csv table in doc for clarity Co-authored-by: Brendan <2bndy5@gmail.com>

chore(dev): auto fixes from pre-commit.ci hooks

7abc650

add required version in doc conf for new options

e6bfe69

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ScottNotFound added 2 commits February 3, 2026 16:10

fix doc linking to pygit2

402a6d8

change ignore_index to just be a flag

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2bndy5 and others added 2 commits February 4, 2026 13:29

fix git syntax in doc comment

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update --help description of --ignore-index

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typo

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2bndy5 merged commit b3c28b6 into cpp-linter:main Feb 4, 2026
41 checks passed

2bndy5 added the minor A minor version bump label Feb 5, 2026

2bndy5 added a commit to cpp-linter/cpp-linter-rs that referenced this pull request Feb 5, 2026

feat: allow specifying the base commit for local (non-CI) diffs

02b78b4

- ref cpp-linter/cpp-linter#180 - as discussed in cpp-linter/cpp-linter#179

2bndy5 mentioned this pull request Feb 5, 2026

feat: allow specifying the base commit for local (non-CI) diffs cpp-linter/cpp-linter-rs#260

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2bndy5 mentioned this pull request Feb 6, 2026

perf: small optimizations to get_diff() #185

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2bndy5 added a commit that referenced this pull request Feb 6, 2026

perf: small optimizations to get_sha()

47dfc15

In porting #180 to rust (cpp-linter/cpp-linter-rs#260), I found a few spots for improvement. These changes should be more performant when there are staged changes.

2bndy5 added a commit that referenced this pull request Feb 6, 2026

perf: small optimizations to get_sha()

b6fa83e

In porting #180 to rust (cpp-linter/cpp-linter-rs#260), I found a few spots for improvement. These changes should be more performant when there are staged changes.

2bndy5 added a commit that referenced this pull request Feb 6, 2026

perf: small optimizations to get_diff() (#185)

7659996

In porting #180 to rust (cpp-linter/cpp-linter-rs#260), I found a few spots for improvement. These changes should be more performant when there are staged changes.

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feat: Allow specifying the base commit for local (non-CI) diffs #180

feat: Allow specifying the base commit for local (non-CI) diffs #180

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