Fix #1825 - improve behaviour of callable reconciliation

src/Psalm/Internal/Analyzer/TypeAnalyzer.php

@@ -865,6 +865,12 @@ class TypeAnalyzer
             return true;
         }
 
+        if ($input_type_part instanceof Type\Atomic\TCallableObject &&
+            $container_type_part instanceof TObject
+        ) {
+            return true;
+        }
+
         if ($container_type_part instanceof TNumeric &&
             ($input_type_part->isNumericType() || $input_type_part instanceof TString)
         ) {

src/Psalm/Type/Reconciler.php

@@ -911,6 +911,7 @@ class Reconciler
             foreach ($existing_var_atomic_types as $type) {
                 if ($type instanceof TBool) {
                     $bool_types[] = $type;
+                    $type->from_docblock = false;
                 } elseif ($type instanceof TScalar) {
                     $bool_types[] = new TBool;
                     $did_remove_type = true;
@@ -942,6 +943,54 @@ class Reconciler
             return Type::getMixed();
         }
 
+        if ($new_var_type === 'string' && !$existing_var_type->hasMixed()) {
+            $string_types = [];
+            $did_remove_type = false;
+
+            foreach ($existing_var_atomic_types as $type) {
+                if ($type instanceof TString) {
+                    $string_types[] = $type;
+
+                    if (get_class($type) === TString::class) {
+                        $type->from_docblock = false;
+                    }
+                } elseif ($type instanceof TCallable) {
+                    $string_types[] = new Type\Atomic\TCallableString;
+                    $did_remove_type = true;
+                } elseif ($type instanceof TNumeric) {
+                    $string_types[] = new TNumericString;
+                    $did_remove_type = true;
+                } elseif ($type instanceof TScalar || $type instanceof TArrayKey) {
+                    $string_types[] = new TString;
+                    $did_remove_type = true;
+                } else {
+                    $did_remove_type = true;
+                }
+            }
+
+            if ((!$did_remove_type || !$string_types) && !$is_equality) {
+                if ($key && $code_location) {
+                    self::triggerIssueForImpossible(
+                        $existing_var_type,
+                        $old_var_type_string,
+                        $key,
+                        $new_var_type,
+                        !$did_remove_type,
+                        $code_location,
+                        $suppressed_issues
+                    );
+                }
+            }
+
+            if ($string_types) {
+                return new Type\Union($string_types);
+            }
+
+            $failed_reconciliation = 2;
+
+            return Type::getMixed();
+        }
+
         $is_maybe_callable_array = false;
 
         if ($new_var_type === 'array' && isset($existing_var_atomic_types['callable'])) {
@@ -950,14 +999,14 @@ class Reconciler
             if (!isset($existing_var_atomic_types['array'])) {
                 $existing_var_type->addType(
                     new TCallableObjectLikeArray([
-                        Type::getMixed(),
+                        new Type\Union([new TObject, new TString]),
                         Type::getString()
                     ])
                 );
             } else {
                 $array_combination = \Psalm\Internal\Type\TypeCombination::combineTypes([
                     new TCallableObjectLikeArray([
-                        Type::getMixed(),
+                        new Type\Union([new TObject, new TString]),
                         Type::getString()
                     ]),
                     $existing_var_atomic_types['array']

tests/CallableTest.php

@@ -874,8 +874,8 @@ class CallableTest extends TestCase
                      * @psalm-suppress MixedArgument
                      */
                     function foo($c) : void {
-                        if (is_array($c)) {
-                            echo $c[2];
+                        if (is_array($c) && is_string($c[1])) {
+                            echo $c[1];
                         }
                     }',
             ],

tests/RedundantConditionTest.php

@@ -272,7 +272,20 @@ class RedundantConditionTest extends TestCase
                 'assertions' => [],
                 'error_levels' => ['MixedAssignment', 'MixedArrayAccess'],
             ],
-            'hardPhpTypeAssertionsOnDocblockType' => [
+            'hardPhpTypeAssertionsOnDocblockBoolType' => [
+                '<?php
+                    /** @param bool|null $bar */
+                    function foo($bar): void {
+                        if (!is_null($bar) && !is_bool($bar)) {
+                            throw new \Exception("bad");
+                        }
+
+                        if ($bar !== null) {}
+                    }',
+                'assertions' => [],
+                'error_levels' => ['DocblockTypeContradiction'],
+            ],
+            'hardPhpTypeAssertionsOnDocblockStringType' => [
                 '<?php
                     /** @param string|null $bar */
                     function foo($bar): void {

tests/TypeReconciliationTest.php

@@ -1363,6 +1363,20 @@ class TypeReconciliationTest extends TestCase
                         }
                     }',
             ],
+            'reconcileCallable' => [
+                '<?php
+                    function reflectCallable(callable $callable): ReflectionFunctionAbstract {
+                        if (\is_array($callable)) {
+                            return new \ReflectionMethod($callable[0], $callable[1]);
+                        } elseif ($callable instanceof \Closure || \is_string($callable)) {
+                            return new \ReflectionFunction($callable);
+                        } elseif (\is_object($callable)) {
+                            return new \ReflectionMethod($callable, "__invoke");
+                        } else {
+                            throw new \InvalidArgumentException("Bad");
+                        }
+                    }'
+            ],
         ];
     }