Add range checks to identify for loops that always enter

vimeo · Jan 4, 2020 · 8cbc26c · 8cbc26c
1 parent 9fa2db1
commit 8cbc26c
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Showing 2 changed files with 59 additions and 0 deletions.
diff --git a/src/Psalm/Internal/Analyzer/Statements/Block/ForAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Block/ForAnalyzer.php
@@ -32,10 +32,20 @@ public static function analyze(
         $pre_assigned_var_ids = $context->assigned_var_ids;
         $context->assigned_var_ids = [];
 
+        $init_var_types = [];
+
         foreach ($stmt->init as $init) {
             if (ExpressionAnalyzer::analyze($statements_analyzer, $init, $context) === false) {
                 return false;
             }
+
+            if ($init instanceof PhpParser\Node\Expr\Assign
+                && $init->var instanceof PhpParser\Node\Expr\Variable
+                && is_string($init->var->name)
+                && ($init_var_type = $statements_analyzer->node_data->getType($init->expr))
+            ) {
+                $init_var_types[$init->var->name] = $init_var_type;
+            }
         }
 
         $assigned_var_ids = $context->assigned_var_ids;
@@ -94,6 +104,37 @@ public static function analyze(
                     break;
                 }
             }
+
+            if ($cond instanceof PhpParser\Node\Expr\BinaryOp
+                && $cond->right instanceof PhpParser\Node\Scalar\LNumber
+                && $cond->left instanceof PhpParser\Node\Expr\Variable
+                && is_string($cond->left->name)
+                && isset($init_var_types[$cond->left->name])
+                && $init_var_types[$cond->left->name]->isSingleIntLiteral()
+            ) {
+                $init_value = $init_var_types[$cond->left->name]->getSingleIntLiteral()->value;
+                $cond_value = $cond->right->value;
+
+                if ($cond instanceof PhpParser\Node\Expr\BinaryOp\Smaller && $init_value < $cond_value) {
+                    $always_enters_loop = true;
+                    break;
+                }
+
+                if ($cond instanceof PhpParser\Node\Expr\BinaryOp\SmallerOrEqual && $init_value <= $cond_value) {
+                    $always_enters_loop = true;
+                    break;
+                }
+
+                if ($cond instanceof PhpParser\Node\Expr\BinaryOp\Greater && $init_value > $cond_value) {
+                    $always_enters_loop = true;
+                    break;
+                }
+
+                if ($cond instanceof PhpParser\Node\Expr\BinaryOp\GreaterOrEqual && $init_value >= $cond_value) {
+                    $always_enters_loop = true;
+                    break;
+                }
+            }
         }
 
         if ($while_true) {

diff --git a/tests/Loop/ForTest.php b/tests/Loop/ForTest.php
@@ -109,6 +109,14 @@ function test(Node $head) {
                     for ($i = 0; $i < 5; $i++);
                     echo $i;',
             ],
+            'nestedEchoAfterFor' => [
+                '<?php
+                    for ($i = 1; $i < 2; $i++) {
+                        for ($j = 1; $j < 2; $j++) {}
+                    }
+
+                    echo $i * $j;'
+            ],
         ];
     }
 
@@ -146,6 +154,16 @@ public function providerInvalidCodeParse()
                     echo $a;',
                 'error_message' => 'UndefinedGlobalVariable',
             ],
+            'nestedEchoAfterFor' => [
+                '<?php
+                    for ($i = 1; $i < 2; $i++) {
+                        if (rand(0, 1)) break;
+                        for ($j = 1; $j < 2; $j++) {}
+                    }
+
+                    echo $i * $j;',
+                'error_message' => 'PossiblyUndefinedGlobalVariable',
+            ],
         ];
     }
 }