Re: [PATCH] checkpatch: error if file terminates without a new-line

[Joe Perches]

On Tue, 2024-04-16 at 11:59 +0300, Dan Carpenter wrote:
> On Tue, Apr 16, 2024 at 10:48:27AM +0200, Greg KH wrote:
> > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > > index 9c4c4a61bc83..df34c0709410 100755
> > > --- a/scripts/checkpatch.pl
> > > +++ b/scripts/checkpatch.pl
> > > @@ -2795,6 +2795,13 @@ sub process {
> > >             $is_patch = 1;
> > >         }
> > > 
> > > +# check if patch terminates file without a new line (\n)
> > > +        if ($line =~ /^\\ No newline at end of file$/
> > > +            and $rawlines[$linenr - 2] =~ /^\+.*$/) {
> > > +            ERROR("NOEOL_FILE",
> > > +                  "patch terminates file without a new line (\\n).");
> > > +        }
> > 
> > Why is this a problem?  files without a new line should not cause
> > problems with a compiler, right?  You don't have a justification for why
> > this change needs to be checked for anywhere.
> > 
> 
> I gave him such a good reason too...  It breaks `cat file.c`.  Plus, it
> looks weird in `git log -p` because it has a "No newline at the end of
> file" comment.
> 
> regards,
> dan carpenter
> 
> diff --git a/test.c b/test.c
> new file mode 100644
> index 000000000000..d808cac2d962
> --- /dev/null
> +++ b/test.c
> @@ -0,0 +1,12 @@
> +#include <stdio.h>
> +#include <stdbool.h>
> +#include "check_debug.h"
> +
> +void kfree(int *p);
> +
> +int *p;
> +int main(void)
> +{
> +       kfree(p);
> +       *p = 1;
> +}
> \ No newline at end of file
> 
> commit f4a997924122d0094675c897a220371f0a129d90
> 

There's an existing check for this.
I believe it at least used to work.
Fix that instead.

# check for adding lines without a newline.
		if ($line =~ /^\+/ && defined $lines[$linenr] && $lines[$linenr] =~ /^\\ No newline at end of file/) {
			if (WARN("MISSING_EOF_NEWLINE",
			         "adding a line without newline at end of file\n" . $herecurr) &&
			    $fix) {
				fix_delete_line($fixlinenr+1, "No newline at end of file");
			}
		}