Add comments to dmydln.c, dmyenc.c, and dmyext.c

They are used conditionally in miniruby, dynamically-linked ruby, and
statically-linked ruby (--with-static-linked-ext).
I asked @nobu about the conditions. and I leave comments because the
conditions are insanely difficult.

1 files changed, 5 insertions, 0 deletions

diff --git a/dmyext.c b/dmyext.c
index 4d273f7faf..0020246529 100644
--- a/dmyext.c
+++ b/dmyext.c
@@ -1,3 +1,8 @@
+// This file is used by dynamically-linked ruby and miniruby.
+// miniruby uses this Init_ext, which does nothing. It does not support require'ing extension libraries.
+// Dynamically-linked ruby uses this Init_ext, which does nothing. It loads extension libraries by dlopen, etc.
+// Statically-linked ruby does not use this Init_ext. Instead, "ext/extinit.c" (which is a generated file) defines Init_ext, which activates the (statically-linked) extension libraries.
+
 void
 Init_ext(void)
 {