[DeadCode] Skip with assign to call with target has #[NoDiscard] attribute

Author: samsonasik

rules-tests/DeadCode/Rector/Assign/RemoveUnusedVariableAssignRector/Fixture/skip_assign_no_discard_function_call.php.inc

@@ -0,0 +1,19 @@
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\Assign\RemoveUnusedVariableAssignRector\Fixture;
+
+class SkipAssignNoDiscardFunctionCall
+{
+    public function run()
+    {
+        $value = $this->some_call();
+    }
+
+    #[\NoDiscard]
+    private function some_call()
+    {
+
+    }
+}
+
+?>

rules/DeadCode/Rector/Assign/RemoveUnusedVariableAssignRector.php

@@ -8,6 +8,7 @@
 use PhpParser\Node\Expr;
 use PhpParser\Node\Expr\Assign;
 use PhpParser\Node\Expr\AssignRef;
+use PhpParser\Node\Expr\CallLike;
 use PhpParser\Node\Expr\Cast;
 use PhpParser\Node\Expr\Closure;
 use PhpParser\Node\Expr\FuncCall;
@@ -25,6 +26,8 @@
 use Rector\NodeAnalyzer\VariableAnalyzer;
 use Rector\NodeManipulator\StmtsManipulator;
 use Rector\Php\ReservedKeywordAnalyzer;
+use Rector\Php80\NodeAnalyzer\PhpAttributeAnalyzer;
+use Rector\PhpParser\AstResolver;
 use Rector\PhpParser\Enum\NodeGroup;
 use Rector\PhpParser\Node\BetterNodeFinder;
 use Rector\Rector\AbstractRector;
@@ -42,7 +45,9 @@ public function __construct(
         private readonly SideEffectNodeDetector $sideEffectNodeDetector,
         private readonly VariableAnalyzer $variableAnalyzer,
         private readonly BetterNodeFinder $betterNodeFinder,
-        private readonly StmtsManipulator $stmtsManipulator
+        private readonly StmtsManipulator $stmtsManipulator,
+        private readonly AstResolver $astResolver,
+        private readonly PhpAttributeAnalyzer $phpAttributeAnalyzer
     ) {
     }
 
@@ -265,6 +270,14 @@ function (Node $subNode) use (&$refVariableNames) {
                 continue;
             }
 
+            if ($assign->expr instanceof CallLike) {
+                $targetCall = $this->astResolver->resolveClassMethodOrFunctionFromCall($assign->expr);
+                if (($targetCall instanceof ClassMethod || $targetCall instanceof Function_)
+                    && $this->phpAttributeAnalyzer->hasPhpAttribute($targetCall, 'NoDiscard')) {
+                    continue;
+                }
+            }
+
             $assignedVariableNamesByStmtPosition[$key] = $variableName;
         }
 

src/PhpParser/AstResolver.php

@@ -112,7 +112,7 @@ function (Node $node) use ($classLikeName, $methodName, &$classMethod): bool {
     }
 
     public function resolveClassMethodOrFunctionFromCall(
-        FuncCall | StaticCall | MethodCall | New_ $call
+        FuncCall | StaticCall | MethodCall | New_ | NullsafeMethodCall $call
     ): ClassMethod | Function_ | null {
         if ($call instanceof FuncCall) {
             return $this->resolveFunctionFromFuncCall($call);