Fix "T is never" in conditional return type reported as always false

- Added TemplateType handling in NonAcceptingNeverType::isSuperTypeOf()
  and NeverType::isSuperTypeOf() to return Maybe instead of No, since a
  template type can be instantiated to never
- New regression tests in tests/PHPStan/Rules/PhpDoc/data/bug-9634.php
  and tests/PHPStan/Analyser/nsrt/bug-9634.php

Closes phpstan/phpstan#9634

Author: github-actions[bot]

src/Type/NeverType.php

@@ -14,6 +14,7 @@
 use PHPStan\ShouldNotHappenException;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Enum\EnumCaseObjectType;
+use PHPStan\Type\Generic\TemplateType;
 use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
@@ -81,6 +82,10 @@ public function isSuperTypeOf(Type $type): IsSuperTypeOfResult
 			return IsSuperTypeOfResult::createYes();
 		}
 
+		if ($type instanceof TemplateType) {
+			return IsSuperTypeOfResult::createMaybe();
+		}
+
 		return IsSuperTypeOfResult::createNo();
 	}
 

src/Type/NonAcceptingNeverType.php

@@ -2,6 +2,8 @@
 
 namespace PHPStan\Type;
 
+use PHPStan\Type\Generic\TemplateType;
+
 /** @api */
 class NonAcceptingNeverType extends NeverType
 {
@@ -21,6 +23,10 @@ public function isSuperTypeOf(Type $type): IsSuperTypeOfResult
 			return IsSuperTypeOfResult::createMaybe();
 		}
 
+		if ($type instanceof TemplateType) {
+			return IsSuperTypeOfResult::createMaybe();
+		}
+
 		return IsSuperTypeOfResult::createNo();
 	}
 

tests/PHPStan/Analyser/nsrt/bug-9634.php

@@ -0,0 +1,29 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9634;
+
+use function PHPStan\Testing\assertType;
+
+/** @template T */
+interface Option {
+	/** @return self<never> */
+	static function none(): self;
+
+	/** @return T */
+	function unwrap(): mixed;
+
+	/**
+	 * @return (T is never ? false : bool)
+	 */
+	function isSome(): bool;
+}
+
+/** @param Option<never> $o */
+function f(Option $o): void {
+	assertType('false', $o->isSome());
+}
+
+/** @param Option<int> $o */
+function g(Option $o): void {
+	assertType('bool', $o->isSome());
+}

tests/PHPStan/Rules/PhpDoc/MethodConditionalReturnTypeRuleTest.php

@@ -102,4 +102,9 @@ public function testBug11939(): void
 		$this->analyse([__DIR__ . '/data/bug-11939.php'], []);
 	}
 
+	public function testBug9634(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-9634.php'], []);
+	}
+
 }

tests/PHPStan/Rules/PhpDoc/data/bug-9634.php

@@ -0,0 +1,22 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9634;
+
+/** @template T */
+interface Option {
+	/** @return self<never> */
+	static function none(): self;
+
+	/** @return T */
+	function unwrap(): mixed;
+
+	/**
+	 * @return (T is never ? false : bool)
+	 */
+	function isSome(): bool;
+}
+
+/** @param Option<never> $o */
+function f(Option $o): true {
+	return $o->isSome();
+}