Ping.
On Wed, Aug 07, 2013 at 06:12:58PM +0200, Marek Polacek wrote:
> On Wed, Aug 07, 2013 at 10:24:59AM -0400, Jason Merrill wrote:
> > On 08/07/2013 06:06 AM, Marek Polacek wrote:
> > >I might've misunderstood what you mean. If we drop the hunk above,
> > >then we'll call
> > > error ("%q+E is not a constant expression", t);
> > >so, we'll print "is not a constant expression" no matter what
> >
> > Yes, that's fine; 1/0 is not a constant expression, because it has
> > undefined behavior.
>
> Indeed.
>
> > Print something more meaningful to the user.
>
> Something along these lines? (Not including CL/testcase yet on purpose.)
> In beforementioned situation it'd print:
>
> w.C:7:22: error: ‘<ubsan routine call>’ is not a constant expression
> case 0 * (1 / 0):
> ^
> I'm not entirely happy about it, on the other hand, this situation
> should be very rare...
>
> diff --git a/gcc/cp/error.c b/gcc/cp/error.c
> index 440169a..db50b5f 100644
> --- a/gcc/cp/error.c
> +++ b/gcc/cp/error.c
> @@ -32,6 +32,7 @@ along with GCC; see the file COPYING3. If not see
> #include "tree-pretty-print.h"
> #include "pointer-set.h"
> #include "c-family/c-objc.h"
> +#include "ubsan.h"
>
> #define pp_separate_with_comma(PP) pp_cxx_separate_with (PP, ',')
> #define pp_separate_with_semicolon(PP) pp_cxx_separate_with (PP, ';')
> @@ -1972,6 +1973,12 @@ dump_expr (tree t, int flags)
> }
> skipfirst = true;
> }
> + if (flag_sanitize & SANITIZE_UNDEFINED
> + && is_ubsan_builtin_p (fn))
> + {
> + pp_string (cxx_pp, M_("<ubsan routine call>"));
> + break;
> + }
> dump_expr (fn, flags | TFF_EXPR_IN_PARENS);
> dump_call_expr_args (t, flags, skipfirst);
> }
> diff --git a/gcc/ubsan.c b/gcc/ubsan.c
> index 8135cc9..565758d 100644
> --- a/gcc/ubsan.c
> +++ b/gcc/ubsan.c
> @@ -456,3 +456,13 @@ ubsan_instrument_unreachable (location_t loc)
> tree t = builtin_decl_explicit (BUILT_IN_UBSAN_HANDLE_BUILTIN_UNREACHABLE);
> return build_call_expr_loc (loc, t, 1, build_fold_addr_expr_loc (loc,
> data));
> }
> +
> +/* Return true if T is a call to a libubsan routine. */
> +
> +bool
> +is_ubsan_builtin_p (tree t)
> +{
> + gcc_checking_assert (TREE_CODE (t) == FUNCTION_DECL);
> + return strncmp (IDENTIFIER_POINTER (DECL_NAME (t)),
> + "__builtin___ubsan_", 18) == 0;
> +}
> diff --git a/gcc/ubsan.h b/gcc/ubsan.h
> index abf4f5d..3553a6c 100644
> --- a/gcc/ubsan.h
> +++ b/gcc/ubsan.h
> @@ -25,6 +25,7 @@ extern tree ubsan_instrument_unreachable (location_t);
> extern tree ubsan_create_data (const char *, location_t, ...);
> extern tree ubsan_type_descriptor (tree);
> extern tree ubsan_encode_value (tree);
> +extern bool is_ubsan_builtin_p (tree);
>
> #endif /* GCC_UBSAN_H */
Marek
