From 817308ab59daa40bef09838cfc3d810863de0e46 Mon Sep 17 00:00:00 2001
From: Hugo Herbelin
Date: Sun, 2 Aug 2015 16:53:39 +0200
Subject: Fixing #4221 (interpreting bound variables using ltac env was
 possibly capturing bound names unexpectingly).

We moved renaming to after finding bindings, i.e. in pretyping
"fun x y => x + y" in an ltac environment where y is ltac-bound to x,
we type the body in environment "x y |-" but build "fun y y => Rel 2 + Rel 1"
(which later on is displayed into "fun y y0 => y + y0").

We renounced to renaming in "match" patterns, which was anyway not
working well, as e.g. in

let x := ipattern:y in (forall z, match z with S x => x | x => x end = 0).

which was producing

forall z : nat, match z with 0 => z | S y => y end = 0

because the names in default branches are treated specifically.

It would be easy to support renaming in match again, by putting the
ltac env in the Cases.pattern_matching_problem state and to rename the
names in "typs" (from build_branch), just before returning them at the
end of the function (and similarly in abstract_predicate for the names
occurring in the return predicate).

However, we rename binders in fix which were not interpreted.

There are some difficulties with evar because we want them defined in
the interpreted env (see comment to ltac_interp_name_env).

fix ltac name
---
 test-suite/bugs/closed/4221.v | 9 +++++++++
 test-suite/success/ltac.v     | 8 ++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 test-suite/bugs/closed/4221.v

(limited to 'test-suite')

diff --git a/test-suite/bugs/closed/4221.v b/test-suite/bugs/closed/4221.v
new file mode 100644
index 0000000000..bc120fb1ff
--- /dev/null
+++ b/test-suite/bugs/closed/4221.v
@@ -0,0 +1,9 @@
+(* Some test checking that interpreting binder names using ltac
+   context does not accidentally break the bindings *)
+
+Goal (forall x : nat, x = 1 -> False) -> 1 = 1 -> False.
+  intros H0 x.
+  lazymatch goal with
+    | [ x : forall k : nat, _ |- _ ]
+      => specialize (fun H0 => x 1 H0)
+  end.
diff --git a/test-suite/success/ltac.v b/test-suite/success/ltac.v
index badce063e8..952f35bc35 100644
--- a/test-suite/success/ltac.v
+++ b/test-suite/success/ltac.v
@@ -298,3 +298,11 @@ evar(foo:nat).
 let evval := eval compute in foo in not_eq evval 1.
 let evval := eval compute in foo in not_eq 1 evval.
 Abort.
+
+(* Check instantiation of binders using ltac names *)
+
+Goal True.
+let x := ipattern:y in assert (forall x y, x = y + 0).
+intro.
+destruct y. (* Check that the name is y here *).
+Abort.
-- 
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