AmbiguityCause should not eagerly format strings

[compiler-errors]

Minor tweak found when working on some coherence diagnostics stuff (towards -Ztrait-solver=next-coherence stabilization)

[rustbot]

r? @spastorino

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[spastorino]

@bors r+

[bors]

📌 Commit 0750a5d has been approved by spastorino

It is now in the queue for this repository.

[bors]

⌛ Testing commit 0750a5d with merge 0b8a61b...

[bors]

☀️ Test successful - checks-actions
Approved by: spastorino
Pushing 0b8a61b to master...

[rust-timer]

Finished benchmarking commit (0b8a61b): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-0.8%, -0.2%]	5
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.4%	[-0.8%, -0.2%]	5

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)	3.5%	[3.5%, 3.5%]	1
Regressions ❌ (secondary)	3.9%	[3.2%, 4.6%]	3
Improvements ✅ (primary)	-1.4%	[-1.5%, -1.2%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[-1.5%, 3.5%]	3

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.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.6%	[2.5%, 2.6%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 675.058s -> 674.277s (-0.12%)
Artifact size: 313.35 MiB -> 313.37 MiB (0.01%)