Fix #1545 - improve handling of negated binary ops

src/Psalm/Type/Algebra.php

@@ -127,6 +127,20 @@ class Algebra
             return self::combineOredClauses($left_clauses, $right_clauses);
         }
 
+        if ($conditional instanceof PhpParser\Node\Expr\BooleanNot
+            && $conditional->expr instanceof PhpParser\Node\Expr\BinaryOp
+        ) {
+            $negated_clauses = self::getFormula(
+                $conditional->expr,
+                $this_class_name,
+                $source,
+                $codebase,
+                !$inside_negation
+            );
+
+            return self::negateFormula($negated_clauses);
+        }
+
         AssertionFinder::scrapeAssertions(
             $conditional,
             $this_class_name,

tests/TypeAlgebraTest.php

@@ -902,6 +902,22 @@ class TypeAlgebraTest extends TestCase
                         }
                     }',
             ],
+            'invertEquation' => [
+                '<?php
+                /**
+                 * @param mixed $width
+                 * @param mixed $height
+                 *
+                 * @throws RuntimeException
+                 */
+                function Foo($width, $height) : void {
+                    if (!(is_int($width) || is_float($width)) || !(is_int($height) || is_float($height))) {
+                        throw new RuntimeException("bad");
+                    }
+
+                    echo sprintf("padding-top:%s%%;", 100 * ($height/$width));
+                }'
+            ],
         ];
     }