On Mon, Feb 01, 2016 at 03:37:18AM +0100, Nicolai Stange wrote:
> Initializers of static storage duration objects shall be constant
> expressions [6.7.8(4)].
>
> Warn if that requirement is not met and the -Wstatic-initializer-not-const
> flag has been given on sparse's command line.
"-Wstatic-initializer-not-const" s not what is used further in the code.
Also, I think it should be better to introduce this new -W flag in a separate
patch.
> Identify static storage duration objects by having either of
> MOD_TOPLEVEL or MOD_STATIC set.
>
> Check an initializer's constness at the lowest possible subobject
> level, i.e. at the level of the "assignment-expression" production
> in [6.7.8].
>
> For compound objects, make handle_list_initializer() pass the
> surrounding object's storage duration modifiers down to
> handle_simple_initializer() at subobject initializer evaluation.
>
> Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
> ---
> diff --git a/evaluate.c b/evaluate.c
> index dd44cd5..300bfbe 100644
> --- a/evaluate.c
> +++ b/evaluate.c
> @@ -2509,8 +2510,21 @@ found:
> else
> v = &top->ident_expression;
>
> - if (handle_simple_initializer(v, 1, lclass, top->ctype))
> + /*
> + * Temporarily copy storage modifiers down from
> + * surrounding type such that
> + * handle_simple_initializer() can check
> + * initializations of subobjects with static storage
> + * duration.
> + */
> + old_modifiers = top->ctype->ctype.modifiers;
> + top->ctype->ctype.modifiers =
> + old_modifiers | (ctype->ctype.modifiers & MOD_STORAGE);
> + if (handle_simple_initializer(v, 1, lclass, top->ctype)) {
> + top->ctype->ctype.modifiers = old_modifiers;
> continue;
> + }
> + top->ctype->ctype.modifiers = old_modifiers;
This saving/restoring of the modifiers is not very nice.
Hadn't we talked about adding an arg to handle_simple_initializer() or so?
> if (!(lclass & TYPE_COMPOUND)) {
> warning(e->pos, "bogus scalar initializer");
> @@ -2620,6 +2634,16 @@ static int handle_simple_initializer(struct expression **ep, int nested,
> if (!evaluate_expression(e))
> return 1;
> compatible_assignment_types(e, ctype, ep, "initializer");
> + /*
> + * Initializers for static storage duration objects
> + * shall be constant expressions or a string literal [6.7.8(4)].
> + */
> + if ((ctype->ctype.modifiers & (MOD_TOPLEVEL | MOD_STATIC)) &&
> + !(e->constexpr_flags & (CONSTEXPR_FLAG_ARITH_CONST_EXPR
> + | CONSTEXPR_FLAG_ADDR_CONST)) &&
> + Wconstexpr_not_const)
This last line whould be more indented, maybe like the previous line.
> + warning(e->pos, "non-constant initializer for static object");
> +
> return 1;
> }
>
> diff --git a/lib.c b/lib.c
> index 8dc5bcf..75cea42 100644
> --- a/lib.c
> +++ b/lib.c
> @@ -219,6 +219,7 @@ int Waddress_space = 1;
> int Wbitwise = 0;
> int Wcast_to_as = 0;
> int Wcast_truncate = 1;
> +int Wconstexpr_not_const = 0;
This name is quite good.
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