From 45456733aa634ffe68d538a509692f331c5803c2 Mon Sep 17 00:00:00 2001
From: Bob Nystrom <robert@stuffwithstuff.com>
Date: Mon, 30 Dec 2013 07:30:50 -0800
Subject: [PATCH] Fix a few GC bugs.

Adding a to a symbol table can trigger a GC, so we need to make
sure we don't do that while sitting on an unpinned object.
---
 src/wren_compiler.c | 6 ++----
 src/wren_core.c     | 8 +++++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/wren_compiler.c b/src/wren_compiler.c
index 47bbeb6f..26000e62 100644
--- a/src/wren_compiler.c
+++ b/src/wren_compiler.c
@@ -324,10 +324,8 @@ static void writeBuffer(WrenVM* vm, Buffer* buffer, uint8_t byte)
 
 static void freeBuffer(WrenVM* vm, Buffer* buffer)
 {
-  wrenReallocate(vm, buffer->bytes, buffer->capacity, 0);
-  buffer->bytes = NULL;
-  buffer->capacity = 0;
-  buffer->length = 0;
+  wrenReallocate(vm, buffer->bytes, 0, 0);
+  initBuffer(vm, buffer);
 }
 
 // Initializes [compiler].
diff --git a/src/wren_core.c b/src/wren_core.c
index 5c073407..9962a81c 100644
--- a/src/wren_core.c
+++ b/src/wren_core.c
@@ -476,8 +476,10 @@ DEF_NATIVE(os_clock)
 
 static ObjClass* defineClass(WrenVM* vm, const char* name)
 {
-  ObjClass* classObj = wrenNewClass(vm, vm->objectClass, 0);
+  // Add the symbol first since it can trigger a GC.
   int symbol = addSymbol(vm, &vm->globalSymbols, name, strlen(name));
+
+  ObjClass* classObj = wrenNewClass(vm, vm->objectClass, 0);
   vm->globals[symbol] = OBJ_VAL(classObj);
   return classObj;
 }
@@ -486,9 +488,9 @@ void wrenInitializeCore(WrenVM* vm)
 {
   // Define the root Object class. This has to be done a little specially
   // because it has no superclass and an unusual metaclass (Class).
-  vm->objectClass = wrenNewSingleClass(vm, 0);
   int objectSymbol = addSymbol(vm, &vm->globalSymbols,
                                "Object", strlen("Object"));
+  vm->objectClass = wrenNewSingleClass(vm, 0);
   vm->globals[objectSymbol] = OBJ_VAL(vm->objectClass);
 
   NATIVE(vm->objectClass, "== ", object_eqeq);
@@ -499,9 +501,9 @@ void wrenInitializeCore(WrenVM* vm)
 
   // Now we can define Class, which is a subclass of Object, but Object's
   // metaclass.
-  vm->classClass = wrenNewSingleClass(vm, 0);
   int classSymbol = addSymbol(vm, &vm->globalSymbols,
                               "Class", strlen("Class"));
+  vm->classClass = wrenNewSingleClass(vm, 0);
   vm->globals[classSymbol] = OBJ_VAL(vm->classClass);
 
   // Now that Object and Class are defined, we can wire them up to each other.