From 788da0680ec5118b453f597a328ee086a8cf3c2b Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Sun, 29 Mar 2020 10:19:09 -0400
Subject: [PATCH] Allow var_export userland implementation

---
 .../Statements/ExpressionAnalyzer.php         | 57 +++++++++++++++++++
 tests/AnnotationTest.php                      | 16 ++++++
 2 files changed, 73 insertions(+)

diff --git a/src/Psalm/Internal/Analyzer/Statements/ExpressionAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/ExpressionAnalyzer.php
index cdf8cfbea..7c034f2b9 100644
--- a/src/Psalm/Internal/Analyzer/Statements/ExpressionAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/ExpressionAnalyzer.php
@@ -1536,6 +1536,63 @@ class ExpressionAnalyzer
             }
         }
 
+        if ($return_type instanceof Type\Atomic\TConditional && $evaluate) {
+            $all_conditional_return_types = [];
+
+            foreach ($return_type->if_type->getAtomicTypes() as $if_atomic_type) {
+                $candidate = self::fleshOutAtomicType(
+                    $codebase,
+                    $if_atomic_type,
+                    $self_class,
+                    $static_class_type,
+                    $parent_class,
+                    $evaluate,
+                    $final
+                );
+
+                if (is_array($candidate)) {
+                    $all_conditional_return_types = array_merge(
+                        $all_conditional_return_types,
+                        $candidate
+                    );
+                } else {
+                    $all_conditional_return_types[] = $candidate;
+                }
+            }
+
+            foreach ($return_type->else_type->getAtomicTypes() as $else_atomic_type) {
+                $candidate = self::fleshOutAtomicType(
+                    $codebase,
+                    $else_atomic_type,
+                    $self_class,
+                    $static_class_type,
+                    $parent_class,
+                    $evaluate,
+                    $final
+                );
+
+                if (is_array($candidate)) {
+                    $all_conditional_return_types = array_merge(
+                        $all_conditional_return_types,
+                        $candidate
+                    );
+                } else {
+                    $all_conditional_return_types[] = $candidate;
+                }
+            }
+
+            foreach ($all_conditional_return_types as $i => $conditional_return_type) {
+                if ($conditional_return_type instanceof Type\Atomic\TVoid
+                    && count($all_conditional_return_types) > 1
+                ) {
+                    $all_conditional_return_types[$i] = new Type\Atomic\TNull();
+                    $all_conditional_return_types[$i]->from_docblock = true;
+                }
+            }
+
+            return $all_conditional_return_types;
+        }
+
         return $return_type;
     }
 
diff --git a/tests/AnnotationTest.php b/tests/AnnotationTest.php
index 5e3246129..3624a7041 100644
--- a/tests/AnnotationTest.php
+++ b/tests/AnnotationTest.php
@@ -1211,6 +1211,22 @@ class AnnotationTest extends TestCase
                         return true;
                     }'
             ],
+            'userlandVarExport' => [
+                '<?php
+                    /**
+                     * @template TReturnFlag as bool
+                     * @param mixed $expression
+                     * @param TReturnFlag $return
+                     * @psalm-return (TReturnFlag is true ? string : void)
+                     */
+                    function my_var_export($expression, bool $return = false) {
+                        if ($return) {
+                            return var_export($expression, true);
+                        }
+
+                        var_export($expression);
+                    }'
+            ],
         ];
     }