Fix autoload status of statically linked extensions

Previously, for statically-linked extensions, we used
`vm->loading_table` to delay calling the init function until the
extensions are required. This caused the extensions to look like they
are in the middle of being loaded even before they're required.
(`rb_feature_p()` returned true with a loading path output.) Combined
with autoload, queries like `defined?(CONST)` and `Module#autoload?`
were confused by this and returned nil incorrectly. RubyGems uses
`defined?` to detect if OpenSSL is available and failed when OpenSSL was
available in builds using `--with-static-linked-ext`.

Use a dedicated table for the init functions instead of adding them to
the loading table. This lets us remove some logic from non-EXTSTATIC
builds.

[Bug #19115]

load.c

@@ -850,14 +850,6 @@ load_lock(rb_vm_t *vm, const char *ftptr, bool warn)
         st_insert(loading_tbl, (st_data_t)ftptr, data);
         return (char *)ftptr;
     }
-    else if (imemo_type_p(data, imemo_memo)) {
-        struct MEMO *memo = MEMO_CAST(data);
-        void (*init)(void) = memo->u3.func;
-        data = (st_data_t)rb_thread_shield_new();
-        st_insert(loading_tbl, (st_data_t)ftptr, data);
-        (*init)();
-        return (char *)"";
-    }
     if (warn) {
         VALUE warning = rb_warning_string("loading in progress, circular require considered harmful - %s", ftptr);
         rb_backtrace_each(rb_str_append, warning);
@@ -1025,6 +1017,23 @@ search_required(rb_vm_t *vm, VALUE fname, volatile VALUE *path, feature_func rb_
     }
     tmp = fname;
     type = rb_find_file_ext(&tmp, ft == 's' ? ruby_ext : loadable_ext);
+#if EXTSTATIC
+    if (!ft && type != 1) { // not already a feature and not found as a dynamic library
+        VALUE lookup_name = tmp;
+        // Append ".so" if not already present so for example "etc" can find "etc.so".
+        // We always register statically linked extensions with a ".so" extension.
+        // See encinit.c and extinit.c (generated at build-time).
+        if (!ext) {
+            lookup_name = rb_str_dup(lookup_name);
+            rb_str_cat_cstr(lookup_name, ".so");
+        }
+        ftptr = RSTRING_PTR(lookup_name);
+        if (st_lookup(vm->static_ext_inits, (st_data_t)ftptr, NULL)) {
+            *path = rb_filesystem_str_new_cstr(ftptr);
+            return 's';
+        }
+    }
+#endif
     switch (type) {
       case 0:
         if (ft)
@@ -1063,6 +1072,20 @@ load_ext(VALUE path)
     return (VALUE)dln_load(RSTRING_PTR(path));
 }
 
+#if EXTSTATIC
+static bool
+run_static_ext_init(rb_vm_t *vm, const char *feature)
+{
+    st_data_t key = (st_data_t)feature;
+    st_data_t init_func;
+    if (st_delete(vm->static_ext_inits, &key, &init_func)) {
+        ((void (*)(void))init_func)();
+        return true;
+    }
+    return false;
+}
+#endif
+
 static int
 no_feature_p(rb_vm_t *vm, const char *feature, const char *ext, int rb, int expanded, const char **fn)
 {
@@ -1164,6 +1187,11 @@ require_internal(rb_execution_context_t *ec, VALUE fname, int exception, bool wa
             else if (!*ftptr) {
                 result = TAG_RETURN;
             }
+#if EXTSTATIC
+            else if (found == 's' && run_static_ext_init(th->vm, RSTRING_PTR(path))) {
+                result = TAG_RETURN;
+            }
+#endif
             else if (RTEST(rb_hash_aref(realpaths,
                                         realpath = rb_realpath_internal(Qnil, path, 1)))) {
                 result = 0;
@@ -1280,6 +1308,7 @@ rb_require(const char *fname)
     return rb_require_string(rb_str_new_cstr(fname));
 }
 
+#if EXTSTATIC
 static int
 register_init_ext(st_data_t *key, st_data_t *value, st_data_t init, int existing)
 {
@@ -1289,22 +1318,22 @@ register_init_ext(st_data_t *key, st_data_t *value, st_data_t init, int existing
         rb_warn("%s is already registered", name);
     }
     else {
-        *value = (st_data_t)MEMO_NEW(0, 0, init);
+        *value = (st_data_t)init;
-        *key = (st_data_t)ruby_strdup(name);
     }
     return ST_CONTINUE;
 }
 
-RUBY_FUNC_EXPORTED void
+void
 ruby_init_ext(const char *name, void (*init)(void))
 {
     rb_vm_t *vm = GET_VM();
-    st_table *loading_tbl = get_loading_table(vm);
+    st_table *inits_table = vm->static_ext_inits;
 
     if (feature_provided(vm, name, 0))
         return;
-    st_update(loading_tbl, (st_data_t)name, register_init_ext, (st_data_t)init);
+    st_update(inits_table, (st_data_t)name, register_init_ext, (st_data_t)init);
 }
+#endif
 
 /*
  *  call-seq:

test/ruby/test_autoload.rb

@@ -65,6 +65,24 @@ p Foo::Bar
     }
   end
 
+  def test_autoload_p_with_static_extensions
+    require 'rbconfig'
+    omit unless RbConfig::CONFIG['EXTSTATIC'] == 'static'
+    begin
+      require 'fcntl.so'
+    rescue LoadError
+      omit('fcntl not included in the build')
+    end
+
+    assert_separately(['--disable-all'], <<~RUBY)
+      autoload :Fcntl, 'fcntl.so'
+
+      assert_equal('fcntl.so', autoload?(:Fcntl))
+      assert(Object.const_defined?(:Fcntl))
+      assert_equal('constant', defined?(Fcntl), '[Bug #19115]')
+    RUBY
+  end
+
   def test_autoload_with_unqualified_file_name # [ruby-core:69206]
     Object.send(:remove_const, :A) if Object.const_defined?(:A)
 

vm.c

@@ -4005,6 +4005,9 @@ Init_vm_objects(void)
     vm->mark_object_ary = rb_ary_hidden_new(128);
     vm->loading_table = st_init_strtable();
     vm->frozen_strings = st_init_table_with_size(&rb_fstring_hash_type, 10000);
+#if EXTSTATIC
+    vm->static_ext_inits = st_init_strtable();
+#endif
 
 #ifdef HAVE_MMAP
     vm->shape_list = (rb_shape_t *)mmap(NULL, rb_size_mul_or_raise(SHAPE_BITMAP_SIZE * 32, sizeof(rb_shape_t), rb_eRuntimeError),

vm_core.h

@@ -538,6 +538,10 @@ struct rb_iseq_struct {
 
 #define ISEQ_BODY(iseq) ((iseq)->body)
 
+#ifndef EXTSTATIC
+#define EXTSTATIC 0
+#endif
+
 #ifndef USE_LAZY_LOAD
 #define USE_LAZY_LOAD 0
 #endif
@@ -704,6 +708,11 @@ typedef struct rb_vm_struct {
     VALUE loaded_features_realpaths;
     struct st_table *loaded_features_index;
     struct st_table *loading_table;
+#if EXTSTATIC
+    // For running the init function of statically linked
+    // extensions when they are loaded
+    struct st_table *static_ext_inits;
+#endif
 
     /* signal */
     struct {