tra added a comment. In D80450#2418775 <https://reviews.llvm.org/D80450#2418775>, @yaxunl wrote:
> For the call `ag(e)`. There are two candidates: > > 1. `ag` in namespace `b`. The function arguments can match. However it is a > host function, therefore is a wrong-sided candidate and not viable. > > 2. `ag` in default name space. It is a host device function. However the > function arguments requires `a<ae>`, therefore cannot match. > > Before my patch, wrong-sided candidate is allowed. clang resolves to > candidate 1 and this results in a diagnostic about host function referenced > in device host function, which can be deferred. Since `f()` is not emitted on > device side, the deferred diags is not emitted. This used to be a fairly common pattern in existing CUDA code. A lot of templated code had `__host__ __device__` slapped on it because NVCC had no target overloading and it's hard to control who/where/how will instantiate particular template. Some of those templates could only be instantiated on one side of the compilation. Clang's only choice was to allow the wrong-side candidates and/or defer the diagnostics. I vaguely recall that it was one of the trickier bits of the overload resolution rules to handle. > After my patch, wrong-sided candidate is not allowed. clang resolves to > candidate 2, which results in a diagnostic that no matching function, which > is not a deferred diagnostics by default and is emitted even if `f()` is not > emitted on device side. > ... > Basically it all boils down to the issue that overloading resolution > diagnostics are not deferred by default. Looks that way. > I think a conservative solution is that we keep the old overloading > resolution behavior by default (i.e. do not exclude wrong-sided candidates), > whereas enable the correct hostness based overloading resolution when > -fgpu-defer-diags is on. If developers would like correct hostness based > overloading resolution, they can use -fgpu-defer-diags. Then as > -fgpu-defer-diags become stable, we turn it on by default. SGTM. I'll check how the patch fares on our CUDA code. ================ Comment at: clang/test/SemaCUDA/function-overload.cu:614 + +// Two HD candidates competes with H candidate. +// HDs have type mismatch whereas H has type match. ---------------- competes->compete CHANGES SINCE LAST ACTION https://reviews.llvm.org/D80450/new/ https://reviews.llvm.org/D80450 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
