On 21/11/2019 13:11, Luc Van Oostenryck wrote:
> It's common to declare a function with the attribute
> 'pure' or 'noreturn' and to omit the attribute in the
> function definition. It mak somehow sense since the
> information conveyed by these attributes are destined
> to the function users not the function itself.
>
> So, when checking declaration/definition, let the
> current symbol inherit any function attributes present
> in previous declarations.
>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
> ---
>
> The patch is also available for review & testing at:
> git://github.com/lucvoo/sparse-dev.git fun-attr-inherit
>
> Changes since v1:
> * the old name was 'allow omitted function attribute in definition'
> * change the approach: instead of filtering out these attributes at
> check-time, let's inherit them at declaration-time.
Yep, I noticed that you didn't push the last patch #5. I had also
thought that this would be a better approach, or rather that the
test should be that the 'attributes list' given on the function
definition should be a subset of the list given on the declaration.
(so that the 'extra' attributes would be inherited by the function).
This would imply, of course, that sparse should issue a warning/error
when the attribute list on the definition contained some attributes
that were not present in the declaration. Well, it seems reasonable
anyway! ;-)
It seems gcc has other ideas:
$ cat -n junk.c
1
2 extern void exit (int __status) __attribute__ ((__noreturn__));
3
4 void func0(int a) __attribute__ ((pure));
5
6 __attribute__ ((pure)) __attribute__ ((__noreturn__))
7 void func0(int a)
8 {
9 exit(0);
10 }
$
So, sparse (with this patch applied) gets it:
$ ./sparse junk.c
junk.c:7:6: error: symbol 'func0' redeclared with different type (originally declared at junk.c:4) - different modifiers
$
But gcc, not so much:
$ gcc -c junk.c
$ gcc -Wall -c junk.c
$ gcc -Wall -Wextra -c junk.c
junk.c: In function ‘func0’:
junk.c:7:16: warning: unused parameter ‘a’ [-Wunused-parameter]
void func0(int a)
^
$
So, I don't know ...
ATB,
Ramsay Jones
>
>
> symbol.c | 9 +++++++++
> ...ion-attribute-omitted.c => function-redecl-funattr.c} | 3 +--
> validation/function-redecl2.c | 3 ---
> 3 files changed, 10 insertions(+), 5 deletions(-)
> rename validation/{function-attribute-omitted.c => function-redecl-funattr.c} (75%)
>
> diff --git a/symbol.c b/symbol.c
> index 90149e5ae..bafa7c432 100644
> --- a/symbol.c
> +++ b/symbol.c
> @@ -588,6 +588,14 @@ struct symbol *befoul(struct symbol *type)
> return NULL;
> }
>
> +static void inherit_declaration(struct symbol *sym, struct symbol *prev)
> +{
> + unsigned long mods = prev->ctype.modifiers;
> +
> + // inherit function attributes
> + sym->ctype.modifiers |= mods & MOD_FUN_ATTR;
> +}
> +
> void check_declaration(struct symbol *sym)
> {
> int warned = 0;
> @@ -598,6 +606,7 @@ void check_declaration(struct symbol *sym)
> continue;
> if (sym->scope == next->scope) {
> sym->same_symbol = next;
> + inherit_declaration(sym, next);
> return;
> }
> /* Extern in block level matches a TOPLEVEL non-static symbol */
> diff --git a/validation/function-attribute-omitted.c b/validation/function-redecl-funattr.c
> similarity index 75%
> rename from validation/function-attribute-omitted.c
> rename to validation/function-redecl-funattr.c
> index 43b301d8f..b1e2fb195 100644
> --- a/validation/function-attribute-omitted.c
> +++ b/validation/function-redecl-funattr.c
> @@ -9,6 +9,5 @@ void __noreturn n(void);
> void n(void) { while (1) ; }
>
> /*
> - * check-name: function-attribute-omitted
> - * check-known-to-fail
> + * check-name: function-redecl-funattr
> */
> diff --git a/validation/function-redecl2.c b/validation/function-redecl2.c
> index 3435aa00c..ef396137a 100644
> --- a/validation/function-redecl2.c
> +++ b/validation/function-redecl2.c
> @@ -25,7 +25,4 @@ void func2(int a)
>
> /*
> * check-name: function-redecl2
> - *
> - * check-known-to-fail
> - *
> */
>
