c++: constrained auto in lambda using outer tparms [PR103706]
Here we're crashing during satisfaction of the lambda's placeholder type
constraints because the constraints depend on the template arguments
from the enclosing scope, which aren't part of the lambda's DECL_TI_ARGS.
This patch fixes this by making do_auto_deduction consider the
"regenerating" template arguments of a lambda for satisfaction,
mirroring what's done in satisfy_declaration_constraints.
PR c++/103706
gcc/cp/ChangeLog:
* constraint.cc (satisfy_declaration_constraints): Use
lambda_regenerating_args instead.
* cp-tree.h (lambda_regenerating_args): Declare.
* pt.cc (lambda_regenerating_args): Define, split out from
satisfy_declaration_constraints.
(do_auto_deduction): Use lambda_regenerating_args to obtain the
full set of outer template arguments for satisfaction when
inside a lambda.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-lambda18.C: New test.