CHANGELOG.md 32.1 KB
Newer Older
Ralf Jung's avatar
Ralf Jung committed
1
2
3
In this changelog, we document "large-ish" changes to Iris that affect even the
way the logic is used on paper.  We also mention some significant changes in the
Coq development, but not every API-breaking change is listed.  Changes marked
4
`[#]` still need to be ported to the Iris Documentation LaTeX file(s).
5

Robbert Krebbers's avatar
Robbert Krebbers committed
6
7
## Iris master

Ralf Jung's avatar
Ralf Jung committed
8
9
10
11
**Changes in the theory of Iris itself:**

* [#] Redefine invariants as "semantic invariants" so that they support
  splitting and other forms of weakening.
12
13
* Updated the strong variant of the opening lemma for cancellable invariants
  to match that of regular invariants, where you can pick the mask at a later time.
14

Amin Timany's avatar
Amin Timany committed
15
16
17
18
19
**Changes in program logic:**

* In the axiomatization of ectx languages we 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
20
21
22
* Added 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
23

Robbert Krebbers's avatar
Robbert Krebbers committed
24
25
**Changes in Coq:**

Ralf Jung's avatar
Ralf Jung committed
26
* Added support for Coq 8.10 and Coq 8.11; dropped support for Coq 8.7 and Coq 8.8.
Ralf Jung's avatar
Ralf Jung committed
27
28
29
30
* Removed 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`.
Robbert Krebbers's avatar
Robbert Krebbers committed
31
32
* A new tactic `iStopProof` to turn the proof mode entailment into an ordinary
  Coq goal `big star of context ⊢ proof mode goal`.
Robbert Krebbers's avatar
Robbert Krebbers committed
33
34
* 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
35
36
37
* Move derived camera constructions (`frac_auth` and `ufrac_auth`) to the folder
  `algebra/lib`.
* Add derived camera construction `excl_auth A` for `auth (option (excl A))`.
38
39
40
* 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:
Ralf Jung's avatar
Ralf Jung committed
41
42
  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.
Robbert Krebbers's avatar
Robbert Krebbers committed
43
44
  2. Due to the use of `notypeclasses refine`, TC constraints are solved less
     eagerly, see https://github.com/coq/coq/issues/6583.
45
46
47
48
  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).
Ralf Jung's avatar
Ralf Jung committed
49
50
51
* Removed `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.
Robbert Krebbers's avatar
Robbert Krebbers committed
52
53
* Added the type `siProp` of "plain" step-indexed propositions, together with
  basic proofmode support.
54
55
* Sealed the definitions of `big_opS`, `big_opMS`, `big_opM` and `big_sepM2`
  to prevent undesired simplification.
Robbert Krebbers's avatar
Robbert Krebbers committed
56
57
58
59
60
61
62
63
* The tactics `iDestruct`, `iPoseProof`, and `iAssert` have become stronger:
  - 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
64
65
66
67
68
69
70
71
72
* Renamed some accessor-style lemmas to consistently use the suffix `_acc`
  instead of `_open`:
  `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 we also had to rename `inv_acc` -> `inv_alter`.
  (Most developments should be unaffected as the typical way to invoke these
  lemmas is through `iInv`, and that does not change.)
73
74
* Added a construction `bi_rtc` to create reflexive transitive closures of
  PROP-level binary relations.
75
76
* Add new introduction pattern `-# pat` that moves a hypothesis from the
  intuitionistic context to the spatial context.
Robbert Krebbers's avatar
Robbert Krebbers committed
77
78
79
80
81
82
83
* Made 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`.
Robbert Krebbers's avatar
Robbert Krebbers committed
84
* The tactic `iAssumption` also recognizes assumptions `⊢ P` in the Coq context.
Robbert Krebbers's avatar
Robbert Krebbers committed
85
86
* Add notion `ofe_iso A B` that states that OFEs `A` and `B` are isomorphic.
* Make use of `ofe_iso` in the COFE solver.
Robbert Krebbers's avatar
Robbert Krebbers committed
87
88
* The functions `{o,r,ur}Functor_diag` are no longer coercions, and renamed into
  `{o,r,ur}Functor_apply` to better match their intent.
Robbert Krebbers's avatar
Robbert Krebbers committed
89
90
91
92
93
* 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`.
* Add lemma `is_lock_iff` and show that `is_lock` is contractive.
Robbert Krebbers's avatar
Robbert Krebbers committed
94
95
96
* Rename `{o,r,ur}Functor_{ne,id,compose,contractive}` into
  `{o,r,ur}Functor_map_{ne,id,compose,contractive}`.
* Add `{o,r,ur}Functor_oFunctor_compose` for composition of functors.
Robbert Krebbers's avatar
Robbert Krebbers committed
97
98
99
* Affine, absorbing, persistent and timeless instances for telescopes.
* Better support for telescopes in the proof mode, i.e., all tactics should
  recognize and distribute telescopes now.
Robbert Krebbers's avatar
Robbert Krebbers committed
100
* Remove namespace `N` from `is_lock`.
Robbert Krebbers's avatar
Robbert Krebbers committed
101
102
103
104
105
* Make lemma `Excl_included` a bi-implication.
* Add lemma `singleton_included : {[ i := x ]} ≼ ({[ i := y ]} ↔ x ≡ y ∨ x ≼ y`,
  and rename existing asymmetric lemmas (with a singleton on just the LHS):
  + `singleton_includedN``singleton_includedN_l`.
  + `singleton_included``singleton_included_l`.
106
  + `singleton_included_exclusive``singleton_included_exclusive_l`
107
* The proof mode now supports names for pure facts in intro patterns. Support
108
  requires implementing `string_to_ident`. Without this tactic such patterns
109
110
111
  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
112
113
* Make names of `f_op`/`f_core` rewrite lemmas more consistent by always making
  `_core`/`_op` the suffix:
114
115
116
  `op_singleton` -> `singleton_op`, `core_singleton` -> `singleton_core`,
  `discrete_fun_op_singleton` -> `discrete_fun_singleton_op`,
  `discrete_fun_core_singleton` -> `discrete_fun_singleton_core`,
Ralf Jung's avatar
Ralf Jung committed
117
118
  `list_core_singletonM` -> `list_singleton_core`,
  `list_op_singletonM` -> `list_singleton_op`,
119
120
  `sts_op_auth_frag` -> `sts_auth_frag_op`,
  `sts_op_auth_frag_up` -> `sts_auth_frag_up_op`,
Ralf Jung's avatar
Ralf Jung committed
121
122
  `sts_op_frag` -> `sts_frag_op`,
  `list_op_length` -> `list_length_op`.
Ralf Jung's avatar
Ralf Jung committed
123
124
* Make list singleton lemmas consistent with gmap by dropping the `M` suffix of
  `singleton`:
Ralf Jung's avatar
Ralf Jung committed
125
126
127
128
129
130
131
132
133
  `elem_of_list_singletonM` -> `elem_of_list_singleton`,
  `list_lookup_singletonM` -> `list_lookup_singleton`,
  `list_lookup_singletonM_lt` -> `list_lookup_singleton_lt`,
  `list_lookup_singletonM_gt` -> `list_lookup_singleton_gt`,
  `list_lookup_singletonM_ne` -> `list_lookup_singleton_ne`,
  `list_singletonM_validN` -> `list_singleton_validN`,
  `list_singletonM_length` -> `list_singleton_length`,
  `list_alter_singletonM` -> `list_alter_singleton`,
  `list_singletonM_included` -> `list_singleton_included`.
134
135
* New ASCII versions of Iris notations. These are marked printing only and
  can be made available using `Require Import iris.bi.ascii`. The new
Gregory Malecha's avatar
Gregory Malecha committed
136
  notations are (notations marked [†] are disambiguated using notation scopes):
137
  - entailment: `|--` for `⊢` and `-|-` for `⊣⊢`
Gregory Malecha's avatar
Gregory Malecha committed
138
139
  - logic[†]: `->` for `→`, `/\\` for `∧`, `\\/` for `∨`, and `<->` for `↔`
  - quantifiers[†]: `forall` for `∀` and `exists` for `∃`
140
141
  - separation logic: `**` for `∗`, `-*` for `-∗`, and `*-*` for `∗-∗`
  - step indexing: `|>` for `▷`
Gregory Malecha's avatar
Gregory Malecha committed
142
  - modalities: `<#>` for `□` and `<except_0>` for `◇`
143
144
145
146
147
148
149
150
  - 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`
    - `|={E1,E2,E3}|>=> Q` for `|={E1,E2,E3}▷=> Q`
    - `|={E1,E2}|>=>^n Q` for `|={E1,E2}▷=>^n Q`
Gregory Malecha's avatar
Gregory Malecha committed
151
152
    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.
Ralf Jung's avatar
Ralf Jung committed
153

154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
The following `sed` script should perform most of the renaming (FIXME: incomplete)
(on macOS, replace `sed` by `gsed`, installed via e.g. `brew install gnu-sed`):
```
sed -i -E '
# 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/\blist_(op|core)_singletonM\b/list_singleton_\1/g
s/\bsts_op_(auth_frag|auth_frag_up|frag)\b/sts_\1_op/g
s/\blist_op_length\b/list_length_op/g
# list singleton renames
s/\belem_of_list_singletonM\b/elem_of_list_singleton/g
s/\blist_lookup_singletonM(|_lt|_gt|_ne)\b/list_lookup_singleton\1/g
s/\blist_singletonM_(validN|length)\b/list_singleton_\1/g
s/\blist_alter_singletonM\b/list_alter_singleton/g
s/\blist_singletonM_included\b/list_singleton_included/g
' $(find theories -name "*.v")
```

173
174
175
**Changes in heap_lang:**

* Added a fraction to the heap_lang `array` assertion.
176
* Added array_copy library for copying and cloning arrays.
177

Ralf Jung's avatar
Ralf Jung committed
178
## Iris 3.2.0 (released 2019-08-29)
Ralf Jung's avatar
Ralf Jung committed
179

Ralf Jung's avatar
Ralf Jung committed
180
181
182
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
183
184
185
186
187
188
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
189
190
191
192
193
194
195
196
197
198
199
200
201
202

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
203
204
205
206
207
208
209
210
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
211

212
* Change in the definition of WP, so that there is a fancy update between
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
213
214
  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
215
  "update that takes a step".
216
217
218
* 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
219
* Add the notion of an "observation" to the language interface, so that
Ralf Jung's avatar
Ralf Jung committed
220
221
  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
222
  future trace of observations from the beginning.
Ralf Jung's avatar
Ralf Jung committed
223
* The Löb rule is now a derived rule; it follows from later-intro, later
Ralf Jung's avatar
Ralf Jung committed
224
225
  being contractive and the fact that we can take fixpoints of contractive
  functions.
Ralf Jung's avatar
Ralf Jung committed
226
* Add atomic updates and logically atomic triples, including tactic support.
Ralf Jung's avatar
Ralf Jung committed
227
  See `heap_lang/lib/increment.v` for an example.
228
229
230
* 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
231
  `True`).
232
233
234
* 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.
235
236
237
* 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
238
**Changes in heap_lang:**
239

240
241
242
243
244
245
246
247
* 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
248
249
250
251
252
  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
253
254
* 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
255
  behavior) can be found [in the iris/examples repository][prophecy-erasure].
Ralf Jung's avatar
Ralf Jung committed
256
* heap_lang now uses right-to-left evaluation order. This makes it
Ralf Jung's avatar
Ralf Jung committed
257
  significantly easier to write specifications of curried functions.
Ralf Jung's avatar
Ralf Jung committed
258
* heap_lang values are now injected in heap_lang expressions via a specific
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
259
260
  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
261
  the reflection mechanism that was needed for proving closedness, atomicity and
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
262
263
  "valueness" of a term. The price to pay is the addition of new
  "administrative" reductions in the operational semantics of the language.
264
265
* heap_lang now has support for allocating, accessing and reasoning about arrays
  (continuously allocated regions of memory).
Robbert Krebbers's avatar
Robbert Krebbers committed
266
* One can now assign "meta" data to heap_lang locations.
Ralf Jung's avatar
Ralf Jung committed
267

Ralf Jung's avatar
Ralf Jung committed
268
269
[prophecy-erasure]: https://gitlab.mpi-sws.org/iris/examples/blob/3f33781fe6e19cfdb25259c8194d34403f1134d5/theories/logatom/proph_erasure.v

Ralf Jung's avatar
Ralf Jung committed
270
**Changes in Coq:**
271

Ralf Jung's avatar
Ralf Jung committed
272
* An all-new generalized proof mode that abstracts away from Iris!  Major new
Ralf Jung's avatar
Ralf Jung committed
273
274
275
276
277
278
  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
279
    an existing logic (see the paper for more details).
Ralf Jung's avatar
Ralf Jung committed
280
    Developments instantiating the proof mode typeclasses may need significant
Robbert Krebbers's avatar
Robbert Krebbers committed
281
282
    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
283
284
285
286
287
  - 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
288
    searching for the BI to use, which (due to Coq limitations) can lead to
Ralf Jung's avatar
Ralf Jung committed
289
290
291
292
    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
293
294
* 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
295
296
* Added support for defining derived connectives involving n-ary binders using
  telescopes.
Ralf Jung's avatar
Ralf Jung committed
297
298
299
* 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
300
* Improved pretty-printing of Iris connectives (in particular WP and fancy
Ralf Jung's avatar
Ralf Jung committed
301
302
303
  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.
304
* Rename `timelessP` -> `timeless` (projection of the `Timeless` class)
Ralf Jung's avatar
Ralf Jung committed
305
306
* 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
307
  CMRA even for an infinite domain.
Robbert Krebbers's avatar
Robbert Krebbers committed
308
309
310
311
312
* 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`
313
314
* Rename:
  - `frag_auth_op``frac_auth_frag_op`
315
316
317
  - `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
318
* `namespaces` has been moved to std++.
319
320
* 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
321
* `wp_fork` is now written in curried form.
322
* `PureExec`/`wp_pure` now supports taking multiple steps at once.
Jacques-Henri Jourdan's avatar
Jacques-Henri Jourdan committed
323
324
325
* 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
326
* Add `big_sepM_insert_acc`.
327
328
329
330
* 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
331
332
333
* 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
334
335
336
* 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
337
* Export the fact that `iPreProp` is a COFE.
338
339
340
341
342
343
344
* 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.
345
346
* Add a COFE construction (and functor) on dependent pairs `sigTO`, dual to
  `discrete_funO`.
Hai Dang's avatar
Hai Dang committed
347
348
349
350
351
352
* 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
353
354
355
356
357
    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
358
359
  - `auth_both_valid``auth_both_valid_2`
  - `auth_valid_discrete_2``auth_both_valid`
Robbert Krebbers's avatar
Robbert Krebbers committed
360
361
362
* 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.
363
364
* Changed `frac_auth` notation from `●!`/`◯!` to `●F`/`◯F`. sed script:
  `s/◯!/◯F/g; s/●!/●F/g;`.
365
366
* Lemma `prop_ext` works in both directions; its default direction is the
  opposite of what it used to be.
367
* Make direction of `f_op` rewrite lemmas more consistent: Flip `pair_op`,
Paolo G. Giarrusso's avatar
Paolo G. Giarrusso committed
368
369
  `Cinl_op`, `Cinr_op`, `cmra_morphism_op`, `cmra_morphism_pcore`,
  `cmra_morphism_core`.
Robbert Krebbers's avatar
Robbert Krebbers committed
370
371
* 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`.
372
* Rename `C` suffixes into `O` since we no longer use COFEs but OFEs. Also
Ralf Jung's avatar
Ralf Jung committed
373
  rename `ofe_fun` into `discrete_fun` and the corresponding notation `-c>` into
Ralf Jung's avatar
Ralf Jung committed
374
375
  `-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`):
376
```
377
sed -i '
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
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;
429
' $(find theories -name "*.v")
430
```
Hai Dang's avatar
Hai Dang committed
431

Ralf Jung's avatar
Ralf Jung committed
432
## Iris 3.1.0 (released 2017-12-19)
433

Ralf Jung's avatar
Ralf Jung committed
434
**Changes in and extensions of the theory:**
Ralf Jung's avatar
Ralf Jung committed
435

Ralf Jung's avatar
Ralf Jung committed
436
* Define `uPred` as a quotient on monotone predicates `M -> SProp`.
Ralf Jung's avatar
Ralf Jung committed
437
438
* Get rid of some primitive laws; they can be derived:
  `True ⊢ □ True` and `□ (P ∧ Q) ⊢ □ (P ∗ Q)`
439
* Camera morphisms have to be homomorphisms, not just monotone functions.
Ralf Jung's avatar
Ralf Jung committed
440
* Add a proof that `f` has a fixed point if `f^k` is contractive.
441
442
* 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
443
* Add a proof of the inverse of `wp_bind`.
Ralf Jung's avatar
Ralf Jung committed
444
* [Experimental feature] Add new modality: ■ ("plainly").
Ralf Jung's avatar
Ralf Jung committed
445
446
447
448
449
450
451
452
* [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
453

Ralf Jung's avatar
Ralf Jung committed
454
**Changes in Coq:**
Ralf Jung's avatar
Ralf Jung committed
455

456
457
* 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
458
459
460
461
462
463
464
465
466
467
468
* 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
469
* Rename some things and change notation:
470
  - The unit of a camera: `empty` -> `unit`, `∅` -> `ε`
471
  - Disjointness: `⊥` -> `##`
Ralf Jung's avatar
Ralf Jung committed
472
  - A proof mode type class `IntoOp` -> `IsOp`
473
474
475
476
477
478
  - 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`
479
  - Adequacy for non-stuck weakestpre: `adequate_safe` -> `adequate_not_stuck`
Ralf Jung's avatar
Ralf Jung committed
480
  - Consistently SnakeCase identifiers:
481
482
483
484
485
486
487
488
489
490
    + `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
491
492
  - Many lemmas also changed their name.  `always_*` became `persistently_*`,
    and furthermore: (the following list is not complete)
493
494
495
496
497
498
499
500
501
502
    + `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
503
  The following `sed` snippet should get you most of the way (on macOS you will
504
  have to replace `sed` by `gsed`, installed via e.g. `brew install gnu-sed`):
Ralf Jung's avatar
Ralf Jung committed
505
```
506
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
507
```
Ralf Jung's avatar
Ralf Jung committed
508
509
* `PersistentL` and `TimelessL` (persistence and timelessness of lists of
  propositions) are replaces by `TCForall` from std++.
Ralf Jung's avatar
Ralf Jung committed
510
511
* Fix a bunch of consistency issues in the proof mode, and make it overall more
  usable.  In particular:
512
513
514
515
516
517
518
519
520
521
  - 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
522
523
524
525
526
527
528
529
  - 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
530
* Make `ofe_fun` dependently typed, subsuming `iprod`.  The latter got removed.
Ralf Jung's avatar
Ralf Jung committed
531
532
533
* 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
534
535
536
537
538
* 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
539
540
* Restore the original, stronger notion of atomicity alongside the weaker
  notion. These are `Atomic a e` where the stuckness bit `s` indicates whether
541
542
  expression `e` is weakly (`a = WeaklyAtomic`) or strongly
  (`a = StronglyAtomic`) atomic.
543
544
545
546
* 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.
547
* The rules `internal_eq_rewrite` and `internal_eq_rewrite_contractive` are now
Ralf Jung's avatar
Ralf Jung committed
548
  stated in the logic, i.e., they are `iApply`-friendly.
549

Ralf Jung's avatar
Ralf Jung committed
550
## Iris 3.0.0 (released 2017-01-11)
551

Ralf Jung's avatar
Ralf Jung committed
552
553
554
* 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
555
* View shifts are radically simplified to just internalize frame-preserving
556
  updates.  Weakestpre is defined inside the logic, and invariants and view
Ralf Jung's avatar
Ralf Jung committed
557
  shifts with masks are also coded up inside Iris.  Adequacy of weakestpre is
558
  proven in the logic. The old ownership of the entire physical state is
Ralf Jung's avatar
Ralf Jung committed
559
560
  replaced by a user-selected predicate over physical state that is maintained
  by weakestpre.
561
* Use OFEs instead of COFEs everywhere.  COFEs are only used for solving the
562
563
  recursive domain equation.  As a consequence, CMRAs no longer need a proof of
  completeness.  (The old `cofeT` is provided by `algebra.deprecated`.)
564
* Implement a new agreement construction.  Unlike the old one, this one
565
566
  preserves discreteness.  dec_agree is thus no longer needed and has been moved
  to algebra.deprecated.
567
568
569
* 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.
570
571
572
573
* 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
574
575
576
* 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
577
  ⌜φ⌝.  Also removed `=` and `⊥` from the Iris scope.  (The old notations are
Ralf Jung's avatar
Ralf Jung committed
578
  provided in `base_logic.deprecated`.)
579
* Up-closure of namespaces is now a notation (↑) instead of a coercion.
580
581
* 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
582
* The language can now fork off multiple threads at once.
583
584
* 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
585
586
587

## Iris 2.0

Ralf Jung's avatar
Ralf Jung committed
588
589
590
591
* [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.
592
593
* [program_logic/language] The language does not define its own "atomic"
  predicate.  Instead, atomicity is defined as reducing in one step to a value.
594
595
596
597
598
* [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
599
This version matches the final ICFP 2016 paper.
600
601

* [algebra] Make the core of an RA or CMRA a partial function.
Ralf Jung's avatar
Ralf Jung committed
602
* [program_logic/lifting] Lifting lemmas no longer round-trip through a
Ralf Jung's avatar
Ralf Jung committed
603
604
605
  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
606
607
608

## Iris 2.0-rc1

Ralf Jung's avatar
Ralf Jung committed
609
This is the Coq development and Iris Documentation as submitted to ICFP 2016.