semantics.c (describable_type): New function.

gcc/cp:
        * semantics.c (describable_type): New function.
        (finish_decltype_type): Use it for dependent exprs.
        * cp-tree.h: Declare it.
        * mangle.c (write_type) [DECLTYPE_TYPE]: Set skip_evaluation.
        (write_expression): If skip_evaluation, use type stubs.
        * tree.c (cp_tree_equal): Handle PARM_DECLs from different
        declarations of a function.
        * init.c (build_new): Do auto deduction if type is describable.
        * decl.c (cp_finish_decl): Likewise.
        * parser.c (cp_parser_omp_for_loop): Likewise.
gcc/testsuite:
        * g++.dg/cpp0x/auto6.C: Test more stuff.
        * g++.dg/cpp0x/auto12.C: New test.
libiberty:
        * cp-demangle.c (d_expression): Handle rvalue stubs too.
        [DEMANGLE_COMPONENT_CAST]: Update mangling.
        (d_print_comp): Avoid extra ", " with empty template argument packs.
        Remove handling for obsolete T() mangling.

From-SVN: r142799