Re: Signedness of char in BTF

["Jose E. Marchesi" <jose.marchesi@oracle.com>]

> The llvm and pahole generate BTF_INT_BOOL when the dwarf type has
> attribute DW_ATE_boolean.
> But BTF_INT_BOOL is actually used in libbpf to differentiate
> configuration values (CONFIG_* = 'y' vs. CONFIG_* = <value>)
>
> In llvm,
>   uint8_t BTFEncoding;
>   switch (Encoding) {
>   case dwarf::DW_ATE_boolean:
>     BTFEncoding = BTF::INT_BOOL;
>     break;
>   case dwarf::DW_ATE_signed:
>   case dwarf::DW_ATE_signed_char:
>     BTFEncoding = BTF::INT_SIGNED;
>     break;
>   case dwarf::DW_ATE_unsigned:
>   case dwarf::DW_ATE_unsigned_char:
>     BTFEncoding = 0;
>     break;
>   default:
>     llvm_unreachable("Unknown BTFTypeInt Encoding");
>   }

I just sent a patch to make GCC behave the same way:
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598702.html