prepare-ChangeLog reports function above deleted function as deleted; uninitialized value warning when staged non-empty file for commit

• Component: Tools / Tests
• Status: RESOLVED FIXED

[Daniel Bates]

Perl warns of the use of an uninitialized variable in prepare-ChangeLog when the working copy has a non-empty new file staged for commit:

Use of uninitialized value $first_line in pattern match (m//) at Tools/Scripts/prepare-ChangeLog line 644.

Without loss of generality, you can reproduce this issue by running the following terminal commands inside the top-level directory of a Git checkout of the WebKit repository:

$ echo 'A' > A.txt
$ git add A.txt 
$ Tools/Scripts/prepare-ChangeLog

Then you will see output of the form:

  Running status to find changed, added, or removed files.
  Reviewing diff to determine which lines changed.
  Extracting affected function names from source files.
fatal: Path 'A.txt' exists on disk, but not in 'HEAD'.
Use of uninitialized value $first_line in pattern match (m//) at Tools/Scripts/prepare-ChangeLog line 644.
  Change author: Daniel Bates <[e-mail]>.
  Editing the ./ChangeLog file.
-- Please remember to include a detailed description in your ChangeLog entry. --
-- See <http://webkit.org/coding/contributing.html> for more info --

[Daniel Bates]

The logic for parsing a chunk range line of a unified diff is incorrect in extractLineRange{Before, After}Change(). In addition to causes this bug it also causes prepare-ChangeLog to always emit the name of the function f_0 above a deleted function regardless of whether f_0 changed.

[Daniel Bates]

Created attachment 253243 [details]
Patch and unit tests

[Daniel Bates]

Comment on attachment 253243 [details]
Patch and unit tests

View in context: https://bugs.webkit.org/attachment.cgi?id=253243&action=review

> Tools/Scripts/webkitperl/prepare-ChangeLog_unittest/extractLineRangeBeforeAndAfterChange.pl:29
> +use VCSUtils;

Will remove this before landing.

[Daniel Bates]

Committed r184521: <http://trac.webkit.org/changeset/184521>