cpp: support directives within macro argument list

Undefined behavior by the standard but a GNU extension.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/u_io.c b/src/u_io.c
index 1dccb9d..2eada7e 100644
--- a/src/u_io.c
+++ b/src/u_io.c
@@ -562,6 +562,8 @@ vbfmt(WriteBuf *out, const char *fmt, va_list ap)
                   n += tok->len;
                } else if (aisprint(tok->t)) {
                   n += bputc(buf, tok->t);
+               } else if (tok->t == '\n') {
+                  n += bwriteS(buf, "<newline>");
                } else {
                   n += bwriteS(buf, "??");
                }