From c9834ea987879e45b15dce15ee53dbb80f83ca19 Mon Sep 17 00:00:00 2001
From: Alexey Dobriyan <adobriyan@gmail.com>
Date: Fri, 19 Mar 2010 12:48:57 +0200
Subject: [PATCH] acc: warn about trigraphs, do not replace

---
 main.c | 43 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/main.c b/main.c
index b9b62c7..93cee8a 100644
--- a/main.c
+++ b/main.c
@@ -11,12 +11,28 @@
 #include <inttypes.h>
 #include <string.h>
 
+struct pos {
+	unsigned int line, column;
+};
+
 #ifdef __GNUC__
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 #else
 #define __printf(a, b)
 #endif
 
+static void warning(struct pos *pos, const char *fmt, ...) __printf(2, 3);
+static void warning(struct pos *pos, const char *fmt, ...)
+{
+	va_list args;
+
+	fprintf(stderr, "%u:%u: warning: ", pos->line, pos->column);
+	va_start(args, fmt);
+	vfprintf(stderr, fmt, args);
+	va_end(args);
+	fputc('\n', stderr);
+}
+
 static void perror_exit(const char *fmt, ...) __printf(1, 2);
 static void perror_exit(const char *fmt, ...)
 {
@@ -163,10 +179,6 @@ static void fix_newline(uint32_t *c, unsigned int *nr_c)
 	}
 }
 
-struct pos {
-	unsigned int line, column;
-};
-
 static struct pos *line_column(const uint32_t *c, unsigned int nr_c)
 {
 	struct pos *pos;
@@ -192,6 +204,28 @@ static struct pos *line_column(const uint32_t *c, unsigned int nr_c)
 	return pos;
 }
 
+static void warn_trigraph(const uint32_t *c, unsigned int nr_c, struct pos *pos)
+{
+	unsigned int i;
+
+	i = 0;
+	while (i + 2 < nr_c) {
+		if (c[i] == '?' && c[i + 1] == '?') {
+			switch (c[i + 2]) {
+			case '=':case ')':case '!':
+			case '(':case '\'':case '>':
+			case '/':case '<':case '-':
+				warning(&pos[i], "trigraph sequence ??%c, ignoring", c[i + 2]);
+				i += 3;
+				break;
+			default:
+				i++;
+			}
+		} else
+			i++;
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	int fd;
@@ -234,6 +268,7 @@ int main(int argc, char *argv[])
 
 	fix_newline(c, &nr_c);
 	pos = line_column(c, nr_c);
+	warn_trigraph(c, nr_c, pos);
 
 	{
 		unsigned int i;
-- 
2.11.4.GIT