about summary refs log tree commit diff stats
path: root/057immutable.cc
blob: e1a17a841f009808c42e8c5130b2b067e7a696ec (plain) (blame)
1
2
3
4
5
6
7
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
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
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
429
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
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
//: Ingredients of a recipe are meant to be immutable unless they're also
//: products. This layer will start enforcing this check.
//:
//: One hole for now: variables in surrounding spaces are implicitly mutable.
//: [tag: todo]

:(scenario can_modify_ingredients_that_are_also_products)
# mutable container
def main [
  local-scope
  p:point <- merge 34, 35
  p <- foo p
]
def foo p:point -> p:point [
  local-scope
  load-ingredients
  p <- put p, x:offset, 34
]
$error: 0

:(scenario can_modify_ingredients_that_are_also_products_2)
def main [
  local-scope
  p:&:point <- new point:type
  p <- foo p
]
# mutable address to container
def foo p:&:point -> p:&:point [
  local-scope
  load-ingredients
  *p <- put *p, x:offset, 34
]
$error: 0

:(scenario can_modify_ingredients_that_are_also_products_3)
def main [
  local-scope
  p:&:@:num <- new number:type, 3
  p <- foo p
]
# mutable address
def foo p:&:@:num -> p:&:@:num [
  local-scope
  load-ingredients
  *p <- put-index *p, 0, 34
]
$error: 0

:(scenario ignore_literal_ingredients_for_immutability_checks)
def main [
  local-scope
  p:&:d1 <- new d1:type
  q:num <- foo p
]
def foo p:&:d1 -> q:num [
  local-scope
  load-ingredients
  x:&:d1 <- new d1:type
  *x <- put *x, p:offset, 34  # ignore this 'p'
  return 36
]
container d1 [
  p:num
  q:num
]
$error: 0

:(scenario cannot_modify_immutable_ingredients)
% Hide_errors = true;
def main [
  local-scope
  x:&:num <- new number:type
  foo x
]
# immutable address to primitive
def foo x:&:num [
  local-scope
  load-ingredients
  *x <- copy 34
]
+error: foo: cannot modify 'x' in instruction '*x <- copy 34' because it's an ingredient of recipe foo but not also a product

:(scenario cannot_modify_immutable_containers)
% Hide_errors = true;
def main [
  local-scope
  x:point-number <- merge 34, 35, 36
  foo x
]
# immutable container
def foo x:point-number [
  local-scope
  load-ingredients
  # copy an element: ok
  y:point <- get x, xy:offset
  # modify the element: boom
  # This could be ok if y contains no addresses, but we're not going to try to be that smart.
  # It also makes the rules easier to reason about. If it's just an ingredient, just don't try to change it.
  y <- put y, x:offset, 37
]
+error: foo: cannot modify 'y' in instruction 'y <- put y, x:offset, 37' because that would modify 'x' which is an ingredient of recipe foo but not also a product

:(scenario can_modify_immutable_pointers)
def main [
  local-scope
  x:&:num <- new number:type
  foo x
]
def foo x:&:num [
  local-scope
  load-ingredients
  # modify the address, not the payload
  x <- copy 0
]
$error: 0

:(scenario can_modify_immutable_pointers_but_not_their_payloads)
% Hide_errors = true;
def main [
  local-scope
  x:&:num <- new number:type
  foo x
]
def foo x:&:num [
  local-scope
  load-ingredients
  # modify address; ok
  x <- new number:type
  # modify payload: boom
  # this could be ok, but we're not going to try to be that smart
  *x <- copy 34
]
+error: foo: cannot modify 'x' in instruction '*x <- copy 34' because it's an ingredient of recipe foo but not also a product

:(scenario cannot_call_mutating_recipes_on_immutable_ingredients)
% Hide_errors = true;
def main [
  local-scope
  p:&:point <- new point:type
  foo p
]
def foo p:&:point [
  local-scope
  load-ingredients
  bar p
]
def bar p:&:point -> p:&:point [
  local-scope
  load-ingredients
  # p could be modified here, but it doesn't have to be, it's already marked
  # mutable in the header
]
+error: foo: cannot modify 'p' in instruction 'bar p' because it's an ingredient of recipe foo but not also a product

:(scenario cannot_modify_copies_of_immutable_ingredients)
% Hide_errors = true;
def main [
  local-scope
  p:&:point <- new point:type
  foo p
]
def foo p:&:point [
  local-scope
  load-ingredients
  q:&:point <- copy p
  *q <- put *q, x:offset, 34
]
+error: foo: cannot modify 'q' in instruction '*q <- put *q, x:offset, 34' because that would modify p which is an ingredient of recipe foo but not also a product

:(scenario can_modify_copies_of_mutable_ingredients)
def main [
  local-scope
  p:&:point <- new point:type
  foo p
]
def foo p:&:point -> p:&:point [
  local-scope
  load-ingredients
  q:&:point <- copy p
  *q <- put *q, x:offset, 34
]
$error: 0

:(scenario cannot_modify_address_inside_immutable_ingredients)
% Hide_errors = true;
container foo [
  x:&:@:num  # contains an address
]
def main [
  # don't run anything
]
def foo a:&:foo [
  local-scope
  load-ingredients
  x:&:@:num <- get *a, x:offset  # just a regular get of the container
  *x <- put-index *x, 0, 34  # but then a put-index on the result
]
+error: foo: cannot modify 'x' in instruction '*x <- put-index *x, 0, 34' because that would modify a which is an ingredient of recipe foo but not also a product

:(scenario cannot_modify_address_inside_immutable_ingredients_2)
container foo [
  x:&:@:num  # contains an address
]
def main [
  # don't run anything
]
def foo a:&:foo [
  local-scope
  load-ingredients
  b:foo <- merge 0
  # modify b, completely unrelated to immutable ingredient a
  x:&:@:num <- get b, x:offset
  *x <- put-index *x, 0, 34
]
$error: 0

:(scenario cannot_modify_address_inside_immutable_ingredients_3)
% Hide_errors = true;
def main [
  # don't run anything
]
def foo a:&:@:&:num [
  local-scope
  load-ingredients
  x:&:num <- index *a, 0  # just a regular index of the array
  *x <- copy 34  # but then modify the result
]
+error: foo: cannot modify 'x' in instruction '*x <- copy 34' because that would modify a which is an ingredient of recipe foo but not also a product

:(scenario cannot_modify_address_inside_immutable_ingredients_4)
def main [
  # don't run anything
]
def foo a:&:@:&:num [
  local-scope
  load-ingredients
  b:&:@:&:num <- new {(address number): type}, 3
  # modify b, completely unrelated to immutable ingredient a
  x:&:num <- index *b, 0
  *x <- copy 34
]
$error: 0

:(scenario latter_ingredient_of_index_is_immutable)
def main [
  # don't run anything
]
def foo a:&:@:&:@:num, b:num -> a:&:@:&:@:num [
  local-scope
  load-ingredients
  x:&:@:num <- index *a, b
  *x <- put-index *x, 0, 34
]
$error: 0

:(scenario can_traverse_immutable_ingredients)
container test-list [
  next:&:test-list
]
def main [
  local-scope
  p:&:test-list <- new test-list:type
  foo p
]
def foo p:&:test-list [
  local-scope
  load-ingredients
  p2:&:test-list <- bar p
]
def bar x:&:test-list -> y:&:test-list [
  local-scope
  load-ingredients
  y <- get *x, next:offset
]
$error: 0

:(scenario treat_optional_ingredients_as_mutable)
def main [
  k:&:num <- new number:type
  test k
]
# recipe taking an immutable address ingredient
def test k:&:num [
  local-scope
  load-ingredients
  foo k
]
# ..calling a recipe with an optional address ingredient
def foo -> [
  local-scope
  load-ingredients
  k:&:num, found?:bool <- next-ingredient
  # we don't further check k for immutability, but assume it's mutable
]
$error: 0

:(scenario treat_optional_ingredients_as_mutable_2)
% Hide_errors = true;
def main [
  local-scope
  p:&:point <- new point:type
  foo p
]
def foo p:&:point [
  local-scope
  load-ingredients
  bar p
]
def bar [
  local-scope
  load-ingredients
  p:&:point <- next-ingredient  # optional ingredient; assumed to be mutable
]
+error: foo: cannot modify 'p' in instruction 'bar p' because it's an ingredient of recipe foo but not also a product

//: when checking for immutable ingredients, remember to take space into account
:(scenario check_space_of_reagents_in_immutability_checks)
def main [
  a:space <- new-closure
  b:&:num <- new number:type
  run-closure b:&:num, a:space
]
def new-closure [
  new-default-space
  x:&:num <- new number:type
  return default-space
]
def run-closure x:&:num, s:space [
  local-scope
  load-ingredients
  0:space/names:new-closure <- copy s
  # different space; always mutable
  *x:&:num/space:1 <- copy 34
]
$error: 0

:(before "End Transforms")
Transform.push_back(check_immutable_ingredients);  // idempotent

:(code)
void check_immutable_ingredients(const recipe_ordinal r) {
  // to ensure an address reagent isn't modified, it suffices to show that
  //   a) we never write to its contents directly,
  //   b) we never call 'put' or 'put-index' on it, and
  //   c) any non-primitive recipe calls in the body aren't returning it as a product
  const recipe& caller = get(Recipe, r);
  trace(9991, "transform") << "--- check mutability of ingredients in recipe " << caller.name << end();
  if (!caller.has_header) return;  // skip check for old-style recipes calling next-ingredient directly
  for (int i = 0;  i < SIZE(caller.ingredients);  ++i) {
    const reagent& current_ingredient = caller.ingredients.at(i);
    if (is_present_in_products(caller, current_ingredient.name)) continue;  // not expected to be immutable
    // End Immutable Ingredients Special-cases
    set<reagent> immutable_vars;
    immutable_vars.insert(current_ingredient);
    for (int i = 0;  i < SIZE(caller.steps);  ++i) {
      const instruction& inst = caller.steps.at(i);
      check_immutable_ingredient_in_instruction(inst, immutable_vars, current_ingredient.name, caller);
      if (inst.operation == INDEX && SIZE(inst.ingredients) > 1 && inst.ingredients.at(1).name == current_ingredient.name) continue;
      update_aliases(inst, immutable_vars);
    }
  }
}

void update_aliases(const instruction& inst, set<reagent>& current_ingredient_and_aliases) {
  set<int> current_ingredient_indices = ingredient_indices(inst, current_ingredient_and_aliases);
  if (!contains_key(Recipe, inst.operation)) {
    // primitive recipe
    switch (inst.operation) {
      case COPY:
        for (set<int>::iterator p = current_ingredient_indices.begin();  p != current_ingredient_indices.end();  ++p)
          current_ingredient_and_aliases.insert(inst.products.at(*p).name);
        break;
      case GET:
      case INDEX:
      case MAYBE_CONVERT:
        // current_ingredient_indices can only have 0 or one value
        if (!current_ingredient_indices.empty() && !inst.products.empty()) {
          if (is_mu_address(inst.products.at(0)) || is_mu_container(inst.products.at(0)) || is_mu_exclusive_container(inst.products.at(0)))
            current_ingredient_and_aliases.insert(inst.products.at(0));
        }
        break;
      default: break;
    }
  }
  else {
    // defined recipe
    set<int> contained_in_product_indices = scan_contained_in_product_indices(inst, current_ingredient_indices);
    for (set<int>::iterator p = contained_in_product_indices.begin();  p != contained_in_product_indices.end();  ++p) {
      if (*p < SIZE(inst.products))
        current_ingredient_and_aliases.insert(inst.products.at(*p));
    }
  }
}

set<int> scan_contained_in_product_indices(const instruction& inst, set<int>& ingredient_indices) {
  set<reagent> selected_ingredients;
  const recipe& callee = get(Recipe, inst.operation);
  for (set<int>::iterator p = ingredient_indices.begin();  p != ingredient_indices.end();  ++p) {
    if (*p >= SIZE(callee.ingredients)) continue;  // optional immutable ingredient
    selected_ingredients.insert(callee.ingredients.at(*p));
  }
  set<int> result;
  for (int i = 0;  i < SIZE(callee.products);  ++i) {
    const reagent& current_product = callee.products.at(i);
    const string_tree* contained_in_name = property(current_product, "contained-in");
    if (contained_in_name && selected_ingredients.find(contained_in_name->value) != selected_ingredients.end())
      result.insert(i);
  }
  return result;
}

:(scenarios transform)
:(scenario immutability_infects_contained_in_variables)
% Hide_errors = true;
container test-list [
  value:num
  next:&:test-list
]
def main [
  local-scope
  p:&:test-list <- new test-list:type
  foo p
]
def foo p:&:test-list [  # p is immutable
  local-scope
  load-ingredients
  p2:&:test-list <- test-next p  # p2 is immutable
  *p2 <- put *p2, value:offset, 34
]
def test-next x:&:test-list -> y:&:test-list/contained-in:x [
  local-scope
  load-ingredients
  y <- get *x, next:offset
]
+error: foo: cannot modify 'p2' in instruction '*p2 <- put *p2, value:offset, 34' because that would modify p which is an ingredient of recipe foo but not also a product

:(code)
void check_immutable_ingredient_in_instruction(const instruction& inst, const set<reagent>& current_ingredient_and_aliases, const string& original_ingredient_name, const recipe& caller) {
  // first check if the instruction is directly modifying something it shouldn't
  for (int i = 0;  i < SIZE(inst.products);  ++i) {
    if (has_property(inst.products.at(i), "lookup")
        && current_ingredient_and_aliases.find(inst.products.at(i)) != current_ingredient_and_aliases.end()) {
      string current_product_name = inst.products.at(i).name;
      if (current_product_name == original_ingredient_name)
        raise << maybe(caller.name) << "cannot modify '" << current_product_name << "' in instruction '" << to_original_string(inst) << "' because it's an ingredient of recipe " << caller.name << " but not also a product\n" << end();
      else
        raise << maybe(caller.name) << "cannot modify '" << current_product_name << "' in instruction '" << to_original_string(inst) << "' because that would modify " << original_ingredient_name << " which is an ingredient of recipe " << caller.name << " but not also a product\n" << end();
      return;
    }
  }
  // check if there's any indirect modification going on
  set<int> current_ingredient_indices = ingredient_indices(inst, current_ingredient_and_aliases);
  if (current_ingredient_indices.empty()) return;  // ingredient not found in call
  for (set<int>::iterator p = current_ingredient_indices.begin();  p != current_ingredient_indices.end();  ++p) {
    const int current_ingredient_index = *p;
    reagent current_ingredient = inst.ingredients.at(current_ingredient_index);
    canonize_type(current_ingredient);
    const string& current_ingredient_name = current_ingredient.name;
    if (!contains_key(Recipe, inst.operation)) {
      // primitive recipe
      // we got here only because we got an instruction with an implicit product, and the instruction didn't explicitly spell it out
      //    put x, y:offset, z
      // instead of
      //    x <- put x, y:offset, z
      if (inst.operation == PUT || inst.operation == PUT_INDEX) {
        if (current_ingredient_index == 0) {
          if (current_ingredient_name == original_ingredient_name)
            raise << maybe(caller.name) << "cannot modify '" << current_ingredient_name << "' in instruction '" << to_original_string(inst) << "' because it's an ingredient of recipe " << caller.name << " but not also a product\n" << end();
          else
            raise << maybe(caller.name) << "cannot modify '" << current_ingredient_name << "' in instruction '" << to_original_string(inst) << "' because that would modify '" << original_ingredient_name << "' which is an ingredient of recipe " << caller.name << " but not also a product\n" << end();
        }
      }
    }
    else {
      // defined recipe
      if (is_modified_in_recipe(inst.operation, current_ingredient_index, caller)) {
        if (current_ingredient_name == original_ingredient_name)
          raise << maybe(caller.name) << "cannot modify '" << current_ingredient_name << "' in instruction '" << to_original_string(inst) << "' because it's an ingredient of recipe " << caller.name << " but not also a product\n" << end();
        else
          raise << maybe(caller.name) << "cannot modify '" << current_ingredient_name << "' in instruction '" << to_original_string(inst) << "' because that would modify '" << original_ingredient_name << "' which is an ingredient of recipe " << caller.name << " but not also a product\n" << end();
      }
    }
  }
}

bool is_modified_in_recipe(const recipe_ordinal r, const int ingredient_index, const recipe& caller) {
  const recipe& callee = get(Recipe, r);
  if (!callee.has_header) {
    raise << maybe(caller.name) << "can't check mutability of ingredients in recipe " << callee.name << " because it uses 'next-ingredient' directly, rather than a recipe header.\n" << end();
    return true;
  }
  if (ingredient_index >= SIZE(callee.ingredients)) return false;  // optional immutable ingredient
  return is_present_in_products(callee, callee.ingredients.at(ingredient_index).name);
}

bool is_present_in_products(const recipe& callee, const string& ingredient_name) {
  for (int i = 0;  i < SIZE(callee.products);  ++i) {
    if (callee.products.at(i).name == ingredient_name)
      return true;
  }
  return false;
}

set<int> ingredient_indices(const instruction& inst, const set<reagent>& ingredient_names) {
  set<int> result;
  for (int i = 0;  i < SIZE(inst.ingredients);  ++i) {
    if (is_literal(inst.ingredients.at(i))) continue;
    if (ingredient_names.find(inst.ingredients.at(i)) != ingredient_names.end())
      result.insert(i);
  }
  return result;
}

//: Sometimes you want to pass in two addresses, one pointing inside the
//: other. For example, you want to delete a node from a linked list. You
//: can't pass both pointers back out, because if a caller tries to make both
//: identical then you can't tell which value will be written on the way out.
//:
//: Experimental solution: just tell Mu that one points inside the other.
//: This way we can return just one pointer as high up as necessary to capture
//: all modifications performed by a recipe.
//:
//: We'll see if we end up wanting to abuse /contained-in for other reasons.

:(scenarios transform)
:(scenario can_modify_contained_in_addresses)
container test-list [
  value:num
  next:&:test-list
]
def main [
  local-scope
  p:&:test-list <- new test-list:type
  foo p
]
def foo p:&:test-list -> p:&:test-list [
  local-scope
  load-ingredients
  p2:&:test-list <- test-next p
  p <- test-remove p2, p
]
def test-next x:&:test-list -> y:&:test-list [
  local-scope
  load-ingredients
  y <- get *x, next:offset
]
def test-remove x:&:test-list/contained-in:from, from:&:test-list -> from:&:test-list [
  local-scope
  load-ingredients
  *x <- put *x, value:offset, 34  # can modify x
]
$error: 0

:(before "End Immutable Ingredients Special-cases")
if (has_property(current_ingredient, "contained-in")) {
  const string_tree* tmp = property(current_ingredient, "contained-in");
  if (!tmp->atom
      || (!is_present_in_ingredients(caller, tmp->value)
          && !is_present_in_products(caller, tmp->value))) {
    raise << maybe(caller.name) << "/contained-in can only point to another ingredient or product, but got '" << to_string(property(current_ingredient, "contained-in")) << "'\n" << end();
  }
  continue;
}

:(scenario contained_in_product)
container test-list [
  value:num
  next:&:test-list
]
def foo x:&:test-list/contained-in:result -> result:&:test-list [
  local-scope
  load-ingredients
  result <- copy 0
]
$error: 0

:(scenario contained_in_is_mutable)
container test-list [
  value:num
  next:&:test-list
]
def foo x:&:test-list/contained-in:result -> result:&:test-list [
  local-scope
  load-ingredients
  result <- copy x
  put *x, value:offset, 34
]
$error: 0