Re: [PATCH 2/2] Fix C++ side of PR c/70436 (missing -Wparentheses warnings)

[Jakub Jelinek <jakub at redhat dot com>]

On Thu, Mar 31, 2016 at 04:54:04PM -0400, Patrick Palka wrote:
> I think that covers all the vanilla C++ constructs that this warning has
> to consider.  As for C++ extensions, we still fail to warn for
> 
>   if (a)
>   #pragma GCC ivdep
>      while (1)
>        if (b)
>          bar ();
>   else
>     baz ();
> 
> and
> 
>   if (a)
>     _Cilk_for (int i = 0; i < 10; i++)
>       if (b)
>         bar ();
>   else
>     baz ();
> 
> and probably other constructs.  I suppose support for this can be
> implemented in a subsequent patch if deemed appropriate at this stage.
> It would probably just involve more threading of the parameter IF_P.
> 
> Is this OK to commit after bootstrap + regtesting?

If this makes it in, I can take care of OpenMP, perhaps Cilk+ too.

> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -2104,7 +2104,7 @@ static tree cp_parser_selection_statement
>  static tree cp_parser_condition
>    (cp_parser *);
>  static tree cp_parser_iteration_statement
> -  (cp_parser *, bool);
> +  (cp_parser *, bool *if_p, bool);

I wouldn't add a named argument where all others are unnamed in the
prototype.

>  static bool cp_parser_for_init_statement
>    (cp_parser *, tree *decl);
>  static tree cp_parser_for
> @@ -2127,7 +2127,7 @@ static void cp_parser_declaration_statement
>  static tree cp_parser_implicitly_scoped_statement
>    (cp_parser *, bool *, const token_indent_info &, vec<tree> * = NULL);
>  static void cp_parser_already_scoped_statement
> -  (cp_parser *, const token_indent_info &);
> +  (cp_parser *, bool *if_p, const token_indent_info &);

Likewise here.

> +void
> +foo (void)
> +{
> +  if (a) /* { dg-warning "ambiguous" }  */
> +    for (;;)
> +      if (b)
> +        bar ();
> +      else
> +        baz ();

What about multiple nested for or while loops, like:
  if (a)
    for (i = 0; i < 10; i++)
      for (j = 0; j < 10; j++)
        if (b)
          bar ();
  else
    baz ();
and similarly for multiple nested while loops?
I only see while (1) for (;;) in the test.

Otherwise, I'll defer to Jason.

	Jakub