Fix false positive non-existing-offset after array_search()

Author: staabm

Diff for: src/Analyser/TypeSpecifier.php

@@ -661,6 +661,7 @@ public function specifyTypesInCondition(
 			if (!$scope instanceof MutatingScope) {
 				throw new ShouldNotHappenException();
 			}
+
 			if ($context->null()) {
 				$specifiedTypes = $this->specifyTypesInCondition($scope->exitFirstLevelStatements(), $expr->expr, $context)->setRootExpr($expr);
 
@@ -715,7 +716,30 @@ public function specifyTypesInCondition(
 				return $specifiedTypes;
 			}
 
-			return $this->specifyTypesInCondition($scope->exitFirstLevelStatements(), $expr->var, $context)->setRootExpr($expr);
+			$specifiedTypes = $this->specifyTypesInCondition($scope->exitFirstLevelStatements(), $expr->var, $context)->setRootExpr($expr);
+
+			if ($context->true()) {
+				// infer $arr[$key] after $key = array_search($needle, $arr)
+				if (
+					$expr->expr instanceof FuncCall
+					&& $expr->expr->name instanceof Name
+					&& in_array($expr->expr->name->toLowerString(), ['array_search'], true)
+					&& count($expr->expr->getArgs()) >= 2
+				) {
+					$arrayArg = $expr->expr->getArgs()[1]->value;
+					$arrayType = $scope->getType($arrayArg);
+
+					if ($arrayType->isArray()->yes()) {
+						$dimFetch = new ArrayDimFetch($arrayArg, $expr->var);
+						$iterableValueType = $arrayType->getIterableValueType();
+
+						return $specifiedTypes->unionWith(
+							$this->create($dimFetch, $iterableValueType, TypeSpecifierContext::createTrue(), $scope),
+						);
+					}
+				}
+			}
+			return $specifiedTypes;
 		} elseif (
 			$expr instanceof Expr\Isset_
 			&& count($expr->vars) > 0

Diff for: tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -812,4 +812,16 @@ public function testArrayDimFetchAfterCount(): void
 		]);
 	}
 
+	public function testArrayDimFetchAfterArraySearch(): void
+	{
+		$this->reportPossiblyNonexistentGeneralArrayOffset = true;
+
+		$this->analyse([__DIR__ . '/data/array-dim-after-array-search.php'], [
+			[
+				'Offset int|string might not exist on array.',
+				20,
+			],
+		]);
+	}
+
 }

Diff for: tests/PHPStan/Rules/Arrays/data/array-dim-after-array-search.php

@@ -0,0 +1,37 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace ArrayDimAfterArraySeach;
+
+class HelloWorld
+{
+	public function doFoo(array $arr, string $needle): string
+	{
+		if (($key = array_search($needle, $arr, true)) !== false) {
+			echo $arr[$key];
+		}
+	}
+
+	public function doBar(array $arr, string $needle): string
+	{
+		$key = array_search($needle, $arr, true);
+		if ($key !== false) {
+			echo $arr[$key];
+		}
+	}
+
+	public function doFooBar(array $arr, string $needle): string
+	{
+		if (($key = array_search($needle, $arr, false)) !== false) {
+			echo $arr[$key];
+		}
+	}
+
+	public function doBaz(array $arr, string $needle): string
+	{
+		if (($key = array_search($needle, $arr)) !== false) {
+			echo $arr[$key];
+		}
+	}
+}