Use overflow_checks intrinsic so IterRangeFrom yields MAX before panicking in debug

[pitaj]

Based on #128666. For your convenience, here is the diff from that PR.

When overflow_checks are enabled, the following code will output as shown

for n in std::range::RangeFrom::from(253_u8..) {
    println!("{n}");
}
// 253
// 254
// 255
// panic

Which is a change from the current behavior, where it will panic after printing 254.

This behavior was requested by the libs team

r? @Mark-Simulacrum

[rustbot]

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

This PR changes rustc_public

cc @oli-obk, @celinval, @ouz-a

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

This PR changes MIR

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

The Miri subtree was changed

cc @rust-lang/miri

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred to constck

cc @fee1-dead

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[oli-obk]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 9714d5d (9714d5d8a54e3a1cf65e4d45ba7cf4c169034a36, parent: 87f9dcd5e28a301fce81515bd4bea792444dcf29)

[rust-timer]

Finished benchmarking commit (9714d5d): comparison URL.

Overall result: ❌ regressions - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.8%	[0.1%, 1.5%]	2
Regressions ❌ (secondary)	1.4%	[1.4%, 1.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.8%	[0.1%, 1.5%]	2

Max RSS (memory usage)

Results (primary -2.3%, secondary -4.2%)

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)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-4.2%	[-4.2%, -4.2%]	2
All ❌✅ (primary)	-2.3%	[-2.3%, -2.3%]	1

Cycles

Results (primary 2.5%, secondary 2.8%)

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

	mean	range	count
Regressions ❌ (primary)	2.5%	[2.5%, 2.5%]	1
Regressions ❌ (secondary)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.5%	[2.5%, 2.5%]	1

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 475.809s -> 478.419s (0.55%)
Artifact size: 390.93 MiB -> 390.91 MiB (-0.01%)

[Mark-Simulacrum]

This behavior was #125687 (comment)

Does this affect the stable surface area? Or only new(?) range API?

If it does affect stable surface area, I suspect we'll want libs-api FCP (maybe with crater results) on the behavior change, which I don't think has happened yet?

r=me on the implementation itself.

[saethlin]

I don't see any reason to wait on a crater run
@craterbot run mode=build-and-test

[craterbot]

👌 Experiment pr-148703 created and queued.
🤖 Automatically detected try build 9714d5d
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[pitaj]

Does this affect the stable surface area? Or only new(?) range API?

It only affects the unstable new range API. IterRangeFrom is the IntoIter for the new RangeFrom.

So I don't really see a reason to run crater.

[saethlin]

Ah. That seems to contradict the PR description.
@craterbot cancel

[craterbot]

🗑️ Experiment pr-148703 deleted!

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[pitaj]

Oh, good point. Just updated the PR description. Sorry for the confusion.