…d a long lost assertion

This reverts part of commit 9712fa4.

Co-Authored-By: Ralf Jung <post@ralfj.de>

This commit modifies the use of `subst_and_normalize_erasing_regions` on
parts of the MIR bodies returned from `instance_mir`, so that
`InstanceDef::CloneShim` and `InstanceDef::DropGlue` (where there is a
type) do not perform substitutions. This avoids double substitutions and
enables polymorphic `InstanceDef`s.

Signed-off-by: David Wood <david@davidtw.co>

…che.

This commit fixes an issue where if `eprintln!` is used in a TLS
destructor it can accidentally cause the process to abort. TLS
destructors are executed after `main` returns on the main thread, and at
this point we've also deinitialized global `Lazy` values like those
which store the `Stderr` and `Stdout` internals. This means that despite
handling TLS not being accessible in `eprintln!`, we will fail due to
not being able to call `stderr()`. This means that we'll double-panic
quickly because panicking also attempt to write to stderr.

The fix here is to reimplement the global stderr handle to avoid the
need for destruction. This avoids the need for `Lazy` as well as the
hidden panic inside of the `stderr` function.

Overall this should improve the robustness of printing errors and/or
panics in weird situations, since the `stderr` accessor should be
infallible in more situations.

…lfJung

Compute the correct layout for variants of uninhabited enums

r? @eddyb
cc @RalfJung

fixes rust-lang#69191
cc rust-lang#69763

Avoid query type in generics

There are at the moment roughly 170 queries in librustc.
The way ty::query is structured, a lot of code is duplicated for each query.
I suspect this to be responsible for a part of librustc'c compile time.

This PR reduces the amount of code generic on the query,
replacing it by code generic on the key-value types.

This is split out of rust-lang#69808,
and should not contain the perf regression.

cc rust-lang#65031

codegen/mir: support polymorphic `InstanceDef`s

cc rust-lang#69925

This PR modifies the use of `subst_and_normalize_erasing_regions` on parts of the MIR bodies returned from `instance_mir`, so that `InstanceDef::CloneShim` and `InstanceDef::DropGlue` (where there is a type) do not perform substitutions. This avoids double substitutions and enables polymorphic `InstanceDef`s.

r? @eddyb
cc @nikomatsakis

librustc_codegen_llvm: Replace deprecated API usage

…fackler

Fix abort-on-eprintln during process shutdown

This commit fixes an issue where if `eprintln!` is used in a TLS
destructor it can accidentally cause the process to abort. TLS
destructors are executed after `main` returns on the main thread, and at
this point we've also deinitialized global `Lazy` values like those
which store the `Stderr` and `Stdout` internals. This means that despite
handling TLS not being accessible in `eprintln!`, we will fail due to
not being able to call `stderr()`. This means that we'll double-panic
quickly because panicking also attempt to write to stderr.

The fix here is to reimplement the global stderr handle to avoid the
need for destruction. This avoids the need for `Lazy` as well as the
hidden panic inside of the `stderr` function.

Overall this should improve the robustness of printing errors and/or
panics in weird situations, since the `stderr` accessor should be
infallible in more situations.