235b0eb987
This PR gives the `generate` function's "apply @Foo to Goal" trace nodes their own trace sub-class `Meta.synthInstance.apply` instead of sharing the parent `Meta.synthInstance` class. This allows metaprograms that walk synthesis traces to distinguish instance application attempts from other synthesis nodes by checking `td.cls` rather than string-matching on the header text. The new class is registered with `inherited := true`, so `set_option trace.Meta.synthInstance true` continues to show these nodes. Motivated by mathlib's `#defeq_abuse` diagnostic tactic (https://github.com/leanprover-community/mathlib4/pull/35750) which currently checks `headerStr.contains "apply"` to identify these nodes. See https://leanprover.zulipchat.com/#narrow/channel/113488-general/topic/backward.2EisDefEq.2ErespectTransparency 🤖 Prepared with Claude Code --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
52 lines
1.5 KiB
Text
52 lines
1.5 KiB
Text
class Foo (s : String) : Type where
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instance : Foo "one" where
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instance [Foo "three"] : Foo "two" where
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def f (s : String) [Foo s] := ()
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/-- info: () -/
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#guard_msgs in
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#eval f "one"
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/--
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error: failed to synthesize instance of type class
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Foo "two"
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Hint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.
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-/
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#guard_msgs in
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#eval f "two"
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/--
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error: failed to synthesize instance of type class
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Foo "two"
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---
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trace: [Meta.synthInstance] ❌️ Foo "two"
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[Meta.synthInstance] new goal Foo "two"
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[Meta.synthInstance.instances] #[@instFoo_1]
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[Meta.synthInstance.apply] ✅️ apply @instFoo_1 to Foo "two"
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[Meta.synthInstance.tryResolve] ✅️ Foo "two" ≟ Foo "two"
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[Meta.synthInstance] no instances for Foo "three"
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[Meta.synthInstance.instances] #[]
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[Meta.synthInstance] result <not-available>
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[Meta.synthInstance] ❌️ Foo "two"
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[Meta.synthInstance] result <not-available> (cached)
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-/
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#guard_msgs in
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set_option trace.Meta.synthInstance true in
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#eval f "two"
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/--
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error: failed to synthesize instance of type class
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Foo "three"
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---
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trace: [Meta.synthInstance] ❌️ Foo "three"
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[Meta.synthInstance] no instances for Foo "three"
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[Meta.synthInstance.instances] #[]
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[Meta.synthInstance] result <not-available>
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[Meta.synthInstance] ❌️ Foo "three"
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[Meta.synthInstance] result <not-available> (cached)
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-/
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#guard_msgs in
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set_option trace.Meta.synthInstance true in
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#eval f "three"
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