From cc06679015013fa26736e10227967cd38be3d6b5 Mon Sep 17 00:00:00 2001
From: Tej Chajed
Date: Thu, 15 Oct 2020 09:17:15 -0500
Subject: Report a useful error for dependent destruction

Similar to `dependent induction`, report an error message for `dependent
destruction` saying that importing `Coq.Program.Equality` is required,
rather than failing at parsing time.

This is a small extension of #605 to cover dependent destruction as
well. Here I also put in some tests.
---
 test-suite/output/DependentInductionErrors.out |  4 ++++
 test-suite/output/DependentInductionErrors.v   | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 test-suite/output/DependentInductionErrors.out
 create mode 100644 test-suite/output/DependentInductionErrors.v

(limited to 'test-suite')

diff --git a/test-suite/output/DependentInductionErrors.out b/test-suite/output/DependentInductionErrors.out
new file mode 100644
index 0000000000..4a83375f6f
--- /dev/null
+++ b/test-suite/output/DependentInductionErrors.out
@@ -0,0 +1,4 @@
+The command has indeed failed with message:
+Tactic failure: To use dependent destruction, first [Require Import Coq.Program.Equality.].
+The command has indeed failed with message:
+Tactic failure: To use dependent induction, first [Require Import Coq.Program.Equality.].
diff --git a/test-suite/output/DependentInductionErrors.v b/test-suite/output/DependentInductionErrors.v
new file mode 100644
index 0000000000..2fce00f9fd
--- /dev/null
+++ b/test-suite/output/DependentInductionErrors.v
@@ -0,0 +1,17 @@
+Theorem foo (b:bool) : b = true \/ b = false.
+Proof.
+  Fail dependent destruction b.
+  Fail dependent induction b.
+Abort.
+
+From Coq Require Import Program.Equality.
+
+Theorem foo_with_destruction (b:bool) : b = true \/ b = false.
+Proof.
+  dependent destruction b; auto.
+Qed.
+
+Theorem foo_with_induction (b:bool) : b = true \/ b = false.
+Proof.
+  dependent induction b; auto.
+Qed.
-- 
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