Re: ãscripts/checkpatch.plãwhy we expand table key to 8 characters ï

From: Joe Perches
Date: Wed Apr 18 2018 - 15:54:07 EST


Forwarding on to LKML as I didn't realize it wasn't
on the original email chain.

On Wed, 2018-04-18 at 17:48 +0800, Dennis.Dai@xxxxxxxxxxx wrote:
>
> Hi Joe & Andy,
>
> Sorry to interrupt you for scripts/checkpatch.pl.
>
> I always use scripts/checkpatch.pl in kernel to check my code style. It's
> very helpful to improve our code more readable.
>
> We always set 4 characters for table key and most of others do this well in
> China, but I cann't understand why we expand the number to 8 characters and
> check the indent with 8 characters by following code ?

I don't personally mind allowing various tab widths,
but it should be with some command line option like
--tab-width=<n>

Perhaps:
---
scripts/checkpatch.pl | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 24618dffc5cb..95dae55bc94d 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -49,6 +49,7 @@ my @ignore = ();
my $help = 0;
my $configuration_file = ".checkpatch.conf";
my $max_line_length = 80;
+my $tab_width = 8;
my $ignore_perl_version = 0;
my $minimum_perl_version = 5.10.0;
my $min_conf_desc_length = 4;
@@ -92,6 +93,7 @@ Options:
--ignore TYPE(,TYPE2...) ignore various comma separated message types
--show-types show the specific message type in the output
--max-line-length=n set the maximum line length, if exceeded, warn
+ --tab-width=n set the expected tab indentation width (default:8)
--min-conf-desc-length=n set the min description length, if shorter, warn
--root=PATH PATH to the kernel tree root
--no-summary suppress the per-file summary
@@ -209,6 +211,7 @@ GetOptions(
'show-types!' => \$show_types,
'list-types!' => \$list_types,
'max-line-length=i' => \$max_line_length,
+ 'tab-width=i' => \$tab_width,
'min-conf-desc-length=i' => \$min_conf_desc_length,
'root=s' => \$root,
'summary!' => \$summary,
@@ -1162,7 +1165,7 @@ sub expand_tabs {
if ($c eq "\t") {
$res .= ' ';
$n++;
- for (; ($n % 8) != 0; $n++) {
+ for (; ($n % $tab_width) != 0; $n++) {
$res .= ' ';
}
next;
@@ -2175,7 +2178,7 @@ sub string_find_replace {
sub tabify {
my ($leading) = @_;

- my $source_indent = 8;
+ my $source_indent = $tab_width;
my $max_spaces_before_tab = $source_indent - 1;
my $spaces_to_tab = " " x $source_indent;

@@ -3056,7 +3059,7 @@ sub process {
"please, no space before tabs\n" . $herevet) &&
$fix) {
while ($fixed[$fixlinenr] =~
- s/(^\+.*) {8,8}\t/$1\t\t/) {}
+ s/(^\+.*) {$tab_width,$tab_width}\t/$1\t\t/) {}
while ($fixed[$fixlinenr] =~
s/(^\+.*) +\t/$1\t/) {}
}
@@ -3078,11 +3081,11 @@ sub process {
if ($^V && $^V ge 5.10.0 &&
$sline =~ /^\+\t+( +)(?:$c90_Keywords\b|\{\s*$|\}\s*(?:else\b|while\b|\s*$)|$Declare\s*$Ident\s*[;=])/) {
my $indent = length($1);
- if ($indent % 8) {
+ if ($indent % $tab_width) {
if (WARN("TABSTOP",
"Statements should start on a tabstop\n" . $herecurr) &&
$fix) {
- $fixed[$fixlinenr] =~ s@(^\+\t+) +@$1 . "\t" x ($indent/8)@e;
+ $fixed[$fixlinenr] =~ s@(^\+\t+) +@$1 . "\t" x ($indent/$tab_width)@e;
}
}
}
@@ -3100,8 +3103,8 @@ sub process {
my $newindent = $2;

my $goodtabindent = $oldindent .
- "\t" x ($pos / 8) .
- " " x ($pos % 8);
+ "\t" x ($pos / $tab_width) .
+ " " x ($pos % $tab_width);
my $goodspaceindent = $oldindent . " " x $pos;

if ($newindent ne $goodtabindent &&
@@ -3572,11 +3575,11 @@ sub process {
#print "line<$line> prevline<$prevline> indent<$indent> sindent<$sindent> check<$check> continuation<$continuation> s<$s> cond_lines<$cond_lines> stat_real<$stat_real> stat<$stat>\n";

if ($check && $s ne '' &&
- (($sindent % 8) != 0 ||
+ (($sindent % $tab_width) != 0 ||
($sindent < $indent) ||
($sindent == $indent &&
($s !~ /^\s*(?:\}|\{|else\b)/)) ||
- ($sindent > $indent + 8))) {
+ ($sindent > $indent + $tab_width))) {
WARN("SUSPECT_CODE_INDENT",
"suspect code indent for conditional statements ($indent, $sindent)\n" . $herecurr . "$stat_real\n");
}