Re: [PATCH] git-gui: remove lines starting with the comment character

[Eric Sunshine <sunshine@sunshineco.com>]

On Tue, Feb 2, 2021 at 3:07 PM Pratyush Yadav <me@yadavpratyush.com> wrote:
> The comment character is specified by the config variable
> 'core.commentchar'. Any lines starting with this character is considered
> a comment and should not be included in the final commit message.
>
> Teach git-gui to filter out lines in the commit message that start with
> the comment character. If the config is not set, '#' is taken as the
> default.

Thanks. This shortcoming has bugged me for a long time. A few comments below...

> Signed-off-by: Pratyush Yadav <me@yadavpratyush.com>
> ---
> diff --git a/lib/commit.tcl b/lib/commit.tcl
> @@ -209,6 +209,28 @@ You must stage at least 1 file before you can commit.
>         set msg [string trim [$ui_comm get 1.0 end]]
>         regsub -all -line {[ \t\r]+$} $msg {} msg
> +
> +       # Remove lines starting with the comment character.
> +       set comment_char [get_config core.commentchar]
> +       if {[string length $comment_char] > 1} {
> +               error_popup [mc "core.commitchar should only be one character."]
> +               unlock_index
> +               return
> +       }
> +
> +       if {$comment_char eq {}} {
> +               set comment_char "#"
> +       }
> +
> +       # If the comment character is not alphabetical, then we need to escape it
> +       # with a backslash to make sure it is not interpreted as a special character
> +       # in the regex.
> +       if {![string is alpha $comment_char]} {
> +               set comment_char "\\$comment_char"
> +       }
> +
> +       regsub -all -line "$comment_char.*(\\n|\\Z)" $msg {} msg

This regular expression is too loose. It will incorrectly change:

    line one
    line # two
    # line three
    line four

into:

    line one
    line
    line four

You could fix it by anchoring the start of the match while being
careful not to lose the newline at the start of line. Perhaps like
this:

    regsub -all -line "(^|\\A)$comment_char.*(\\n|\\Z)" $msg {} msg

However, an even better approach than doing this manipulation manually
might be to pass the commit message through `git stripspace
--strip-comments` which will do the exact normalization that Git
itself does. That way, you don't have to worry about weird corner
cases. Also, using git-stripspace may allow you to get rid of the
existing `trim` and `regsub` which precede the new code you added.