This commit disables polymorphisation to resolve regressions related to
closures which inherit unused generic parameters and are then used in
casts or reflection.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit changes the span and content of the "collection encountered
polymorphic constant" bug in monomorphization collection to point to the
use of the constant rather than the definition.
Signed-off-by: NDavid Wood <david@davidtw.co>

Fix rust-src component.

The rust-src component could not be installed by rustup because it included some symbolic links. #74520 added the backtrace directory which included some symlinks. Since the rust-src component doesn't need most of the files in the `backtrace` submodule, this changes it to only include the minimum necessary.

Tested with cargo's build-std that it can build from the resulting tarball.

Fixes #74577

Upload builds from GHA instead of Azure Pipelines

This PR does two things:

* Enables RLA comments on PRs (needed after the switch to GHA in RLA).
* Switches GitHub Actions as the CI authorized to upload non-macOS builds.

Note that Docker/LLVM caches will likely be busted.

r? @Mark-Simulacrum

Add `RawFd` to WASI's `std::os::wasi::prelude`.

Add `RawFd` to WASI's `std::os::wasi::prelude`, making it consistent
with all other platforms which also have `AsRawFd`, `FromRawFd`, and
`IntoRawFd` in their respective preludes.

Polymorphization

This PR implements an analysis to detect when functions could remain polymorphic during code generation.

Fixes #46477

r? @EddyB
cc @rust-lang/wg-mir-opt @nikomatsakis @pnkfelix

Rollup of 13 pull requests

Successful merges:

 - #72714 (Fix debug assertion in typeck)
 - #73197 (Impl Default for ranges)
 - #73323 (wf: check foreign fn decls for well-formedness)
 - #74051 (disallow non-static lifetimes in const generics)
 - #74376 (test caching opt_const_param_of on disc)
 - #74501 (Ayu theme: Use different background color for Run button)
 - #74505 (Fix search input focus in ayu theme)
 - #74522 (Update sanitizer docs)
 - #74546 (Fix duplicate maybe_uninit_extra attribute)
 - #74552 (Stabilize TAU constant.)
 - #74555 (Improve "important traits" popup display on mobile)
 - #74557 (Fix an ICE on an invalid `binding @ ...` in a tuple struct pattern)
 - #74561 (update backtrace-rs)

Failed merges:

r? @ghost

update backtrace-rs

Hopefully fixes https://github.com/rust-lang/rust/issues/74484
r? @alexcrichton

Fix an ICE on an invalid `binding @ ...` in a tuple struct pattern

Fixes #74539.

Improve "important traits" popup display on mobile

I implemented what @XAMPPRocky suggested in the [internals thread topic](https://internals.rust-lang.org/t/feedback-on-important-traits-rustdoc-feature/12752/18). I can confirm it works nicely.

r? @Manishearth

@Manishearth: By the way: I realized that when you click on the "i", you have to click again to make the popup disappear. Do you want me to extend the popup removal to any click outside the popup?

Stabilize TAU constant.

Closes #66770.

Fix duplicate maybe_uninit_extra attribute

Introduced in #72414

Update sanitizer docs

* Document AddressSanitizer memory leak detection defaults.
* Remove CC & CFLAGS from MemorySanitizer example - they are now unnecessary for pure Rust projects (backtrace-rs moved away from libbacktrace).

Fix search input focus in ayu theme

Closes #74496.

Before:

![image](https://user-images.githubusercontent.com/13814214/87868463-d0c8fe80-c963-11ea-9003-aa578d869e98.png)

After:

![image](https://user-images.githubusercontent.com/13814214/87868467-dc1c2a00-c963-11ea-89a8-1280f68ff9df.png)

Ayu theme: Use different background color for Run button

Make it clearer that there is a button Run there.

Demo in https://github.com/rust-lang/rust/pull/74501#issuecomment-660597377 .

test caching opt_const_param_of on disc

Followup to #74113, implements parts of #74360

Tried caching `opt_const_param_of` on disk and adding an early exit if `tcx.dep_kind(def_id) != DefKind::AnonConst`.

Ended up causing a perf regression instead, so we just remove the FIXME and a short note to `opt_const_param_of`.

r? @EddyB

disallow non-static lifetimes in const generics

Disallow non-static lifetimes in const generics in order to to patch over an ICE caused when we encounter a non-static lifetime in a const generic during borrow checking. This restriction may be relaxed in the future, but we need more discussion before then, and in the meantime we should still deal with this ICE.

Fixes issue #60814

wf: check foreign fn decls for well-formedness

Fixes #73252 and fixes #73253.

This PR extends current well-formedness checking to apply to foreign function declarations, re-using the existing machinery for regular functions. In doing this, later parts of the compiler (such as the `improper_ctypes` lint) can rely on being operations not failing as a result of invalid code which would normally be caught earlier.

Impl Default for ranges

Couldn't find an issue about it.

`Range` and friends probably can implement `Default` if `Idx: Default`. For example, the following would be possible:

```rust
#[derive(Default)]
struct Foo(core::ops::RangeToInclusive<u64>);

let _ = [1, 2, 3].get(core::ops::Range::default());

core::ops::RangeFrom::<u8>::default().take(20).for_each(|x| { dbg!(x); });

fn stuff<T: Default>() { let instance = T::default(); ... more stuff }
stuff::<core::ops::RangeTo<f32>>();
```

Maybe there are some concerns about safety or misunderstandings?

Fix debug assertion in typeck

Fixes #72410

This commit introduces a `FiniteBitSet` type which replaces the manual
bit manipulation which was being performed in polymorphization.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit replaces the `-Z polymorphize-errors` debugging flag with a
`#[rustc_polymorphize_error]` attribute for use on functions.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit records the results of `unused_generic_params` in crate
metadata, hopefully improving performance.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit normalizes function signatures for instances before
substituting, a workaround for polymorphization considering
parameters unused when they show up in the signature, but not the
body (due to being normalized).

Unfortunately, this causes test output to change with the parallel
compiler only.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit implements the `unused_generic_params` query, an initial
version of polymorphization which detects when an item does not use
generic parameters and is being needlessly monomorphized as a result.
Signed-off-by: NDavid Wood <david@davidtw.co>

⬆ rust-analyzer

r? @ghost

Closes #66770.

This commit makes valid shim asserts more specific - checking for the
specific types that are valid for a given type of shim - and removes
asserts for types which require substitutions.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit adds type metadata for generic parameters (that arise from
polymorphization). Generic parameter metadata is considered zero-sized
and named after the generic parameter.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit skips generating debuginfo type metadata if substitutions
are required by the type. This avoids ICEs that result from layouts
of types with substitutions being computed.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit adds doc comments to the `param_at`, `region_param` and
`const_param` methods on the `Generics` struct.
Signed-off-by: NDavid Wood <david@davidtw.co>

This commit modifies the `substitute_normalize_and_test_predicates`
query, renaming it to `impossible_predicates` and only checking
predicates which do not require substs. By making this change,
polymorphization doesn't have to explicitly support vtables.
Signed-off-by: NDavid Wood <david@davidtw.co>