From 1a1d9c9bf5b48f5e71bdc0a1f9dd19ac20052ea8 Mon Sep 17 00:00:00 2001
From: RobChett <robchett@gmail.com>
Date: Thu, 20 Apr 2023 20:48:12 +0100
Subject: [PATCH] Add return type provider for date/gmdate

---
 .../Provider/FunctionReturnTypeProvider.php   |  2 +
 .../DateReturnTypeProvider.php                | 66 +++++++++++++++++++
 stubs/CoreGenericFunctions.phpstub            | 11 ----
 tests/FunctionCallTest.php                    | 19 +++++-
 4 files changed, 86 insertions(+), 12 deletions(-)
 create mode 100644 src/Psalm/Internal/Provider/ReturnTypeProvider/DateReturnTypeProvider.php

diff --git a/src/Psalm/Internal/Provider/FunctionReturnTypeProvider.php b/src/Psalm/Internal/Provider/FunctionReturnTypeProvider.php
index 0d2552d8e48..ad1827b52c7 100644
--- a/src/Psalm/Internal/Provider/FunctionReturnTypeProvider.php
+++ b/src/Psalm/Internal/Provider/FunctionReturnTypeProvider.php
@@ -23,6 +23,7 @@
 use Psalm\Internal\Provider\ReturnTypeProvider\ArraySliceReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\ArraySpliceReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\BasenameReturnTypeProvider;
+use Psalm\Internal\Provider\ReturnTypeProvider\DateReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\DirnameReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\FilterVarReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\FirstArgStringReturnTypeProvider;
@@ -101,6 +102,7 @@ public function __construct()
         $this->registerClass(InArrayReturnTypeProvider::class);
         $this->registerClass(RoundReturnTypeProvider::class);
         $this->registerClass(MbInternalEncodingReturnTypeProvider::class);
+        $this->registerClass(DateReturnTypeProvider::class);
     }
 
     /**
diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/DateReturnTypeProvider.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/DateReturnTypeProvider.php
new file mode 100644
index 00000000000..7fbfedf22d9
--- /dev/null
+++ b/src/Psalm/Internal/Provider/ReturnTypeProvider/DateReturnTypeProvider.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psalm\Internal\Provider\ReturnTypeProvider;
+
+use Psalm\Internal\Analyzer\StatementsAnalyzer;
+use Psalm\Plugin\EventHandler\Event\FunctionReturnTypeProviderEvent;
+use Psalm\Plugin\EventHandler\FunctionReturnTypeProviderInterface;
+use Psalm\Type;
+use Psalm\Type\Union;
+
+use function array_values;
+use function preg_match;
+
+/**
+ * @internal
+ */
+class DateReturnTypeProvider implements FunctionReturnTypeProviderInterface
+{
+    /**
+     * @return array<lowercase-string>
+     */
+    public static function getFunctionIds(): array
+    {
+        return ['date', 'gmdate'];
+    }
+
+    public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $event): ?Union
+    {
+        $source = $event->getStatementsSource();
+        if (!$source instanceof StatementsAnalyzer) {
+            return null;
+        }
+
+        $call_args = $event->getCallArgs();
+
+        if (isset($call_args[0])) {
+            $type = $source->node_data->getType($call_args[0]->value);
+            if ($type !== null && $type->isSingle()) {
+                $atomic_type = array_values($type->getAtomicTypes())[0];
+                if ($atomic_type instanceof Type\Atomic\TLiteralString
+                    && ($format_val = $atomic_type->value)
+                    && preg_match('/[djNwzWmntLoYyBgGhHisuvZUI]+/', $format_val)
+                ) {
+                    return Type::getNumericString();
+                }
+            }
+        }
+
+        if (!isset($call_args[1])) {
+            return Type::getString();
+        }
+
+        $type = $source->node_data->getType($call_args[1]->value);
+        if ($type !== null && $type->isSingle()) {
+            $atomic_type = array_values($type->getAtomicTypes())[0];
+            if ($atomic_type instanceof Type\Atomic\TNumeric
+                || $atomic_type instanceof Type\Atomic\TInt
+            ) {
+                return Type::getString();
+            }
+        }
+        return Type::combineUnionTypes(Type::getString(), Type::getFalse());
+    }
+}
diff --git a/stubs/CoreGenericFunctions.phpstub b/stubs/CoreGenericFunctions.phpstub
index 64af461e130..a03447b1f4b 100644
--- a/stubs/CoreGenericFunctions.phpstub
+++ b/stubs/CoreGenericFunctions.phpstub
@@ -559,17 +559,6 @@ function abs($num) {}
  */
 function range($start, $end, $step = 1) {}
 
-/**
- * @psalm-pure
- *
- * @return (
- *     $format is 'd'|'j'|'N'|'w'|'z'|'W'|'m'|'n'|'t'|'L'|'o'|'Y'|'y'|'B'|'g'|'G'|'h'|'H'|'i'|'s'|'u'|'v'|'Z'|'U'|'I'
- *     ? numeric-string
- *     : ($timestamp is numeric ? string : string|false)
- * )
- */
-function date(string $format, int $timestamp = 0) {}
-
 /**
  * @psalm-pure
  *
diff --git a/tests/FunctionCallTest.php b/tests/FunctionCallTest.php
index 96c960031c7..12d23a8b4c6 100644
--- a/tests/FunctionCallTest.php
+++ b/tests/FunctionCallTest.php
@@ -1731,19 +1731,36 @@ function test() : void {
             'dateTest' => [
                 'code' => '<?php
                     $y = date("Y");
+                    $ym = date("Ym");
                     $m = date("m");
                     $F = date("F");
                     $y2 = date("Y", 10000);
                     $F2 = date("F", 10000);
                     /** @psalm-suppress MixedArgument */
-                    $F3 = date("F", $GLOBALS["F3"]);',
+                    $F3 = date("F", $GLOBALS["F3"]);
+                    $gm_y = gmdate("Y");
+                    $gm_ym = gmdate("Ym");
+                    $gm_m = gmdate("m");
+                    $gm_F = gmdate("F");
+                    $gm_y2 = gmdate("Y", 10000);
+                    $gm_F2 = gmdate("F", 10000);
+                    /** @psalm-suppress MixedArgument */
+                    $gm_F3 = gmdate("F", $GLOBALS["F3"]);',
                 'assertions' => [
                     '$y===' => 'numeric-string',
+                    '$ym===' => 'numeric-string',
                     '$m===' => 'numeric-string',
                     '$F===' => 'string',
                     '$y2===' => 'numeric-string',
                     '$F2===' => 'string',
                     '$F3===' => 'false|string',
+                    '$gm_y===' => 'numeric-string',
+                    '$gm_ym===' => 'numeric-string',
+                    '$gm_m===' => 'numeric-string',
+                    '$gm_F===' => 'string',
+                    '$gm_y2===' => 'numeric-string',
+                    '$gm_F2===' => 'string',
+                    '$gm_F3===' => 'false|string',
                 ],
             ],
             'sscanfReturnTypeWithTwoParameters' => [