Provide more specific explode() return type (#5350)

Fixes #5347 `explode()` now omits `false` from the return type when separator is a definitely non-empty string.
vimeo · Mar 11, 2021 · 4f8ba04 · 4f8ba04
1 parent 8be77aa
commit 4f8ba04
Show file tree

Hide file tree

Showing 2 changed files with 58 additions and 9 deletions.
diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/ExplodeReturnTypeProvider.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/ExplodeReturnTypeProvider.php
@@ -54,18 +54,36 @@ public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $ev
             } elseif (($first_arg_type = $statements_source->node_data->getType($call_args[0]->value))
                 && $first_arg_type->hasString()
             ) {
-                $falsable_array = new Type\Union([
-                    $can_return_empty
-                        ? new Type\Atomic\TList($inner_type)
-                        : new Type\Atomic\TNonEmptyList($inner_type),
-                    new Type\Atomic\TFalse
-                ]);
+                $can_be_false = true;
+                if ($first_arg_type->isString()) {
+                    $can_be_false = false;
+                    foreach ($first_arg_type->getAtomicTypes() as $string_type) {
+                        if (!($string_type instanceof Type\Atomic\TNonEmptyString)) {
+                            $can_be_false = true;
+                            break;
+                        }
+                    }
+                }
+                if ($can_be_false) {
+                    $array_type = new Type\Union([
+                        $can_return_empty
+                            ? new Type\Atomic\TList($inner_type)
+                            : new Type\Atomic\TNonEmptyList($inner_type),
+                        new Type\Atomic\TFalse
+                    ]);
 
-                if ($statements_source->getCodebase()->config->ignore_internal_falsable_issues) {
-                    $falsable_array->ignore_falsable_issues = true;
+                    if ($statements_source->getCodebase()->config->ignore_internal_falsable_issues) {
+                        $array_type->ignore_falsable_issues = true;
+                    }
+                } else {
+                    $array_type = new Type\Union([
+                        $can_return_empty
+                            ? new Type\Atomic\TList($inner_type)
+                            : new Type\Atomic\TNonEmptyList($inner_type),
+                    ]);
                 }
 
-                return $falsable_array;
+                return $array_type;
             }
         }
 

diff --git a/tests/FunctionCallTest.php b/tests/FunctionCallTest.php
@@ -428,6 +428,37 @@ public static function Baz($mixed) : string {
                     '$elements' => 'false|list<string>',
                 ],
             ],
+            'explodeWithDynamicNonEmptyDelimiter' => [
+                '<?php
+                    /**
+                     * @var non-empty-string $delim
+                     * @var string $string
+                     */
+                    $elements = explode($delim, $string);',
+                'assertions' => [
+                    '$elements' => 'non-empty-list<string>',
+                ],
+            ],
+            'explodeWithLiteralNonEmptyDelimiter' => [
+                '<?php
+                    /**
+                     * @var string $string
+                     */
+                    $elements = explode(" ", $string);',
+                'assertions' => [
+                    '$elements' => 'non-empty-list<string>',
+                ],
+            ],
+            'explodeWithLiteralEmptyDelimiter' => [
+                '<?php
+                    /**
+                     * @var string $string
+                     */
+                    $elements = explode("", $string);',
+                'assertions' => [
+                    '$elements' => 'false',
+                ],
+            ],
             'explodeWithPossiblyFalse' => [
                 '<?php
                     /** @return non-empty-list<string> */