From a6630c49a25f2ae24d2fbb61d30206dd1526fa52 Mon Sep 17 00:00:00 2001
From: orklah <ronan_morin@hotmail.com>
Date: Sun, 12 Sep 2021 20:53:11 +0200
Subject: [PATCH] fix mod calculation with ranges

---
 .../BinaryOp/ArithmeticOpAnalyzer.php         | 63 +++++++++++++++++++
 tests/IntRangeTest.php                        | 61 ++++++++++++++++++
 2 files changed, 124 insertions(+)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php
index 2bb261209..4985ca14b 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php
@@ -915,6 +915,69 @@ class ArithmeticOpAnalyzer
             return;
         }
 
+        if ($parent instanceof PhpParser\Node\Expr\BinaryOp\Mod) {
+            //result of Mod is not directly dependant on the bounds of the range
+            if ($right_type_part->min_bound !== null && $right_type_part->min_bound === $right_type_part->max_bound) {
+                //if the second operand is a literal, we can be pretty detailed
+                if ($right_type_part->min_bound === 0) {
+                    $new_result_type = Type::getEmpty();
+                } else {
+                    if ($left_type_part->isPositiveOrZero()) {
+                        if ($right_type_part->isPositive()) {
+                            $max = $right_type_part->min_bound - 1;
+                            $new_result_type = new Type\Union([new TIntRange(0, $max)]);
+                        } else {
+                            $max = $right_type_part->min_bound + 1;
+                            $new_result_type = new Type\Union([new TIntRange($max, 0)]);
+                        }
+                    } elseif ($left_type_part->isNegativeOrZero()) {
+                        if ($right_type_part->isPositive()) {
+                            $max = $right_type_part->min_bound - 1;
+                            $new_result_type = new Type\Union([new TIntRange(-$max, 0)]);
+                        } else {
+                            $max = $right_type_part->min_bound + 1;
+                            $new_result_type = new Type\Union([new TIntRange(-$max, 0)]);
+                        }
+                    } else {
+                        if ($right_type_part->isPositive()) {
+                            $max = $right_type_part->min_bound - 1;
+                        } else {
+                            $max = -$right_type_part->min_bound - 1;
+                        }
+                        $new_result_type = new Type\Union([new TIntRange(-$max, $max)]);
+                    }
+                }
+            } elseif ($right_type_part->isPositive()) {
+                if ($left_type_part->isPositiveOrZero()) {
+                    $new_result_type = new Type\Union([new TIntRange(0, null)]);
+                } elseif ($left_type_part->isNegativeOrZero()) {
+                    $new_result_type = new Type\Union([new TIntRange(null, 0)]);
+                } else {
+                    $new_result_type = Type::getInt(true);
+                }
+            } elseif ($right_type_part->isNegative()) {
+                if ($left_type_part->isPositiveOrZero()) {
+                    $new_result_type = new Type\Union([new TIntRange(null, 0)]);
+                } elseif ($left_type_part->isNegativeOrZero()) {
+                    $new_result_type = new Type\Union([new TIntRange(null, 0)]);
+                } else {
+                    $new_result_type = Type::getInt(true);
+                }
+            } else {
+                $new_result_type = Type::getInt(true);
+            }
+
+            if (!$result_type) {
+                $result_type = new Type\Union([$new_result_type]);
+            } else {
+                $result_type = Type::combineUnionTypes(
+                    new Type\Union([$new_result_type]),
+                    $result_type
+                );
+            }
+            return;
+        }
+
         if ($parent instanceof PhpParser\Node\Expr\BinaryOp\BitwiseAnd ||
             $parent instanceof PhpParser\Node\Expr\BinaryOp\BitwiseOr ||
             $parent instanceof PhpParser\Node\Expr\BinaryOp\BitwiseXor
diff --git a/tests/IntRangeTest.php b/tests/IntRangeTest.php
index 0ef3551ac..4d2829b5f 100644
--- a/tests/IntRangeTest.php
+++ b/tests/IntRangeTest.php
@@ -183,6 +183,67 @@ class IntRangeTest extends TestCase
                     '$e===' => 'int<500, 4999>'
                 ]
             ],
+            'mod' => [
+                '<?php
+                    function getInt(): int{return 0;}
+                    $a = $b = $c = $d = getInt();
+                    assert($a >= 20);//positive range
+                    assert($b <= -20);//negative range
+                    /** @var int<0, 0> $c */; // 0 range
+                    assert($d >= -100);// mixed range
+                    assert($d <= 100);// mixed range
+                    /** @var int<5, 5> $e */; // 5 range
+
+                    $f = $a % $e;
+                    $g = $b % $e;
+                    $h = $d % $e;
+                    $i = -3 % $a;
+                    $j = -3 % $b;
+                    $k = -3 % $c;
+                    $l = -3 % $d;
+                    $m = 3 % $a;
+                    $n = 3 % $b;
+                    $o = 3 % $c;
+                    $p = 3 % $d;
+                    $q = $a % 0;
+                    $r = $a % 3;
+                    $s = $a % -3;
+                    $t = $b % 0;
+                    $u = $b % 3;
+                    $v = $b % -3;
+                    $w = $c % 0;
+                    $x = $c % 3;
+                    $y = $c % -3;
+                    $z = $d % 0;
+                    $aa = $d % 3;
+                    $ab = $d % -3;
+                ',
+                'assertions' => [
+                    '$f===' => 'int<0, 4>',
+                    '$g===' => 'int<-4, 0>',
+                    '$h===' => 'int<-4, 4>',
+                    '$i===' => 'int<min, 0>',
+                    '$j===' => 'int<min, 0>',
+                    '$k===' => 'empty',
+                    '$l===' => 'int',
+                    '$m===' => 'int<0, max>',
+                    '$n===' => 'int<min, 0>',
+                    '$o===' => 'empty',
+                    '$p===' => 'int',
+                    '$q===' => 'empty',
+                    '$r===' => 'int<0, 2>',
+                    '$s===' => 'int<-2, 0>',
+                    '$t===' => 'empty',
+                    '$u===' => 'int<-2, 0>',
+                    '$v===' => 'int<2, 0>',
+                    '$w===' => 'empty',
+                    '$x===' => 'int<0, 2>',
+                    '$y===' => 'int<-2, 0>',
+                    '$z===' => 'empty',
+                    '$aa===' => 'int<-2, 2>',
+                    '$ab===' => 'int<-2, 2>',
+                ]
+            ],
             'pow' => [
                 '<?php
                     function getInt(): int{return 0;}