Annex D (normative) Compatibility features [depr]

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

For compatibility with prior revisions of C++, a lambda-expression with capture-default = ([expr.prim.lambda.capture]) may implicitly capture *this by reference.
[Example 1: 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]