`ungrind` mode error message refers to non-existent `show_patterns` tactic

[datokrat]

Prerequisites

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• Reduce the issue to a minimal, self-contained, reproducible test case.
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Description

When grind tactic mode fails to instantiate new facts, it prints an error message suggesting to take a look at the theorems' patterns via a show_patterns tactic. However, such a tactic does not exist.

Steps to Reproduce

Take a look at the test grind_preinstance_set_bug.lean:

opaque f : Nat → Nat
opaque g : Nat → Nat
theorem fax : f (x + 1) = g (f x) := sorry

/--
error: `instantiate` tactic failed to instantiate new facts, use `show_patterns` to see active theorems and their patterns.
-/
#guard_msgs in
example : f (x + 5) = a := by
  grind =>
    use [fax]; use [fax]; use [fax]; use [fax]; use [fax];
    use [fax] -- Should fail - no new facts
    -- try writing `show_patterns` here; tactic does not exist

Expected behavior: [Clear and concise description of what you expect to happen]

If a tactic (or command?) is mentioned, it should exist. Therefore, I would expect a show_patterns tactic to exist alongside show_local_thms etc.

Actual behavior: [Clear and concise description of what actually happens]

show_patterns does not exist. The other tactics I know of, such as show_local_thms, do not actually show the e-matching patterns of the local theorems.

Versions

Lean 4.28.0-nightly-2026-01-12
Target: x86_64-unknown-linux-gnu

Impact

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