Issue #2142 - Support SuperProperty in field initializers

Based-on: m-c 1555037/2

5 files changed, 72 insertions, 16 deletions

diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index 931b414f10..47ea774f86 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -8029,6 +8029,13 @@ BytecodeEmitter::emitCreateFieldInitializers(ClassEmitter& ce, ListNode* obj)
             //          [stack] HOMEOBJ HERITAGE? ARRAY LAMBDA
             return false;
         }
+        if (initializer->funbox()->needsHomeObject()) {
+            MOZ_ASSERT(initializer->funbox()->function()->allowSuperProperty());
+            if (!ce.emitFieldInitializerHomeObject()) {
+                //          [stack] CTOR OBJ ARRAY LAMBDA
+                return false;
+            }
+        }
         if (!ce.emitStoreFieldInitializer()) {
             //          [stack] HOMEOBJ HERITAGE? ARRAY
             return false;
diff --git a/js/src/frontend/ObjectEmitter.cpp b/js/src/frontend/ObjectEmitter.cpp
index a13104870a..28cf4a1416 100644
--- a/js/src/frontend/ObjectEmitter.cpp
+++ b/js/src/frontend/ObjectEmitter.cpp
@@ -510,9 +510,25 @@ bool ClassEmitter::prepareForFieldInitializers(size_t numFields)
     return true;

 }

 

-bool ClassEmitter::emitStoreFieldInitializer()

+bool ClassEmitter::emitFieldInitializerHomeObject()

 {

     MOZ_ASSERT(classState_ == ClassState::FieldInitializers);

+    //          [stack] OBJ HERITAGE? ARRAY METHOD

+    if (!bce_->emit2(JSOP_INITHOMEOBJECT, isDerived_ ? 2 : 1)) {

+        //              [stack] OBJ HERITAGE? ARRAY METHOD

+        return false;

+    }

+

+#ifdef DEBUG

+    classState_ = ClassState::FieldInitializerWithHomeObject;

+#endif

+    return true;

+}

+

+bool ClassEmitter::emitStoreFieldInitializer()

+{

+    MOZ_ASSERT(classState_ == ClassState::FieldInitializers ||

+               classState_ == ClassState::FieldInitializerWithHomeObject);

     MOZ_ASSERT(fieldIndex_ < numFields_);

     //          [stack] HOMEOBJ HERITAGE? ARRAY METHOD

 

@@ -522,6 +538,9 @@ bool ClassEmitter::emitStoreFieldInitializer()
     }

 

     fieldIndex_++;

+#ifdef DEBUG

+    classState_ = ClassState::FieldInitializers;

+#endif

     return true;

 }

 

@@ -529,7 +548,8 @@ bool ClassEmitter::emitFieldInitializersEnd()
 {

     MOZ_ASSERT(propertyState_ == PropertyState::Start ||

                propertyState_ == PropertyState::Init);

-    MOZ_ASSERT(classState_ == ClassState::FieldInitializers);

+    MOZ_ASSERT(classState_ == ClassState::FieldInitializers ||

+               classState_ == ClassState::FieldInitializerWithHomeObject);

     MOZ_ASSERT(fieldIndex_ == numFields_);

 

     if (!initializersAssignment_->emitAssignment()) {

diff --git a/js/src/frontend/ObjectEmitter.h b/js/src/frontend/ObjectEmitter.h
index 2504947314..1ee6071fdd 100644
--- a/js/src/frontend/ObjectEmitter.h
+++ b/js/src/frontend/ObjectEmitter.h
@@ -536,7 +536,7 @@ class MOZ_RAII AutoSaveLocalStrictMode
 //

 //     ce.prepareForFieldInitializers(fields.length());

 //     for (auto field : fields) {

-//       emit(field.expr_method());

+//       emit(field.initializer_method());

 //       ce.emitStoreFieldInitializer();

 //     }

 //     ce.emitFieldInitializersEnd();

@@ -545,6 +545,18 @@ class MOZ_RAII AutoSaveLocalStrictMode
 //     ce.emitInitConstructor(/* needsHomeObject = */ false);

 //     ce.emitEnd(ClassEmitter::Kind::Expression);

 //

+//   `class X { field0 = super.method(); ... }`

+//     // after emitClass/emitDerivedClass

+//     ce.prepareForFieldInitializers(1);

+//     for (auto field : fields) {

+//       emit(field.initializer_method());

+//       if (field.initializer_contains_super_or_eval()) {

+//         ce.emitFieldInitializerHomeObject();

+//       }

+//       ce.emitStoreFieldInitializer();

+//     }

+//     ce.emitFieldInitializersEnd();

+//

 //   `m() {}` in class

 //     // after emitInitConstructor/emitInitDefaultConstructor

 //     ce.prepareForPropValue(Some(offset_of_m));

@@ -673,14 +685,24 @@ class MOZ_STACK_CLASS ClassEmitter : public PropertyEmitter
     //                                     |

     //     +-------------------------------+

     //     |

-    //     | prepareForFieldInitializers  +-------------------+

-    //     +----------------------------->| FieldInitializers |-+

-    //     |                              +-------------------+ |

-    //     |                                                    |

-    //     |  +-------------------------------------------------+

-    //     |  |

-    //     |  | (expr emitStoreFieldInitializer)*

-    //     |  |

+    //     | prepareForFieldInitializers

+    //     +-----------------------------+

+    //     |                             |

+    //     |                             |    +-------------------+

+    //     |      +--------------------->+--->| FieldInitializers |-+

+    //     |      |                           +-------------------+ |

+    //     |      |                                                 |

+    //     |      |      (emit initializer method)                  |

+    //     |      |   +<--------------------------------------------+

+    //     |      |   |

+    //     |      |   | emitFieldInitializerHomeObject  +--------------------------------+

+    //     |      |   +-------------------------------->| FieldInitializerWithHomeObject |-+

+    //     |      |   |                                 +--------------------------------+ |

+    //     |      |   |                                                                    |

+    //     |      |   +------------------------------------------------------------------->+

+    //     |      |                                                                        |

+    //     |      |     emitStoreFieldInitializer                                          |

+    //     |  +<--+<-----------------------------------------------------------------------+

     //     |  |

     //     |  | emitFieldInitializersEnd  +----------------------+

     //     |  +-------------------------->| FieldInitializersEnd |-+

@@ -714,9 +736,12 @@ class MOZ_STACK_CLASS ClassEmitter : public PropertyEmitter
         InitConstructor,

 

         // After calling prepareForFieldInitializers

-        // and 0 or more calls to emitFieldInitializersEnd.

+        // and 0 or more calls to emitStoreFieldInitializer.

         FieldInitializers,

 

+        // After calling emitFieldInitializerHomeObject

+        FieldInitializerWithHomeObject,

+

         // After calling emitFieldInitializersEnd.

         FieldInitializersEnd,

 

@@ -759,6 +784,7 @@ class MOZ_STACK_CLASS ClassEmitter : public PropertyEmitter
         const mozilla::Maybe<uint32_t>& classEnd);

 

     MOZ_MUST_USE bool prepareForFieldInitializers(size_t numFields);

+    MOZ_MUST_USE bool emitFieldInitializerHomeObject();

     MOZ_MUST_USE bool emitStoreFieldInitializer();

     MOZ_MUST_USE bool emitFieldInitializersEnd();

 

diff --git a/js/src/frontend/ParseNode.h b/js/src/frontend/ParseNode.h
index c4e6945e5a..554703da46 100644
--- a/js/src/frontend/ParseNode.h
+++ b/js/src/frontend/ParseNode.h
@@ -625,7 +625,7 @@ enum class FunctionSyntaxKind
     Expression,                                  // A non-arrow function expression.
     Statement,                                   // A named function appearing as a Statement.
     Arrow,
-    Method,
+    Method,                                      // Method of a class or object. Field initializers also desugar to methods.
     ClassConstructor,
     DerivedClassConstructor,
     Getter,
diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index e74a8d3ee9..b5044c6ca2 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -222,7 +222,6 @@ SharedContext::computeAllowSyntax(Scope* scope)
             allowSuperProperty_ = fun->allowSuperProperty();
             allowSuperCall_ = fun->isDerivedClassConstructor();
             if (funScope->isFieldInitializer()) {
-                allowSuperProperty_ = false;
                 allowSuperCall_ = false;
                 allowArguments_ = false;
             }
@@ -7975,14 +7974,14 @@ Parser<ParseHandler>::fieldInitializerOpt(HandleAtom propAtom, size_t& numFieldK
 
     // Create the anonymous function object.
     RootedFunction fun(context,
-                       newFunction(nullptr, FunctionSyntaxKind::Expression,
+                       newFunction(nullptr, FunctionSyntaxKind::Method,
                                    GeneratorKind::NotGenerator,
                                    FunctionAsyncKind::SyncFunction));
     if (!fun)
         return null();
 
     // Create the top-level field initializer node.
-    FunctionNodeType funNode = handler.newFunction(FunctionSyntaxKind::Expression, firstTokenPos);
+    FunctionNodeType funNode = handler.newFunction(FunctionSyntaxKind::Method, firstTokenPos);
     if (!funNode)
         return null();
 
@@ -8117,6 +8116,10 @@ Parser<ParseHandler>::fieldInitializerOpt(HandleAtom propAtom, size_t& numFieldK
 
     handler.setFunctionBody(funNode, initializerBody);
 
+    if (pc->superScopeNeedsHomeObject()) {
+        funbox->setNeedsHomeObject();
+    }
+
     if (!finishFunction(false, true))
         return null();