CHANGELOG.md 59 KB
Newer Older
Ralf Jung's avatar
Ralf Jung committed
1
In this changelog, we document "large-ish" changes to Iris that affect even the
Ralf Jung's avatar
Ralf Jung committed
2
3
4
way the logic is used on paper.  We also document changes in the Coq
development; every API-breaking change should be listed, but not every new
lemma.
5

Ralf Jung's avatar
Ralf Jung committed
6
## Iris 3.4.0
7

Ralf Jung's avatar
Ralf Jung committed
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
The highlights and most notable changes of this release are as follows:
* Coq 8.13 is now supported; the old Coq 8.9 and Coq 8.10 are not supported any
  more.
* The new `view` RA construction generalizes `auth` to user-defined abstraction
  relations.
* The new `dfrac` RA extends `frac` (fractions `0 < q ≤ 1`) with support for
  "discarding" some part of the fraction in exchange for a persistent witness
  that discarding has happened. This can be used to easily generalize fractional
  permissions with support for persistently owning "any part" of the resource.
* The new `gmap_view` RA provides convenient lemma for ghost ownership
  of heap-like structures with an "authoritative" view. Thanks to `dfrac`, it
  supports both exclusive (mutable) and persistent (immutable) ownership of
  individual map elements.
* With this release we are beginning to provide logic-level abstractions for
  ghost state, which have the advantage that the user does not have to directly
  interact with RAs to use them.
  - `ghost_var` provides a logic-level abstraction of ghost variables: a mutable
    "variable" with fractional ownership.
  - `mono_nat` provides a "monotone counter" with persistent witnesses
    representing a lower bound of the current counter value.
  - `gset_bij` provides a monotonically growing partial bijection; this is
    useful in particular when building binary logical relations for languages
    with a heap.
* HeapLang provides a persistent read-only points-to assertion `l ↦□ v`.
* We split Iris into multiple opam packages: `coq-iris` no longer contains
  HeapLang, which is now in a separate package `coq-iris-heap-lang`. The two
  packages `coq-iris-deprecated` (for old modules that we eventually plan to
  remove entirely) and `coq-iris-staging` (for new modules that are not yet
  ready for prime time) exist only as development version, so they are not part
  of this release.
* The proofmode now does a better job at picking reasonable names when moving
  variables into the Coq context without a name being explicitly given by the
  user. However, the exact variable names remain unspecified.
Ralf Jung's avatar
Ralf Jung committed
41

Ralf Jung's avatar
Ralf Jung committed
42
43
44
45
46
47
Further details are given in the changelog below.

This release of Iris received contributions by Arthur Azevedo de Amorim, Dan
Frumin, Enrico Tassi, Hai Dang, Michael Sammler, Paolo G. Giarrusso, Ralf Jung,
Robbert Krebbers, Rodolphe Lepigre, Simon Friis Vindum, Tej Chajed, and Yusuke
Matsushita.  Thanks a lot to everyone involved!
48

49
50
**Changes in `algebra`:**

51
* Add constructions to define a camera through restriction of the validity predicate
Robbert Krebbers's avatar
Robbert Krebbers committed
52
  (`iso_cmra_mixin_restrict`) and through an isomorphism (`iso_cmra_mixin`).
53
54
* Add a `frac_agree` library which encapsulates `frac * agree A` for some OFE
  `A`, and provides some useful lemmas.
Ralf Jung's avatar
Ralf Jung committed
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
* Add the view camera `view`, which generalizes the authoritative camera
  `auth` by being parameterized by a relation that relates the authoritative
  element with the fragments.
* Add the camera of discardable fractions `dfrac`. This is a generalization of
  the normal fractional camera.
  See [algebra.dfrac](iris/algebra/dfrac.v) for further information.
* Add `gmap_view`, a camera providing a "view of a `gmap`". The authoritative
  element is any `gmap`; the fragment provides fractional ownership of a single
  key, including support for persistent read-only ownership through `dfrac`.
  See [algebra.lib.gmap_view](iris/algebra/lib/gmap_view.v) for further information.
* Add `mono_nat`, a wrapper for `auth max_nat`. The result is an authoritative
  `nat` where a fragment is a lower bound whose ownership is persistent.
  See [algebra.lib.mono_nat](iris/algebra/lib/mono_nat.v) for further information.
* Add the `gset_bij` resource algebra for monotone partial bijections.
  See [algebra.lib.gset_bij](iris/algebra/lib/gset_bij.v) for further information.
* Rename `agree_op_inv'``to_agree_op_inv`,
  `agree_op_invL'``to_agree_op_inv_L`, and add `to_agree_op_invN`.
* Rename `auth_auth_frac_op_invL``auth_auth_frac_op_inv_L`,
  `excl_auth_agreeL``excl_auth_agree_L`,
  `frac_auth_agreeL``frac_auth_agree_L`, and
  `ufrac_auth_agreeL``ufrac_auth_agree_L`.
76
77
* Fix direction of `auth_auth_validN` to make it consistent with similar lemmas,
  e.g., `auth_auth_valid`. The direction is now `✓{n} (● a) ↔ ✓{n} a`.
78
79
80
* Rename `auth_both_valid` to `auth_both_valid_discrete` and
  `auth_both_frac_valid` to `auth_both_frac_valid_discrete`. The old name is
  used for new, stronger lemmas that do not assume discreteness.
Robbert Krebbers's avatar
Robbert Krebbers committed
81
82
83
84
85
* Redefine the authoritative camera in terms of the view camera. As part of this
  change, we have removed lemmas that leaked implementation details. Hence, the
  only way to construct elements of `auth` is via the elements `●{q} a` and
  `◯ b`. The constructor `Auth`, and the projections `auth_auth_proj` and
  `auth_frag_proj` no longer exist. Lemmas that referred to these constructors
Ralf Jung's avatar
Ralf Jung committed
86
87
88
  have been removed, in particular: `auth_equivI`, `auth_validI`,
  `auth_included`, `auth_valid_discrete`, and `auth_both_op`.  For validity, use
  `auth_auth_valid*`, `auth_frag_valid*`, or `auth_both_valid*` instead.
Robbert Krebbers's avatar
Robbert Krebbers committed
89
* Rename `auth_update_core_id` into `auth_update_frac_alloc`.
Robbert Krebbers's avatar
Robbert Krebbers committed
90
91
* Rename `cmra_monotone_valid` into `cmra_morphism_valid` (this rename was
  forgotten in !56).
Ralf Jung's avatar
Ralf Jung committed
92
93
94
* Move the `*_validI` and `*_equivI` lemmas to a new module, `base_logic.algebra`.
  That module is exported by `base_logic.base_logic` so it should usually be
  available everywhere without further changes.
Robbert Krebbers's avatar
Robbert Krebbers committed
95
96
* The authoritative fragment `✓ (◯ b : auth A)` is no longer definitionally
  equal to `✓ b`.
97
* Change `*_valid` lemma statements involving fractions to use `Qp` addition and
98
99
  inequality instead of RA composition and validity (also in `base_logic` and
  the higher layers).
Ralf Jung's avatar
Ralf Jung committed
100
* Move `algebra.base` module to `prelude.prelude`.
Ralf Jung's avatar
Ralf Jung committed
101
102
* Strengthen `cmra_op_discrete` to assume only `✓{0} (x1 ⋅ x2)` instead of `✓
  (x1 ⋅ x2)`.
103
* Rename the types `ofeT``ofe`, `cmraT``cmra`, `ucmraT``ucmra`, and the
Robbert Krebbers's avatar
Robbert Krebbers committed
104
105
106
  constructors `OfeT``Ofe`, `CmraT``Cmra`, and `UcmraT``Ucmra` since the `T`
  suffix is not needed. This change makes these names consistent with `bi`,
  which also does not have a `T` suffix.
Ralf Jung's avatar
Ralf Jung committed
107
108
109
* Rename typeclass instances of CMRA operational typeclasses (`Op`, `Core`,
  `PCore`, `Valid`, `ValidN`, `Unit`) to have a `_instance` suffix, so that
  their original names are available to use as lemma names.
110
* Rename `frac_valid'``frac_valid`, `frac_op'``frac_op`,
111
112
113
114
115
  `ufrac_op'``ufrac_op`, `coPset_op_union``coPset_op`, `coPset_core_self`
  `coPset_core`, `gset_op_union``gset_op`, `gset_core_self``gset_core`,
  `gmultiset_op_disj_union``gmultiset_op`, `gmultiset_core_empty`
  `gmultiset_core`, `nat_op_plus``nat_op`, `max_nat_op_max`
  `max_nat_op`. Those names were previously blocked by typeclass instances.
116

Ralf Jung's avatar
Ralf Jung committed
117
118
119
120
**Changes in `bi`:**

* Add big op lemmas `big_op{L,L2,M,M2,S}_intuitionistically_forall` and
  `big_sepL2_forall`, `big_sepMS_forall`, `big_sepMS_impl`, and `big_sepMS_dup`.
Ralf Jung's avatar
Ralf Jung committed
121
122
123
124
125
* Add lemmas to big-ops that provide ownership of a single element and permit
  changing the quantified-over predicate when re-assembling the big-op:
  `big_sepL_lookup_acc_impl`, `big_sepL2_lookup_acc_impl`,
  `big_sepM_lookup_acc_impl`, `big_sepM2_lookup_acc_impl`,
  `big_sepS_elem_of_acc_impl`, `big_sepMS_elem_of_acc_impl`.
Ralf Jung's avatar
Ralf Jung committed
126
127
* Add lemmas `big_sepM_filter'` and `big_sepM_filter` matching the corresponding
  `big_sepS` lemmas.
Ralf Jung's avatar
Ralf Jung committed
128
129
* Add lemmas for big-ops of magic wands: `big_sepL_wand`, `big_sepL2_wand`,
  `big_sepM_wand`, `big_sepM2_wand`, `big_sepS_wand`, `big_sepMS_wand`.
Ralf Jung's avatar
Ralf Jung committed
130
131
132
133
134
135
136
137
138
* Add notation `¬ P` for `P → False` to `bi_scope`.
* Remove `bi.tactics` with tactics that predate the proofmode (and that have not
  been working properly for quite some time).
* Strengthen `persistent_sep_dup` to support propositions that are persistent
  and either affine or absorbing.
* Fix the statement of the lemma `fupd_plainly_laterN`; the old lemma was a
  duplicate of `fupd_plain_laterN`.
* Strengthen `big_sepL2_app_inv` by weakening a premise (it is sufficient for
  one of the two pairs of lists to have equal length).
139
140
* Rename `equiv_entails``equiv_entails_1_1`,
  `equiv_entails_sym``equiv_entails_1_2`, and `equiv_spec``equiv_entails`.
141
142
* Remove the laws `pure_forall_2 : (∀ a, ⌜ φ a ⌝) ⊢ ⌜ ∀ a, φ a ⌝` from the BI
  interface and factor it into a type class `BiPureForall`.
Ralf Jung's avatar
Ralf Jung committed
143

Ralf Jung's avatar
Ralf Jung committed
144
145
146
147
148
149
150
151
152
153
154
155
156
157
* Add `fupd_mask_intro` which can be conveniently `iApply`ed to goals of the
  form `|={E1,E2}=>` to get rid of the `fupd` in the goal if `E2 ⊆ E1`. The
  lemma `fupd_mask_weaken Enew` can be `iApply`ed to shrink the first mask to
  `Enew` without getting rid of the modality; the same effect can also be
  obtained slightly more conveniently by using `iMod` with `fupd_mask_subseteq
  Enew`. To make the new names work, rename some existing lemmas:
  `fupd_intro_mask``fupd_mask_intro_subseteq`,
  `fupd_intro_mask'``fupd_mask_subseteq` (implicit arguments also changed
  here), `fupd_mask_weaken``fupd_mask_intro_discard`. Remove `fupd_mask_same`
  since it was unused and obscure.  In the `BiFUpd` axiomatization, rename
  `bi_fupd_mixin_fupd_intro_mask` to `bi_fupd_mixin_fupd_mask_subseteq` and
  weaken the lemma to be specifically about `emp` (the stronger version can be
  derived).

158
159
160
161
162
163
164
165
166
**Changes in `proofmode`:**

* The proofmode now preserves user-supplied names for existentials when using
  `iDestruct ... as (?) "..."`. This is backwards-incompatible if you were
  relying on the previous automatic names (which were always "H", possibly
  freshened). It also requires some changes if you were implementing `IntoExist`
  yourself, since the typeclass now forwards names. If your instance transforms
  one `IntoExist` into another, you can generally just forward the name from the
  premise.
167
168
169
170
171
* The proofmode also preserves user-supplied names in `iIntros`, for example
  with `iIntros (?)` and `iIntros "%"`, as described for destructing
  existentials above. As part of this change, it now uses a base name of `H` for
  pure facts rather than the previous default of `a`. This also requires some
  changes if you were implementing `FromForall`, in order to forward names.
Robbert Krebbers's avatar
Robbert Krebbers committed
172
173
174
175
176
* Make `iFrame` "less" smart w.r.t. clean up of modalities. It now consistently
  removes the modalities `<affine>`, `<absorbing>`, `<persistent>` and `□` only
  if the result after framing is `True` or `emp`. In particular, it no longer
  removes `<affine>` if the result after framing is affine, and it no longer
  removes `□` if the result after framing is intuitionistic.
Robbert Krebbers's avatar
Robbert Krebbers committed
177
178
179
* Allow framing below an `<affine>` modality if the hypothesis that is framed is
  affine. (Previously, framing below `<affine>` was only possible if the
  hypothesis that is framed resides in the intuitionistic context.)
Robbert Krebbers's avatar
Robbert Krebbers committed
180
181
* Add Coq side-condition `φ` to class `ElimAcc` (similar to what we already had
  for `ElimInv` and `ElimModal`).
182
183
* Add a tactic `iSelect pat tac` (similar to `select` in std++) which runs the
  tactic `tac H` with the name `H` of the last hypothesis of the intuitionistic
184
  or spatial context matching `pat`. The tactic `iSelect` is used to implement:
185
186
187
188
189
  + `iRename select (pat)%I into name` which renames the matching hypothesis,
  + `iDestruct select (pat)%I as ...` which destructs the matching hypothesis,
  + `iClear select (pat)%I` which clears the matching hypothesis,
  + `iRevert select (pat)%I` which reverts the matching hypothesis,
  + `iFrame select (pat)%I` which cancels the matching hypothesis.
190

191
192
193
194
**Changes in `base_logic`:**

* Add a `ghost_var` library that provides (fractional) ownership of a ghost
  variable of arbitrary `Type`.
Ralf Jung's avatar
Ralf Jung committed
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
* Define a ghost state library on top of the `mono_nat` resource algebra.
  See [base_logic.lib.mono_nat](iris/base_logic/lib/mono_nat.v) for further
  information.
* Define a ghost state library on top of the `gset_bij` resource algebra.
  See [base_logic.lib.gset_bij](iris/base_logic/lib/gset_bij.v) for further
  information.
* Extend the `gen_heap` library with read-only points-to assertions using
  [discardable fractions](iris/algebra/dfrac.v).
  + The `mapsto` connective now takes a `dfrac` rather than a `frac` (i.e.,
    positive rational number `Qp`).
  + The notation `l ↦{ dq } v` is generalized to discardable fractions
    `dq : dfrac`.
  + The new notation `l ↦{# q} v` is used for a concrete fraction `q : frac`
    (e.g., to enable writing `l ↦{# 1/2} v`).
  + The new notation `l ↦□ v` is used for the discarded fraction. This
    persistent proposition provides read-only access to `l`.
  + The lemma `mapsto_persist : l ↦{dq} v ==∗ l ↦□ v` is used for making the
    location `l` read-only.
  + See the [changes to HeapLang](https://gitlab.mpi-sws.org/iris/iris/-/merge_requests/554)
    for an indication on how to adapt your language.
  + See the [changes to iris-examples](https://gitlab.mpi-sws.org/iris/examples/-/commit/a8425b708ec51d918d5cf6eb3ab6fde88f4e2c2a)
    for an indication on how to adapt your development. In particular, instead
    of `∃ q, l ↦{q} v` you likely want to use `l ↦□ v`, which has the advantage
    of being persistent (rather than just duplicable).
Ralf Jung's avatar
Ralf Jung committed
219
220
221
222
223
224
225
226
* Change type of some ghost state lemmas (mostly about allocation) to use `∗`
  instead of `∧` (consistent with our usual style).  This affects the following
  lemmas: `own_alloc_strong_dep`, `own_alloc_cofinite_dep`, `own_alloc_strong`,
  `own_alloc_cofinite`, `own_updateP`, `saved_anything_alloc_strong`,
  `saved_anything_alloc_cofinite`, `saved_prop_alloc_strong`,
  `saved_prop_alloc_cofinite`, `saved_pred_alloc_strong`,
  `saved_pred_alloc_cofinite`, `auth_alloc_strong`, `auth_alloc_cofinite`,
  `auth_alloc`.
Ralf Jung's avatar
Ralf Jung committed
227
* Change `uPred_mono` to only require inclusion at the smaller step-index.
Robbert Krebbers's avatar
Robbert Krebbers committed
228
229
230
231
232
233
* Put `iProp`/`iPreProp`-isomorphism into the `own` construction. This affects
  clients that define higher-order ghost state constructions. Concretely, when
  defining an `inG`, the functor no longer needs to be applied to `iPreProp`,
  but should be applied to `iProp`. This avoids clients from having to push
  through the `iProp`/`iPreProp`-isomorphism themselves, which is now handled
  once and for all by the `own` construction.
234
235
236
237
* Rename `gen_heap_ctx` to `gen_heap_interp`, since it is meant to be used in
  the state interpretation of WP and since `_ctx` is elsewhere used as a suffix
  indicating "this is a persistent assumption that clients should always have in
  their context". Likewise, rename `proph_map_ctx` to `proph_map_interp`.
Ralf Jung's avatar
Ralf Jung committed
238
239
240
241
* Move `uPred.prod_validI`, `uPred.option_validI`, and
  `uPred.discrete_fun_validI` to the new `base_logic.algebra` module. That
  module is exported by `base_logic.base_logic` so these names are now usually
  available everywhere, and no longer inside the `uPred` module.
Ralf Jung's avatar
Ralf Jung committed
242
243
244
245
* Remove the `gen_heap` notations `l ↦ -` and `l ↦{q} -`. They were barely used
  and looked very confusing in context: `l ↦ - ∗ P` looks like a magic wand.
* Change `gen_inv_heap` notation `l ↦□ I` to `l ↦_I □`, so that `↦□` can be used
  by `gen_heap`.
Ralf Jung's avatar
Ralf Jung committed
246
247
* Strengthen `mapsto_valid_2` conclusion from `✓ (q1 + q2)%Qp` to
  `⌜✓ (q1 + q2)%Qp ∧ v1 = v2⌝`.
Ralf Jung's avatar
Ralf Jung committed
248
249
* Change `gen_heap_init` to also return ownership of the points-to facts for the
  initial heap.
250
251
* Rename `mapsto_mapsto_ne` to `mapsto_frac_ne`, and add a simpler
  `mapsto_ne` that does not require reasoning about fractions.
Ralf Jung's avatar
Ralf Jung committed
252
253
254
255
256
257
258
* Deprecate the `auth` and `sts` modules. These were logic-level wrappers around
  the underlying RAs; as far as we know, they are unused since they were not
  flexible enough for practical use.
* Deprecate the `viewshift` module, which defined a binary view-shift connective
  with an implicit persistence modality. It was unused and too easily confused
  with `={_}=∗`, the binary view-shift (fancy update) *without* a persistence
  modality.
259

260
261
262
263
264
**Changes in `program_logic`:**

* `wp_strong_adequacy` now applies to an initial state with multiple
  threads instead of only a single thread. The derived adequacy lemmas
  are unchanged.
Ralf Jung's avatar
Ralf Jung committed
265
266
* `pure_exec_fill` is no longer registered as an instance for `PureExec`, to
  avoid TC search attempting to apply this instance all the time.
Ralf Jung's avatar
Ralf Jung committed
267
* Merge `wp_value_inv`/`wp_value_inv'` into `wp_value_fupd`/`wp_value_fupd'` by
Ralf Jung's avatar
Ralf Jung committed
268
  making the lemmas bidirectional.
Robbert Krebbers's avatar
Robbert Krebbers committed
269
270
271
* Generalize HeapLang's `mapsto` (`↦`), `array` (`↦∗`), and atomic heap
  connectives to discardable fractions. See the CHANGELOG entry in the category
  `base_logic` for more information.
Robbert Krebbers's avatar
Robbert Krebbers committed
272
* Opening an invariant or eliminating a mask-changing update modality around a
273
274
  non-atomic weakest precondition creates a side-condition `Atomic ...`.
  Before, this would fail with the unspecific error "iMod: cannot eliminate
Robbert Krebbers's avatar
Robbert Krebbers committed
275
  modality (|={E1,E2}=> ...) in (WP ...)".
Ralf Jung's avatar
Ralf Jung committed
276
277
* In `Ectx_step` and `step_atomic`, mark the parameters that are determined by
  the goal as implicit.
Ralf Jung's avatar
Ralf Jung committed
278
279
* Deprecate the `hoare` module to prevent accidental usage; the recommended way
  to write Hoare-style specifications is to use Texan triples.
280

Ralf Jung's avatar
Ralf Jung committed
281
282
283
**Changes in `heap_lang`:**

* `wp_pures` now turns goals of the form `WP v {{ Φ }}` into `Φ v`.
Ralf Jung's avatar
Ralf Jung committed
284
285
* Fix `wp_bind` in case of a NOP (i.e., when the given expression pattern is
  already at the top level).
Ralf Jung's avatar
Ralf Jung committed
286
287
* The `wp_` tactics now preserve the possibility of doing a fancy update when
  the expression reduces to a value.
Robbert Krebbers's avatar
Robbert Krebbers committed
288
289
290
291
* Move `IntoVal`, `AsVal`, `Atomic`, `AsRecV`, and `PureExec` instances to their
  own file [heap_lang.class_instances](iris_heap_lang/class_instances.v).
* Move `inv_head_step` tactic and `head_step` auto hints (now part of new hint
  database `head_step`) to [heap_lang.tactics](iris_heap_lang/tactics.v).
Robbert Krebbers's avatar
Robbert Krebbers committed
292
293
294
* The tactic `wp_apply` no longer performs `wp_pures` before applying the given
  lemma. The new tactic `wp_smart_apply` repeatedly performs single `wp_pure`
  steps until the lemma matches the goal.
Ralf Jung's avatar
Ralf Jung committed
295

Ralf Jung's avatar
Ralf Jung committed
296
297
298
299
300
301
The following `sed` script helps adjust your code to the renaming (on macOS,
replace `sed` by `gsed`, installed via e.g. `brew install gnu-sed`).
Note that the script is not idempotent, do not run it twice.
```
sed -i -E -f- $(find theories -name "*.v") <<EOF
# agree and L suffix renames
Ralf Jung's avatar
Ralf Jung committed
302
303
s/\bagree_op_inv'/to_agree_op_inv/g
s/\bagree_op_invL'/to_agree_op_inv_L/g
Ralf Jung's avatar
Ralf Jung committed
304
305
s/\bauth_auth_frac_op_invL\b/auth_auth_frac_op_inv_L/g
s/\b(excl|frac|ufrac)_auth_agreeL/\1_auth_agree_L/g
306
307
308
# auth_both_valid
s/\bauth_both_valid\b/auth_both_valid_discrete/g
s/\bauth_both_frac_valid\b/auth_both_frac_valid_discrete/g
309
310
311
# gen_heap_ctx and proph_map_ctx
s/\bgen_heap_ctx\b/gen_heap_interp/g
s/\bproph_map_ctx\b/proph_map_interp/g
312
313
# other gen_heap changes
s/\bmapsto_mapsto_ne\b/mapsto_frac_ne/g
314
315
316
317
318
# remove Ts in algebra
s/\bofeT\b/ofe/g
s/\bOfeT\b/Ofe/g
s/\bcmraT\b/cmra/g
s/\bCmraT\b/Cmra/g
Robbert Krebbers's avatar
Robbert Krebbers committed
319
320
s/\bucmraT\b/ucmra/g
s/\bUcmraT\b/Ucmra/g
321
# _op/valid/core lemmas
322
s/\b(u?frac_(op|valid))'/\1/g
323
324
325
326
327
328
s/\b((coPset|gset)_op)_union\b/\1/g
s/\b((coPset|gset)_core)_self\b/\1/g
s/\b(gmultiset_op)_disj_union\b/\1/g
s/\b(gmultiset_core)_empty\b/\1/g
s/\b(nat_op)_plus\b/\1/g
s/\b(max_nat_op)_max\b/\1/g
329
330
331
332
# equiv_spec
s/\bequiv_entails\b/equiv_entails_1_1/g
s/\bequiv_entails_sym\b/equiv_entails_1_2/g
s/\bequiv_spec\b/equiv_entails/g
Ralf Jung's avatar
Ralf Jung committed
333
334
335
EOF
```

Ralf Jung's avatar
Ralf Jung committed
336
## Iris 3.3.0 (released 2020-07-15)
Robbert Krebbers's avatar
Robbert Krebbers committed
337

Ralf Jung's avatar
Ralf Jung committed
338
This release does not have any outstanding highlights, but contains a large
Ralf Jung's avatar
Ralf Jung committed
339
number of improvements all over the board.  For instance:
Ralf Jung's avatar
Ralf Jung committed
340
341

* `heap_lang` now supports deallocation as well as better reasoning about
Ralf Jung's avatar
Ralf Jung committed
342
343
  "invariant locations" (locations that perpetually satisfy some Coq-level
  invariant).
Ralf Jung's avatar
Ralf Jung committed
344
345
346
347
348
* Invariants (`inv N P`) are more flexible, now also supporting splitting
  and merging of invariants with respect to separating conjunction.
* Performance of the proofmode for BIs constructed on top of other BIs (e.g.,
  `monPred`) was greatly improved, leading to up to 70% speedup in individual
  files. As part of this refactoring, the proofmode can now also be instantiated
Ralf Jung's avatar
Ralf Jung committed
349
350
351
352
353
  with entirely "logical" notion of BIs that do not have a (non-trivial) metric
  structure, and still support reasoning about ▷.
* The proof mode now provides experimental support for naming pure facts in
  intro patterns.  See
  [iris/string-ident](https://gitlab.mpi-sws.org/iris/string-ident) for details.
Ralf Jung's avatar
Ralf Jung committed
354
355
356
357
358
359
360
361
* Iris now provides official ASCII notation. We still recommend using the
  Unicode notation for better consistency and interoperability with other Iris
  libraries, but provide ASCII notation for when Unicode is not an option.
* We removed several coercions, fixing "ambiguous coercion path" warnings and
  solving some readability issues.
* Coq 8.10, 8.11, and 8.12 are newly supported by this release, and Coq 8.7 and
  8.8 are no longer supported.

Ralf Jung's avatar
Ralf Jung committed
362
363
Further details are given in the changelog below. We always first list the
potentially breaking changes, then (some of) the additions.
Ralf Jung's avatar
Ralf Jung committed
364
365
366
367
368
369

This release of Iris received contributions by Abel Nieto, Amin Timany, Dan
Frumin, Derek Dreyer, Dmitry Khalanskiy, Gregory Malecha, Jacques-Henri Jourdan,
Jonas Kastberg, Jules Jacobs, Matthieu Sozeau, Maxime Dénès, Michael Sammler,
Paolo G. Giarrusso, Ralf Jung, Robbert Krebbers, Simon Friis Vindum, Simon
Spies, and Tej Chajed.  Thanks a lot to everyone involved!
Ralf Jung's avatar
Ralf Jung committed
370

371
**Changes in `heap_lang`:**
Ralf Jung's avatar
Ralf Jung committed
372

Ralf Jung's avatar
Ralf Jung committed
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
* Remove global `Open Scope Z_scope` from `heap_lang.lang`, and leave it up to
  reverse dependencies if they want to `Open Scope Z_scope` or not.
* Fix all binary operators performing pointer arithmetic (instead of just the
  dedicated `OffsetOp` operator doing that).
* Rename `heap_lang.lifting` to `heap_lang.primitive_laws`. There now also
  exists `heap_lang.derived_laws`.
* Make lemma names for `fill` more consistent
  - Use the `_inv` suffix for the the backwards directions:
   `reducible_fill``reducible_fill_inv`,
   `reducible_no_obs_fill``reducible_no_obs_fill_inv`,
   `not_stuck_fill``not_stuck_fill_inv`.
  - Use the non-`_inv` names (that freed up) for the forwards directions:
   `reducible_fill`, `reducible_no_obs_fill`, `irreducible_fill_inv`.
* Remove namespace `N` from `is_lock`.

Ralf Jung's avatar
Ralf Jung committed
388
389
390
* Add support for deallocation of locations via the `Free` operation.
* Add a fraction to the heap_lang `array` assertion.
* Add `lib.array` module for deallocating, copying and cloning arrays.
Ralf Jung's avatar
Ralf Jung committed
391
392
393
394
* Add TWP (total weakest-pre) lemmas for arrays.
* Add a library for "invariant locations": heap locations that will not be
  deallocated (i.e., they are GC-managed) and satisfy some pure, Coq-level
  invariant.  See `iris.base_logic.lib.gen_inv_heap` for details.
Ralf Jung's avatar
Ralf Jung committed
395
* Add the ghost state for "invariant locations" to `heapG`.  This affects the
Ralf Jung's avatar
Ralf Jung committed
396
397
  statement of `heap_adequacy`, which is now responsible for initializing the
  "invariant locations" invariant.
398
* Add lemma `mapsto_mapsto_ne : ¬ ✓(q1 + q2)%Qp → l1 ↦{q1} v1 -∗ l2 ↦{q2} v2 -∗ ⌜l1 ≠ l2⌝`.
Ralf Jung's avatar
Ralf Jung committed
399
* Add lemma `is_lock_iff` and show that `is_lock` is contractive.
Ralf Jung's avatar
Ralf Jung committed
400

401
**Changes in `program_logic`:**
Ralf Jung's avatar
Ralf Jung committed
402
403
404
405
406

* In the axiomatization of ectx languages, replace the axiom of positivity of
  context composition with an axiom that says if `fill K e` takes a head step,
  then either `K` is the empty evaluation context or `e` is a value.

Ralf Jung's avatar
Ralf Jung committed
407
**Changes in the logic (`base_logic`, `bi`):**
Robbert Krebbers's avatar
Robbert Krebbers committed
408

Ralf Jung's avatar
Ralf Jung committed
409
* Rename some accessor-style lemmas to consistently use the suffix `_acc`
Ralf Jung's avatar
Ralf Jung committed
410
  instead of `_open`:
411
412
413
414
415
  `inv_open``inv_acc`, `inv_open_strong``inv_acc_strong`,
  `inv_open_timeless``inv_acc_timeless`, `na_inv_open``na_inv_acc`,
  `cinv_open``cinv_acc`, `cinv_open_strong``cinv_acc_strong`,
  `auth_open``auth_acc`, `sts_open``sts_acc`.
  To make this work, also rename `inv_acc``inv_alter`.
Ralf Jung's avatar
Ralf Jung committed
416
417
  (Most developments should be unaffected as the typical way to invoke these
  lemmas is through `iInv`, and that does not change.)
Robbert Krebbers's avatar
Robbert Krebbers committed
418
419
420
421
* Change `inv_iff`, `cinv_iff` and `na_inv_iff` to make order of arguments
  consistent and more convenient for `iApply`. They are now of the form
  `inv N P -∗ ▷ □ (P ↔ Q) -∗ inv N Q` and (similar for `na_inv_iff` and
  `cinv_iff`), following e.g., `inv_alter` and `wp_wand`.
Ralf Jung's avatar
Ralf Jung committed
422
423
* Rename `inv_sep_1``inv_split_1`, `inv_sep_2``inv_split_2`, and
  `inv_sep``inv_split` to be consistent with the naming convention in boxes.
Ralf Jung's avatar
Ralf Jung committed
424
425
426
427
* Update the strong variant of the accessor lemma for cancellable invariants to
  match that of regular invariants, where you can pick the mask at a later time.
  (The other part that makes it strong is that you get back the token for the
  invariant immediately, not just when the invariant is closed again.)
Ralf Jung's avatar
Ralf Jung committed
428
429
* Rename `iProp`/`iPreProp` to `iPropO`/`iPrePropO` since they are `ofeT`s.
  Introduce `iProp` for the `Type` carrier of `iPropO`.
Robbert Krebbers's avatar
Robbert Krebbers committed
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
* Flatten the BI hierarchy by merging the `bi` and `sbi` canonical structures.
  This gives significant performance benefits on developments that construct BIs
  from BIs (e.g., use `monPred`). For, example it gives a performance gain of 37%
  overall on lambdarust-weak, with improvements for individual files up to 72%,
  see Iris issue #303. The concrete changes are as follows:
  + The `sbi` canonical structure has been removed.
  + The `bi` canonical structure contains the later modality. It does not
    require the later modality to be contractive or to satisfy the Löb rule, so
    we provide a smart constructor `bi_later_mixin_id` to get the later axioms
    "for free" if later is defined to be the identity function.
  + There is a separate class `BiLöb`, and a "free" instance of that class if
    the later modality is contractive. A `BiLöb` instance is required for the
    `iLöb` tactic, and for timeless instances of implication and wand.
  + There is a separate type class `BiInternalEq` for BIs with a notion of
    internal equality (internal equality was part of `sbi`). An instance of this
    class is needed for the `iRewrite` tactic, and the various lemmas about
    internal equality.
  + The class `SbiEmbed` has been removed and been replaced by classes
    `BiEmbedLater` and `BiEmbedInternalEq`.
  + The class `BiPlainly` has been generalized to BIs without internal equality.
    As a consequence, there is a separate class `BiPropExt` for BIs with
    propositional extensionality (i.e., `■ (P ∗-∗ Q) ⊢ P ≡ Q`).
  + The class `BiEmbedPlainly` is a bi-entailment (i.e., `⎡■ P⎤ ⊣⊢ ■ ⎡P⎤`
    instead of `■ ⎡P⎤ ⊢ ⎡■ P⎤`) as it has been generalized to BIs without a
    internal equality. In the past, the left-to-right direction was obtained for
    "free" using the rules of internal equality.
Ralf Jung's avatar
Ralf Jung committed
456
457
458
459
* Remove coercion from `iProp` (and other MoSeL propositions) to `Prop`.
  Instead, use the new unary notation `⊢ P`, or `⊢@{PROP} P` if the proposition
  type cannot be inferred. This also means that `%I` should not be necessary any
  more when stating lemmas, as `P` above is automatically parsed in scope `%I`.
Ralf Jung's avatar
Ralf Jung committed
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
* Some improvements to the `bi/lib/core` construction:
  + Rename `coreP_wand` into `coreP_entails` since it does not involve wands.
  + Generalize `coreP_entails` to non-affine BIs, and prove more convenient
    version `coreP_entails'` for `coreP P` with `P` affine.
  + Add instance `coreP_affine P : Affine P → Affine (coreP P)` and
    lemma `coreP_wand P Q : <affine> ■ (P -∗ Q) -∗ coreP P -∗ coreP Q`.
* Remove notation for 3-mask step-taking updates, and made 2-mask notation less
  confusing by distinguishing it better from mask-changing updates.
  Old: `|={Eo,Ei}▷=> P`. New: `|={Eo}[Ei]▷=> P`.
  Here, `Eo` is the "outer mask" (used at the beginning and end) and `Ei` the
  "inner mask" (used around the ▷ in the middle).
  As part of this, the lemmas about the 3-mask variant were changed to be about
  the 2-mask variant instead, and `step_fupd_mask_mono` now also has a more
  consistent argument order for its masks.

* Add a counterexample showing that sufficiently powerful cancellable invariants
  with a linear token subvert the linearity guarantee (see
  `bi.lib.counterexmples` for details).
* Redefine invariants as "semantic invariants" so that they support
  splitting and other forms of weakening.
* Add lemmas `inv_combine` and `inv_combine_dup_l` for combining invariants.
* Add the type `siProp` of "plain" step-indexed propositions, together with
  basic proofmode support.
Ralf Jung's avatar
Ralf Jung committed
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
* New ASCII versions of Iris notations. These are marked parsing only and
  can be made available using `Require Import iris.bi.ascii`. The new
  notations are (notations marked [†] are disambiguated using notation scopes):
  - entailment: `|-` for `⊢` and `-|-` for `⊣⊢`
  - logic[†]: `->` for `→`, `/\\` for `∧`, `\\/` for `∨`, and `<->` for `↔`
  - quantifiers[†]: `forall` for `∀` and `exists` for `∃`
  - separation logic: `**` for `∗`, `-*` for `-∗`, and `*-*` for `∗-∗`
  - step indexing: `|>` for `▷`
  - modalities: `<#>` for `□` and `<except_0>` for `◇`
  - most derived notations can be computed from previous notations using the
    substitutions above, e.g. replace `∗` with `*` and `▷` with `|>`. Examples
    include the following:
    - `|={E1,E2}=* P` for `|={E1,E2}=∗`
    - `P ={E}=* Q` for `P ={E}=∗ Q`
    - `P ={E1,E2}=* Q` for `P ={E1,E2}=∗ Q`
Ralf Jung's avatar
Ralf Jung committed
498
    - `|={E1}[E2]|>=> Q` for `|={E1}[E2]▷=> Q`
Ralf Jung's avatar
Ralf Jung committed
499
500
501
502
503
    The full list can be found in [theories/bi/ascii.v](theories/bi/ascii.v),
    where the ASCII notations are defined in terms of the unicode notations.
* Add affine, absorbing, persistent and timeless instances for telescopes.
* Add a construction `bi_rtc` to create reflexive transitive closures of
  PROP-level binary relations.
504
505
506
507
* Slightly strengthen the lemmas `big_sepL_nil'`, `big_sepL2_nil'`,
  `big_sepM_nil'` `big_sepM2_empty'`, `big_sepS_empty'`, and `big_sepMS_empty'`.
  They now only require that the argument `P` is affine instead of the whole BI
  being affine.
Ralf Jung's avatar
Ralf Jung committed
508
509
510
511
512
513
* Add `big_sepL_insert_acc`, a variant of `big_sepL_lookup_acc` which allows
  updating the value.
* Add many missing `Proper`/non-expansiveness lemmas for big-ops.
* Add `big_*_insert_delete` lemmas to split a `<[i:=x]> m` map into `i` and the rest.
* Seal the definitions of `big_opS`, `big_opMS`, `big_opM` and `big_sepM2`
  to prevent undesired simplification.
514
* Fix `big_sepM2_fmap*` only working for `nat` keys.
Ralf Jung's avatar
Ralf Jung committed
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536

**Changes in `proofmode`:**

* Make use of `notypeclasses refine` in the implementation of `iPoseProof` and
  `iAssumption`, see <https://gitlab.mpi-sws.org/iris/iris/merge_requests/329>.
  This has two consequences:
  1. Coq's "new" unification algorithm (the one in `refine`, not the "old" one
     in `apply`) is used more often by the proof mode tactics.
  2. Due to the use of `notypeclasses refine`, TC constraints are solved less
     eagerly, see <https://github.com/coq/coq/issues/6583>.
  In order to port your development, it is often needed to instantiate evars
  explicitly (since TC search is performed less eagerly), and in few cases it is
  needed to unfold definitions explicitly (due to new unification algorithm
  behaving differently).
* Strengthen the tactics `iDestruct`, `iPoseProof`, and `iAssert`:
  - They succeed in certain cases where they used to fail.
  - They keep certain hypotheses in the intuitionistic context, where they were
    moved to the spatial context before.
  The latter can lead to stronger proof mode contexts, and therefore to
  backwards incompatibility. This can usually be fixed by manually clearing some
  hypotheses. A more detailed description of the changes can be found in
  <https://gitlab.mpi-sws.org/iris/iris/merge_requests/341>.
Ralf Jung's avatar
Ralf Jung committed
537
538
539
540
541
542
* Remove the long-deprecated `cofeT` alias (for `ofeT`) and `dec_agree` RA (use
  `agree` instead).

* Add `auto` hint for `∗-∗`.
* Add new tactic `iStopProof` to turn the proof mode entailment into an ordinary
  Coq goal `big star of context ⊢ proof mode goal`.
Ralf Jung's avatar
Ralf Jung committed
543
544
545
546
547
548
549
550
551
552
* Add new introduction pattern `-# pat` that moves a hypothesis from the
  intuitionistic context to the spatial context.
* The tactic `iAssumption` also recognizes assumptions `⊢ P` in the Coq context.
* Better support for telescopes in the proof mode, i.e., all tactics should
  recognize and distribute telescopes now.
* The proof mode now supports names for pure facts in intro patterns. Support
  requires implementing `string_to_ident`. Without this tactic such patterns
  will fail. We provide one implementation using Ltac2 which works with Coq 8.11
  and can be installed with opam; see
  [iris/string-ident](https://gitlab.mpi-sws.org/iris/string-ident) for details.
Ralf Jung's avatar
Ralf Jung committed
553

554
555
556
557
558
559
**Changes in `algebra`:**

* Remove `Core` type class for defining the total core; it is now always
  defined in terms of the partial core. The only user of this type class was the
  STS RA.
* The functions `{o,r,ur}Functor_diag` are no longer coercions, and renamed into
560
561
  `{o,r,ur}Functor_apply` to better match their intent. This fixes "ambiguous
  coercion path" warnings.
562
563
* Rename `{o,r,ur}Functor_{ne,id,compose,contractive}` into
  `{o,r,ur}Functor_map_{ne,id,compose,contractive}`.
Ralf Jung's avatar
Ralf Jung committed
564
565
* Move derived camera constructions (`frac_auth` and `ufrac_auth`) to the folder
  `algebra/lib`.
566
567
568
569
570
571
572
573
574
575
576
577
578
579
* Rename `mnat` to `max_nat` and "box" it by creating a separate type for it.
* Move the RAs for `nat` and `positive` and the `mnat` RA into a separate
  module. They must now be imported from `From iris.algebra Require Import
  numbers`.
* Make names of `f_op`/`f_core` rewrite lemmas more consistent by always making
  `_core`/`_op` the suffix:
  `op_singleton``singleton_op`, `core_singleton``singleton_core`,
  `discrete_fun_op_singleton``discrete_fun_singleton_op`,
  `discrete_fun_core_singleton``discrete_fun_singleton_core`,
  `list_core_singletonM``list_singleton_core`,
  `list_op_singletonM``list_singleton_op`,
  `sts_op_auth_frag``sts_auth_frag_op`,
  `sts_op_auth_frag_up``sts_auth_frag_up_op`,
  `sts_op_frag``sts_frag_op`,
580
581
582
583
584
585
586
587
588
589
590
  `list_op_length``list_length_op`,
  `list_core_singletonM``list_singletonM_core`,
  `list_op_singletonM``list_singletonM_op`.
* All list "map singleton" lemmas consistently use `singletonM` in their name:
  `list_singleton_valid``list_singletonM_valid`,
  `list_singleton_core_id``list_singletonM_core_id`,
  `list_singleton_snoc``list_singletonM_snoc`,
  `list_singleton_updateP``list_singletonM_updateP`,
  `list_singleton_updateP'``list_singletonM_updateP'`,
  `list_singleton_update``list_singletonM_update`,
  `list_alloc_singleton_local_update``list_alloc_singletonM_local_update`.
Ralf Jung's avatar
Ralf Jung committed
591
* Remove `auth_both_op` and rename `auth_both_frac_op` into `auth_both_op`.
592
593
* Add lemma `singleton_included : {[ i := x ]} ≼ ({[ i := y ]} ↔ x ≡ y ∨ x ≼ y`,
  and rename existing asymmetric lemmas (with a singleton on just the LHS):
Ralf Jung's avatar
Ralf Jung committed
594
595
596
  `singleton_includedN``singleton_includedN_l`,
  `singleton_included``singleton_included_l`,
  `singleton_included_exclusive``singleton_included_exclusive_l`.
Ralf Jung's avatar
Ralf Jung committed
597
598
599
600
601
602
603
604
605

* Add notion `ofe_iso A B` that states that OFEs `A` and `B` are
  isomorphic. This is used in the COFE solver.
* Add `{o,r,ur}Functor_oFunctor_compose` for composition of functors.
* Add `pair_op_1` and `pair_op_2` to split a pair where one component is the unit.
* Add derived camera construction `excl_auth A` for `auth (option (excl A))`.
* Make lemma `Excl_included` a bi-implication.
* Make `auth_update_core_id` work with any fraction of the authoritative
  element.
Yusuke Matsushita's avatar
Yusuke Matsushita committed
606
* Add `min_nat`, an RA for natural numbers with `min` as the operation.
Ralf Jung's avatar
Ralf Jung committed
607
* Add many missing `Proper`/non-expansiveness lemmas for maps and lists.
Ralf Jung's avatar
Ralf Jung committed
608
609
610
611
* Add `list_singletonM_included` and `list_lookup_singletonM_{lt,gt}` lemmas
  about singletons in the list RA.
* Add `list_core_id'`, a stronger version of `list_core_id` which only talks
  about elements that are actually in the list.
612

613
614
615
The following `sed` script helps adjust your code to the renaming (on macOS,
replace `sed` by `gsed`, installed via e.g. `brew install gnu-sed`).
Note that the script is not idempotent, do not run it twice.
616
617
```
sed -i -E '
618
619
620
621
622
623
# functor renames
s/\b(o|r|ur)Functor_(ne|id|compose|contractive)\b/\1Functor_map_\2/g
# singleton_included renames
s/\bsingleton_includedN\b/singleton_includedN_l/g
s/\bsingleton_included\b/singleton_included_l/g
s/\bsingleton_included_exclusive\b/singleton_included_exclusive_l/g
624
625
626
627
# f_op/f_core renames
s/\b(op|core)_singleton\b/singleton_\1/g
s/\bdiscrete_fun_(op|core)_singleton\b/discrete_fun_singleton_\1/g
s/\bsts_op_(auth_frag|auth_frag_up|frag)\b/sts_\1_op/g
628
s/\blist_(op|core)_singletonM\b/list_singletonM_\1/g
629
s/\blist_op_length\b/list_length_op/g
630
631
632
633
634
635
636
# list "singleton map" renames
s/\blist_singleton_valid\b/list_singletonM_valid/g
s/\blist_singleton_core_id\b/list_singletonM_core_id/g
s/\blist_singleton_snoc\b/list_singletonM_snoc/g
s/\blist_singleton_updateP\b/list_singletonM_updateP/g
s/\blist_singleton_update\b/list_singletonM_update/g
s/\blist_alloc_singleton_local_update\b/list_alloc_singletonM_local_update/g
637
638
639
640
641
642
643
# inv renames
s/\binv_sep(|_1|_2)\b/inv_split\1/g
s/\binv_acc\b/inv_alter/g
s/\binv_open(|_strong|_timeless)\b/inv_acc\1/g
s/\bcinv_open(|_strong)\b/cinv_acc\1/g
s/\b(na_inv|auth|sts)_open\b/\1_acc/g
# miscellaneous
644
s/\bauth_both_frac_op\b/auth_both_op/g
645
s/\bmnat\b/max_nat/g
646
s/\bcoreP_wand\b/coreP_entails/g
647
648
649
' $(find theories -name "*.v")
```

Ralf Jung's avatar
Ralf Jung committed
650
## Iris 3.2.0 (released 2019-08-29)
Ralf Jung's avatar
Ralf Jung committed
651

Ralf Jung's avatar
Ralf Jung committed
652
653
654
The highlight of this release is the completely re-engineered interactive proof
mode.  Not only did many tactics become more powerful; the entire proof mode can
now be used not just for Iris but also for other separation logics satisfying
Ralf Jung's avatar
Ralf Jung committed
655
656
657
658
659
660
the proof mode interface (e.g., [Iron] and [GPFSL]). Also see the
[accompanying paper][MoSeL].

[Iron]: https://iris-project.org/iron/
[GPFSL]: https://gitlab.mpi-sws.org/iris/gpfsl/
[MoSeL]: https://iris-project.org/mosel/
Ralf Jung's avatar
Ralf Jung committed
661
662
663
664
665
666
667
668
669
670
671
672
673
674

Beyond that, the Iris program logic gained the ability to reason about
potentially stuck programs, and a significantly strengthened adequacy theorem
that unifies the three previously separately presented theorems.  There are now
also Hoare triples for total program correctness (but with very limited support
for invariants) and logical atomicity.

And finally, our example language HeapLang was made more realistic
(Compare-and-set got replaced by compare-exchange and limited to only compare
values that can actually be compared atomically) and more powerful, with added
support for arrays and prophecy variables.

Further details are given in the changelog below.

Ralf Jung's avatar
Ralf Jung committed
675
676
677
678
679
680
681
682
This release of Iris received contributions by Aleš Bizjak, Amin Timany, Dan
Frumin, Glen Mével, Hai Dang, Hugo Herbelin, Jacques-Henri Jourdan, Jan Menz,
Jan-Oliver Kaiser, Jonas Kastberg Hinrichsen, Joseph Tassarotti, Mackie Loeffel,
Marianna Rapoport, Maxime Dénès, Michael Sammler, Paolo G. Giarrusso,
Pierre-Marie Pédrot, Ralf Jung, Robbert Krebbers, Rodolphe Lepigre, and Tej
Chajed. Thanks a lot to everyone involved!

**Changes in the theory of Iris itself:**
Ralf Jung's avatar
Ralf Jung committed
683

684
* Change in the definition of WP, so that there is a fancy update between
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
685
686
  the quantification over the next states and the later modality. This makes it
  possible to prove more powerful lifting lemmas: The new versions feature an
Ralf Jung's avatar
Ralf Jung committed
687
  "update that takes a step".
688
689
690
* Add weakest preconditions for total program correctness.
* "(Potentially) stuck" weakest preconditions and the "plainly modality" are no
  longer considered experimental.
Ralf Jung's avatar
Ralf Jung committed
691
* Add the notion of an "observation" to the language interface, so that
Ralf Jung's avatar
Ralf Jung committed
692
693
  every reduction step can optionally be marked with an event, and an execution
  trace has a matching list of events.  Change WP so that it is told the entire
694
  future trace of observations from the beginning.
Ralf Jung's avatar
Ralf Jung committed
695
* The Löb rule is now a derived rule; it follows from later-intro, later
Ralf Jung's avatar
Ralf Jung committed
696
697
  being contractive and the fact that we can take fixpoints of contractive
  functions.
Ralf Jung's avatar
Ralf Jung committed
698
* Add atomic updates and logically atomic triples, including tactic support.
Ralf Jung's avatar
Ralf Jung committed
699
  See `heap_lang/lib/increment.v` for an example.
700
701
702
* Extend the state interpretation with a natural number that keeps track of
  the number of forked-off threads, and have a global fixed proposition that
  describes the postcondition of each forked-off thread (instead of it being
Robbert Krebbers's avatar
Robbert Krebbers committed
703
  `True`).
704
705
706
* A stronger adequacy statement for weakest preconditions that involves
  the final state, the post-condition of forked-off threads, and also applies if
  the main-thread has not terminated.
707
708
709
* The user-chosen functor used to instantiate the Iris logic now goes from
  COFEs to Cameras (it was OFEs to Cameras).

Ralf Jung's avatar
Ralf Jung committed
710
**Changes in heap_lang:**
711

712
713
714
715
716
717
718
719
* CAS (compare-and-set) got replaced by CmpXchg (compare-exchange).  The
  difference is that CmpXchg returns a pair consisting of the old value and a
  boolean indicating whether the comparison was successful and hence the
  exchange happened.  CAS can be obtained by simply projecting to the second
  component, but also providing the old value more closely models the primitive
  typically provided in systems languages (C, C++, Rust).
  The comparison by this operation also got weakened to be efficiently
  implementable: CmpXchg may only be used to compare "unboxed" values that can
Ralf Jung's avatar
Ralf Jung committed
720
721
722
723
724
  be represented in a single machine word. It is sufficient if one of the two
  compared values is unboxed.
* For consistency, the restrictions CmpXchg imposes on comparison also apply to
  the `=` binary operator. This also fixes the long-standing problem that that
  operator allowed compared closures with each other.
Ralf Jung's avatar
Ralf Jung committed
725
726
* Implement prophecy variables using the new support for "observations". The
  erasure theorem (showing that prophecy variables do not alter program
Ralf Jung's avatar
Ralf Jung committed
727
  behavior) can be found [in the iris/examples repository][prophecy-erasure].
Ralf Jung's avatar
Ralf Jung committed
728
* heap_lang now uses right-to-left evaluation order. This makes it
Ralf Jung's avatar
Ralf Jung committed
729
  significantly easier to write specifications of curried functions.
Ralf Jung's avatar
Ralf Jung committed
730
* heap_lang values are now injected in heap_lang expressions via a specific
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
731
732
  constructor of the expr inductive type. This simplifies much the tactical
  infrastructure around the language. In particular, this allow us to get rid
Robbert Krebbers's avatar
Robbert Krebbers committed
733
  the reflection mechanism that was needed for proving closedness, atomicity and
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
734
735
  "valueness" of a term. The price to pay is the addition of new
  "administrative" reductions in the operational semantics of the language.
736
737
* heap_lang now has support for allocating, accessing and reasoning about arrays
  (continuously allocated regions of memory).
Robbert Krebbers's avatar
Robbert Krebbers committed
738
* One can now assign "meta" data to heap_lang locations.
Ralf Jung's avatar
Ralf Jung committed
739

Ralf Jung's avatar
Ralf Jung committed
740
741
[prophecy-erasure]: https://gitlab.mpi-sws.org/iris/examples/blob/3f33781fe6e19cfdb25259c8194d34403f1134d5/theories/logatom/proph_erasure.v

Ralf Jung's avatar
Ralf Jung committed
742
**Changes in Coq:**
743

Ralf Jung's avatar
Ralf Jung committed
744
* An all-new generalized proof mode that abstracts away from Iris!  Major new
Ralf Jung's avatar
Ralf Jung committed
745
746
747
748
749
750
  features:
  - The proof mode can now be used with logics derived from Iris (like iGPS),
    with non-step-indexed logics and even with non-affine (i.e., linear) logics.
  - `iModIntro` is more flexible and more powerful, it now also subsumes
    `iNext` and `iAlways`.
  - General infrastructure for deriving a logic for monotone predicates over
Ralf Jung's avatar
Ralf Jung committed
751
    an existing logic (see the paper for more details).
Ralf Jung's avatar
Ralf Jung committed
752
    Developments instantiating the proof mode typeclasses may need significant
Robbert Krebbers's avatar
Robbert Krebbers committed
753
754
    changes.  For developments just using the proof mode tactics, porting should
    not be too much effort.  Notable things to port are:
Ralf Jung's avatar
Ralf Jung committed
755
756
757
758
759
  - All the BI laws moved from the `uPred` module to the `bi` module.  For
    example, `uPred.later_equivI` became `bi.later_equivI`.
  - Big-ops are automatically imported, imports of `iris.base_logic.big_op` have
    to be removed.
  - The ⊢ notation can sometimes infer different (but convertible) terms when
Robbert Krebbers's avatar
Robbert Krebbers committed
760
    searching for the BI to use, which (due to Coq limitations) can lead to
Ralf Jung's avatar
Ralf Jung committed
761
762
763
764
    failing rewrites, in particular when rewriting at function types.
* The `iInv` tactic can now be used without the second argument (the name for
  the closing update).  It will then instead add the obligation to close the
  invariant to the goal.
Ralf Jung's avatar
Ralf Jung committed
765
766
* The new `iEval` tactic can be used to execute a simplification or rewriting
  tactic on some specific part(s) of the proofmode goal.
Ralf Jung's avatar
Ralf Jung committed
767
768
* Added support for defining derived connectives involving n-ary binders using
  telescopes.
Ralf Jung's avatar
Ralf Jung committed
769
770
771
* The proof mode now more consistently "prettifies" the goal after each tactic.
  Prettification also simplifies some BI connectives, like conditional
  modalities and telescope quantifiers.
Ralf Jung's avatar
Ralf Jung committed
772
* Improved pretty-printing of Iris connectives (in particular WP and fancy
Ralf Jung's avatar
Ralf Jung committed
773
774
775
  updates) when Coq has to line-wrap the output.  This goes hand-in-hand with an
  improved test suite that also tests pretty-printing.
* Added a `gmultiset` RA.
776
* Rename `timelessP``timeless` (projection of the `Timeless` class)
Ralf Jung's avatar
Ralf Jung committed
777
778
* The CMRA axiom `cmra_extend` is now stated in `Type`, using `sigT` instead of
  in `Prop` using `exists`. This makes it possible to define the function space
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
779
  CMRA even for an infinite domain.
Robbert Krebbers's avatar
Robbert Krebbers committed
780
781
782
783
784
* Rename proof mode type classes for laters:
  - `IntoLaterN``MaybeIntoLaterN` (this one _may_ strip a later)
  - `IntoLaterN'``IntoLaterN` (this one _should_ strip a later)
  - `IntoLaterNEnv``MaybeIntoLaterNEnv`
  - `IntoLaterNEnvs``MaybeIntoLaterNEnvs`
785
786
* Rename:
  - `frag_auth_op``frac_auth_frag_op`
787
788
789
  - `cmra_opM_assoc``cmra_op_opM_assoc`
  - `cmra_opM_assoc_L``cmra_op_opM_assoc_L`
  - `cmra_opM_assoc'``cmra_opM_opM_assoc`
Robbert Krebbers's avatar
Robbert Krebbers committed
790
* `namespaces` has been moved to std++.
791
792
* Changed `IntoVal` to be directly usable for rewriting `e` into `of_val v`, and
  changed `AsVal` to be usable for rewriting via the `[v <-]` destruct pattern.
Ralf Jung's avatar
Ralf Jung committed
793
* `wp_fork` is now written in curried form.
794
* `PureExec`/`wp_pure` now supports taking multiple steps at once.
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
795
796
797
* A new tactic, `wp_pures`, executes as many pure steps as possible, excluding
  steps that would require unlocking subterms. Every impure wp_ tactic executes
  this tactic before doing anything else.
Dan Frumin's avatar
Dan Frumin committed
798
* Add `big_sepM_insert_acc`.
799
800
801
802
* Add big separating conjunctions that operate on pairs of lists (`big_sepL2`)
  and on pairs of maps (`big_sepM2`). In the former case the lists are required
  to have the same length, and in the latter case the maps are required to
  have the same domains.
Dan Frumin's avatar
Dan Frumin committed
803
804
805
* The `_strong` lemmas (e.g. `own_alloc_strong`) work for all infinite
  sets, instead of just for cofinite sets. The versions with cofinite
  sets have been renamed to use the `_cofinite` suffix.
Robbert Krebbers's avatar
Robbert Krebbers committed
806
807
808
* Remove locked value lambdas. The value scope notations `rec: f x := e` and
  `(λ: x, e)` no longer add a `locked`. Instead, we made the `wp_` tactics
  smarter to no longer unfold lambdas/recs that occur behind definitions.
Ralf Jung's avatar
Ralf Jung committed
809
* Export the fact that `iPreProp` is a COFE.
810
811
812
813
814
815
816
* The CMRA `auth` now can have fractional authoritative parts. So now `auth` has
  3 types of elements: the fractional authoritative `●{q} a`, the full
  authoritative `● a ≡ ●{1} a`, and the non-authoritative `◯ a`. Updates are
  only possible with the full authoritative element `● a`, while fractional
  authoritative elements have agreement: `✓ (●{p} a ⋅ ●{q} b) ⇒ a ≡ b`. As a
  consequence, `auth` is no longer a COFE and does not preserve Leibniz
  equality.
817
818
* Add a COFE construction (and functor) on dependent pairs `sigTO`, dual to
  `discrete_funO`.
Hai Dang's avatar
Hai Dang committed
819
820
821
822
823
824
* Rename in `auth`:
  - Use `auth_auth_proj`/`auth_frag_proj` for the projections of `auth`:
    `authoritative``auth_auth_proj` and `auth_own``auth_frag_proj`.
  - Use `auth_auth` and `auth_frag` for the injections into authoritative
    elements and non-authoritative elements respectively.
  - Lemmas for the projections and injections are renamed accordingly.
Hai Dang's avatar
Hai Dang committed
825
826
827
828
829
    For examples:
    + `authoritative_validN``auth_auth_proj_validN`
    + `auth_own_validN``auth_frag_proj_validN`
    + `auth_auth_valid` was not renamed because it was already used for the
      authoritative injection.
Hai Dang's avatar
Hai Dang committed
830
831
  - `auth_both_valid``auth_both_valid_2`
  - `auth_valid_discrete_2``auth_both_valid`
Robbert Krebbers's avatar
Robbert Krebbers committed
832
833
834
* Add the camera `ufrac` for unbounded fractions (i.e. without fractions that
  can be `> 1`) and the camera `ufrac_auth` for a variant of the authoritative
  fractional camera (`frac_auth`) with unbounded fractions.
835
836
* Changed `frac_auth` notation from `●!`/`◯!` to `●F`/`◯F`. sed script:
  `s/◯!/◯F/g; s/●!/●F/g;`.
837
838
* Lemma `prop_ext` works in both directions; its default direction is the
  opposite of what it used to be.
839
* Make direction of `f_op` rewrite lemmas more consistent: Flip `pair_op`,
Paolo G. Giarrusso's avatar
Paolo G. Giarrusso committed
840
841
  `Cinl_op`, `Cinr_op`, `cmra_morphism_op`, `cmra_morphism_pcore`,
  `cmra_morphism_core`.
Robbert Krebbers's avatar
Robbert Krebbers committed
842
843
* Rename lemmas `fupd_big_sep{L,M,S,MS}` into `big_sep{L,M,S,MS}_fupd` to be
  consistent with other such big op lemmas. Also add such lemmas for `bupd`.
844
* Rename `C` suffixes into `O` since we no longer use COFEs but OFEs. Also
Ralf Jung's avatar
Ralf Jung committed
845
  rename `ofe_fun` into `discrete_fun` and the corresponding notation `-c>` into
Ralf Jung's avatar
Ralf Jung committed
846
847
  `-d>`. The renaming can be automatically done using the following script
  (on macOS, replace `sed` by `gsed`, installed via e.g. `brew install gnu-sed`):
848
```
849
sed -i '
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
s/\bCofeMor/OfeMor/g;
s/\-c>/\-d>/g;
s/\bcFunctor/oFunctor/g;
s/\bCFunctor/OFunctor/g;
s/\b\%CF/\%OF/g;
s/\bconstCF/constOF/g;
s/\bidCF/idOF/g
s/\bdiscreteC/discreteO/g;
s/\bleibnizC/leibnizO/g;
s/\bunitC/unitO/g;
s/\bprodC/prodO/g;
s/\bsumC/sumO/g;
s/\bboolC/boolO/g;
s/\bnatC/natO/g;
s/\bpositiveC/positiveO/g;
s/\bNC/NO/g;
s/\bZC/ZO/g;
s/\boptionC/optionO/g;
s/\blaterC/laterO/g;
s/\bofe\_fun/discrete\_fun/g;
s/\bdiscrete\_funC/discrete\_funO/g;
s/\bofe\_morC/ofe\_morO/g;
s/\bsigC/sigO/g;
s/\buPredC/uPredO/g;
s/\bcsumC/csumO/g;
s/\bagreeC/agreeO/g;
s/\bauthC/authO/g;
s/\bnamespace_mapC/namespace\_mapO/g;
s/\bcmra\_ofeC/cmra\_ofeO/g;
s/\bucmra\_ofeC/ucmra\_ofeO/g;
s/\bexclC/exclO/g;
s/\bgmapC/gmapO/g;
s/\blistC/listO/g;
s/\bvecC/vecO/g;
s/\bgsetC/gsetO/g;
s/\bgset\_disjC/gset\_disjO/g;
s/\bcoPsetC/coPsetO/g;
s/\bgmultisetC/gmultisetO/g;
s/\bufracC/ufracO/g
s/\bfracC/fracO/g;
s/\bvalidityC/validityO/g;
s/\bbi\_ofeC/bi\_ofeO/g;
s/\bsbi\_ofeC/sbi\_ofeO/g;
s/\bmonPredC/monPredO/g;
s/\bstateC/stateO/g;
s/\bvalC/valO/g;
s/\bexprC/exprO/g;
s/\blocC/locO/g;
s/\bdec\_agreeC/dec\_agreeO/g;
s/\bgnameC/gnameO/g;
s/\bcoPset\_disjC/coPset\_disjO/g;
901
' $(find theories -name "*.v")
902
```
Hai Dang's avatar
Hai Dang committed
903

Ralf Jung's avatar
Ralf Jung committed
904
## Iris 3.1.0 (released 2017-12-19)
905

Ralf Jung's avatar
Ralf Jung committed
906
**Changes in and extensions of the theory:**
Ralf Jung's avatar
Ralf Jung committed
907

Ralf Jung's avatar
Ralf Jung committed
908
* Define `uPred` as a quotient on monotone predicates `M -> SProp`.
Ralf Jung's avatar
Ralf Jung committed
909
910
* Get rid of some primitive laws; they can be derived:
  `True ⊢ □ True` and `□ (P ∧ Q) ⊢ □ (P ∗ Q)`
911
* Camera morphisms have to be homomorphisms, not just monotone functions.
Ralf Jung's avatar
Ralf Jung committed
912
* Add a proof that `f` has a fixed point if `f^k` is contractive.
913
914
* Constructions for least and greatest fixed points over monotone predicates
  (defined in the logic of Iris using impredicative quantification).
Ralf Jung's avatar
Ralf Jung committed
915
* Add a proof of the inverse of `wp_bind`.
Ralf Jung's avatar
Ralf Jung committed
916
* [Experimental feature] Add new modality: ■ ("plainly").
Ralf Jung's avatar
Ralf Jung committed
917
918
919
920
921
922
923
924
* [Experimental feature] Support verifying code that might get stuck by
  distinguishing "non-stuck" vs. "(potentially) stuck" weakest
  preconditions. (See [Swasey et al., OOPSLA '17] for examples.) The non-stuck
  `WP e @ E {{ Φ }}` ensures that, as `e` runs, it does not get stuck. The stuck
  `WP e @ E ?{{ Φ }}` ensures that, as usual, all invariants are preserved while
  `e` runs, but it permits execution to get stuck. The former implies the
  latter. The full judgment is `WP e @ s; E {{ Φ }}`, where non-stuck WP uses
  *stuckness bit* `s = NotStuck` while stuck WP uses `s = MaybeStuck`.
Ralf Jung's avatar
Ralf Jung committed
925

Ralf Jung's avatar
Ralf Jung committed
926
**Changes in Coq:**
Ralf Jung's avatar
Ralf Jung committed
927

928
929
* Move the `prelude` folder to its own project:
  [coq-std++](https://gitlab.mpi-sws.org/robbertkrebbers/coq-stdpp)
Ralf Jung's avatar
Ralf Jung committed
930
931
932
933
934
935
936
937
938
939
940
* Some extensions/improvements of heap_lang:
  - Improve handling of pure (non-state-dependent) reductions.
  - Add fetch-and-add (`FAA`) operation.
  - Add syntax for all Coq's binary operations on `Z`.
* Generalize `saved_prop` to let the user choose the location of the type-level
  later.  Rename the general form to `saved_anything`.  Provide `saved_prop` and
  `saved_pred` as special cases.
* Improved big operators:
  + They are no longer tied to cameras, but work on any monoid
  + The version of big operations over lists was redefined so that it enjoys
    more definitional equalities.
Ralf Jung's avatar
Ralf Jung committed
941
* Rename some things and change notation:
942
  - The unit of a camera: `empty` -> `unit`, `∅` -> `ε`
943
  - Disjointness: `⊥` -> `##`
Ralf Jung's avatar
Ralf Jung committed
944
  - A proof mode type class `IntoOp` -> `IsOp`
945
946
947
948
949
950
  - OFEs with all elements being discrete: `Discrete` -> `OfeDiscrete`
  - OFE elements whose equality is discrete: `Timeless` -> `Discrete`
  - Timeless propositions: `TimelessP` -> `Timeless`
  - Camera elements such that `core x = x`: `Persistent` -> `CoreId`
  - Persistent propositions: `PersistentP` -> `Persistent`
  - The persistent modality: `always` -> `persistently`
951
  - Adequacy for non-stuck weakestpre: `adequate_safe` -> `adequate_not_stuck`
Ralf Jung's avatar
Ralf Jung committed
952
  - Consistently SnakeCase identifiers:
953
954
955
956
957
958
959
960
961
962
    + `CMRAMixin` -> `CmraMixin`
    + `CMRAT` -> `CmraT`
    + `CMRATotal` -> `CmraTotal`
    + `CMRAMorphism` -> `CmraMorphism`
    + `CMRADiscrete` -> `CmraDiscrete`
    + `UCMRAMixin` -> `UcmraMixin`
    + `UCMRAT` -> `UcmraT`
    + `DRAMixin` -> `DraMixin`
    + `DRAT` -> `DraT`
    + `STS` -> `Sts`
Ralf Jung's avatar
Ralf Jung committed
963
964
  - Many lemmas also changed their name.  `always_*` became `persistently_*`,
    and furthermore: (the following list is not complete)
965
966
967
968
969
970
971
972
973
974
    + `impl_wand` -> `impl_wand_1` (it only involves one direction of the
      equivalent)
    + `always_impl_wand` -> `impl_wand`
    + `always_and_sep_l` -> `and_sep_l`
    + `always_and_sep_r` -> `and_sep_r`
    + `always_sep_dup` -> `sep_dup`
    + `wand_impl_always` -> `impl_wand_persistently` (additionally,
      the direction of this equivalence got swapped for consistency's sake)
    + `always_wand_impl` -> `persistently_impl_wand` (additionally, the
      direction of this equivalence got swapped for consistency's sake)
Ralf Jung's avatar
Ralf Jung committed
975
  The following `sed` snippet should get you most of the way (on macOS you will
976
  have to replace `sed` by `gsed`, installed via e.g. `brew install gnu-sed`):
Ralf Jung's avatar
Ralf Jung committed
977
```
978
sed -i 's/\bPersistentP\b/Persistent/g; s/\bTimelessP\b/Timeless/g; s/\bCMRADiscrete\b/CmraDiscrete/g; s/\bCMRAT\b/CmraT/g; s/\bCMRAMixin\b/CmraMixin/g; s/\bUCMRAT\b/UcmraT/g; s/\bUCMRAMixin\b/UcmraMixin/g; s/\bSTS\b/Sts/g' $(find -name "*.v")
Ralf Jung's avatar
Ralf Jung committed
979
```
Ralf Jung's avatar
Ralf Jung committed
980
981
* `PersistentL` and `TimelessL` (persistence and timelessness of lists of
  propositions) are replaces by `TCForall` from std++.
Ralf Jung's avatar
Ralf Jung committed
982
983
* Fix a bunch of consistency issues in the proof mode, and make it overall more
  usable.  In particular:
984
985
986
987
988
989
990
991
992
993
  - All proof mode tactics start the proof mode if necessary; `iStartProof` is
    no longer needed and should only be used for building custom proof mode
    tactics.
  - Change in the grammar of specialization patterns: `>[...]` -> `[> ...]`
  - Various new specification patterns for `done` and framing.
  - There is common machinery for symbolic execution of pure reductions. This
    is provided by the type classes `PureExec` and `IntoVal`.
  - There is a new connective `tc_opaque`, which can be used to make definitions
    opaque for type classes, and thus opaque for most tactics of the proof
    mode.
Ralf Jung's avatar
Ralf Jung committed
994
995
996
997
998
999
1000
1001
  - Define Many missing type class instances for distributing connectives.
  - Implement the tactics `iIntros (?)` and `iIntros "!#"` (i.e. `iAlways`)
    using type classes. This makes them more generic, e.g., `iIntros (?)` also
    works when the universal quantifier is below a modality, and `iAlways` also
    works for the plainness modality.  A breaking change, however, is that these
    tactics now no longer work when the universal quantifier or modality is
    behind a type class opaque definition.  Furthermore, this can change the
    name of anonymous identifiers introduced with the "%" pattern.
Ralf Jung's avatar
Ralf Jung committed
1002
* Make `ofe_fun` dependently typed, subsuming `iprod`.  The latter got removed.
Ralf Jung's avatar
Ralf Jung committed
1003
1004
1005
* Define the generic `fill` operation of the `ectxi_language` construct in terms
  of a left fold instead of a right fold. This gives rise to more definitional
  equalities.
Robbert Krebbers's avatar
Robbert Krebbers committed
1006
1007
1008
1009
1010
* The language hierarchy (`language`, `ectx_language`, `ectxi_language`) is now
  fully formalized using canonical structures instead of using a mixture of
  type classes and canonical structures. Also, it now uses explicit mixins. The
  file `program_logic/ectxi_language` contains some documentation on how to
  setup Iris for your language.
Ralf Jung's avatar
Ralf Jung committed
1011
1012
* Restore the original, stronger notion of atomicity alongside the weaker
  notion. These are `Atomic a e` where the stuckness bit `s` indicates whether
1013
1014
  expression `e` is weakly (`a = WeaklyAtomic`) or strongly
  (`a = StronglyAtomic`) atomic.
1015
1016
1017
1018
* Various improvements to `solve_ndisj`.
* Use `Hint Mode` to prevent Coq from making arbitrary guesses in the presence
  of evars, which often led to divergence. There are a few places where type
  annotations are now needed.
1019
* The rules `internal_eq_rewrite` and `internal_eq_rewrite_contractive` are now
Ralf Jung's avatar
Ralf Jung committed
1020
  stated in the logic, i.e., they are `iApply`-friendly.
1021

Ralf Jung's avatar
Ralf Jung committed
1022
## Iris 3.0.0 (released 2017-01-11)
1023

Ralf Jung's avatar
Ralf Jung committed
1024
1025
1026
* There now is a deprecation process.  The modules `*.deprecated` contain
  deprecated notations and definitions that are provided for backwards
  compatibility and will be removed in a future version of Iris.
Ralf Jung's avatar
Ralf Jung committed
1027
* View shifts are radically simplified to just internalize frame-preserving
1028
  updates.  Weakestpre is defined inside the logic, and invariants and view
Ralf Jung's avatar
Ralf Jung committed
1029
  shifts with masks are also coded up inside Iris.  Adequacy of weakestpre is
1030
  proven in the logic. The old ownership of the entire physical state is
Ralf Jung's avatar
Ralf Jung committed
1031
1032
  replaced by a user-selected predicate over physical state that is maintained
  by weakestpre.
1033
* Use OFEs instead of COFEs everywhere.  COFEs are only used for solving the
1034
1035
  recursive domain equation.  As a consequence, CMRAs no longer need a proof of
  completeness.  (The old `cofeT` is provided by `algebra.deprecated`.)
1036
* Implement a new agreement construction.  Unlike the old one, this one
1037
1038
  preserves discreteness.  dec_agree is thus no longer needed and has been moved
  to algebra.deprecated.
1039
1040
1041
* Renaming and moving things around: uPred and the rest of the base logic are in
  `base_logic`, while `program_logic` is for everything involving the general
  Iris notion of a language.
1042
1043
1044
1045
* Renaming in prelude.list: Rename `prefix_of` -> `prefix` and `suffix_of` ->
  `suffix` in lemma names, but keep notation ``l1 `prefix_of` l2`` and ``l1
  `suffix_of` l2``.  `` l1 `sublist` l2`` becomes ``l1 `sublist_of` l2``. Rename
  `contains` -> `submseteq` and change `` l1 `contains` l2`` to ``l1 ⊆+ l2``.
Ralf Jung's avatar
Ralf Jung committed
1046
1047
1048
* Slightly weaker notion of atomicity: an expression is atomic if it reduces in
  one step to something that does not reduce further.
* Changed notation for embedding Coq assertions into Iris.  The new notation is
1049
  ⌜φ⌝.  Also removed `=` and `⊥` from the Iris scope.  (The old notations are
Ralf Jung's avatar
Ralf Jung committed
1050
  provided in `base_logic.deprecated`.)
1051
* Up-closure of namespaces is now a notation (↑) instead of a coercion.
1052
1053
* With invariants and the physical state being handled in the logic, there is no
  longer any reason to demand the CMRA unit to be discrete.
Ralf Jung's avatar
Ralf Jung committed
1054
* The language can now fork off multiple threads at once.
1055
1056
* Local Updates (for the authoritative monoid) are now a 4-way relation with
  syntax-directed lemmas proving them.
Ralf Jung's avatar
Ralf Jung committed
1057
1058
1059

## Iris 2.0

Ralf Jung's avatar
Ralf Jung committed
1060
1061
1062
1063
* [heap_lang] No longer use dependent types for expressions.  Instead, values
  carry a proof of closedness.  Substitution, closedness and value-ness proofs
  are performed by computation after reflecting into a term langauge that knows
  about values and closed expressions.
1064
1065
* [program_logic/language] The language does not define its own "atomic"
  predicate.  Instead, atomicity is defined as reducing in one step to a value.
1066
1067
1068
1069
1070
* [program_logic] Due to a lack of maintenance and usefulness, lifting lemmas
  for Hoare triples are removed.

## Iris 2.0-rc2

Ralf Jung's avatar
Ralf Jung committed
1071
This version matches the final ICFP 2016 paper.
1072
1073

* [algebra] Make the core of an RA or CMRA a partial function.
Ralf Jung's avatar
Ralf Jung committed
1074
* [program_logic/lifting] Lifting lemmas no longer round-trip through a
Ralf Jung's avatar
Ralf Jung committed
1075
1076
1077
  user-chosen predicate to define the configurations we can reduce to; they
  directly relate to the operational semantics.  This is equivalent and
  much simpler to read.
Ralf Jung's avatar
Ralf Jung committed
1078
1079
1080

## Iris 2.0-rc1

Ralf Jung's avatar
Ralf Jung committed
1081
This is the Coq development and Iris Documentation as submitted to ICFP 2016.