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Trevor Gross
6ceeb0849e
Support for `f16` and `f128` is varied across targets, backends, and backend versions. Eventually we would like to reach a point where all backends support these approximately equally, but until then we have to work around some of these nuances of support being observable. Introduce the `cfg_target_has_reliable_f16_f128` internal feature, which provides the following new configuration gates: * `cfg(target_has_reliable_f16)` * `cfg(target_has_reliable_f16_math)` * `cfg(target_has_reliable_f128)` * `cfg(target_has_reliable_f128_math)` `reliable_f16` and `reliable_f128` indicate that basic arithmetic for the type works correctly. The `_math` versions indicate that anything relying on `libm` works correctly, since sometimes this hits a separate class of codegen bugs. These options match configuration set by the build script at [1]. The logic for LLVM support is duplicated as-is from the same script. There are a few possible updates that will come as a follow up. The config introduced here is not planned to ever become stable, it is only intended to replace the build scripts for `std` tests and `compiler-builtins` that don't have any way to configure based on the codegen backend. MCP: https://github.com/rust-lang/compiler-team/issues/866 Closes: https://github.com/rust-lang/compiler-team/issues/866 [1]: https://github.com/rust-lang/rust/blob/555e1d0386f024a8359645c3217f4b3eae9be042/library/std/build.rs#L84-L186