re PR c++/80370 (ICE when using structured bindings and nested generic lambdas (tsubst_decomp_names))

	PR c++/80370
	* decl.c (cp_finish_decomp): If processing_template_decl on
	non-dependent decl, only set TREE_TYPE on the v[i] decls, but don't
	change their DECL_VALUE_EXPR nor cp_finish_decl them.  Instead make
	sure DECL_VALUE_EXPR is the canonical NULL type ARRAY_REF for tsubst
	processing.
	* pt.c (value_dependent_expression_p) <case VAR_DECL>: For variables
	with DECL_VALUE_EXPR, return true if DECL_VALUE_EXPR is type
	dependent.

	* g++.dg/cpp1z/decomp28.C: New test.

From-SVN: r246857