rust/tests/run-make/alloc-no-oom-handling/Makefile

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include ../tools.mk
alloc: Add unstable Cfg feature `no-global_oom_handling` For certain sorts of systems, programming, it's deemed essential that all allocation failures be explicitly handled where they occur. For example, see Linus Torvald's opinion in [1]. Merely not calling global panic handlers, or always `try_reserving` first (for vectors), is not deemed good enough, because the mere presence of the global OOM handlers is burdens static analysis. One option for these projects to use rust would just be to skip `alloc`, rolling their own allocation abstractions. But this would, in my opinion be a real shame. `alloc` has a few `try_*` methods already, and we could easily have more. Features like custom allocator support also demonstrate and existing to support diverse use-cases with the same abstractions. A natural way to add such a feature flag would a Cargo feature, but there are currently uncertainties around how std library crate's Cargo features may or not be stable, so to avoid any risk of stabilizing by mistake we are going with a more low-level "raw cfg" token, which cannot be interacted with via Cargo alone. Note also that since there is no notion of "default cfg tokens" outside of Cargo features, we have to invert the condition from `global_oom_handling` to to `not(no_global_oom_handling)`. This breaks the monotonicity that would be important for a Cargo feature (i.e. turning on more features should never break compatibility), but it doesn't matter for raw cfg tokens which are not intended to be "constraint solved" by Cargo or anything else. To support this use-case we create a new feature, "global-oom-handling", on by default, and put the global OOM handler infra and everything else it that depends on it behind it. By default, nothing is changed, but users concerned about global handling can make sure it is disabled, and be confident that all OOM handling is local and explicit. For this first iteration, non-flat collections are outright disabled. `Vec` and `String` don't yet have `try_*` allocation methods, but are kept anyways since they can be oom-safely created "from parts", and we hope to add those `try_` methods in the future. [1]: https://lore.kernel.org/lkml/CAHk-=wh_sNLoz84AUUzuqXEsYH35u=8HV3vK-jbRbJ_B-JjGrg@mail.gmail.com/
2021-04-16 19:18:04 -05:00
all:
$(RUSTC) --edition=2021 -Dwarnings --crate-type=rlib ../../../library/alloc/src/lib.rs --cfg no_global_oom_handling