ruby.h: relax rb_funcall check on extra args for clang

clang 5.+ (tested clang 7.0.0) seems to be attempting division-by-zero
and giving a very large number for static args to rb_funcall.

* include/ruby/ruby.h (rb_varargs_bad_length): relax check for clang
* ext/-test-/funcall/funcall.c: renamed from passing_block.c
  define extra_args_name function
* test/-ext-/funcall/test_funcall.rb: new test
  [ruby-core:85266] [Bug #14425]

From: Eric Wong <e@80x24.org>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62116 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 44 insertions, 0 deletions

diff --git a/ext/-test-/funcall/funcall.c b/ext/-test-/funcall/funcall.c
new file mode 100644
index 0000000000..4e13c952e5
--- /dev/null
+++ b/ext/-test-/funcall/funcall.c
@@ -0,0 +1,44 @@
+#include "ruby.h"
+
+VALUE rb_funcall_passing_block(VALUE, ID, int, const VALUE*);
+
+static VALUE
+with_funcall2(int argc, VALUE *argv, VALUE self)
+{
+    return rb_funcallv(self, rb_intern("target"), argc, argv);
+}
+
+static VALUE
+with_funcall_passing_block(int argc, VALUE *argv, VALUE self)
+{
+    return rb_funcall_passing_block(self, rb_intern("target"), argc, argv);
+}
+
+static VALUE
+extra_args_name(VALUE self)
+{
+    /*
+     * at least clang 5.x gets tripped by the extra 0 arg
+     * [ruby-core:85266] [Bug #14425]
+     */
+    return rb_funcall(self, rb_intern("name"), 0, 0);
+}
+
+void
+Init_funcall(void)
+{
+    VALUE cTestFuncall = rb_path2class("TestFuncall");
+    VALUE cRelay = rb_define_module_under(cTestFuncall, "Relay");
+
+    rb_define_singleton_method(cRelay,
+			       "with_funcall2",
+			       with_funcall2,
+			       -1);
+    rb_define_singleton_method(cRelay,
+			       "with_funcall_passing_block",
+			       with_funcall_passing_block,
+			       -1);
+    rb_define_singleton_method(cTestFuncall, "extra_args_name",
+                                extra_args_name,
+                                0);
+}