had been fixed by upstream in commit

https://github.com/ruby/io-console/commit/dd013030dd276a7372df34cf43ada1c14d0cbc21

This patch is a cherry picked version.

From 3226f1e3cc4787d4a00e639ff763a8b4cfcd5cdd Mon Sep 17 00:00:00 2001
From: "Z. Liu" <zhixu.liu@gmail.com>
Date: Sun, 29 Jun 2025 21:41:42 +0800
Subject: [PATCH 1/2] [ruby/io-console]: add header "ruby/io.h" for rb_io_*
MIME-Version: 1.0
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otherwise, when compiling using gcc 15 with "-flto
-Werror=lto-type-mismatch", ext/io/console/extconf.h will have:

> #define HAVE_RB_IO_PATH 1
> #define HAVE_RB_IO_DESCRIPTOR 1
> #define HAVE_RB_IO_GET_WRITE_IO 1
> #define HAVE_RB_IO_CLOSED_P 1
> #define HAVE_RB_IO_OPEN_DESCRIPTOR 1

the build is failed with:

> console.c:1417:1: error: static declaration of ‘rb_io_closed_p’ follows non-static declaration
>  1417 | rb_io_closed_p(VALUE io)
>       | ^~~~~~~~~~~~~~
> ../../.././include/ruby/io.h:385:7: note: previous declaration of ‘rb_io_closed_p’ with type ‘VALUE(VALUE)’ {aka ‘long unsigned int(long unsigned int)’}
>   385 | VALUE rb_io_closed_p(VALUE io);
>       |       ^~~~~~~~~~~~~~

Signed-off-by: Z. Liu <zhixu.liu@gmail.com>

diff --git a/ext/io/console/extconf.rb b/ext/io/console/extconf.rb
index 4ad7ed6996..dd3d221ae5 100644
--- a/ext/io/console/extconf.rb
+++ b/ext/io/console/extconf.rb
@@ -10,11 +10,11 @@
   abort

 have_func("rb_interned_str_cstr")
-have_func("rb_io_path")
-have_func("rb_io_descriptor")
-have_func("rb_io_get_write_io")
-have_func("rb_io_closed_p")
-have_func("rb_io_open_descriptor")
+have_func("rb_io_path", "ruby/io.h")
+have_func("rb_io_descriptor", "ruby/io.h")
+have_func("rb_io_get_write_io", "ruby/io.h")
+have_func("rb_io_closed_p", "ruby/io.h")
+have_func("rb_io_open_descriptor", "ruby/io.h")
 have_func("rb_ractor_local_storage_value_newkey")
 
 is_wasi = /wasi/ =~ MakeMakefile::RbConfig::CONFIG["platform"]
-- 
2.45.2