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Fix #6683 by improving simplification of CNF #7631

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merged 1 commit into from Feb 11, 2022
Merged

Fix #6683 by improving simplification of CNF #7631

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85 changes: 83 additions & 2 deletions src/Psalm/Internal/Algebra.php
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Expand Up @@ -9,13 +9,15 @@

use function array_diff_key;
use function array_filter;
use function array_intersect_key;
use function array_keys;
use function array_map;
use function array_merge;
use function array_pop;
use function array_unique;
use function array_values;
use function count;
use function in_array;
use function mt_rand;

/**
Expand Down Expand Up @@ -238,11 +240,90 @@ public static function simplifyCNF(array $clauses): array
}

if (!$is_redundant) {
$simplified_clauses[] = $clause_a;
$simplified_clauses[$clause_a->hash] = $clause_a;
}
}

return $simplified_clauses;
$clause_count = count($simplified_clauses);

// simplify (A || X) && (!A || Y) && (X || Y)
// to
// simplify (A || X) && (!A || Y)
// where X and Y are sets of orred terms
if ($clause_count > 2 && $clause_count < 256) {
$clauses = array_values($simplified_clauses);
for ($i = 0; $i < $clause_count; $i++) {
$clause_a = $clauses[$i];
for ($k = $i + 1; $k < $clause_count; $k++) {
$clause_b = $clauses[$k];
$common_keys = array_keys(
array_intersect_key($clause_a->possibilities, $clause_b->possibilities)
);
if ($common_keys) {
$common_negated_keys = [];
foreach ($common_keys as $common_key) {
if (count($clause_a->possibilities[$common_key]) === 1
&& count($clause_b->possibilities[$common_key]) === 1
&& $clause_a->possibilities[$common_key][0]->isNegationOf(
$clause_b->possibilities[$common_key][0]
)
) {
$common_negated_keys[] = $common_key;
}
}

if ($common_negated_keys) {
$new_possibilities = [];

foreach ($clause_a->possibilities as $var_id => $possibilities) {
if (in_array($var_id, $common_negated_keys, true)) {
continue;
}

if (!isset($new_possibilities[$var_id])) {
$new_possibilities[$var_id] = $possibilities;
} else {
$new_possibilities[$var_id] = array_merge(
$new_possibilities[$var_id],
$possibilities,
);
}
}

foreach ($clause_b->possibilities as $var_id => $possibilities) {
if (in_array($var_id, $common_negated_keys, true)) {
continue;
}

if (!isset($new_possibilities[$var_id])) {
$new_possibilities[$var_id] = $possibilities;
} else {
$new_possibilities[$var_id] = array_merge(
$new_possibilities[$var_id],
$possibilities,
);
}
}

/** @psalm-suppress MixedArgumentTypeCoercion due I think to Psalm bug */
$conflict_clause = (new Clause(
$new_possibilities,
$clause_a->creating_conditional_id,
$clause_a->creating_conditional_id,
false,
true,
true,
[]
))->makeUnique();

unset($simplified_clauses[$conflict_clause->hash]);
}
}
}
}
}

return array_values($simplified_clauses);
}

/**
Expand Down
9 changes: 4 additions & 5 deletions src/Psalm/Internal/Analyzer/Statements/Block/IfElseAnalyzer.php
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Expand Up @@ -172,14 +172,13 @@ function (Clause $c) use ($mixed_var_ids, $cond_object_id): Clause {
$assigned_in_conditional_var_ids
);

// if we have assignments in the if, we may have duplicate clauses
if ($assigned_in_conditional_var_ids) {
$if_clauses = Algebra::simplifyCNF($if_clauses);
}
$if_clauses = Algebra::simplifyCNF($if_clauses);

$if_context_clauses = array_merge($entry_clauses, $if_clauses);

$if_context->clauses = Algebra::simplifyCNF($if_context_clauses);
$if_context->clauses = $entry_clauses
? Algebra::simplifyCNF($if_context_clauses)
: $if_context_clauses;

if ($if_context->reconciled_expression_clauses) {
$reconciled_expression_clauses = $if_context->reconciled_expression_clauses;
Expand Down
20 changes: 20 additions & 0 deletions tests/TypeReconciliation/TypeAlgebraTest.php
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Expand Up @@ -1160,6 +1160,26 @@ final public function map(Throwable $throwable, string $class): ?Throwable
}
}'
],
'combineTwoOrredClausesWithUnnecessaryTerm' => [
'code' => '<?php
function foo(bool $a, bool $b, bool $c): void {
if (($a && $b) || (!$a && $c)) {
//
} else {
if ($c) {}
}
}'
],
'combineTwoOrredClausesWithMoreComplexUnnecessaryTerm' => [
'code' => '<?php
function foo(bool $a, bool $b, bool $c): void {
if ((!$a && !$b) || ($a && $b) || ($a && $c)) {
throw new \Exception();
}

if ($a) {}
}'
],
];
}

Expand Down