Handle rustc_mir_dataflow cases of rustc::potential_query_instability lint

[ismailarilik]

This PR removes #![allow(rustc::potential_query_instability)] occurrences from compiler/rustc_mir_dataflow/ and converts FxHash{Map,Set} types into FxIndex{Map,Set} to suppress lint errors.

A somewhat tracking issue: #84447

r? @compiler-errors

[cjgillot]

The current code is correct. It just needs a comment explaining why the #[allow(..)] is ok.

[compiler-errors]

r? @cjgillot

[ismailarilik]

So what can be the rationale; I can add it.

[cjgillot]

The issue with FxHashMap/FxHashSet is that the iteration order is not deterministic. For instance, it may depend on the bit-width or the endianness of the host compiler. We want to avoid this. Multiple ways to achieve that:

• use FxIndexMap/FxIndexSet which iteration order is deterministic;
• sort the result of iteration;
• the iteration order does not matter.

So the need is not to replace all containers, but rather to discriminate between cases that need replacement, from cases that don't need it.

[ismailarilik]

Hmm. I don't have the knowledge to do that I guess.

[alex-semenyuk]

@ismailarilik
From wg-triage. Do you want to proceed with this PR?

[ismailarilik]

@ismailarilik From wg-triage. Do you want to proceed with this PR?

Let me check the last time.

[rustbot]

Some changes occurred to the CTFE machinery

cc @rust-lang/wg-const-eval

This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @celinval, @vakaras

Some changes occurred in exhaustiveness checking

cc @Nadrieril

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

These commits modify compiler targets.
(See the Target Tier Policy.)

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred in coverage instrumentation.

cc @Zalathar

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred in match lowering

cc @Nadrieril

Some changes occurred in match checking

cc @Nadrieril

HIR ty lowering was modified

cc @fmease

Some changes occurred in src/tools/cargo

cc @ehuss

The Miri subtree was changed

cc @rust-lang/miri

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

These commits modify the library/Cargo.lock file. Unintentional changes to library/Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

[ismailarilik]

@rustbot label -WG-trait-system-refactor