Make tuples implicitly sized

[oli-obk]

Since #137728 there is no sound way to create unsized tuples anymore.

Let's see if we can get away with making tuples unsized at least as far as crater is concerned. With that information we can then discuss whether to actually do this or what path forward we have.

r? @ghost

[oli-obk]

@bors try

[bors]

⌛ Trying commit c42f697 with merge 5482d17...

[oli-obk]

@rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[rust-log-analyzer]

The job x86_64-gnu-tools failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

   Compiling derive_setters v0.1.6
error[E0277]: the size for values of type `T` cannot be known at compilation time
   --> /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/zerovec-0.10.4/src/varzerovec/slice.rs:102:25
    |
101 | pub struct VarZeroSlice<T: ?Sized, F = Index16> {
    |                         - this type parameter needs to be `Sized`
102 |     marker: PhantomData<(F, T)>,
    |
help: consider removing the `?Sized` bound to make the type parameter `Sized`
    |
    |
101 - pub struct VarZeroSlice<T: ?Sized, F = Index16> {
101 + pub struct VarZeroSlice<T, F = Index16> {

   Compiling ctrlc v3.4.5
   Compiling ppv-lite86 v0.2.20
   Compiling hashbrown v0.14.5

[rust-log-analyzer]

The job dist-x86_64-linux failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

file:.git/config remote.origin.url=https://github.com/rust-lang-ci/rust
file:.git/config remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*
file:.git/config gc.auto=0
file:.git/config http.https://github.com/.extraheader=AUTHORIZATION: basic ***
file:.git/config branch.try.remote=origin
file:.git/config branch.try.merge=refs/heads/try
file:.git/config remote.upstream.fetch=+refs/heads/*:refs/remotes/upstream/*
file:.git/config submodule.library/backtrace.active=true
file:.git/config submodule.library/backtrace.url=https://github.com/rust-lang/backtrace-rs.git
file:.git/config submodule.library/stdarch.active=true
---
   Compiling derive-where v1.2.7
error[E0277]: the size for values of type `T` cannot be known at compilation time
   --> /rust/deps/zerovec-0.10.4/src/varzerovec/slice.rs:102:25
    |
101 | pub struct VarZeroSlice<T: ?Sized, F = Index16> {
    |                         - this type parameter needs to be `Sized`
102 |     marker: PhantomData<(F, T)>,
    |
help: consider removing the `?Sized` bound to make the type parameter `Sized`
    |
    |
101 - pub struct VarZeroSlice<T: ?Sized, F = Index16> {
101 + pub struct VarZeroSlice<T, F = Index16> {

[RUSTC-TIMING] rustc_index_macros test:false 0.626
   Compiling thiserror-impl v1.0.69
[RUSTC-TIMING] unic_langid_macros_impl test:false 0.553
---
Caused by:
    Command RUST_BACKTRACE=full python3 /checkout/x.py build --target x86_64-unknown-linux-gnu --host x86_64-unknown-linux-gnu --stage 2 library/std --rust-profile-generate /tmp/tmp-multistage/opt-artifacts/rustc-pgo --set llvm.thin-lto=false --set llvm.link-shared=true [at /checkout/obj] has failed with exit code Some(1)

Stack backtrace:
   0: <anyhow::Error>::msg::<alloc::string::String>
             at /rust/deps/anyhow-1.0.95/src/backtrace.rs:27:14
   1: <opt_dist::exec::CmdBuilder>::run
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/exec.rs:80:17
   2: <opt_dist::exec::Bootstrap>::run
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/exec.rs:181:9
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/main.rs:222:13
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/main.rs:222:13
   4: <opt_dist::timer::TimerSection>::section::<opt_dist::execute_pipeline::{closure#1}::{closure#0}, ()>
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/timer.rs:111:22
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/main.rs:211:9
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/main.rs:211:9
   6: <opt_dist::timer::TimerSection>::section::<opt_dist::execute_pipeline::{closure#1}, opt_dist::training::RustcPGOProfile>
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/timer.rs:111:22
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/main.rs:208:29
   8: opt_dist::main
             at /rustc/5482d17c79ef6fdb109cee082f8c7b67486cf798/src/tools/opt-dist/src/main.rs:400:18
   9: <fn() -> core::result::Result<(), anyhow::Error> as core::ops::function::FnOnce<()>>::call_once
   9: <fn() -> core::result::Result<(), anyhow::Error> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/f0cb41030579cd1a6f72bd23f38e677052d5d485/library/core/src/ops/function.rs:250:5
  10: std::sys::backtrace::__rust_begin_short_backtrace::<fn() -> core::result::Result<(), anyhow::Error>, core::result::Result<(), anyhow::Error>>
             at /rustc/f0cb41030579cd1a6f72bd23f38e677052d5d485/library/std/src/sys/backtrace.rs:152:18
  11: std::rt::lang_start::<core::result::Result<(), anyhow::Error>>::{closure#0}
             at /rustc/f0cb41030579cd1a6f72bd23f38e677052d5d485/library/std/src/rt.rs:199:18
  12: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once
  13: std::panicking::try::do_call
             at /rustc/f0cb41030579cd1a6f72bd23f38e677052d5d485/library/std/src/panicking.rs:587:40
  14: std::panicking::try
             at /rustc/f0cb41030579cd1a6f72bd23f38e677052d5d485/library/std/src/panicking.rs:550:19

[oli-obk]

Nevermind, this doesn't even bootstrap. PhantomData<(F, T)> where T: ?Sized 😞 Could just be two phantom datas, so we do have a path forward, but it will take years to migrate everyone