Fix specifying types for left side of null coalesce

Author: rvanvelzen

src/Analyser/TypeSpecifier.php

@@ -1279,6 +1279,15 @@ private function createForExpr(
 			$expr = NullsafeOperatorHelper::getNullsafeShortcircuitedExpr($expr);
 		}
 
+		if (
+			$scope !== null
+			&& $context->true()
+			&& $expr instanceof Expr\BinaryOp\Coalesce
+			&& $type->isSuperTypeOf($scope->getType($expr->right))->no()
+		) {
+			$expr = $expr->left;
+		}
+
 		if (
 			$expr instanceof FuncCall
 			&& $expr->name instanceof Name

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1019,6 +1019,12 @@ public function dataFileAsserts(): iterable
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7921.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7928.php');
+
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7949.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7639.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5304.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7244.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7501.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/bug-5304.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Bug5304;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param array{foo?: string} $in
+ */
+function takesArg(array $in): void
+{
+	if(is_string($in['foo'] ?? null)) {
+		assertType('array{foo: string}', $in);
+	}
+
+	if(isset($in['foo'])) {
+		assertType('array{foo: string}', $in);
+	}
+
+}

tests/PHPStan/Analyser/data/bug-7244.php

@@ -0,0 +1,26 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7244;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	/**
+	 * @param array<string, mixed> $arguments
+	 */
+	public function getFormat(array $arguments): string {
+		$value = \is_string($arguments['format'] ?? null) ? $arguments['format'] : 'Y-m-d';
+		assertType('string', $value);
+		return $value;
+	}
+
+	/**
+	 * @param array<string, mixed> $arguments
+	 */
+	public function getFormatWithoutFallback(array $arguments): string {
+		$value = \is_string($arguments['format']) ? $arguments['format'] : 'Y-m-d';
+		assertType('string', $value);
+		return $value;
+	}
+}

tests/PHPStan/Analyser/data/bug-7501.php

@@ -0,0 +1,19 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7501;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param array{key?: mixed} $a
+ */
+function f(array $a): void
+{
+	if (isset($a['key']) && is_int($a['key'])) {
+		assertType('array{key: int}', $a);
+	}
+
+	if (is_int($a['key'] ?? null)) {
+		assertType('array{key: int}', $a);
+	}
+}

tests/PHPStan/Analyser/data/bug-7639.php

@@ -0,0 +1,38 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7639;
+
+use function PHPStan\Testing\assertType;
+
+abstract class TestCase
+{
+	/**
+	 * @return static|null
+	 */
+	public static function getTestFromBacktrace()
+	{
+		foreach (debug_backtrace(\DEBUG_BACKTRACE_IGNORE_ARGS | \DEBUG_BACKTRACE_PROVIDE_OBJECT) as $frame) {
+			if (($frame['object'] ?? null) instanceof static) {
+				assertType('static(Bug7639\\TestCase)', $frame['object']);
+				return $frame['object'];
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * @return static|null
+	 */
+	public static function getTestFromBacktraceWithoutNullCoalesce()
+	{
+		foreach (debug_backtrace(\DEBUG_BACKTRACE_IGNORE_ARGS | \DEBUG_BACKTRACE_PROVIDE_OBJECT) as $frame) {
+			if (isset($frame['object']) && $frame['object'] instanceof static) {
+				assertType('static(Bug7639\\TestCase)', $frame['object']);
+				return $frame['object'];
+			}
+		}
+
+		return null;
+	}
+}

tests/PHPStan/Analyser/data/bug-7949.php

@@ -0,0 +1,19 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7949;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	public function bar(?string $price): void
+	{
+		$price = strlen($price ?? '') > 0 ? $price : '0';
+		assertType('non-empty-string', $price);
+
+		$this->foo($price);
+	}
+
+	public function foo(string $test): void {
+	}
+}