fix(init/meta/interactive): whnf in assume tactic

library/init/meta/interactive.lean

@@ -523,6 +523,7 @@ meta def «assume» (p : parse parse_binders) : tactic unit :=
 list.mfor' p $ λ b,
   do t ← target,
      when (not $ t.is_pi ∨ t.is_let) whnf_target,
+     t ← target,
      when (not $ t.is_pi ∨ t.is_let) $
        fail "assume tactic failed, Pi/let expression expected",
      ty ← i_to_expr b.local_type,

library/init/meta/smt/interactive.lean

@@ -78,14 +78,7 @@ meta def exact (q : parse texpr) : smt_tactic unit :=
 tactic.interactive.exact q
 
 meta def «assume» (p : parse parse_binders) : smt_tactic unit :=
-list.mfor' p $ λ b,
-  do t ← tactic.target,
-     when (not $ t.is_pi ∨ t.is_let) tactic.whnf_target,
-     when (not $ t.is_pi ∨ t.is_let) $
-       fail "assume tactic failed, Pi/let expression expected",
-     ty ← tactic.i_to_expr b.local_type,
-     tactic.unify ty t.binding_domain,
-     smt_tactic.intro_lst [b.local_pp_name]
+tactic.interactive.assume p
 
 meta def «suppose» (h : parse ident?) (q : parse (tk ":" *> texpr)?) : smt_tactic unit :=
 let h := h.get_or_else `this in

tests/lean/keyword_tactics.lean

@@ -10,6 +10,12 @@ begin
   apply n
 end
 
+example : ¬false :=
+begin
+  assume contr,
+  apply contr
+end
+
 example : ℕ → ℕ → ℕ :=
 begin
   assume n m : bool,

tests/lean/keyword_tactics.lean.expected.out

@@ -1,4 +1,4 @@
-keyword_tactics.lean:15:2: error: unify tactic failed, failed to unify
+keyword_tactics.lean:21:2: error: unify tactic failed, failed to unify
   bool : Type
 and
   ℕ : Type