feat(library/init/meta/interactive): add apply_with interactive tactic

The new tactic allows us to set apply_cfg in interactive mode.

library/init/meta/interactive.lean

@@ -177,6 +177,12 @@ that have not been fixed by type inference or type class resolution.
 meta def eapply (q : parse texpr) : tactic unit :=
 i_to_expr_for_apply q >>= tactic.eapply
 
+/--
+Similar to the `apply` tactic, but allows the user to provide a `apply_cfg` configuration object.
+-/
+meta def apply_with (q : parse qexpr) (cfg : apply_cfg) : tactic unit :=
+do e ← i_to_expr_for_apply q, tactic.apply e cfg
+
 /--
 This tactic tries to close the main goal `... |- U` using type class resolution.
 It succeeds if it generates a term of type `U` using type class resolution.

library/init/meta/tactic.lean

@@ -832,7 +832,9 @@ private meta def try_apply_opt_auto_param (cfg : apply_cfg) (ms : list expr) : t
 when (cfg.auto_param || cfg.opt_param) $
 mwhen (has_opt_auto_param ms) $ do
   gs ← get_goals,
-  ms.mfor' (λ m, set_goals [m] >> try apply_opt_param >> try apply_auto_param),
+  ms.mfor' (λ m, set_goals [m] >>
+                 when cfg.opt_param (try apply_opt_param) >>
+                 when cfg.auto_param (try apply_auto_param)),
   set_goals gs
 
 meta def apply (e : expr) (cfg : apply_cfg := {}) : tactic unit :=

tests/lean/apply_tac.lean

@@ -56,7 +56,7 @@ eq.trans h₁ h₂
 
 example (a b c : nat) (h₁ : a = b) (h₂ : b = c) : a = c :=
 begin
-  apply foo h₁ -- uses auto_param for solving goal
+  apply @foo a b c h₁ -- uses auto_param for solving goal
 end
 
 lemma my_div_self (a : nat) (h : a ≠ 0 . assumption) : a / a = 1 :=
@@ -66,3 +66,29 @@ example (a : nat) (h : a ≠ 0) : a / a = 1 :=
 begin
   apply my_div_self -- uses auto_param for solving goal
 end
+
+example (a b c : nat) (h₁ : a = b) (h₂ : b = c) : a = c :=
+begin
+  apply_with (@foo a b c h₁) {auto_param := ff},
+  assumption
+end
+
+example (a : nat) (h : a ≠ 0) : a / a = 1 :=
+begin
+  apply_with my_div_self {auto_param := ff},
+  assumption
+end
+
+example (a : nat) (h : a ≠ 0) : a / a = 1 :=
+begin
+  apply_with my_div_self {opt_param := ff} -- uses auto_param for solving goal
+end
+
+def bla2 : nat :=
+begin
+  apply_with f {opt_param := ff},
+  exact 20
+end
+
+example : bla2 = 21 :=
+rfl