From 06581ce4b0e5751446eec44075c48f7bd9e61dc6 Mon Sep 17 00:00:00 2001
From: Greg Hargreaves <greg.hargreaves@sturents.com>
Date: Fri, 14 Oct 2022 01:54:06 +0100
Subject: [PATCH 1/2] Add additional checks for concat of non-empty strings to
 return non-falsy

---
 .../Expression/BinaryOp/ConcatAnalyzer.php    | 25 +++++++++++++++---
 src/Psalm/Type.php                            |  8 ++++++
 tests/BinaryOperationTest.php                 | 26 +++++++++++++++++++
 3 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php
index e317de46e75..ff0e8eef4a0 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php
@@ -199,6 +199,17 @@ public static function analyze(
                     $numeric_type
                 );
 
+                $numeric_type = Type::getNumericString();
+                $numeric_type->addType(new TInt());
+                $numeric_type->addType(new TFloat());
+                $right_is_numeric = UnionTypeComparator::isContainedBy(
+                    $codebase,
+                    $right_type,
+                    $numeric_type
+                );
+
+                $has_numeric_type = $left_is_numeric || $right_is_numeric;
+
                 if ($left_is_numeric) {
                     $right_uint = Type::getPositiveInt();
                     $right_uint->addType(new TLiteralInt(0));
@@ -230,16 +241,23 @@ public static function analyze(
                 $non_empty_string = clone $numeric_type;
                 $non_empty_string->addType(new TNonEmptyString());
 
-                $has_non_empty = UnionTypeComparator::isContainedBy(
+                $left_non_empty = UnionTypeComparator::isContainedBy(
                     $codebase,
                     $left_type,
                     $non_empty_string
-                ) || UnionTypeComparator::isContainedBy(
+                );
+
+                $right_non_empty = UnionTypeComparator::isContainedBy(
                     $codebase,
                     $right_type,
                     $non_empty_string
                 );
 
+                $has_non_empty = $left_non_empty || $right_non_empty;
+                $all_non_empty = $left_non_empty && $right_non_empty;
+
+                $has_numeric_and_non_empty = $has_numeric_type && $has_non_empty;
+
                 $all_literals = $left_type->allLiterals() && $right_type->allLiterals();
 
                 if ($has_non_empty) {
@@ -248,7 +266,8 @@ public static function analyze(
                     } elseif ($all_lowercase) {
                         $result_type = Type::getNonEmptyLowercaseString();
                     } else {
-                        $result_type = Type::getNonEmptyString();
+                        $result_type = $all_non_empty || $has_numeric_and_non_empty ?
+                            Type::getNonFalsyString() : Type::getNonEmptyString();
                     }
                 } else {
                     if ($all_literals) {
diff --git a/src/Psalm/Type.php b/src/Psalm/Type.php
index 35ca811372e..15d7f1f2c3d 100644
--- a/src/Psalm/Type.php
+++ b/src/Psalm/Type.php
@@ -34,6 +34,7 @@
 use Psalm\Type\Atomic\TNonEmptyList;
 use Psalm\Type\Atomic\TNonEmptyLowercaseString;
 use Psalm\Type\Atomic\TNonEmptyString;
+use Psalm\Type\Atomic\TNonFalsyString;
 use Psalm\Type\Atomic\TNull;
 use Psalm\Type\Atomic\TNumeric;
 use Psalm\Type\Atomic\TNumericString;
@@ -219,6 +220,13 @@ public static function getNonEmptyString(): Union
         return new Union([$type]);
     }
 
+    public static function getNonFalsyString(): Union
+    {
+        $type = new TNonFalsyString();
+
+        return new Union([$type]);
+    }
+
     public static function getNumeric(): Union
     {
         $type = new TNumeric;
diff --git a/tests/BinaryOperationTest.php b/tests/BinaryOperationTest.php
index 241e573e27d..a9dc74982b0 100644
--- a/tests/BinaryOperationTest.php
+++ b/tests/BinaryOperationTest.php
@@ -830,6 +830,32 @@ function example(object $foo): string
                         return ($foo instanceof FooInterface ? $foo->toString() : null) ?? "Not a stringable foo";
                     }',
             ],
+            'concatNonEmptyReturnNonFalsyString' => [
+                '<?php
+                    /** @var  non-empty-string $s1 */
+                    $s1 = "0";
+                    /** @var  non-empty-string $s1 */
+                    $s2 = "0";
+
+                    $a = $s1.$s2;',
+                'assertions' => [
+                    '$a===' => 'non-falsy-string',
+                ],
+            ],
+            'concatNumericWithNonEmptyReturnNonFalsyString' => [
+                '<?php
+                    /** @var  numeric-string $s1 */
+                    $s1 = "1";
+                    /** @var  non-empty-string $s2 */
+                    $s2 = "0";
+
+                    $a = $s1.$s2;
+                    $b = $s2.$s1;',
+                'assertions' => [
+                    '$a===' => 'non-falsy-string',
+                    '$b===' => 'non-falsy-string',
+                ],
+            ],
         ];
     }
 

From b89ff32b7a2494444b7529da892d48a58d7ecac4 Mon Sep 17 00:00:00 2001
From: Greg Hargreaves <greg.hargreaves@sturents.com>
Date: Fri, 14 Oct 2022 02:00:25 +0100
Subject: [PATCH 2/2] Remove duplicated numeric type declaration

---
 .../Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php
index ff0e8eef4a0..44d5e5d4f7b 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ConcatAnalyzer.php
@@ -199,9 +199,6 @@ public static function analyze(
                     $numeric_type
                 );
 
-                $numeric_type = Type::getNumericString();
-                $numeric_type->addType(new TInt());
-                $numeric_type->addType(new TFloat());
                 $right_is_numeric = UnionTypeComparator::isContainedBy(
                     $codebase,
                     $right_type,