Remove --export-dynamic from the link arguments on the wasm32-wasi
target, as it emits spurious exports and increases code size.

Leave it in place for wasm32-unknown-unknown and
wasm32-unknown-emscripten. Even though it isn't a great solution
there, users are likely depending on its behavior there.

- This allows us add fake information after handling migrations if
  needed.
- Capture analysis also priortizes what we see earlier, which means
  fake information should go in last.

- No Derefs in move closure, this will result in value behind a reference getting moved.
- No projections are applied to raw pointers, since these require unsafe blocks. We capture
  them completely.

Motivations for these are recorded here: https://hackmd.io/71qq-IOpTNqzMkPpAI1dVg?view

When `capture_disjoint_fields` is not enabled, checking if the root variable
binding is mutable would suffice.

However with the feature enabled, the captured place might be mutable
because it dereferences a mutable reference.

This PR computes the mutability of each capture after capture analysis
in rustc_typeck. We store this in `ty::CapturedPlace` and then use
`ty::CapturedPlace::mutability` in mir_build and borrow_check.

2229: Fix issues with move closures and mutability

This PR fixes two issues when feature `capture_disjoint_fields` is used.

1. Can't mutate using a mutable reference
2. Move closures try to move value out through a reference.

To do so, we
1. Compute the mutability of the capture and store it as part of the `CapturedPlace`  that is written in TypeckResults
2. Restrict capture precision. Note this is temporary for now, to allow the feature to be used with move closures and ByValue captures and might change depending on discussions with the lang team.
    - No Derefs are captured for ByValue captures, since that will result in value behind a reference getting moved.
    - No projections are applied to raw pointers since these require unsafe blocks. We capture
    them completely.

r? ```@nikomatsakis```

Remove const_in_array_repeat

Fixes #80371. Fixes #81315. Fixes #80767. Fixes #75682.

I thought there might be some issue with `Repeats(_, 0)`, but if you increase the items in the array it still ICEs. I'm not sure if this is the best fix but it does fix the given issue.

Add lint for 2229 migrations

Implements the first for RFC 2229 where we make the decision to migrate a root variable based on if the type of the variable needs Drop and if the root variable would be moved into the closure when the feature isn't enabled.

r? `@nikomatsakis`

…ichton

Don't link with --export-dynamic on wasm32-wasi

Remove --export-dynamic from the link arguments on the wasm32-wasi
target, as it emits spurious exports and increases code size.

Leave it in place for wasm32-unknown-unknown and
wasm32-unknown-emscripten. Even though it isn't a great solution
there, users are likely depending on its behavior there.

combine: stop eagerly evaluating consts

`super_relate_consts` eagerly evaluates constants which doesn't seem too great.

I now also finally understand why all of the unused substs test passed. The reason being
that we just evaluated the constants in `super_relate_consts` 😆

While this change isn't strictly necessary as evaluating consts here doesn't hurt, it still feels a lot cleaner to do it this way

r? ``@oli-obk`` ``@nikomatsakis``

Add suggestion for nested fields

Closes #81220

r? `@estebank`

Fix small typo in string.rs

Stabilize int_bits_const

Closes #76904

The FCP to stabilize the `int_bits_const` feature completed on the tracking issue.