Fix erroneous marking of external-mutation-free method as unused

vimeo · Aug 31, 2019 · 4a38ab1 · 4a38ab1
1 parent 900cfc0
commit 4a38ab1
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Showing 4 changed files with 27 additions and 2 deletions.
diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/MethodCallAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/MethodCallAnalyzer.php
@@ -1250,7 +1250,8 @@ function (PhpParser\Node\Arg $arg) {
                                     // fall through
                                 }
                             } elseif (($method_storage->mutation_free
-                                    || $method_pure_compatible)
+                                    || ($method_storage->external_mutation_free
+                                        && (isset($stmt->var->external_mutation_free) || isset($stmt->var->pure))))
                                 && $codebase->find_unused_variables
                                 && !$context->inside_conditional
                                 && !$context->inside_unset

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NewAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NewAnalyzer.php
@@ -475,6 +475,8 @@ public static function analyze(
                 }
 
                 if ($storage->external_mutation_free) {
+                    /** @psalm-suppress UndefinedPropertyAssignment */
+                    $stmt->external_mutation_free = true;
                     $stmt->inferredType->external_mutation_free = true;
                 }
             }

diff --git a/src/Psalm/Internal/Visitor/CheckTrivialExprVisitor.php b/src/Psalm/Internal/Visitor/CheckTrivialExprVisitor.php
@@ -46,7 +46,7 @@ private function checkNonTrivialExpr(PhpParser\Node\Expr $node)
                 return false;
             }
 
-            if ($node instanceof PhpParser\Node\Expr\New_ && !empty($node->inferredType->external_mutation_free)) {
+            if ($node instanceof PhpParser\Node\Expr\New_ && isset($node->external_mutation_free)) {
                 return false;
             }
 

diff --git a/tests/UnusedCodeTest.php b/tests/UnusedCodeTest.php
@@ -584,6 +584,28 @@ function inc(array $arr) : array {
                         return $arr;
                     }'
             ],
+            'pureFunctionUsesMethodBeforeReturning' => [
+                '<?php
+                    /** @psalm-external-mutation-free */
+                    class Counter {
+                        private int $count = 0;
+
+                        public function __construct(int $count) {
+                            $this->count = $count;
+                        }
+
+                        public function increment() : void {
+                            $this->count++;
+                        }
+                    }
+
+                    /** @psalm-pure */
+                    function makesACounter(int $i) : Counter {
+                        $c = new Counter($i);
+                        $c->increment();
+                        return $c;
+                    }',
+            ],
         ];
     }