Don’t check newly-scoped vars in conditional

src/Psalm/Checker/Statements/Block/IfChecker.php

@@ -62,6 +62,8 @@ class IfChecker
 
         $context->inside_conditional = true;
 
+        $pre_condition_vars_in_scope = $context->vars_in_scope;
+
         $referenced_var_ids = $context->referenced_var_ids;
         $context->referenced_var_ids = [];
 
@@ -144,6 +146,20 @@ class IfChecker
         // get all the var ids that were referened in the conditional, but not assigned in it
         $cond_referenced_var_ids = array_diff_key($cond_referenced_var_ids, $cond_assigned_var_ids);
 
+        // remove all newly-asserted var ids too
+        $cond_referenced_var_ids = array_filter(
+            $cond_referenced_var_ids,
+            /**
+             * @param string $var_id
+             *
+             * @return bool
+             */
+            function ($var_id) use ($pre_condition_vars_in_scope) {
+                return isset($pre_condition_vars_in_scope[$var_id]);
+            },
+            ARRAY_FILTER_USE_KEY
+        );
+
         $if_context->inside_conditional = false;
 
         $mixed_var_ids = [];

src/Psalm/Checker/Statements/Expression/BinaryOpChecker.php

@@ -55,6 +55,7 @@ class BinaryOpChecker
 
             $pre_referenced_var_ids = $context->referenced_var_ids;
             $context->referenced_var_ids = [];
+            $original_vars_in_scope = $context->vars_in_scope;
 
             $pre_assigned_var_ids = $context->assigned_var_ids;
 
@@ -69,6 +70,20 @@ class BinaryOpChecker
 
             $new_referenced_var_ids = array_diff_key($new_referenced_var_ids, $new_assigned_var_ids);
 
+            // remove all newly-asserted var ids too
+            $new_referenced_var_ids = array_filter(
+                $new_referenced_var_ids,
+                /**
+                 * @param string $var_id
+                 *
+                 * @return bool
+                 */
+                function ($var_id) use ($original_vars_in_scope) {
+                    return isset($original_vars_in_scope[$var_id]);
+                },
+                ARRAY_FILTER_USE_KEY
+            );
+
             $simplified_clauses = AlgebraChecker::simplifyCNF(array_merge($context->clauses, $if_clauses));
 
             $left_type_assertions = AlgebraChecker::getTruthsFromFormula($simplified_clauses);

src/Psalm/Type.php

@@ -3,7 +3,6 @@ namespace Psalm;
 
 use Psalm\Exception\TypeParseTreeException;
 use Psalm\Type\Atomic;
-use Psalm\Type\Atomic\Generic;
 use Psalm\Type\Atomic\ObjectLike;
 use Psalm\Type\Atomic\TArray;
 use Psalm\Type\Atomic\TBool;

src/Psalm/Type/Atomic/Fn.php

@@ -4,6 +4,9 @@ namespace Psalm\Type\Atomic;
 use Psalm\FunctionLikeParameter;
 use Psalm\Type\Union;
 
+/**
+ * Represents a closure where we know the return type and params
+ */
 class Fn extends TNamedObject
 {
     /**

src/Psalm/Type/Atomic/Generic.php

@@ -1,6 +0,0 @@
-<?php
-namespace Psalm\Type\Atomic;
-
-interface Generic
-{
-}

src/Psalm/Type/Atomic/TArray.php

@@ -1,7 +1,7 @@
 <?php
 namespace Psalm\Type\Atomic;
 
-class TArray extends \Psalm\Type\Atomic implements Generic
+class TArray extends \Psalm\Type\Atomic
 {
     use GenericTrait;
 

src/Psalm/Type/Atomic/TGenericObject.php

@@ -1,7 +1,7 @@
 <?php
 namespace Psalm\Type\Atomic;
 
-class TGenericObject extends TNamedObject implements Generic
+class TGenericObject extends TNamedObject
 {
     use GenericTrait;
 

src/Psalm/Type/Union.php

@@ -283,7 +283,7 @@ class Union
     public function hasGeneric()
     {
         foreach ($this->types as $type) {
-            if ($type instanceof Atomic\Generic) {
+            if ($type instanceof Atomic\TGenericObject || $type instanceof Atomic\TArray) {
                 return true;
             }
         }

tests/RedundantConditionTest.php

@@ -303,6 +303,18 @@ class RedundantConditionTest extends TestCase
                 'assertions' => [],
                 'error_levels' => ['RedundantConditionGivenDocblockType'],
             ],
+            'nullToMixedWithNullCheckNoContinue' => [
+                '<?php
+                    function getStrings(): array {
+                        return ["hello", "world", 50];
+                    }
+
+                    $a = getStrings();
+
+                    if (is_string($a[0]) && strlen($a[0]) > 3) {}',
+                'assignments' => [],
+                'error_levels' => [],
+            ],
         ];
     }