Commit: patch 9.1.2039: if_ruby: crash when using Ruby/dyn 4.0

[Christian Brabandt]

patch 9.1.2039: if_ruby: crash when using Ruby/dyn 4.0

Commit: https://github.com/vim/vim/commit/871d2cc2ef4e32b091368a9b1e197b00ff664f08
Author: Yee Cheng Chin <ychi...@gmail.com>
Date: Thu Jan 1 16:25:10 2026 +0000

patch 9.1.2039: if_ruby: crash when using Ruby/dyn 4.0

Problem: if_ruby: crash when using Ruby/dyn 4.0
(after v9.1.2036)
Solution: Fix Ruby 4.0 dynamic builds correctly by inlining
rb_check_typeddata (Yee Cheng Chin)

Ruby 4.0 broke Vim compilation in dynamic builds. That's because the
function `rb_check_typeddata` is now used in an inline function defined
in Ruby headers, which causes it to link against the lib statically
rather than using the one we load in dynamically
(`dll_rb_check_typeddata`) as we only remap it later (after the Ruby
header include).

A previous fix (v9.1.2036) did a wrong fix by stubbing in the actual
inline function `rbimpl_check_typeddata` instead. This does not work
because the inline function is not part of the dynamic lib and therefore
it's not possible to load it in dynamically (the patch also did not
actually attempt to load in the stub). With that patch, Vim would
crash when this function is used as the function pointer is null.

Fix this properly by reverting the previous change, and simply stub
`rb_check_typeddata` using similar mechanisms the file had already set
up for similar situations.

fixes: #18884
related: #19051
closes: #19060

Signed-off-by: Yee Cheng Chin <ychi...@gmail.com>
Signed-off-by: Christian Brabandt <c...@256bit.org>

diff --git a/src/if_ruby.c b/src/if_ruby.c
index 49fdc34dd..913936174 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -73,6 +73,11 @@
# define rb_num2int rb_num2int_stub
# endif

+# if RUBY_VERSION >= 20
+// USE_TYPEDDATA is not defined yet. We just check for 2.0.
+# define rb_check_typeddata rb_check_typeddata_stub
+#endif
+
# if RUBY_VERSION == 21
// Ruby 2.1 adds new GC called RGenGC and RARRAY_PTR uses
// rb_gc_writebarrier_unprotect_promoted if USE_RGENGC
@@ -243,12 +248,6 @@ static int ruby_convert_to_vim_value(VALUE val, typval_T *rettv);
# if RUBY_VERSION < 30
# define rb_check_type dll_rb_check_type
# endif
-# ifdef USE_TYPEDDATA
-# if RUBY_VERSION >= 40
-# define rbimpl_check_typeddata dll_rbimpl_check_typeddata
-# endif
-# define rb_check_typeddata dll_rb_check_typeddata
-# endif
# define rb_class_path dll_rb_class_path
# ifdef USE_TYPEDDATA
# if RUBY_VERSION >= 23
@@ -376,9 +375,6 @@ VALUE *dll_rb_cTrueClass;
static VALUE (*dll_rb_class_new_instance) (int,VALUE*,VALUE);
static void (*dll_rb_check_type) (VALUE,int);
# ifdef USE_TYPEDDATA
-# if RUBY_VERSION >= 40
-static void *(*dll_rbimpl_check_typeddata) (VALUE,const rb_data_type_t *);
-# endif
static void *(*dll_rb_check_typeddata) (VALUE,const rb_data_type_t *);
# endif
static VALUE (*dll_rb_class_path) (VALUE);
@@ -607,6 +603,12 @@ rb_unexpected_type_stub(VALUE self, int t)
dll_rb_unexpected_type(self, t);
}
# endif
+# ifdef USE_TYPEDDATA
+void *rb_check_typeddata_stub(VALUE obj, const rb_data_type_t *data_type)
+{
+ return dll_rb_check_typeddata(obj, data_type);
+}
+# endif
# endif // ifndef PROTO

static HINSTANCE hinstRuby = NULL; // Instance of ruby.dll
diff --git a/src/version.c b/src/version.c
index 76b823a31..99804297e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -734,6 +734,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 2039,
/**/
2038,
/**/