(*Set Debug SsrMatching.*)
Tactic Notation "at" "[" ssrpatternarg(pat) "]" tactic(t) :=
let name := fresh in
let def_name := fresh in
ssrpattern pat;
intro name;
pose proof (refl_equal name) as def_name;
unfold name at 1 in def_name;
t def_name;
[ rewrite <- def_name | idtac.. ];
clear name def_name.

Lemma test (H : True -> True -> 3 = 7) : 28 = 3 * 4.