bindTo first cut

gistfile1.diff

diff --git a/hphp/runtime/base/types.h b/hphp/runtime/base/types.h
--- a/hphp/runtime/base/types.h
+++ b/hphp/runtime/base/types.h
@@ -574,6 +574,7 @@
   AttrSkipFrame     = (1 << 22), //                     X    //
   AttrNative        = (1 << 23), //                     X    //
   AttrVMEntry       = (1 << 24), //                     X    //
+  AttrClonedClosure = (1 << 25), //                     X    //
 };
 
 inline Attr operator|(Attr a, Attr b) { return Attr((int)a | (int)b); }
diff --git a/hphp/runtime/ext/ext_closure.h b/hphp/runtime/ext/ext_closure.h
--- a/hphp/runtime/ext/ext_closure.h
+++ b/hphp/runtime/ext/ext_closure.h
@@ -58,6 +58,9 @@
 
 public: // ObjectData overrides
   void t___construct(); // must not be called for Closures
+  Variant t_bindto(CVarRef newthis, CVarRef newscope = "static");
+  static Variant ti_bind(CObjRef closureObj, CVarRef newthis,
+                         CVarRef newscope = "static");
 
 public:
 
diff --git a/hphp/runtime/ext/ext_closure.cpp b/hphp/runtime/ext/ext_closure.cpp
--- a/hphp/runtime/ext/ext_closure.cpp
+++ b/hphp/runtime/ext/ext_closure.cpp
@@ -78,5 +78,111 @@
   return closure;
 }
 
+Variant c_Closure::t_bindto(CVarRef newthis,
+                            CVarRef newscope /* = "static" */) {
+  return ti_bind(this, newthis, newscope);
+}
+
+Variant c_Closure::ti_bind(CObjRef closureObj, CVarRef newthis,
+                           CVarRef newscope /* = "static" */) {
+
+  if (RuntimeOption::RepoAuthoritative) {
+    throw NotSupportedException(__func__,
+      "bindTo won't work with RepoAuthoritative mode "
+      "(it breaks so many assumed invariants)"
+    );
+  }
+
+  if (closureObj.isNull()) {
+    raise_error("closureObj is null");
+  }
+
+  c_Closure* closure = static_cast<c_Closure*>(closureObj.get());
+  c_Closure* ret = static_cast<c_Closure*>(closure->clone());
+
+  if (newthis.isNull()) {
+    // A bit of a hack. The JIT assumes that for every BareThis opcode there is
+    // either a valid $this or a late bound class.
+    // Lets make it have a class instead of just nullptr.
+    ret->setClass(nullptr);
+  } else {
+    if (!newthis.isObject()) {
+      raise_warning("Closure::bind() expects parameter 1 to be object");
+      return null_variant;
+    } else if (closure->m_func->attrs() & AttrStatic) {
+      raise_warning("Cannot bind an instance to a static closure");
+    } else {
+      auto od = newthis.asCObjRef().get();
+      ret->setThis(od);
+      od->incRefCount();
+    }
+  }
+
+  Class* newClass = nullptr;
+  // Differentiate nullptr from "don't change the class"
+  bool leaveClass = false;
+
+  if (newscope.isString()) {
+    StringData* className = newscope.asCStrRef().get();
+    if (className->equal(s_static.get())) {
+      leaveClass = true;
+    } else {
+      newClass = Unit::lookupClass(className);
+      if (!newClass) {
+        raise_warning("Undefined class: %s", className->data());
+        return null_variant;
+      }
+    }
+  } else if (newscope.isObject()) {
+    newClass = newscope.asCObjRef()->getVMClass();
+  } else if (newscope.isNull()) {
+    newClass = nullptr;
+  } else {
+    raise_warning("newscope param is neither a string nor an object");
+    return null_variant;
+  }
+
+  if (auto od = ret->getThis()) {
+    if (newClass && !od->getVMClass()->classof(newClass)) {
+      raise_error(
+        "parameter 1 is not an instanceof class %s, its class is %s",
+        newClass->name()->data(),
+        od->getVMClass()->name()->data()
+      );
+    }
+  }
+
+  Func* clonedFunc = nullptr;
+
+  if (!leaveClass) {
+    clonedFunc = ret->m_func->cloneAndSetClass(newClass);
+    if (!ret->hasThis()) {
+      ret->setClass(newClass);
+    }
+  }
+
+  // php-5.4 only does this if we didn't already clone for some reason...
+  if (!clonedFunc) {
+    // Make the staticness of the class match hasThis()
+    bool isStatic = ret->m_func->attrs() & AttrStatic;
+    if (ret->hasThis() && isStatic) {
+      clonedFunc = ret->m_func->clone(ret->m_func->cls());
+      clonedFunc->setNewFuncId();
+      clonedFunc->setAttrs(Attr(ret->m_func->attrs() & ~AttrStatic));
+    } else if (!ret->hasThis() && !isStatic) {
+      clonedFunc = ret->m_func->clone(ret->m_func->cls());
+      clonedFunc->setNewFuncId();
+      clonedFunc->setAttrs(ret->m_func->attrs() | AttrStatic);
+    }
+  }
+
+  if (clonedFunc) {
+    clonedFunc->setAttrs(clonedFunc->attrs() | AttrClonedClosure);
+    ret->m_func = clonedFunc;
+  }
+
+  return ret;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 }
diff --git a/hphp/runtime/vm/func.h b/hphp/runtime/vm/func.h
--- a/hphp/runtime/vm/func.h
+++ b/hphp/runtime/vm/func.h
@@ -404,6 +404,10 @@
     return ((Func**)this)[-1 - (int)isGenerator()];
   }
 
+  bool isReboundClosureBody() const {
+    return isClosureBody() && attrs() & AttrClonedClosure;
+  }
+
   static void* allocFuncMem(
     const StringData* name, int numParams,
     bool needsGeneratorOrigFunc,
diff --git a/hphp/runtime/vm/jit/hhbc-translator.cpp b/hphp/runtime/vm/jit/hhbc-translator.cpp
--- a/hphp/runtime/vm/jit/hhbc-translator.cpp
+++ b/hphp/runtime/vm/jit/hhbc-translator.cpp
@@ -478,15 +478,15 @@
 }
 
 void HhbcTranslator::emitThis() {
-  if (!curClass()) {
+  if (!curClass() && !curFunc()->isReboundClosureBody()) {
     emitInterpOne(Type::Obj, 0); // will throw a fatal
     return;
   }
   pushIncRef(gen(LdThis, makeExitSlow(), m_tb->fp()));
 }
 
 void HhbcTranslator::emitCheckThis() {
-  if (!curClass()) {
+  if (!curClass() && !curFunc()->isReboundClosureBody()) {
     emitInterpOne(Type::None, 0); // will throw a fatal
     return;
   }
@@ -512,7 +512,7 @@
   // $this is null, we can be sure in the rest of the trace that we
   // have the this object on top of the stack, and we can eliminate
   // further null checks of this.
-  if (!curClass()) {
+  if (!curClass() && !curFunc()->isReboundClosureBody()) {
     emitInterpOne(Type::InitNull, 0); // will raise notice and push null
     return;
   }
diff --git a/hphp/system/idl/closure.idl.json b/hphp/system/idl/closure.idl.json
--- a/hphp/system/idl/closure.idl.json
+++ b/hphp/system/idl/closure.idl.json
@@ -21,6 +21,49 @@
                     ],
                     "args": [
                     ]
+                },
+                {
+                    "name": "bindTo",
+                    "return": {
+                        "type": "Variant"
+                    },
+                    "flags": [
+                    ],
+                    "args": [
+                        {
+                            "name": "newthis",
+                            "type": "Variant"
+                        },
+                        {
+                            "name": "newscope",
+                            "type": "Variant",
+                            "value": "\"static\""
+                        }
+                    ]
+                },
+                {
+                    "name": "bind",
+                    "return": {
+                        "type": "Variant"
+                    },
+                    "flags": [
+                        "IsStatic"
+                    ],
+                    "args": [
+                        {
+                            "name": "closure",
+                            "type": "Object"
+                        },
+                        {
+                            "name": "newthis",
+                            "type": "Variant"
+                        },
+                        {
+                            "name": "newscope",
+                            "type": "Variant",
+                            "value": "\"static\""
+                        }
+                    ]
                 }
             ],
             "consts": [
diff --git a/hphp/test/zend/bad/ext/session/tests/session_set_save_handler_closures.php.skipif b/hphp/test/zend/bad/ext/session/tests/session_set_save_handler_closures.php.skipif
new file mode 100644
--- /dev/null
+++ b/hphp/test/zend/bad/ext/session/tests/session_set_save_handler_closures.php.skipif
@@ -0,0 +1 @@
+<?php include('skipif.inc'); ?>
\ No newline at end of file
diff --git a/hphp/test/zend/good/ext/standard/tests/general_functions/ob_start_closures.php b/hphp/test/zend/good/ext/standard/tests/general_functions/ob_start_closures.php
--- a/hphp/test/zend/good/ext/standard/tests/general_functions/ob_start_closures.php
+++ b/hphp/test/zend/good/ext/standard/tests/general_functions/ob_start_closures.php
@@ -1,6 +1,4 @@
 <?php
-ini_set('output_buffering', 0);
-
 echo "*** Testing ob_start() : closures as output handlers ***\n";
 
 ob_start(function ($output) {