diff.c: migrate emit_line_checked to use emit_diff_symbol

Add a new flags field to emit_diff_symbol, that will be used by
context lines for:
* white space rules that are applicable (The first 12 bits)
  Take a note in cahe.c as well, when this ws rules are extended we have
  to fix the bits in the flags field.
* how the rules are evaluated (actually this double encodes the sign
  of the line, but the code is easier to keep this way, bits 13,14,15)
* if the line a blank line at EOF (bit 16)

The check if new lines need to be marked up as extra lines at the end of
file, is now done unconditionally. That should be ok, as
'new_blank_line_at_eof' has a quick early return.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/diff.h b/diff.h
index 2d442e2..ea66168 100644
--- a/diff.h
+++ b/diff.h
@@ -148,9 +148,9 @@ struct diff_options {
 	int abbrev;
 	int ita_invisible_in_index;
 /* white-space error highlighting */
-#define WSEH_NEW 1
-#define WSEH_CONTEXT 2
-#define WSEH_OLD 4
+#define WSEH_NEW (1<<12)
+#define WSEH_CONTEXT (1<<13)
+#define WSEH_OLD (1<<14)
 	unsigned ws_error_highlight;
 	const char *prefix;
 	int prefix_length;