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tame/tamer/rust-toolchain.toml

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tamer: Support nightly Rust toolchain pinning I had never intended to avoid pinning nightly. This is an unfortunate thing to have to do---require a _specific_ version of a compiler to build your software; it's madness. But the unstable features utilized by TAMER (as rationalized in `src/lib.rs`) are still worth the effort. It's not _actually_ that case that we need a specific version of the compiler, granted; this is outlined in `rust-toolchain.toml`'s rationale. You should look there for more information; my approach still utilizes explicit channels via cargo. Unfortunately, I had hard-coded it previously, putting me in a bit of a bind an unable to override the behavior without modifying the software. The reason for this change is that `adt_const_params` has a BC break involving the introduction of `ConstParamTy`. This is only the second time I've been bitten by a nightly BC break; the other was the renaming of `int_log`'s API, as mentioned in 709291b1073bf0bb7898d2437fbeff5bef18820b. This pinning will in fact mitigate those future issues---TAMER will be able to resolve the issue at its leisure, and will further be able to continue to build earlier commits in the future by simply re-bootstrapping with the committed nightly version. If you're curious of my rationale for wanting to inhibit toolchain downloading during build, or use system libraries, have a look at GNU Guix's approach to building software safely and reproducibly. In particular, dependencies are also built from source (rather than downloading binaries from external sources), and builds take place in network-isolated containers. The `TAMER_RUST_TOOLCHAIN` configure parameter is meant to facilitate these situations by giving more flexibility to packagers. DEV-14476
2023-06-05 15:58:26 -04:00
# See <https://rust-lang.github.io/rustup/overrides.html?highlight=rust-toolchain#the-toolchain-file>
#
# This file is used to pin the version of Rust used to build TAMER. This is
# not at all an ideal situation, but is necessary because TAMER uses nightly
# features, and those features will occaisonally make
# backwards-incompatabile changes.
#
# The default behavior caused by this file is not ideal: If the user uses
# rustup, it'll cause the toolchain to be downloaded during build,
# _ignoring_ any `--offline` flag provided to Cargo. Projects ought to be
# able to build without network access; the `bootstrap` script is intended
# to install necessary dependencies on a system prior to building.
#
# By explicitly specifying the toolchain via `cargo +toolchain`, we bypass
# the system utilizing this file. It becomes clear that TAMER is being
# compiled with a particular toolchain version---the invoked command (by
# `make`) explicitly says so. This also avoids automatically downloading
# the toolchain if it's missing, relying instead on any prior bootstrapping
# or system-installed toolchain.
#
# Why have `rust-toolchain.toml` at all, then? Because then `cargo` will
# work when invoked independently, if someone chooses not to use `make` for
# any reason. It is still recommended that `make` be utilized so that all
# the other build configuration takes effect.
#
# `configure.ac` will extract the channel from this file and utilize it to
# configure the build to explicitly pass the channel via each cargo
# invocation via the `Makefile`. Changing this file will will cause
# reconfiguration automatically.
#
# Alternatively, `TAMER_RUST_TOOLCHAIN` may be used to explicitly specify
# the channel for the toolchain. If you do this, then modifying
# `rust-toolchain.toml` will _not_ trigger a reconfiguration automatically.
#
# If you are building an earlier commit that does not have this file, then
# you will need to modify `configure.ac` / `Makefile.am` to do your bidding.
[toolchain]
tamer: nightly pin: Describe problems with adt_const_param's ConstParamTy See commit for description of the problem, describing why I'm not yet upgrading to a currently nightly version. DEV-14476
2023-06-06 10:58:33 -04:00
channel = "nightly-2023-04-15" #¹
tamer: Support nightly Rust toolchain pinning I had never intended to avoid pinning nightly. This is an unfortunate thing to have to do---require a _specific_ version of a compiler to build your software; it's madness. But the unstable features utilized by TAMER (as rationalized in `src/lib.rs`) are still worth the effort. It's not _actually_ that case that we need a specific version of the compiler, granted; this is outlined in `rust-toolchain.toml`'s rationale. You should look there for more information; my approach still utilizes explicit channels via cargo. Unfortunately, I had hard-coded it previously, putting me in a bit of a bind an unable to override the behavior without modifying the software. The reason for this change is that `adt_const_params` has a BC break involving the introduction of `ConstParamTy`. This is only the second time I've been bitten by a nightly BC break; the other was the renaming of `int_log`'s API, as mentioned in 709291b1073bf0bb7898d2437fbeff5bef18820b. This pinning will in fact mitigate those future issues---TAMER will be able to resolve the issue at its leisure, and will further be able to continue to build earlier commits in the future by simply re-bootstrapping with the committed nightly version. If you're curious of my rationale for wanting to inhibit toolchain downloading during build, or use system libraries, have a look at GNU Guix's approach to building software safely and reproducibly. In particular, dependencies are also built from source (rather than downloading binaries from external sources), and builds take place in network-isolated containers. The `TAMER_RUST_TOOLCHAIN` configure parameter is meant to facilitate these situations by giving more flexibility to packagers. DEV-14476
2023-06-05 15:58:26 -04:00
# The components should be checked in `configure.ac`
# - Note that `cargo-fmt` is `rustfmt`.
components = ["rustfmt", "clippy"]
# A note on the above version: it's not likely to be the case that _this
# specific version_ is necessary to build TAMER. Instead, this is an upper
# bound, whereas the Rust version in `configure.ac` is a lower bound. Some,
# or all, of the versions within that bound are likely to work. If you know
# another version that works (e.g. you are packaging TAMER and want to use
# another version of Rust already available elsewhere), you may use the
# `TAMER_RUST_TOOLCHAIN` `configure` parameter.
tamer: nightly pin: Describe problems with adt_const_param's ConstParamTy See commit for description of the problem, describing why I'm not yet upgrading to a currently nightly version. DEV-14476
2023-06-06 10:58:33 -04:00
# ¹ TAMER uses the incomplete feature `adt_const_params`. "Incomplete"
# features require a special flag to enable---`incomplete_features`---and
# are described as "incomplete and may not be safe to use and/or cause
# compiler crashes".
#
# The `ConstParamTy` trait was introduced by
# <https://github.com/rust-lang/rust/pull/111670> and merged in early
# June 2023. After this change, const params types must implement this
# trait.
#
# Unfortunately, at the time of writing (2023-06), while the trait is
# implemented on a number of core primitives, it is _not_ implemented on the
# `NonZero*` types. There is an inquiry into this limitation on Zulip, and
# it is expected to be resolved in the future:
# <https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/ConstParamTy.20for.20NonZero*.20types>
#
# We will sit on this and watch how it evolves over the following
# weeks/months to assess how to best proceed.
#
# Aside from this, there seems to be a rustdoc bug at some point between
# April and June that causes documentation failures. This needs further
# investigation, and possibly a bug report.