Fix phpstan/phpstan#8031: Union of constant string type lost when used with generics.

src/Type/Generic/TemplateTypeHelper.php

@@ -142,9 +142,9 @@
 	{
 		if (!$templateType->getVariance()->covariant()) {
 			$isArrayKey = $templateType->getBound()->describe(VerbosityLevel::precise()) === '(int|string)';
-			if ($type->isScalar()->yes() && $isArrayKey) {
+			if ($type->isInteger()->yes() && $isArrayKey) {
 				$type = $type->generalize(GeneralizePrecision::templateArgument());
-			} elseif ($type->isConstantValue()->yes() && (!$templateType->getBound()->isScalar()->yes() || $isArrayKey)) {
+			} elseif ($type->isConstantValue()->yes() && !$templateType->getBound()->isScalar()->yes()) {
 				$type = $type->generalize(GeneralizePrecision::templateArgument());
 			}
 		}

tests/PHPStan/Analyser/nsrt/bug-13144.php

@@ -8,7 +8,7 @@
 
 $arr = new ArrayObject(['a' => 1, 'b' => 2]);
 
-assertType('ArrayObject<string, int>', $arr); // correctly inferred as `ArrayObject<string, int>`
+assertType("ArrayObject<'a'|'b', int>", $arr);
 
 $a = $arr['a']; // ok
 $b = $arr['b']; // ok

tests/PHPStan/Analyser/nsrt/bug-8031.php

@@ -0,0 +1,32 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug8031;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template TKey of array-key
+ * @template TValue of mixed
+ */
+class Collection
+{
+	/**
+	 * @param array<TKey, TValue> $val
+	 */
+	public function __construct(protected array $val) {}
+}
+
+/**
+ * @return Collection<'one'|'two', int>
+ */
+function test(): Collection
+{
+	$c = new Collection([
+		'one' => 1,
+		'two' => 2,
+	]);
+	assertType("Bug8031\Collection<'one'|'two', int>", $c);
+	return $c;
+}

tests/PHPStan/Analyser/nsrt/native-reflection-default-values.php

@@ -7,5 +7,5 @@
 function () {
 	assertType('ArrayObject<*NEVER*, *NEVER*>', new \ArrayObject());
 	assertType('ArrayObject<*NEVER*, *NEVER*>', new \ArrayObject([]));
-	assertType('ArrayObject<string, int>', new \ArrayObject(['key' => 1]));
+	assertType("ArrayObject<'key', int>", new \ArrayObject(['key' => 1]));
 };