[Webkit-unassigned] [Bug 236843] ReferenceError when using extra parens in class fields

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=236843

--- Comment #5 from Keith Miller <keith_miller at apple.com> ---
Looks like we're failing to create a lexical environment when the extra parens are there for some reason...

(function foo() {
  const a = (x) => x

  class B {
//    c = a('OK');
      c = a(('OK'));
  }

  // Should write 'OK'
  print(new B().c)
})()

produces the following byte code:

foo#CMKAuY:[0x1078f4130->0x107871300, NoneFunctionCall, 100]: 25 instructions (0 16-bit instructions, 0 32-bit instructions, 8 instructions with metadata); 216 bytes (116 metadata bytes); 1 parameter(s); 20 callee register(s); 7 variable(s); scope at loc4

bb#1
Predecessors: [ ]
[   0] enter
[   1] get_scope          dst:loc4
[   3] mov                dst:loc5, src:loc4
[   6] check_traps
[   7] mov                dst:loc6, src:callee
[  10] mov                dst:loc7, src:<JSValue()>(const0)
[  13] mov                dst:loc8, src:<JSValue()>(const0)
[  16] new_func_exp       dst:loc7, scope:loc4, functionDecl:0
[  20] mov                dst:loc9, src:<JSValue()>(const0)
[  23] new_func_exp       dst:loc10, scope:loc4, functionDecl:1
[  27] new_object         dst:loc11, inlineCapacity:0
[  31] define_data_property base:loc11, property:String (atomic),8Bit:(1),length:(11): constructor, StructureID: 16608(const1), value:loc10, attributes:Int32: 89(const2)
[  36] define_data_property base:loc10, property:String (atomic),8Bit:(1),length:(9): prototype, StructureID: 16608(const3), value:loc11, attributes:Int32: 74(const4)
[  41] new_func_exp       dst:loc12, scope:loc4, functionDecl:2
[  45] put_by_id          base:loc12, property:0, value:loc11, flags:Strict
[  51] put_by_id          base:loc10, property:1, value:loc12, flags:IsDirect|Strict
[  57] mov                dst:loc9, src:loc10
[  60] mov                dst:loc8, src:loc10
[  63] resolve_scope      dst:loc12, scope:loc4, var:2, resolveType:GlobalProperty, localScopeDepth:0
[  70] get_from_scope     dst:loc9, scope:loc12, var:2, getPutInfo:2048<ThrowIfNotFound|GlobalProperty|NotInitialization|NotStrictMode>, localScopeDepth:0, offset:0
[  78] mov                dst:loc14, src:loc8
[  81] construct          dst:loc13, callee:loc8, argc:1, argv:20
[  87] get_by_id          dst:loc11, base:loc13, property:3
[  92] call               dst:loc9, callee:loc9, argc:2, argv:18
[  98] ret                value:Undefined(const5)
Successors: [ ]

but if the comments are flipped we get:

foo#CpArJP:[0x103ff4130->0x103f71300, NoneFunctionCall, 113]: 27 instructions (0 16-bit instructions, 0 32-bit instructions, 9 instructions with metadata); 229 bytes (116 metadata bytes); 1 parameter(s); 20 callee register(s); 7 variable(s); scope at loc4

bb#1
Predecessors: [ ]
[   0] enter
[   1] get_scope          dst:loc4
[   3] mov                dst:loc5, src:loc4
[   6] check_traps
[   7] mov                dst:loc6, src:callee
[  10] create_lexical_environment dst:loc8, scope:loc4, symbolTable:Cell: 0x104100da8 (0x280004700:[0x4700/18176, SymbolTable, (0/0, 0/0){}, NonArray, Leaf]), StructureID: 18176(const0), initialValue:<JSValue()>(const1)
[  15] mov                dst:loc4, src:loc8
[  18] mov                dst:loc7, src:<JSValue()>(const1)
[  21] new_func_exp       dst:loc9, scope:loc4, functionDecl:0
[  25] put_to_scope       scope:loc8, var:0, value:loc9, getPutInfo:1049604<DoNotThrowIfNotFound|ResolvedClosureVar|ConstInitialization|NotStrictMode>, symbolTableOrScopeDepth:0, offset:0
[  33] mov                dst:loc9, src:<JSValue()>(const1)
[  36] new_func_exp       dst:loc10, scope:loc4, functionDecl:1
[  40] new_object         dst:loc11, inlineCapacity:0
[  44] define_data_property base:loc11, property:String (atomic),8Bit:(1),length:(11): constructor, StructureID: 16608(const2), value:loc10, attributes:Int32: 89(const3)
[  49] define_data_property base:loc10, property:String (atomic),8Bit:(1),length:(9): prototype, StructureID: 16608(const4), value:loc11, attributes:Int32: 74(const5)
[  54] new_func_exp       dst:loc12, scope:loc4, functionDecl:2
[  58] put_by_id          base:loc12, property:1, value:loc11, flags:Strict
[  64] put_by_id          base:loc10, property:2, value:loc12, flags:IsDirect|Strict
[  70] mov                dst:loc9, src:loc10
[  73] mov                dst:loc7, src:loc10
[  76] resolve_scope      dst:loc12, scope:loc4, var:3, resolveType:GlobalProperty, localScopeDepth:1
[  83] get_from_scope     dst:loc9, scope:loc12, var:3, getPutInfo:2048<ThrowIfNotFound|GlobalProperty|NotInitialization|NotStrictMode>, localScopeDepth:1, offset:0
[  91] mov                dst:loc14, src:loc7
[  94] construct          dst:loc13, callee:loc7, argc:1, argv:20
[ 100] get_by_id          dst:loc11, base:loc13, property:4
[ 105] call               dst:loc9, callee:loc9, argc:2, argv:18
[ 111] ret                value:Undefined(const6)
Successors: [ ]

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