[v2] c-family: ICE with [[gnu::nocf_check]] [PR106937]

On Fri, Sep 30, 2022 at 09:12:24AM -0400, Jason Merrill wrote:
> On 9/29/22 18:49, Marek Polacek wrote:
> > When getting the name of an attribute, we ought to use
> > get_attribute_name, which handles both [[ ]] and __attribute__(())
> > forms.  Failure to do so may result in an ICE, like here.
> > 
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> How do we print the attributes with this patch?  Don't we also want to print
> the namespace, and use [[]] in the output?

Good point, however: while the testcase indeed has an attribute
in the [[]] form in the typedef, here we're printing its "aka":

warning: initialization of 'FuncPointerWithNoCfCheck' {aka 'void (__attribute__((nocf_check)) *)(void)'} from incompatible pointer type 'FuncPointer' {aka 'void (*)(void)'}

c-pretty-print.cc doesn't seem to know how to print an [[]] attribute.
I could do that, but then we'd print

  aka 'void ([[nocf_check]] *)(void)'

in the above, but that's invalid syntax!  pp_c_attributes_display appears
to be called for * and & only where you can't use an [[]] attribute.  So
perhaps we want to keep printing the GNU form here?

I noticed that pp_c_attributes has never been used, so we can just remove it.

I've also adjusted the test not to use "-w".

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

-- >8 --
When getting the name of an attribute, we ought to use
get_attribute_name, which handles both [[ ]] and __attribute__(())
forms.  Failure to do so may result in an ICE, like here.

pp_c_attributes has been unused since its introduction in r56273.

	PR c++/106937

gcc/c-family/ChangeLog:

	* c-pretty-print.cc (pp_c_attributes): Remove.
	(pp_c_attributes_display): Use get_attribute_name.
	* c-pretty-print.h (pp_c_attributes): Remove.

gcc/testsuite/ChangeLog:

	* gcc.dg/fcf-protection-1.c: New test.
---
 gcc/c-family/c-pretty-print.cc          | 30 +++----------------------
 gcc/c-family/c-pretty-print.h           |  1 -
 gcc/testsuite/gcc.dg/fcf-protection-1.c | 13 +++++++++++
 3 files changed, 16 insertions(+), 28 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/fcf-protection-1.c


base-commit: ade1e0d5896221500d1cbda38cd631cf80325aaa

On 10/4/22 19:06, Marek Polacek wrote:
> On Fri, Sep 30, 2022 at 09:12:24AM -0400, Jason Merrill wrote:
>> On 9/29/22 18:49, Marek Polacek wrote:
>>> When getting the name of an attribute, we ought to use
>>> get_attribute_name, which handles both [[ ]] and __attribute__(())
>>> forms.  Failure to do so may result in an ICE, like here.
>>>
>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>
>> How do we print the attributes with this patch?  Don't we also want to print
>> the namespace, and use [[]] in the output?
> 
> Good point, however: while the testcase indeed has an attribute
> in the [[]] form in the typedef, here we're printing its "aka":
> 
> warning: initialization of 'FuncPointerWithNoCfCheck' {aka 'void (__attribute__((nocf_check)) *)(void)'} from incompatible pointer type 'FuncPointer' {aka 'void (*)(void)'}
> 
> c-pretty-print.cc doesn't seem to know how to print an [[]] attribute.
> I could do that, but then we'd print
> 
>    aka 'void ([[nocf_check]] *)(void)'
> 
> in the above, but that's invalid syntax!

Indeed, it should be

void (* [[gnu::nocf_check]])(void)

> pp_c_attributes_display appears
> to be called for * and & only where you can't use an [[]] attribute.  So
> perhaps we want to keep printing the GNU form here?
> 
> I noticed that pp_c_attributes has never been used, so we can just remove it.
> 
> I've also adjusted the test not to use "-w".
> 
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> -- >8 --
> When getting the name of an attribute, we ought to use
> get_attribute_name, which handles both [[ ]] and __attribute__(())
> forms.  Failure to do so may result in an ICE, like here.
> 
> pp_c_attributes has been unused since its introduction in r56273.
> 
> 	PR c++/106937
> 
> gcc/c-family/ChangeLog:
> 
> 	* c-pretty-print.cc (pp_c_attributes): Remove.
> 	(pp_c_attributes_display): Use get_attribute_name.
> 	* c-pretty-print.h (pp_c_attributes): Remove.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/fcf-protection-1.c: New test.
> ---
>   gcc/c-family/c-pretty-print.cc          | 30 +++----------------------
>   gcc/c-family/c-pretty-print.h           |  1 -
>   gcc/testsuite/gcc.dg/fcf-protection-1.c | 13 +++++++++++
>   3 files changed, 16 insertions(+), 28 deletions(-)
>   create mode 100644 gcc/testsuite/gcc.dg/fcf-protection-1.c
> 
> diff --git a/gcc/c-family/c-pretty-print.cc b/gcc/c-family/c-pretty-print.cc
> index efa1768f4d6..2419e149333 100644
> --- a/gcc/c-family/c-pretty-print.cc
> +++ b/gcc/c-family/c-pretty-print.cc
> @@ -850,32 +850,8 @@ c_pretty_printer::declaration (tree t)
>     pp_c_init_declarator (this, t);
>   }
>   
> -/* Pretty-print ATTRIBUTES using GNU C extension syntax.  */
> -
> -void
> -pp_c_attributes (c_pretty_printer *pp, tree attributes)
> -{
> -  if (attributes == NULL_TREE)
> -    return;
> -
> -  pp_c_ws_string (pp, "__attribute__");
> -  pp_c_left_paren (pp);
> -  pp_c_left_paren (pp);
> -  for (; attributes != NULL_TREE; attributes = TREE_CHAIN (attributes))
> -    {
> -      pp_tree_identifier (pp, TREE_PURPOSE (attributes));
> -      if (TREE_VALUE (attributes))
> -	pp_c_call_argument_list (pp, TREE_VALUE (attributes));
> -
> -      if (TREE_CHAIN (attributes))
> -	pp_separate_with (pp, ',');
> -    }
> -  pp_c_right_paren (pp);
> -  pp_c_right_paren (pp);
> -}
> -
>   /* Pretty-print ATTRIBUTES using GNU C extension syntax for attributes
> -   marked to be displayed on disgnostic.  */
> +   marked to be displayed on diagnostic.  */
>   
>   void
>   pp_c_attributes_display (c_pretty_printer *pp, tree a)
> @@ -888,7 +864,7 @@ pp_c_attributes_display (c_pretty_printer *pp, tree a)
>     for (; a != NULL_TREE; a = TREE_CHAIN (a))
>       {
>         const struct attribute_spec *as;
> -      as = lookup_attribute_spec (TREE_PURPOSE (a));
> +      as = lookup_attribute_spec (get_attribute_name (a));
>         if (!as || as->affects_type_identity == false)
>           continue;
>         if (c_dialect_cxx ()
> @@ -906,7 +882,7 @@ pp_c_attributes_display (c_pretty_printer *pp, tree a)
>          {
>            pp_separate_with (pp, ',');
>          }
> -      pp_tree_identifier (pp, TREE_PURPOSE (a));
> +      pp_tree_identifier (pp, get_attribute_name (a));
>         if (TREE_VALUE (a))
>          pp_c_call_argument_list (pp, TREE_VALUE (a));
>       }
> diff --git a/gcc/c-family/c-pretty-print.h b/gcc/c-family/c-pretty-print.h
> index be86bed4fee..92674ab4d06 100644
> --- a/gcc/c-family/c-pretty-print.h
> +++ b/gcc/c-family/c-pretty-print.h
> @@ -119,7 +119,6 @@ void pp_c_space_for_pointer_operator (c_pretty_printer *, tree);
>   /* Declarations.  */
>   void pp_c_tree_decl_identifier (c_pretty_printer *, tree);
>   void pp_c_function_definition (c_pretty_printer *, tree);
> -void pp_c_attributes (c_pretty_printer *, tree);
>   void pp_c_attributes_display (c_pretty_printer *, tree);
>   void pp_c_cv_qualifiers (c_pretty_printer *pp, int qualifiers, bool func_type);
>   void pp_c_type_qualifier_list (c_pretty_printer *, tree);
> diff --git a/gcc/testsuite/gcc.dg/fcf-protection-1.c b/gcc/testsuite/gcc.dg/fcf-protection-1.c
> new file mode 100644
> index 00000000000..baad74cd86f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/fcf-protection-1.c
> @@ -0,0 +1,13 @@
> +/* PR c++/106937 */
> +/* { dg-options "-fcf-protection" } */
> +
> +[[gnu::nocf_check]] typedef void (*FuncPointerWithNoCfCheck)(void);
> +typedef void (*FuncPointer)(void);
> +[[gnu::nocf_check]] void testNoCfCheck();
> +void testNoCfCheck(){};
> +int i;
> +void testNoCfCheckImpl(double i) {}
> +void testNoCfCheckMismatch(FuncPointer f) {
> +  FuncPointerWithNoCfCheck fNoCfCheck = f; /* { dg-warning "initialization" } */
> +  (*fNoCfCheck)();
> +}
> 
> base-commit: ade1e0d5896221500d1cbda38cd631cf80325aaa