Merge branch 'jc/whitespace-incomplete-line' into jch

Both "git apply" and "git diff" learn a new whitespace error class,
"incomplete-line".

Comments?

* jc/whitespace-incomplete-line:
  attr: enable incomplete-line whitespace error for this project
  diff: highlight and error out on incomplete lines
  apply: check and fix incomplete lines
  whitespace: allocate a few more bits and define WS_INCOMPLETE_LINE
  apply: revamp the parsing of incomplete lines
  diff: update the way rewrite diff handles incomplete lines
  diff: call emit_callback ecbdata everywhere
  diff: refactor output of incomplete line
  diff: fix incorrect counting of line numbers
  diff: correct suppress_blank_empty hack
  diff: emit_line_ws_markup() if/else style fix
  whitespace: correct bit assignment comments

Author: gitster

.gitattributes

@@ -1,6 +1,6 @@
 * whitespace=!indent,trail,space
-*.[ch] whitespace=indent,trail,space diff=cpp
-*.sh whitespace=indent,trail,space text eol=lf
+*.[ch] whitespace=indent,trail,space,incomplete diff=cpp
+*.sh whitespace=indent,trail,space,incomplete text eol=lf
 *.perl text eol=lf diff=perl
 *.pl text eof=lf diff=perl
 *.pm text eol=lf diff=perl

Documentation/config/core.adoc

@@ -629,6 +629,8 @@ core.whitespace::
   part of the line terminator, i.e. with it, `trailing-space`
   does not trigger if the character before such a carriage-return
   is not a whitespace (not enabled by default).
+* `incomplete-line` treats the last line of a file that is missing the
+  newline at the end as an error (not enabled by default).
 * `tabwidth=<n>` tells how many character positions a tab occupies; this
   is relevant for `indent-with-non-tab` and when Git fixes `tab-in-indent`
   errors. The default tab width is 8. Allowed values are 1 to 63.

apply.c

@@ -1640,6 +1640,14 @@ static void record_ws_error(struct apply_state *state,
 	    state->squelch_whitespace_errors < state->whitespace_error)
 		return;
 
+	/*
+	 * line[len] for an incomplete line points at the "\n" at the end
+	 * of patch input line, so "%.*s" would drop the last letter on line;
+	 * compensate for it.
+	 */
+	if (result & WS_INCOMPLETE_LINE)
+		len++;
+
 	err = whitespace_error_string(result);
 	if (state->apply_verbosity > verbosity_silent)
 		fprintf(stderr, "%s:%d: %s.\n%.*s\n",
@@ -1670,6 +1678,35 @@ static void check_old_for_crlf(struct patch *patch, const char *line, int len)
 }
 
 
+/*
+ * Just saw a single line in a fragment.  If it is a part of this hunk
+ * that is a context " ", an added "+", or a removed "-" line, it may
+ * be followed by "\\ No newline..." to signal that the last "\n" on
+ * this line needs to be dropped.  Depending on locale settings when
+ * the patch was produced we don't know what this line would exactly
+ * say. The only thing we do know is that it begins with "\ ".
+ * Checking for 12 is just for sanity check; "\ No newline..." would
+ * be at least that long in any l10n.
+ *
+ * Return 0 if the line we saw is not followed by "\ No newline...",
+ * or length of that line.  The caller will use it to skip over the
+ * "\ No newline..." line.
+ */
+static int adjust_incomplete(const char *line, int len,
+			     unsigned long size)
+{
+	int nextlen;
+
+	if (*line != '\n' && *line != ' ' && *line != '+' && *line != '-')
+		return 0;
+	if (size - len < 12 || memcmp(line + len, "\\ ", 2))
+		return 0;
+	nextlen = linelen(line + len, size - len);
+	if (nextlen < 12)
+		return 0;
+	return nextlen;
+}
+
 /*
  * Parse a unified diff. Note that this really needs to parse each
  * fragment separately, since the only way to know the difference
@@ -1684,6 +1721,7 @@ static int parse_fragment(struct apply_state *state,
 {
 	int added, deleted;
 	int len = linelen(line, size), offset;
+	int skip_len = 0;
 	unsigned long oldlines, newlines;
 	unsigned long leading, trailing;
 
@@ -1710,6 +1748,22 @@ static int parse_fragment(struct apply_state *state,
 		len = linelen(line, size);
 		if (!len || line[len-1] != '\n')
 			return -1;
+
+		/*
+		 * For an incomplete line, skip_len counts the bytes
+		 * on "\\ No newline..." marker line that comes next
+		 * to the current line.
+		 *
+		 * Reduce "len" to drop the newline at the end of
+		 * line[], but add one to "skip_len", which will be
+		 * added back to "len" for the next iteration, to
+		 * compensate.
+		 */
+		skip_len = adjust_incomplete(line, len, size);
+		if (skip_len) {
+			len--;
+			skip_len++;
+		}
 		switch (*line) {
 		default:
 			return -1;
@@ -1745,19 +1799,12 @@ static int parse_fragment(struct apply_state *state,
 			newlines--;
 			trailing = 0;
 			break;
+		}
 
-		/*
-		 * We allow "\ No newline at end of file". Depending
-		 * on locale settings when the patch was produced we
-		 * don't know what this line looks like. The only
-		 * thing we do know is that it begins with "\ ".
-		 * Checking for 12 is just for sanity check -- any
-		 * l10n of "\ No newline..." is at least that long.
-		 */
-		case '\\':
-			if (len < 12 || memcmp(line, "\\ ", 2))
-				return -1;
-			break;
+		/* eat the "\\ No newline..." as well, if exists */
+		if (skip_len) {
+			len += skip_len;
+			state->linenr++;
 		}
 	}
 	if (oldlines || newlines)
@@ -1768,14 +1815,6 @@ static int parse_fragment(struct apply_state *state,
 	fragment->leading = leading;
 	fragment->trailing = trailing;
 
-	/*
-	 * If a fragment ends with an incomplete line, we failed to include
-	 * it in the above loop because we hit oldlines == newlines == 0
-	 * before seeing it.
-	 */
-	if (12 < size && !memcmp(line, "\\ ", 2))
-		offset += linelen(line, size);
-
 	patch->lines_added += added;
 	patch->lines_deleted += deleted;