Make missing argument placeholder more obvious that it's a placeholder

[compiler-errors]

Use /* ty */ instead of {ty}, since people might be misled into thinking that this is valid syntax, and not just a diagnostic placeholder.

Fixes #96880

[rust-highfive]

r? @jackh726

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[jackh726]

Nice approach. Less misleading.

@bors r+

[bors]

📌 Commit 4400a26 has been approved by jackh726

[bors]

⌛ Testing commit 4400a26 with merge a5c039c...

[bors]

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing a5c039c to master...

[rust-timer]

Finished benchmarking commit (a5c039c): comparison url.

Instruction count

• Primary benchmarks: no relevant changes found
• Secondary benchmarks: 🎉 relevant improvement found

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-0.4%	-0.4%	1
All 😿🎉 (primary)	N/A	N/A	0

Max RSS (memory usage)

Results

• Primary benchmarks: no relevant changes found
• Secondary benchmarks: 😿 relevant regressions found

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	4.3%	4.3%	2
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	N/A	N/A	0
All 😿🎉 (primary)	N/A	N/A	0

Cycles

Results

• Primary benchmarks: no relevant changes found
• Secondary benchmarks: 🎉 relevant improvement found

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-3.7%	-3.7%	1
All 😿🎉 (primary)	N/A	N/A	0

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

Footnotes

1. the arithmetic mean of the percent change ↩ ↩² ↩³

2. number of relevant changes ↩ ↩² ↩³