Reset the API stack after a foreign constructor returns.

test/api/main.c

@@ -12,6 +12,7 @@
 #include "handle.h"
 #include "lists.h"
 #include "new_vm.h"
+#include "reset_stack_after_foreign_construct.h"
 #include "slots.h"
 
 // The name of the currently executing API test.
@@ -73,9 +74,11 @@ static WrenForeignClassMethods bindForeignClass(
   foreignClassBindClass(className, &methods);
   if (methods.allocate != NULL) return methods;
   
-  slotsBindClass(className, &methods);
+  resetStackAfterForeignConstructBindClass(className, &methods);
   if (methods.allocate != NULL) return methods;
   
+  slotsBindClass(className, &methods);
+  if (methods.allocate != NULL) return methods;
   
   fprintf(stderr,
           "Unknown foreign class '%s' for test '%s'\n", className, testName);
@@ -85,6 +88,10 @@ static WrenForeignClassMethods bindForeignClass(
 
 static void afterLoad(WrenVM* vm) {
   if (strstr(testName, "/call.wren") != NULL) callRunTests(vm);
+  if (strstr(testName, "/reset_stack_after_foreign_construct.wren") != NULL)
+  {
+    resetStackAfterForeignConstructRunTests(vm);
+  }
 }
 
 int main(int argc, const char* argv[])

test/api/reset_stack_after_foreign_construct.c

@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "foreign_class.h"
+
+static void counterAllocate(WrenVM* vm)
+{
+  double* counter = (double*)wrenSetSlotNewForeign(vm, 0, 0, sizeof(double));
+  *counter = wrenGetSlotDouble(vm, 1);
+}
+
+void resetStackAfterForeignConstructBindClass(
+    const char* className, WrenForeignClassMethods* methods)
+{
+  if (strcmp(className, "ResetStackForeign") == 0)
+  {
+    methods->allocate = counterAllocate;
+    return;
+  }
+}
+
+void resetStackAfterForeignConstructRunTests(WrenVM* vm)
+{
+  wrenEnsureSlots(vm, 1);
+  wrenGetVariable(vm, "main", "Test", 0);
+  WrenHandle* testClass = wrenGetSlotHandle(vm, 0);
+  
+  WrenHandle* callConstruct = wrenMakeCallHandle(vm, "callConstruct()");
+  WrenHandle* afterConstruct = wrenMakeCallHandle(vm, "afterConstruct(_,_)");
+  
+  wrenEnsureSlots(vm, 1);
+  wrenSetSlotHandle(vm, 0, testClass);
+  wrenCall(vm, callConstruct);
+
+  wrenEnsureSlots(vm, 3);
+  wrenSetSlotHandle(vm, 0, testClass);
+  wrenSetSlotDouble(vm, 1, 1.0);
+  wrenSetSlotDouble(vm, 2, 2.0);
+  wrenCall(vm, afterConstruct);
+  
+  wrenReleaseHandle(vm, testClass);
+  wrenReleaseHandle(vm, callConstruct);
+  wrenReleaseHandle(vm, afterConstruct);
+}

test/api/reset_stack_after_foreign_construct.h

@@ -0,0 +1,5 @@
+#include "wren.h"
+
+void resetStackAfterForeignConstructBindClass(
+    const char* className, WrenForeignClassMethods* methods);
+void resetStackAfterForeignConstructRunTests(WrenVM* vm);

test/api/reset_stack_after_foreign_construct.wren

@@ -0,0 +1,18 @@
+// Regression test.
+//
+// After a foreign constructor was called, it did not reset the API stack. If
+// you tried to immediately reuse the API stack by calling wrenCall(), it
+// would be in a broken state.
+foreign class ResetStackForeign {
+  construct new(a) {}
+}
+
+class Test {
+  static callConstruct() {
+    ResetStackForeign.new(1)
+  }
+
+  static afterConstruct(a, b) {
+    System.print(a + b) // expect: 3
+  }
+}