Pass Truffle::CExt explicitly to C extension support

* Avoid polyglot import/export which are meant for the application.

Author: eregon

lib/truffle/truffle/cext.rb

@@ -1789,5 +1789,3 @@ def rb_sprintf(format, *args)
   end
 
 end
-
-Truffle::Interop.export(:ruby_cext, Truffle::CExt)

src/main/c/cext/ruby.c

@@ -33,8 +33,8 @@ void* rb_tr_nil;
 
 // Run when loading C-extension support
 
-void rb_tr_init(void) {
-  truffle_assign_managed(&rb_tr_cext, (void *)polyglot_import("ruby_cext"));
+void rb_tr_init(void *ruby_cext) {
+  truffle_assign_managed(&rb_tr_cext, ruby_cext);
   truffle_assign_managed(&rb_tr_undef, rb_tr_get_undef());
   truffle_assign_managed(&rb_tr_true, rb_tr_get_true());
   truffle_assign_managed(&rb_tr_false, rb_tr_get_false());

src/main/java/org/truffleruby/core/CoreLibrary.java

@@ -1349,6 +1349,10 @@ public DynamicObject getSystemCallErrorClass() {
         return systemCallErrorClass;
     }
 
+    public DynamicObject getTruffleModule() {
+        return truffleModule;
+    }
+
     public DynamicObject getTruffleInternalModule() {
         return truffleInternalModule;
     }

src/main/java/org/truffleruby/language/loader/FeatureLoader.java

@@ -17,10 +17,12 @@
 import com.oracle.truffle.api.interop.UnsupportedMessageException;
 import com.oracle.truffle.api.interop.UnsupportedTypeException;
 import com.oracle.truffle.api.nodes.Node;
+import com.oracle.truffle.api.object.DynamicObject;
 import com.oracle.truffle.api.source.SourceSection;
 
 import org.jcodings.Encoding;
 import org.jcodings.specific.UTF8Encoding;
+import org.truffleruby.Layouts;
 import org.truffleruby.RubyContext;
 import org.truffleruby.RubyLanguage;
 import org.truffleruby.cext.WrapNodeGen;
@@ -315,6 +317,8 @@ public void ensureCExtImplementationLoaded(String feature, RequireNode requireNo
             Metrics.printTime("before-load-cext-support");
             try {
                 requireNode.executeRequire("truffle/cext");
+                final DynamicObject truffleModule = context.getCoreLibrary().getTruffleModule();
+                final Object truffleCExt = Layouts.MODULE.getFields(truffleModule).getConstant("CExt").getValue();
 
                 final String rubySUpath = context.getRubyHome() + "/lib/cext/ruby.su";
                 final List<TruffleObject> libraries = loadCExtLibRuby(rubySUpath, feature);
@@ -324,7 +328,7 @@ public void ensureCExtImplementationLoaded(String feature, RequireNode requireNo
                 final TruffleObject initFunction = requireNode.findFunctionInLibraries(libraries, "rb_tr_init", rubySUpath);
                 final Node executeInitNode = Message.EXECUTE.createNode();
                 try {
-                    ForeignAccess.sendExecute(executeInitNode, initFunction);
+                    ForeignAccess.sendExecute(executeInitNode, initFunction, truffleCExt);
                 } catch (UnsupportedTypeException | ArityException | UnsupportedMessageException e) {
                     throw new JavaException(e);
                 }