c++: ICE with redundant capture [PR108829]

c++: ICE with redundant capture [PR108829]

Here we crash in is_capture_proxy:

  /* Location wrappers should be stripped or otherwise handled by the
     caller before using this predicate.  */
  gcc_checking_assert (!location_wrapper_p (decl));

We only crash with the redundant capture:

  int abyPage = [=, abyPage] { ... }

because prune_lambda_captures is only called when there was a default
capture, and with [=] only abyPage won't be in LAMBDA_EXPR_CAPTURE_LIST.

The problem is that LAMBDA_CAPTURE_EXPLICIT_P wasn't propagated
correctly and so var_to_maybe_prune proceeded where it shouldn't.

Co-Authored by: Patrick Palka <ppalka@redhat.com>

	PR c++/108829

gcc/cp/ChangeLog:

	* pt.cc (prepend_one_capture): Set LAMBDA_CAPTURE_EXPLICIT_P.
	(tsubst_lambda_expr): Pass LAMBDA_CAPTURE_EXPLICIT_P to
	prepend_one_capture.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/lambda/lambda-108829-2.C: New test.
	* g++.dg/cpp0x/lambda/lambda-108829.C: New test.