Re: [PATCH] c++: make some cp_trait_kind switch statements exhaustive

[Jason Merrill <jason@redhat.com>]

On 9/30/22 13:37, Patrick Palka wrote:
> 
> On Fri, 30 Sep 2022, Patrick Palka wrote:
> 
>> This replaces the unreachable default case in some cp_trait_kind
>> switches with an exhaustive listing of the _unexpected_ trait codes,
>> so that when adding a new trait we'll get a -Wswitch diagnostic if we
>> forget to handle the trait code in one of these switches.
>>
>> Bootstrappend and regtested on x86_64-pc-linux-gnu, does this look OK
>> for trunk?
>>
>> gcc/cp/ChangeLog:
>>
>> 	* semantics.cc (trait_expr_value): Make cp_trait_kind switch
>> 	exhaustive.
>> 	(finish_trait_expr): Likewise.
>> 	(finish_trait_type): Likewise.
>> ---
>>   gcc/cp/semantics.cc | 31 +++++++++++++++++++++++++------
>>   1 file changed, 25 insertions(+), 6 deletions(-)
>>
>> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
>> index 66ee2186a84..91ad8aa340f 100644
>> --- a/gcc/cp/semantics.cc
>> +++ b/gcc/cp/semantics.cc
>> @@ -12052,10 +12052,15 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
>>       case CPTK_REF_CONVERTS_FROM_TEMPORARY:
>>         return ref_xes_from_temporary (type1, type2, /*direct_init=*/false);
>>   
>> -    default:
>> -      gcc_unreachable ();
>> -      return false;
>> +#define DEFTRAIT_TYPE(CODE, NAME, ARITY) \
>> +    case CPTK_##CODE:
>> +#include "cp-trait.def"
>> +#undef DEFTRAIT_EXPR
> 
> Whoops, this should be #undef DEFTRAIT_TYPE

OK with that fix.

>> +      /* These are handled by finish_trait_type.  */
>> +      break;
>>       }
>> +
>> +  gcc_unreachable ();
>>   }
>>   
>>   /* Returns true if TYPE meets the requirements for the specified KIND,
>> @@ -12204,7 +12209,11 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
>>   	return error_mark_node;
>>         break;
>>   
>> -    default:
>> +#define DEFTRAIT_TYPE(CODE, NAME, ARITY) \
>> +    case CPTK_##CODE:
>> +#include "cp-trait.def"
>> +#undef DEFTRAIT_TYPE
>> +      /* These are handled by finish_trait_type.  */
>>         gcc_unreachable ();
>>       }
>>   
>> @@ -12250,9 +12259,19 @@ finish_trait_type (cp_trait_kind kind, tree type1, tree type2)
>>         if (TYPE_REF_P (type1))
>>   	type1 = TREE_TYPE (type1);
>>         return cv_unqualified (type1);
>> -    default:
>> -      gcc_unreachable ();
>> +
>> +#define DEFTRAIT_EXPR(CODE, NAME, ARITY) \
>> +    case CPTK_##CODE:
>> +#include "cp-trait.def"
>> +#undef DEFTRAIT_EXPR
>> +      /* These are handled by finish_trait_expr.  */
>> +    case CPTK_BASES:
>> +    case CPTK_DIRECT_BASES:
>> +      /* These are handled by finish_bases.  */
>> +      break;
>>       }
>> +
>> +  gcc_unreachable ();
>>   }
>>   
>>   /* Do-nothing variants of functions to handle pragma FLOAT_CONST_DECIMAL64,
>> -- 
>> 2.38.0.rc2
>>
>>
>