On Mon, Jan 25, 2016 at 03:57:45PM +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.
>
> 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.
Better here also to split the patch in two:
one add the -W flag flag and another one which will use it.
ch > Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
> ---
> evaluate.c | 26 ++++++++++-
> lib.c | 2 +
> lib.h | 2 +-
> sparse.1 | 7 +++
> validation/constexpr-init.c | 110 ++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 145 insertions(+), 2 deletions(-)
> create mode 100644 validation/constexpr-init.c
>
> diff --git a/evaluate.c b/evaluate.c
> index 70f419f..e3b08e4 100644
> --- a/evaluate.c
> +++ b/evaluate.c
> @@ -2468,6 +2468,7 @@ static void handle_list_initializer(struct expression *expr,
> {
> struct expression *e, *last = NULL, *top = NULL, *next;
> int jumped = 0;
> + unsigned long old_modifiers;
>
> FOR_EACH_PTR(expr->expr_list, e) {
> struct expression **v;
> @@ -2522,8 +2523,21 @@ 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;
I don't understand why saving the mods is needed.
It feels hackish to me. Isn't it because something is done wrongly at another
level or maybe handle_simple_initializer() need an additional arg or so?
> @@ -2633,6 +2647,16 @@ static int handle_simple_initializer(struct expression **ep, int nested,
...
> + warning(e->pos, "initializer for static storage duration object is not a constant expression");
This is quite longish message.
What about something like "non-constant initializer"?
> diff --git a/lib.c b/lib.c
> --- a/lib.c
> +++ b/lib.c
> @@ -241,6 +241,7 @@ int Wtypesign = 0;
> int Wundef = 0;
> int Wuninitialized = 1;
> int Wvla = 1;
> +int Wstatic_initializer_not_const = 0;
Here also it's quite longish. Yes I'm a lazy typer :)
What about simply -Wconst-initializer ?
One thing that could be added (later and in another patch) is to
set it by default when the C99 variant is selected.
> enum {
> diff --git a/lib.h b/lib.h
> index 15b69fa..1b38db2 100644
> --- a/lib.h
> +++ b/lib.h
> @@ -127,7 +127,7 @@ extern int Wtypesign;
> extern int Wundef;
> extern int Wuninitialized;
> extern int Wvla;
> -
> +extern int Wstatic_initializer_not_const;
Better to leave the blank line where it was.
Luc
--
To unsubscribe from this list: send the line "unsubscribe linux-sparse" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
