From fd913546287ac1ec0eb0eb2a4ac38b2a4920b1d4 Mon Sep 17 00:00:00 2001
From: Yuta Saito <kateinoigakukun@gmail.com>
Date: Wed, 21 Feb 2024 10:17:13 +0000
Subject: [PATCH] [DOC] Comment about logic to care about static/dynamic hetero
 build

The condition is rarely met in usual cases, so it's worth to note about
the situation and the reason why we care about it.
---
 template/exts.mk.tmpl | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/template/exts.mk.tmpl b/template/exts.mk.tmpl
index 29c29df37c..e04fb50bbe 100644
--- a/template/exts.mk.tmpl
+++ b/template/exts.mk.tmpl
@@ -69,6 +69,13 @@ Dir.glob("{ext,.bundle/gems}/*/exts.mk") do |e|
   end
 end
 deps.uniq!
+
+# NOTE: Only if extensions are configured as static and dynamic heterogeneously
+# (e.g. --with-static-linked-ext=foo or ext/Setup can mix static and dynamic
+# extensions), EXTOBJS may contain both extinit.o and dmyext.o. In such case,
+# prefer extinit.o, which does actual Init_${ext} function calls for statically
+# linked extensions, and drop dmyext.o, which does nothing but just to make the
+# linker happy.
 if objs = macros["EXTOBJS"] and objs.any? {|e|e.start_with?("ext/extinit.")}
   objs.delete_if {|e|e.start_with?("dmyext.")}
 end