The war on trailing whitespace

On Sat, 25 Feb 2006, Andrew Morton wrote:
>
> I'd suggest a) git will simply refuse to apply such a patch unless given a
> special `forcing' flag, b) even when thus forced, it will still warn and c)
> with a different flag, it will strip-then-apply, without generating a
> warning.

This doesn't do the "strip-then-apply" thing, but it allows you to make
git-apply generate a warning or error on extraneous whitespace.

Use --whitespace=warn to warn, and (surprise, surprise) --whitespace=error
to make it a fatal error to have whitespace at the end.

Totally untested, of course. But it compiles, so it must be fine.

HOWEVER! Note that this literally will check every single patch-line with
"+" at the beginning. Which means that if you fix a simple typo, and the
line had a space at the end before, and you didn't remove it, that's still
considered a "new line with whitespace at the end", even though obviously
the line wasn't really new.

I assume this is what you wanted, and there isn't really any sane
alternatives (you could make the warning activate only for _pure_
additions with no deletions at all in that hunk, but that sounds a bit
insane).

		Linus

apply.c

@@ -34,6 +34,12 @@ static int line_termination = '\n';
 static const char apply_usage[] =
 "git-apply [--stat] [--numstat] [--summary] [--check] [--index] [--apply] [--no-add] [--index-info] [--allow-binary-replacement] [-z] [-pNUM] <patch>...";
 
+static enum whitespace_eol {
+	nowarn,
+	warn_on_whitespace,
+	error_on_whitespace
+} new_whitespace = nowarn;
+
 /*
  * For "diff-stat" like behaviour, we keep track of the biggest change
  * we've seen, and the longest filename. That allows us to do simple
@@ -815,6 +821,22 @@ static int parse_fragment(char *line, unsigned long size, struct patch *patch, s
 			oldlines--;
 			break;
 		case '+':
+			/*
+			 * We know len is at least two, since we have a '+' and
+			 * we checked that the last character was a '\n' above
+			 */
+			if (isspace(line[len-2])) {
+				switch (new_whitespace) {
+				case nowarn:
+					break;
+				case warn_on_whitespace:
+					new_whitespace = nowarn;	/* Just once */
+					error("Added whitespace at end of line at line %d", linenr);
+					break;
+				case error_on_whitespace:
+					die("Added whitespace at end of line at line %d", linenr);
+				}
+			}
 			added++;
 			newlines--;
 			break;
@@ -1839,6 +1861,17 @@ int main(int argc, char **argv)
 			line_termination = 0;
 			continue;
 		}
+		if (!strncmp(arg, "--whitespace=", 13)) {
+			if (strcmp(arg+13, "warn")) {
+				new_whitespace = warn_on_whitespace;
+				continue;
+			}
+			if (strcmp(arg+13, "error")) {
+				new_whitespace = error_on_whitespace;
+				continue;
+			}
+			die("unrecognixed whitespace option '%s'", arg+13);
+		}
 
 		if (check_index && prefix_length < 0) {
 			prefix = setup_git_directory();