Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
596827c0e9
This PR adds regression tests that catch issues where structures/classes
with class-typed fields produce HEq goals in `congr` instead of handling
Prop fields automatically.
Both tests pass on v4.28.0-rc1 (before isInstance detection changes).
## Test 1: Structure extending classes (mirrors Mathlib's GroupTopology)
```lean
structure MyGroupTopology (α : Type) extends MyTopology α, IsContinuousMul α
theorem MyGroupTopology.toMyTopology_injective {α : Type} :
Function.Injective (MyGroupTopology.toMyTopology : MyGroupTopology α → MyTopology α) := by
intro f g h
cases f
cases g
congr
```
**Failure mode:** `⊢ toIsContinuousMul✝¹ ≍ toIsContinuousMul✝`
## Test 2: Class with explicit class-typed field (mirrors Mathlib's
PseudoEMetricSpace)
```lean
class MyMetricSpace (α : Type) extends MyDist α where
dist_self : ∀ x : α, dist x x = 0
toMyUniformity : MyUniformity α -- explicit class-typed field (NOT from extends)
uniformity_dist : toMyUniformity.uniformity (fun x y => dist x y = 0)
protected theorem MyMetricSpace.ext {α : Type} {m m' : MyMetricSpace α}
(h : m.toMyDist = m'.toMyDist) (hU : m.toMyUniformity = m'.toMyUniformity) : m = m' := by
cases m
cases m'
congr 1 <;> assumption
```
**Failure mode:** `⊢ dist_self✝¹ ≍ dist_self✝` and `⊢ uniformity_dist✝¹
≍ uniformity_dist✝`
## Context
These tests are related to #12172, which changes instance parameter
detection from binder-based to `isClass?`-based. That change can affect
how structure fields are classified in congruence lemma generation.
🤖 Prepared with Claude Code
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
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