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SubjectRe: [PATCH] checkpatch: Improve TYPECAST_INT_CONSTANT test message
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On 2021-01-18 12:19 p.m., Joe Perches wrote:
> Improve the TYPECAST_INT_CONSTANT test by showing the suggested
> conversion for various type of uses like (unsigned int)1 to 1U.

The questionable code snippet was:
unsigned int nent, nalloc;

....
if (check_add_overflow(nent, (unsigned int)1, &nalloc))

where the check_add_overflow() macro [include/linux/overflow.h]
uses typeid to check its first and second arguments have the
same type. So it is likely others could meet this issue.

Doug Gilbert


> Signed-off-by: Joe Perches <joe@perches.com>
> ---
>
> Douglas Gilbert sent me a private email (and in that email said he
> 'loves to hate checkpatch' ;) complaining that checkpatch warned on the
> use of the cast of '(unsigned int)1' so make it more obvious why the
> message is emitted by always showing the suggested conversion.
>
> scripts/checkpatch.pl | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 016115a62a9f..4f8494527139 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -6527,18 +6527,18 @@ sub process {
> if ($line =~ /(\(\s*$C90_int_types\s*\)\s*)($Constant)\b/) {
> my $cast = $1;
> my $const = $2;
> + my $suffix = "";
> + my $newconst = $const;
> + $newconst =~ s/${Int_type}$//;
> + $suffix .= 'U' if ($cast =~ /\bunsigned\b/);
> + if ($cast =~ /\blong\s+long\b/) {
> + $suffix .= 'LL';
> + } elsif ($cast =~ /\blong\b/) {
> + $suffix .= 'L';
> + }
> if (WARN("TYPECAST_INT_CONSTANT",
> - "Unnecessary typecast of c90 int constant\n" . $herecurr) &&
> + "Unnecessary typecast of c90 int constant - '$cast$const' could be '$const$suffix'\n" . $herecurr) &&
> $fix) {
> - my $suffix = "";
> - my $newconst = $const;
> - $newconst =~ s/${Int_type}$//;
> - $suffix .= 'U' if ($cast =~ /\bunsigned\b/);
> - if ($cast =~ /\blong\s+long\b/) {
> - $suffix .= 'LL';
> - } elsif ($cast =~ /\blong\b/) {
> - $suffix .= 'L';
> - }
> $fixed[$fixlinenr] =~ s/\Q$cast\E$const\b/$newconst$suffix/;
> }
> }
>
>

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