1 files changed, 58 insertions, 25 deletions

diff --git a/src/debug.c b/src/debug.c
index c146719..0f0e0fe 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -3,16 +3,7 @@
 
 #include <posthaste/debug.h>
 
-/**
- * Find position in file buffer where line number \p no
- * starts. Lines are assumed to be one-indexed, with
- * \p no = \c 0 and \p no = \c 1 both considered the first line.
- *
- * @param buf Buffer to look in.
- * @param no Line number whose start to look for.
- * @return Pointer to location in buffer where line number \p no
- * starts.
- */
+/* find the start of line number no in buffer buf */
 static const char *find_lineno(const char *buf, size_t no)
 {
 	if (no == 0 || no == 1)
@@ -32,37 +23,79 @@ static const char *find_lineno(const char *buf, size_t no)
 	return buf;
 }
 
-void vsrc_issue(struct src_issue issue, const char *msg, va_list args)
+static void print_bar(int lineno_len)
 {
-	const char *line_start = find_lineno(issue.buf, issue.loc.first_line);
-	const char *line_end = strchr(line_start, '\n');
-	if (!line_end)
-		line_end = strchr(line_start, 0);
+	fprintf(stderr, "%*s", lineno_len + 4, "| ");
+}
+
+static void vsrc_multi_line(struct src_issue issue, const char *line_start, int lineno_len)
+{
+	/* just dump lines as they are, adding bars to the left */
+	size_t line = issue.loc.first_line;
+	for (size_t i = 0;; ++i) {
+		char c = line_start[i];
+		if (c == 0) {
+			fputc('\n', stderr);
+			break;
+		}
+
+		fputc(c, stderr);
+
+
+		if (c == '\n') {
+			if (++line > issue.loc.last_line)
+				break;
+
+			print_bar(lineno_len);
+		}
+	}
+}
 
-	int line_len = line_end - line_start;
+void vsrc_issue(struct src_issue issue, const char *msg, va_list args)
+{
+	/* with color support we could start coloring the actual error region at
+	 * issue.loc.first_column on issue.loc.first_line, but messing with
+	 * xterm color codes is a bit cumbersome so for now just stick to
+	 * monochrome */
 
-	fprintf(stderr, "%s:%i:%i: ", issue.fname,
+	fprintf(stderr, "%s:%i:%i: ",
+		issue.fname,
 	        issue.loc.first_line,
 	        issue.loc.first_col);
 
 	vfprintf(stderr, msg, args);
 	fputc('\n', stderr);
 
+	/* figure out how many spaces line number takes up */
 	int lineno_len = snprintf(NULL, 0, "%i", issue.loc.first_line);
-	fputc(' ', stderr);
-	fprintf(stderr, "%i | ", issue.loc.first_line);
+	fprintf(stderr, " %i | ", issue.loc.first_line);
+
+	const char *line_start = find_lineno(issue.buf, issue.loc.first_line);
+	if (issue.loc.first_line != issue.loc.last_line) {
+		/* multiline location requires slightly different handling */
+		return vsrc_multi_line(issue, line_start, lineno_len);
+	}
 
-	fprintf(stderr, "%.*s\n", line_len, line_start);
+	/* print the offending line */
+	for (size_t i = 0;; ++i) {
+		char c = line_start[i];
+		if (c == 0 || c == '\n')
+			break;
 
-	for (int i = 0; i < lineno_len + 2; ++i)
-		fputc(' ', stderr);
+		fputc(c, stderr);
+	}
+	fputc('\n', stderr);
 
-	fprintf(stderr, "| ");
+	/* the rest is just to print a little squiggly line to highlight exact location */
+	print_bar(lineno_len);
 
-	for (int i = 0; i < issue.loc.first_col - 1; ++i)
+	/* print tabs on tabs, otherwise spaces to make start of squiggle line
+	 * up with start of offending location */
+	for (size_t i = 0; i < issue.loc.first_col - 1; ++i)
 		fputc(line_start[i] == '\t' ? '\t' : ' ', stderr);
 
-	for (int i = issue.loc.first_col; i < issue.loc.last_col; ++i) {
+	/* highlight the offending location */
+	for (size_t i = issue.loc.first_col; i < issue.loc.last_col; ++i) {
 		if (i == issue.loc.first_col)
 			fputc('^', stderr);
 		else