Fix format_args capture for macro expanded format strings

[Alexendoo]

Since #100996 format_args capture for macro expanded strings aren't prevented when the span of the expansion points to a string literal, e.g.

// not a terribly realistic example, but also happens for proc_macros that set
// the span of the output to an input str literal, such as indoc
macro_rules! x {
    ($e:expr) => { $e }
}

fn main() {
    let a = 1;
    println!(x!("{a}"));
}

The tests didn't catch it as the span of concat!() points to the macro invocation

r? @m-ou-se

[m-ou-se]

Thanks!

@bors r+

[bors]

📌 Commit 71db0dd has been approved by m-ou-se

It is now in the queue for this repository.

[bors]

⌛ Testing commit 71db0dd with merge edadc7c...

[bors]

☀️ Test successful - checks-actions
Approved by: m-ou-se
Pushing edadc7c to master...

[rust-timer]

Finished benchmarking commit (edadc7c): 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.

	mean1	range	count2
Regressions ❌ (primary)	8.3%	[5.4%, 13.9%]	3
Regressions ❌ (secondary)	2.5%	[1.7%, 2.9%]	3
Improvements ✅ (primary)	-8.6%	[-19.8%, -2.4%]	22
Improvements ✅ (secondary)	-3.3%	[-3.5%, -3.1%]	2
All ❌✅ (primary)	-6.6%	[-19.8%, 13.9%]	25

Cycles

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.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-6.2%	[-29.5%, -1.3%]	189
Improvements ✅ (secondary)	-4.1%	[-14.3%, -1.3%]	98
All ❌✅ (primary)	-6.2%	[-29.5%, -1.3%]	189

Footnotes

1. the arithmetic mean of the percent change ↩ ↩²

2. number of relevant changes ↩ ↩²

[matthiaskrgr]

Hm, this slowed down rustc compiler bootstrap by almost a minute (8%) ?? on perf.rlo
https://perf.rust-lang.org/compare.html?start=744e397d8855f7da87d70aa8d0bd9e0f5f0b51a1&end=edadc7ccdda644ef8149869d2f24018a1dac202a&stat=instructions:u

[Alexendoo]

Seems pretty unlikely as this just changes a snippet span back to what it was a few days ago