re PR c++/61636 (generic lambda: segfault / "cannot call member function without object")
PR c++/61636
* cp-tree.h (maybe_generic_this_capture): Declare.
* lambda.c (resolvable_dummy_lambda): New, broken out of ...
(maybe_resolve_dummy): ... here. Call it.
(maybe_generic_this_capture): New.
* parser.c (cp_parser_postfix_expression): Speculatively capture
this in generic lambda in unresolved member function call.
* pt.c (tsubst_copy_and_build): Force hard error from failed
member function lookup in generic lambda.