replace_target uses id_locked.
The id_locked solution is more robust because simp may build a proof
using refl lemmas, but type_context may not be able to establish that
the previous and new target are definitionally equal.
@Armael This commit fixes the issue in the KreMLin proof you showed me.
Now, the following tactic succeeds (as expected)
```
simp [lowstar_semantics.apply_ectx],
```
and the resulting goal is
```
...
|- exp.subbuf (exp.loc (b, n, list.nil field)) a_1 = exp.subbuf ↑?m_1 ?m_2
```
This allows users to now use to apply a tactic in all hypotheses as well as the goal, we add support for all
interactive tactics using location: rewrite, simp, dsimp, unfold, and delta including each tactics many variants.
They can be used to store user state in the tactic_state object.
@Armael @jroesch: The new file tests/lean/run/tactic_ref.lean contains a few examples.
closes#1634
This commit also changes the semantic of `tactic.focus [tac_1, ..., tac_n]`.
It now fails if the number of goals is not `n`.
Before it would only fail if there were more tactics than goals.
@Armael: See tests/lean/run/handthen.lean for examples of the new notation.
@kha @gebner I added the `show_goal` tactic for selecting arbitrary
subgoals. This feature is similar to the one available in Isabelle.
This commit allows us to use the `show` keyword as syntax sugar for
`show_goal`. The test `show_goal.lean` has a small example.
What do you think?
@Armael: you can use `show` to structure your proofs in tactic mode.
See `tests/lean/run/show_goal.lean` for a small example.
We were getting the following error non deterministically:
```
library/init/data/nat/bitwise.lean:131:6: error: exact tactic failed, type mismatch, given expression has type
z = f ff 0 z
but is expected to have type
eq.rec z e = f ff 0 (binary_rec f z 0)
state:
C : ℕ → Sort u,
f : Π (b : bool) (n : ℕ), C n → C (bit b n),
z : C 0,
h : f ff 0 z = z,
b : bool,
n : ℕ,
b0 : bit b n = 0,
bf : bodd 0 = b,
n0 : shiftr 0 1 = n,
e : 0 = bit ff 0
⊢ eq.rec z e = f ff 0 (binary_rec f z 0)
```
This error was happening because of the type_context.unfold_lemmas new
flag. The type context thread local cache must be flushed whenever the
value of type_context.unfold_lemmas has changed.
