Re: PATCH RFA: Avoid enum bitfield in C++ frontend

[Ian Lance Taylor <iant at google dot com>]

And now with the patch.

Ian

On Mon, Apr 13, 2009 at 1:28 PM, Ian Lance Taylor <iant@google.com> wrote:
> In C++, this kind of code is invalid:
>
> enum e { A = 1, B = 2, C = 4 };
> extern void f1(enum e);
> void f2() { f1(A | B); }
>
> The expression A | B has type "int", not type "enum e". ?Passing an int
> to a function which expects an enum is an invalid conversion in C++.
>
> gcc's C++ frontend uses this construct all over the place in the form of
> the tsubst_flags_t enum. ?The values are bitmasks (tf_error, tf_warning,
> etc.) which are or'ed together. ?The functions which take combinations
> of these bits are declared with the type tsubst_flags_t.
>
> I have an unsubmitted patch to the C frontend which makes cases like
> this an error when using -Wc++-compat. ?In preparation for submitting
> that patch, I would like to clean up the C++ frontend.
>
> The patch in this e-mail messages changes tsubst_flags_t to int. ?It
> eliminates the tsubst_flags_t typedef. ?Since type names ending in "_t"
> are reserved by POSIX, I also renamed the enum type (the "_t" is
> probably OK in C but probably not OK in C++).
>
> This is how I think the code looks best--I don't see a need for a
> special type to hold this combination of bitfields. ?However, it would
> be a smaller change to let the C++ frontend continue to use
> tsubst_flags_t, and simply do "typedef int tsubst_flags_t". ?If the C++
> frontend maintainers would prefer that patch, I can do that instead.
>
> This patch was bootstrapped and tested on i686-pc-linux-gnu.
>
> OK for mainline?
>
> Ian
>
>
> 2009-04-13 ?Ian Lance Taylor ?<iant@google.com>
>
> ? ? ? ?* cp-tree.h (enum tsubst_flags): Rename from enum tsubst_flags_t.
> ? ? ? ?(tsubst_flags_t): Remove typedef.
> ? ? ? ?* cp-tree.h: Change parameter types from tsubst_flags_t to int in
> ? ? ? ?declarations.
> ? ? ? ?* call.c (standard_conversion): Change tflags from tsubst_flags_t
> ? ? ? ?to int.
> ? ? ? ?(build_new_function_call): Change parameter type from
> ? ? ? ?tsubst_flags_t to int.
> ? ? ? ?(build_object_call, build_conditional_expr): Likewise.
> ? ? ? ?(build_new_op, convert_like_real, build_over_call): Likewise.
> ? ? ? ?(build_special_member_call, build_new_method_call): Likewise.
> ? ? ? ?(perform_implicit_conversion): Likewise.
> ? ? ? ?(perform_direct_initialization_if_possible): Likewise.
> ? ? ? ?* class.c (resolve_address_of_overloaded_function): Likewise.
> ? ? ? ?(instantiate_type): Likewise.
> ? ? ? ?* cp-lang.c (objcp_tsubst_copy_and_build): Likewise.
> ? ? ? ?* cvt.c (convert_to_void): Likewise.
> ? ? ? ?* decl.c (make_typename_type): Likewise.
> ? ? ? ?(make_unbound_class_template): Likewise.
> ? ? ? ?* init.c (build_aggr_init): Likewise.
> ? ? ? ?(expand_default_init, expand_aggr_init_1): Likewise.
> ? ? ? ?(build_new_1, build_new, build_vec_init): Likewise.
> ? ? ? ?* pt.c (reduce_template_parm_level): Likewise.
> ? ? ? ?(coerce_template_template_parm): Likewise.
> ? ? ? ?(coerce_template_template_parms): Likewise.
> ? ? ? ?(convert_template_argument): Likewise.
> ? ? ? ?(coerce_template_parameter_pack): Likewise.
> ? ? ? ?(coerce_template_parms, lookup_template_class): Likewise.
> ? ? ? ?(apply_late_template_attributes): Likewise.
> ? ? ? ?(tsubst_template_arg, tsubst_pack_expansion): Likewise.
> ? ? ? ?(tsubst_template_args, tsubst_template_parms): Likewise.
> ? ? ? ?(tsubst_aggr_type, tsubst_decl, tsubst_arg_types): Likewise.
> ? ? ? ?(tsubst_function_type, tsubst_exception_specification): Likewise.
> ? ? ? ?(tsubst, tsubst_baselink, tsubst_copy): Likewise.
> ? ? ? ?(tsubst_omp_clauses, tsubst_copy_asm_operands): Likewise.
> ? ? ? ?(tsubst_omp_for_iterator, tsubst_expr): Likewise.
> ? ? ? ?(tsubst_non_call_postfix_expression): Likewise.
> ? ? ? ?(tsubst_copy_and_build): Likewise.
> ? ? ? ?(check_instantiated_arg, check_instantiated_args): Likewise.
> ? ? ? ?(instantiate_template, do_type_instantiation): Likewise.
> ? ? ? ?(invalid_nontype_parm_type_p): Likewise.
> ? ? ? ?* rtti.c (build_dynamic_cast_1): Likewise.
> ? ? ? ?(build_dynamic_cast): Likewise.
> ? ? ? ?* semantics.c (finish_call_expr): Likewise.
> ? ? ? ?* tree.c (cp_build_qualified_type_real): Likewise.
> ? ? ? ?* typeck.c (composite_pointer_type_r): Likewise.
> ? ? ? ?(composite_pointer_type, cxx_sizeof_expr): Likewise.
> ? ? ? ?(cxx_alignof_expr, invalid_nonstatic_memfn_p): Likewise.
> ? ? ? ?(rationalize_conditional_expr): Likewise.
> ? ? ? ?(build_class_member_access_expr): Likewise.
> ? ? ? ?(finish_class_member_access_expr): Likewise.
> ? ? ? ?(build_x_indirect_ref, cp_build_indirect_ref): Likewise.
> ? ? ? ?(cp_build_function_call, convert_arguments): Likewise.
> ? ? ? ?(build_x_binary_op, build_x_array_ref): Likewise.
> ? ? ? ?(cp_build_binary_op, build_x_unary_op): Likewise.
> ? ? ? ?(cp_build_unary_op, build_x_conditional_expr): Likewise.
> ? ? ? ?(build_x_compound_expr, cp_build_compound_expr): Likewise.
> ? ? ? ?(build_static_cast_1, build_static_cast): Likewise.
> ? ? ? ?(build_reinterpret_cast_1, build_reinterpret_cast): Likewise.
> ? ? ? ?(build_const_cast, cp_build_c_cast): Likewise.
> ? ? ? ?(cp_build_modify_expr, build_x_modify_expr): Likewise.
> ? ? ? ?(convert_for_assignment, convert_for_initialization): Likewise.
> ? ? ? ?(lvalue_or_else): Likewise.
> ? ? ? ?* typeck2.c (build_functional_cast): Likewise.
> ? ? ? ?* cp-objcp-common.h (objcp_tsubst_copy_and_build): Update
> ? ? ? ?declaration.
>

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