Database#enable_load_extension def only if extensions are available

On some platforms where dlopen can't be found at build time,
HAVE_SQLITE3_LOAD_EXTENSION is false by
HAVE_SQLITE3_ENABLE_LOAD_EXTENSION could still be true.

Only define `enable_load_extension` if both are true.

Author: flavorjones

ext/sqlite3/database.c

@@ -789,7 +789,7 @@ load_extension_internal(VALUE self, VALUE file)
 }
 #endif
 
-#ifdef HAVE_SQLITE3_ENABLE_LOAD_EXTENSION
+#if defined(HAVE_SQLITE3_ENABLE_LOAD_EXTENSION) && defined(HAVE_SQLITE3_LOAD_EXTENSION)
 /* call-seq: db.enable_load_extension(onoff)
  *
  * Enable or disable extension loading.
@@ -992,11 +992,11 @@ init_sqlite3_database(void)
 
 #ifdef HAVE_SQLITE3_LOAD_EXTENSION
     rb_define_private_method(cSqlite3Database, "load_extension_internal", load_extension_internal, 1);
-#endif
-
 #ifdef HAVE_SQLITE3_ENABLE_LOAD_EXTENSION
     rb_define_method(cSqlite3Database, "enable_load_extension", enable_load_extension, 1);
 #endif
+#endif
+
 
     rb_sqlite3_aggregator_init();
 }

test/test_database.rb

@@ -667,16 +667,27 @@ def test_strict_mode
       assert_match(/no such column: "?nope"?/, error.message)
     end
 
+    def test_load_extension_is_defined_on_expected_platforms
+      if ::RUBY_PLATFORM =~ /mingw|mswin/ &&
+          SQLite3::SQLITE_PACKAGED_LIBRARIES &&
+          !SQLite3::SQLITE_PRECOMPILED_LIBRARIES
+        skip("as of sqlite 3.48.0, the autoconf amalgamation does not reliably find dlopen" \
+             "on windows when building sqlite from source")
+      end
+      assert_respond_to(db, :load_extension)
+      assert_respond_to(db, :enable_load_extension)
+    end
+
     def test_load_extension_error_with_nonexistent_path
-      skip("extensions are not enabled") unless db.respond_to?(:load_extension)
+      skip("extensions are not enabled") unless db.respond_to?(:enable_load_extension)
       db.enable_load_extension(true)
 
       assert_raises(SQLite3::Exception) { db.load_extension("/nonexistent/path") }
       assert_raises(SQLite3::Exception) { db.load_extension(Pathname.new("nonexistent")) }
     end
 
     def test_load_extension_error_with_invalid_argument
-      skip("extensions are not enabled") unless db.respond_to?(:load_extension)
+      skip("extensions are not enabled") unless db.respond_to?(:enable_load_extension)
       db.enable_load_extension(true)
 
       assert_raises(TypeError) { db.load_extension(1) }
@@ -686,6 +697,8 @@ def test_load_extension_error_with_invalid_argument
     end
 
     def test_load_extension_with_an_extension_descriptor
+      skip("extensions are not enabled") unless db.respond_to?(:enable_load_extension)
+
       mock_database_load_extension_internal(db)
 
       db.load_extension(Pathname.new("/path/to/ext2"))
@@ -698,7 +711,10 @@ def test_load_extension_with_an_extension_descriptor
     end
 
     def test_initialize_extensions_with_extensions_calls_enable_load_extension
+      skip("extensions are not enabled") unless db.respond_to?(:enable_load_extension)
+
       mock_database_load_extension_internal(db)
+
       class << db
         attr_accessor :enable_load_extension_called
         attr_reader :enable_load_extension_arg
@@ -734,6 +750,8 @@ def enable_load_extension(val)
     end
 
     def test_initialize_extensions_object_is_an_extension_specifier
+      skip("extensions are not enabled") unless db.respond_to?(:enable_load_extension)
+
       mock_database_load_extension_internal(db)
 
       db.initialize_extensions([Pathname.new("/path/to/extension")])
@@ -746,6 +764,8 @@ def test_initialize_extensions_object_is_an_extension_specifier
     end
 
     def test_initialize_extensions_object_not_an_extension_specifier
+      skip("extensions are not enabled") unless db.respond_to?(:enable_load_extension)
+
       mock_database_load_extension_internal(db)
 
       db.initialize_extensions(["/path/to/extension"])