Consolidate obligation cause codes for where clauses

[compiler-errors]

Removes some unncessary redundancy between SpannedWhereClause/WhereClause

r? lcnr

[rustbot]

changes to the core type system

cc @compiler-errors, @lcnr

[lcnr]

r=me after nits

[lcnr]

@bors r+ rollup

[bors]

📌 Commit e444017 has been approved by lcnr

It is now in the queue for this repository.

[lcnr]

@bors rollup=iffy

[bors]

⌛ Testing commit e444017 with merge 78a7751...

[bors]

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing 78a7751 to master...

[rust-timer]

Finished benchmarking commit (78a7751): 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)	-2.2%	[-2.2%, -2.2%]	1
Improvements ✅ (secondary)	-4.1%	[-4.1%, -4.1%]	1
All ❌✅ (primary)	-2.2%	[-2.2%, -2.2%]	1

Cycles

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

Binary size

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

Bootstrap: 673.703s -> 674.128s (0.06%)
Artifact size: 315.98 MiB -> 315.87 MiB (-0.03%)