Implement missing TrustedLen and FusedIterator for core and alloc types

[fereidani]

While working on #160813 I noticed TrustedLen is missing for the LinkedList, I suspected that other modules are missing the implementation too, so I wrote a small script to scan the project and found these candidates which implement ExactSizeIterator but not the TrustedLen, Reviewed the code just to make sure they are actually meet TrustedLen requirement and then I've added missing implementations.

While editting I found out there are instances of FusedIterator missing too, So I've added them too.

I think most important missing one is the impl<I: TrustedLen + ?Sized, A: Allocator> TrustedLen for Box<I, A> which inherits TrustedLen for a Box to a TrustedLen implementer.

I did this only for core and alloc, I ignored script reports for the std but I think it worth looking into, specially for the HashMap:

FusedIterator::missing CommandArgs in library/std/src/process.rs
TrustedLen::missing CommandArgs in library/std/src/process.rs
FusedIterator::missing CommandEnvs in library/std/src/process.rs
TrustedLen::missing CommandEnvs in library/std/src/process.rs
FusedIterator::missing Args in library/std/src/env.rs
TrustedLen::missing Args in library/std/src/env.rs
FusedIterator::missing ArgsOs in library/std/src/env.rs
TrustedLen::missing ArgsOs in library/std/src/env.rs
TrustedLen::missing Iter in library/std/src/collections/hash/set.rs
TrustedLen::missing IntoIter in library/std/src/collections/hash/set.rs
TrustedLen::missing Drain in library/std/src/collections/hash/set.rs
TrustedLen::missing Iter in library/std/src/collections/hash/map.rs
TrustedLen::missing IterMut in library/std/src/collections/hash/map.rs
TrustedLen::missing IntoIter in library/std/src/collections/hash/map.rs
TrustedLen::missing Keys in library/std/src/collections/hash/map.rs
TrustedLen::missing Values in library/std/src/collections/hash/map.rs
TrustedLen::missing ValuesMut in library/std/src/collections/hash/map.rs
TrustedLen::missing IntoKeys in library/std/src/collections/hash/map.rs
TrustedLen::missing IntoValues in library/std/src/collections/hash/map.rs
TrustedLen::missing Drain in library/std/src/collections/hash/map.rs
FusedIterator::missing CommandArgs in library/std/src/sys/process/unsupported.rs
TrustedLen::missing CommandArgs in library/std/src/sys/process/unsupported.rs
FusedIterator::missing CommandArgs in library/std/src/sys/process/windows.rs
TrustedLen::missing CommandArgs in library/std/src/sys/process/windows.rs
FusedIterator::missing CommandArgs in library/std/src/sys/process/uefi.rs
TrustedLen::missing CommandArgs in library/std/src/sys/process/uefi.rs
FusedIterator::missing CommandArgs in library/std/src/sys/process/motor.rs
TrustedLen::missing CommandArgs in library/std/src/sys/process/motor.rs
FusedIterator::missing CommandEnvs in library/std/src/sys/process/env.rs
TrustedLen::missing CommandEnvs in library/std/src/sys/process/env.rs
FusedIterator::missing CommandArgs in library/std/src/sys/process/unix/common.rs
TrustedLen::missing CommandArgs in library/std/src/sys/process/unix/common.rs
FusedIterator::missing CStringIter in library/std/src/sys/process/unix/common/cstring_array.rs
TrustedLen::missing CStringIter in library/std/src/sys/process/unix/common/cstring_array.rs
FusedIterator::missing Args in library/std/src/sys/args/common.rs
TrustedLen::missing Args in library/std/src/sys/args/common.rs
FusedIterator::missing Args in library/std/src/sys/args/unsupported.rs
TrustedLen::missing Args in library/std/src/sys/args/unsupported.rs
FusedIterator::missing Args in library/std/src/sys/args/sgx.rs
TrustedLen::missing Args in library/std/src/sys/args/sgx.rs
FusedIterator::missing Args in library/std/src/sys/args/zkvm.rs
TrustedLen::missing Args in library/std/src/sys/args/zkvm.rs

This is related to #37572

• I did not use an LLM to create a change in this PR.
• I used an LLM to create a change in this PR, and I have explained below how it was used.

[rustbot]

r? @Mark-Simulacrum

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The reviewer was selected based on:

• Owners of files modified in this PR: libs
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[Kobzol]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 9a3fc0e (9a3fc0e26f41ccaf3ebb3a1bcfa6e28817886e86)
Base parent: 8a2fbe3 (8a2fbe3ea881ec68b9f06510fd1a1484cdf5bb6b)

[rust-timer]

Finished benchmarking commit (9a3fc0e): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

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

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Results (secondary -1.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.1%	[-6.9%, -0.4%]	27
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -0.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.7%	[0.5%, 1.2%]	9
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.8%	[-1.3%, -0.4%]	9
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 454.914s -> 461.019s (1.34%)
Artifact size: 398.40 MiB -> 398.35 MiB (-0.01%)