Add a method to StableMIR to check if a type is a CStr

[celinval]

Also add a check that StableMIR works properly with C string literal.

[rustbot]

r? @ouz-a

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[rustbot]

This PR changes Stable MIR

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

[ouz-a]

@bors r+ rollup

[bors]

📌 Commit 86451ba has been approved by ouz-a

It is now in the queue for this repository.

[bors]

⌛ Testing commit 86451ba with merge 9f13b9d...

[bors]

☀️ Test successful - checks-actions
Approved by: ouz-a
Pushing 9f13b9d to master...

[rust-timer]

Finished benchmarking commit (9f13b9d): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.9%	[-2.9%, -2.9%]	1
All ❌✅ (primary)	-	-	0

Cycles

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

Binary size

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

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

Bootstrap: 670.539s -> 673.096s (0.38%)
Artifact size: 312.41 MiB -> 312.45 MiB (0.01%)