Annex D (normative) Compatibility features [depr]

D.2 Implicit capture of *this by reference [depr.capture.this]

1
#
For compatibility with prior C++ International Standards, a lambda-expression with capture-default = ([expr.prim.lambda.capture]) may implicitly capture *this by reference.
[Example
: 
struct X {
  int x;
  void foo(int n) {
    auto f = [=]() { x = n; };          // deprecated: x means this->x, not a copy thereof
    auto g = [=, this]() { x = n; };    // recommended replacement
  }
};
— end example
]