PR c++/81197
	* cp-tree.h (cp_maybe_mangle_decomp): Declare.
	* decl.c (cp_maybe_mangle_decomp): New function.
	(cp_finish_decomp): Don't SET_DECL_ASSEMBLER_NAME here.
	* parser.c (cp_convert_range_for,
	cp_parser_decomposition_declaration): Call cp_maybe_mangle_decomp.
	* pt.c (tsubst_expr): Likewise.
	* mangle.c (find_decomp_unqualified_name): New function.
	(write_unqualified_name): Handle DECL_DECOMPOSITION_P
	where DECL_ASSEMBLER_NAME is already set.

	* g++.dg/cpp1z/decomp34.C: New test.

From-SVN: r255705