On Mon, Jul 11, 2022 at 6:35 PM Alexander Monakov <amona...@ispras.ru> wrote:
>
> On Mon, 11 Jul 2022, Martin Liška wrote:
>
> > I've clarified that linker should return a value that is in range
> > [minimal_api_supported, maximal_api_supported] and added an abort
> > if it's not the case.
>
> I noticed that we are placing a trap for C++ consumers such as mold
> by passing min/max_api_supported as enum values. Unlike C, C++ disallows
> out-of-range enum values, so when mold does
>
> enum PluginLinkerAPIVersion {
> LAPI_V0 = 0,
> LAPI_V1,
> };
>
> get_api_version(const char *plugin_identifier,
> unsigned plugin_version,
> PluginLinkerAPIVersion minimal_api_supported,
> PluginLinkerAPIVersion maximal_api_supported,
> const char **linker_identifier,
> const char **linker_version) {
>
> checks such as 'min_api_supported > LAPI_V1' can be optimized out. Also,
> if a future tool passes LAPI_V2, it will trigger Clang's UBSan (GCC
> -fsanitize-undefined=enum instruments loads but not retrieval of function
> arguments).
>
> I'd suggest to fix this on both sides by changing the arguments to plain
> integer types.
That's a good point - the enum itself is then also somewhat redundant
if it just specifies symbolic names for 0, 1, ... but we can keep it for
documentation purposes.
>
> Alexander
