Add BCHelper

src/Psalm/Internal/Analyzer/FunctionLike/ReturnTypeCollector.php

@@ -6,6 +6,7 @@
 use PhpParser\NodeTraverser;
 use Psalm\Codebase;
 use Psalm\Internal\Analyzer\Statements\Block\ForeachAnalyzer;
+use Psalm\Internal\BCHelper;
 use Psalm\Internal\PhpVisitor\YieldTypeCollector;
 use Psalm\Internal\Provider\NodeDataProvider;
 use Psalm\Type;
@@ -83,7 +84,8 @@ public static function getReturnTypes(
             }
 
             if ($stmt instanceof PhpParser\Node\Stmt\Expression) {
-                if ($stmt->expr instanceof PhpParser\Node\Expr\Exit_) {
+                if ($stmt->expr instanceof PhpParser\Node\Expr\Exit_
+                    || (!BCHelper::usePHPParserV4() && $stmt->expr instanceof PhpParser\Node\Expr\Throw_)) {
                     $return_types[] = Type::getNever();
 
                     break;

src/Psalm/Internal/Analyzer/ScopeAnalyzer.php

@@ -3,6 +3,7 @@
 namespace Psalm\Internal\Analyzer;
 
 use PhpParser;
+use Psalm\Internal\BCHelper;
 use Psalm\Internal\Provider\NodeDataProvider;
 use Psalm\NodeTypeProvider;
 
@@ -48,7 +49,7 @@ public static function getControlActions(
 
         foreach ($stmts as $stmt) {
             if ($stmt instanceof PhpParser\Node\Stmt\Return_ ||
-                $stmt instanceof PhpParser\Node\Stmt\Throw_ ||
+                BCHelper::isThrow($stmt) ||
                 ($stmt instanceof PhpParser\Node\Stmt\Expression && $stmt->expr instanceof PhpParser\Node\Expr\Exit_)
             ) {
                 if (!$return_is_exit && $stmt instanceof PhpParser\Node\Stmt\Return_) {
@@ -406,7 +407,7 @@ public static function onlyThrowsOrExits(NodeTypeProvider $type_provider, array
         for ($i = count($stmts) - 1; $i >= 0; --$i) {
             $stmt = $stmts[$i];
 
-            if ($stmt instanceof PhpParser\Node\Stmt\Throw_
+            if (BCHelper::isThrow($stmt)
                 || ($stmt instanceof PhpParser\Node\Stmt\Expression
                     && $stmt->expr instanceof PhpParser\Node\Expr\Exit_)
             ) {
@@ -436,7 +437,7 @@ public static function onlyThrows(array $stmts): bool
         }
 
         foreach ($stmts as $stmt) {
-            if ($stmt instanceof PhpParser\Node\Stmt\Throw_) {
+            if (BCHelper::isThrow($stmt)) {
                 return true;
             }
         }

src/Psalm/Internal/Analyzer/Statements/ExpressionAnalyzer.php

@@ -42,6 +42,7 @@
 use Psalm\Internal\Analyzer\Statements\Expression\YieldAnalyzer;
 use Psalm\Internal\Analyzer\Statements\Expression\YieldFromAnalyzer;
 use Psalm\Internal\Analyzer\StatementsAnalyzer;
+use Psalm\Internal\BCHelper;
 use Psalm\Internal\FileManipulation\FileManipulationBuffer;
 use Psalm\Internal\Type\TemplateResult;
 use Psalm\Issue\RiskyTruthyFalsyComparison;
@@ -456,7 +457,9 @@ private static function handleExpression(
             return MatchAnalyzer::analyze($statements_analyzer, $stmt, $context);
         }
 
-        if ($stmt instanceof PhpParser\Node\Expr\Throw_ && $analysis_php_version_id >= 8_00_00) {
+        if ($stmt instanceof PhpParser\Node\Expr\Throw_
+            && ($analysis_php_version_id >= 8_00_00 || !BCHelper::usePHPParserV4())
+        ) {
             return ThrowAnalyzer::analyze($statements_analyzer, $stmt, $context);
         }
 

src/Psalm/Internal/BCHelper.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Psalm\Internal;
+
+use PhpParser;
+use PhpParser\Node;
+
+use function class_exists;
+
+/**
+ * @internal
+ */
+final class BCHelper
+{
+    public static function usePHPParserV4(): bool
+    {
+        return class_exists('\PhpParser\Node\Stmt\Throw');
+    }
+
+    public static function isThrow(Node $stmt): bool
+    {
+        if (self::usePHPParserV4()) {
+            return $stmt instanceof PhpParser\Node\Stmt\Throw_;
+        }
+
+        return $stmt instanceof PhpParser\Node\Stmt\Expression
+            && $stmt->expr instanceof PhpParser\Node\Expr\Throw_;
+    }
+}