diff --git a/.github/workflows/bc.yml b/.github/workflows/bc.yml
index 75f97a7..ba3e9ef 100644
--- a/.github/workflows/bc.yml
+++ b/.github/workflows/bc.yml
@@ -3,13 +3,12 @@ on:
   - push
 
 name: backwards compatibility
+
 jobs:
   roave_bc_check:
-    name: Roave BC Check
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@master
-      - name: fetch tags
-        run: git fetch --depth=1 origin +refs/tags/*:refs/tags/*
-      - name: Roave BC Check
-        uses: docker://nyholm/roave-bc-check-ga
+    uses: yiisoft/actions/.github/workflows/bc.yml@master
+    with:
+      os: >-
+        ['ubuntu-latest']
+      php: >-
+        ['8.0']
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 0dde6b6..ed9a60b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -28,4 +28,4 @@ jobs:
       os: >-
         ['ubuntu-latest', 'windows-latest']
       php: >-
-        ['7.4', '8.0', '8.1']
+        ['8.0', '8.1', '8.2']
diff --git a/.github/workflows/rector.yml b/.github/workflows/rector.yml
new file mode 100644
index 0000000..adacd73
--- /dev/null
+++ b/.github/workflows/rector.yml
@@ -0,0 +1,21 @@
+on:
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - 'README.md'
+      - 'CHANGELOG.md'
+      - '.gitignore'
+      - '.gitattributes'
+      - 'infection.json.dist'
+      - 'psalm.xml'
+
+name: rector
+
+jobs:
+  rector:
+    uses: yiisoft/actions/.github/workflows/rector.yml@master
+    with:
+      os: >-
+        ['ubuntu-latest']
+      php: >-
+        ['8.0']
diff --git a/.github/workflows/static.yml b/.github/workflows/static.yml
index 40ac260..fb7fc77 100644
--- a/.github/workflows/static.yml
+++ b/.github/workflows/static.yml
@@ -28,4 +28,4 @@ jobs:
       os: >-
         ['ubuntu-latest']
       php: >-
-        ['7.4', '8.0', '8.1']
+        ['8.0', '8.1', '8.2']
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3aa4c2e..c83fc4f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,16 +1,17 @@
 # Yii Config Change Log
 
-## 1.1.2 under development
+## 1.2.0 under development
 
-- Enh #119: Improve performance of collecting data for `ReverseMerge` and `RecursiveMerge` (samdark)
+- Enh #119: Improve performance of collecting data for `ReverseMerge` and `RecursiveMerge` (@samdark)
+- Enh #122: Raise minimal PHP version to 8.0 (@vjik, @xepozz)
 
 ## 1.1.1 January 05, 2022
 
-- Enh #110: Improve the error message by displaying a name of the group where the error occurred when merging (devanych)
+- Enh #110: Improve the error message by displaying a name of the group where the error occurred when merging (@devanych)
 
 ## 1.1.0 December 31, 2021
 
-- New #108: Add `Yiisoft\Config\ConfigInterface` to allow custom implementations of a config loader (devanych)
+- New #108: Add `Yiisoft\Config\ConfigInterface` to allow custom implementations of a config loader (@devanych)
 
 ## 1.0.0 December 17, 2021
 
diff --git a/README.md b/README.md
index bc76231..a6b436f 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ a plugin system. The package becomes a plugin holding both the code and its conf
 
 ## Requirements
 
-- PHP 7.4 or higher.
+- PHP 8.0 or higher.
 - Composer 2.0 or higher.
 
 ## Installation
diff --git a/composer.json b/composer.json
index 5a32384..41cfe12 100644
--- a/composer.json
+++ b/composer.json
@@ -28,18 +28,19 @@
         }
     ],
     "require": {
-        "php": "^7.4|^8.0",
+        "php": "^8.0",
         "composer-plugin-api": "^2.0",
         "yiisoft/strings": "^2.0",
         "yiisoft/var-dumper": "^1.1"
     },
     "require-dev": {
+        "ext-json": "*",
         "composer/composer": "^2.0",
         "phpunit/phpunit": "^9.5",
+        "rector/rector": "^0.15.7",
         "roave/infection-static-analysis-plugin": "^1.16",
         "spatie/phpunit-watcher": "^1.23",
-        "vimeo/psalm": "^4.18",
-        "ext-json": "*"
+        "vimeo/psalm": "^4.18"
     },
     "config": {
         "sort-packages": true,
diff --git a/rector.php b/rector.php
new file mode 100644
index 0000000..e5f54a6
--- /dev/null
+++ b/rector.php
@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\CodeQuality\Rector\Class_\InlineConstructorDefaultToPropertyRector;
+use Rector\Config\RectorConfig;
+use Rector\Php70\Rector\FuncCall\NonVariableToVariableOnFunctionCallRector;
+use Rector\Php71\Rector\FuncCall\RemoveExtraParametersRector;
+use Rector\Set\ValueObject\LevelSetList;
+
+return static function (RectorConfig $rectorConfig): void {
+    $rectorConfig->paths([
+        __DIR__ . '/src',
+        __DIR__ . '/tests',
+    ]);
+
+    // register a single rule
+    $rectorConfig->rule(InlineConstructorDefaultToPropertyRector::class);
+
+    // define sets of rules
+    $rectorConfig->sets([
+        LevelSetList::UP_TO_PHP_80,
+    ]);
+
+    $rectorConfig->skip([
+        RemoveExtraParametersRector::class,
+        NonVariableToVariableOnFunctionCallRector::class,
+    ]);
+};
diff --git a/src/Composer/PackageFile.php b/src/Composer/PackageFile.php
index 7f8ff4b..41d848c 100644
--- a/src/Composer/PackageFile.php
+++ b/src/Composer/PackageFile.php
@@ -9,15 +9,11 @@
  */
 final class PackageFile
 {
-    private string $filename;
-    private string $relativePath;
-    private string $absolutePath;
-
-    public function __construct(string $filename, string $relativePath, string $absolutePath)
-    {
-        $this->filename = $filename;
-        $this->relativePath = $relativePath;
-        $this->absolutePath = $absolutePath;
+    public function __construct(
+        private string $filename,
+        private string $relativePath,
+        private string $absolutePath,
+    ) {
     }
 
     public function filename(): string
diff --git a/src/Composer/PackagesListBuilder.php b/src/Composer/PackagesListBuilder.php
index 4a8a442..6766a85 100644
--- a/src/Composer/PackagesListBuilder.php
+++ b/src/Composer/PackagesListBuilder.php
@@ -15,11 +15,9 @@
  */
 final class PackagesListBuilder
 {
-    private Composer $composer;
-
-    public function __construct(Composer $composer)
-    {
-        $this->composer = $composer;
+    public function __construct(
+        private Composer $composer,
+    ) {
     }
 
     /**
diff --git a/src/Config.php b/src/Config.php
index 2796c8d..1146301 100644
--- a/src/Config.php
+++ b/src/Config.php
@@ -21,7 +21,6 @@ final class Config implements ConfigInterface
 {
     private Merger $merger;
     private FilesExtractor $filesExtractor;
-    private string $paramsGroup;
     private bool $isBuildingParams = false;
 
     /**
@@ -41,10 +40,9 @@ public function __construct(
         ConfigPaths $paths,
         string $environment = null,
         array $modifiers = [],
-        string $paramsGroup = 'params'
+        private string $paramsGroup = 'params'
     ) {
         $environment = empty($environment) ? Options::DEFAULT_ENVIRONMENT : $environment;
-        $this->paramsGroup = $paramsGroup;
 
         /** @psalm-suppress UnresolvableInclude, MixedArgument */
         $mergePlan = new MergePlan(require $paths->absolute(Options::MERGE_PLAN_FILENAME));
@@ -196,8 +194,6 @@ private function buildFile(string $filePath): array
     }
 
     /**
-     * @param string $message
-     *
      * @throws ErrorException
      */
     private function throwException(string $message): void
diff --git a/src/ConfigPaths.php b/src/ConfigPaths.php
index 333fd46..f9dd5e0 100644
--- a/src/ConfigPaths.php
+++ b/src/ConfigPaths.php
@@ -5,7 +5,6 @@
 namespace Yiisoft\Config;
 
 use function strlen;
-use function strpos;
 use function substr;
 use function trim;
 
@@ -14,7 +13,6 @@
  */
 final class ConfigPaths
 {
-    private string $rootPath;
     private string $configPath;
     private string $vendorPath;
 
@@ -23,10 +21,11 @@ final class ConfigPaths
      * @param string|null $configDirectory The relative path to the configuration storage location.
      * @param string|null $vendorDirectory The relative path to the vendor directory.
      */
-    public function __construct(string $rootPath, string $configDirectory = null, string $vendorDirectory = null)
-    {
-        $this->rootPath = $rootPath;
-
+    public function __construct(
+        private string $rootPath,
+        string $configDirectory = null,
+        string $vendorDirectory = null,
+    ) {
         $configDirectory = trim($configDirectory ?? Options::DEFAULT_CONFIG_DIRECTORY, '/');
         $this->configPath = $rootPath . ($configDirectory === '' ? '' : "/$configDirectory");
 
@@ -64,7 +63,7 @@ public function absolute(string $file, string $package = Options::ROOT_PACKAGE_N
      */
     public function relative(string $file): string
     {
-        return strpos($file, "$this->rootPath/") === 0
+        return str_starts_with($file, "$this->rootPath/")
             ? substr($file, strlen("$this->rootPath/"))
             : $file;
     }
diff --git a/src/Context.php b/src/Context.php
index e1c94f8..280e5d5 100644
--- a/src/Context.php
+++ b/src/Context.php
@@ -14,19 +14,13 @@ final class Context
     public const APPLICATION = 3;
     public const ENVIRONMENT = 4;
 
-    private string $group;
-    private string $package;
-    private int $layer;
-    private string $file;
-    private bool $isVariable;
-
-    public function __construct(string $group, string $package, int $layer, string $file, bool $isVariable)
-    {
-        $this->group = $group;
-        $this->package = $package;
-        $this->layer = $layer;
-        $this->file = $file;
-        $this->isVariable = $isVariable;
+    public function __construct(
+        private string $group,
+        private string $package,
+        private int $layer,
+        private string $file,
+        private bool $isVariable,
+    ) {
     }
 
     public function group(): string
diff --git a/src/DataModifiers.php b/src/DataModifiers.php
index f9f23bc..19c69d5 100644
--- a/src/DataModifiers.php
+++ b/src/DataModifiers.php
@@ -33,12 +33,12 @@ final class DataModifiers
     /**
      * @psalm-var array<string, true>
      */
-    private array $removeFromVendorGroupsIndex;
+    private array $removeFromVendorGroupsIndex = [];
 
     /**
      * @psalm-var array<string, array<string, mixed>>
      */
-    private array $removeFromVendorKeysIndex;
+    private array $removeFromVendorKeysIndex = [];
 
     /**
      * @param object[] $modifiers Modifiers that affect merge process.
@@ -48,9 +48,6 @@ public function __construct(array $modifiers = [])
         $reverseMergeGroups = [];
         $recursiveMergeGroups = [];
 
-        $this->removeFromVendorGroupsIndex = [];
-        $this->removeFromVendorKeysIndex = [];
-
         foreach ($modifiers as $modifier) {
             if ($modifier instanceof ReverseMerge) {
                 array_unshift($reverseMergeGroups, $modifier->getGroups());
diff --git a/src/FilesExtractor.php b/src/FilesExtractor.php
index d42ec3a..a40be43 100644
--- a/src/FilesExtractor.php
+++ b/src/FilesExtractor.php
@@ -17,21 +17,12 @@
  */
 final class FilesExtractor
 {
-    private ConfigPaths $paths;
-    private MergePlan $mergePlan;
-    private DataModifiers $dataModifiers;
-    private string $environment;
-
     public function __construct(
-        ConfigPaths $paths,
-        MergePlan $mergePlan,
-        DataModifiers $dataModifiers,
-        string $environment
+        private ConfigPaths $paths,
+        private MergePlan $mergePlan,
+        private DataModifiers $dataModifiers,
+        private string $environment,
     ) {
-        $this->paths = $paths;
-        $this->mergePlan = $mergePlan;
-        $this->dataModifiers = $dataModifiers;
-        $this->environment = $environment;
     }
 
     /**
@@ -171,8 +162,6 @@ private function prepareEnvironment(string $group): string
     }
 
     /**
-     * @param string $message
-     *
      * @throws ErrorException
      */
     private function throwException(string $message): void
diff --git a/src/MergePlan.php b/src/MergePlan.php
index b505e39..ca9bea4 100644
--- a/src/MergePlan.php
+++ b/src/MergePlan.php
@@ -9,17 +9,12 @@
  */
 final class MergePlan
 {
-    /**
-     * @psalm-var array<string, array<string, array<string, string[]>>>
-     */
-    private array $mergePlan;
-
     /**
      * @psalm-param array<string, array<string, array<string, string[]>>> $mergePlan
      */
-    public function __construct(array $mergePlan = [])
-    {
-        $this->mergePlan = $mergePlan;
+    public function __construct(
+        private array $mergePlan = [],
+    ) {
     }
 
     /**
diff --git a/src/Merger.php b/src/Merger.php
index e4f77dd..a10aacc 100644
--- a/src/Merger.php
+++ b/src/Merger.php
@@ -22,9 +22,6 @@
  */
 final class Merger
 {
-    private ConfigPaths $paths;
-    private DataModifiers $dataModifiers;
-
     /**
      * @psalm-var array<int, array>
      */
@@ -34,10 +31,10 @@ final class Merger
      * @param ConfigPaths $configPaths The config paths instance.
      * @param DataModifiers $dataModifiers The data modifiers that affect merge process.
      */
-    public function __construct(ConfigPaths $configPaths, DataModifiers $dataModifiers)
-    {
-        $this->paths = $configPaths;
-        $this->dataModifiers = $dataModifiers;
+    public function __construct(
+        private ConfigPaths $configPaths,
+        private DataModifiers $dataModifiers,
+    ) {
     }
 
     public function reset(): void
@@ -80,8 +77,6 @@ public function merge(Context $context, array $arrayA, array $arrayB): array
      * @param string[] $recursiveKeyPath The key path for recursive merging of arrays in configuration files.
      * @param array $arrayA First array to merge.
      * @param array $arrayB Second array to merge.
-     * @param bool $isRecursiveMerge
-     * @param bool $isReverseMerge
      *
      * @throws ErrorException If an error occurred during the merge.
      *
@@ -231,11 +226,9 @@ private function prepareArrayForReverse(
     }
 
     /**
-     * @param mixed $value
-     *
      * @psalm-param non-empty-array<array-key, string> $keyPath
      */
-    private function setValue(Context $context, array $keyPath, array &$array, string $key, $value): bool
+    private function setValue(Context $context, array $keyPath, array &$array, string $key, mixed $value): bool
     {
         if ($this->dataModifiers->shouldRemoveKeyFromVendor($context, $keyPath)) {
             return false;
@@ -262,7 +255,7 @@ private function throwDuplicateKeyErrorException(
         array $absoluteFilePaths
     ): void {
         $filePaths = array_map(
-            fn (string $filePath) => ' - ' . $this->paths->relative($filePath),
+            fn (string $filePath) => ' - ' . $this->configPaths->relative($filePath),
             $absoluteFilePaths,
         );
 
diff --git a/src/Modifier/RecursiveMerge.php b/src/Modifier/RecursiveMerge.php
index edb0a55..fa3535a 100644
--- a/src/Modifier/RecursiveMerge.php
+++ b/src/Modifier/RecursiveMerge.php
@@ -78,17 +78,12 @@
  */
 final class RecursiveMerge
 {
-    /**
-     * @var string[]
-     */
-    private array $groups;
-
     /**
      * @param string[] $groups
      */
-    private function __construct(array $groups)
-    {
-        $this->groups = $groups;
+    private function __construct(
+        private array $groups,
+    ) {
     }
 
     public static function groups(string ...$groups): self
diff --git a/src/Modifier/RemoveGroupsFromVendor.php b/src/Modifier/RemoveGroupsFromVendor.php
index e9756e6..041c709 100644
--- a/src/Modifier/RemoveGroupsFromVendor.php
+++ b/src/Modifier/RemoveGroupsFromVendor.php
@@ -12,14 +12,13 @@ final class RemoveGroupsFromVendor
     /**
      * @psalm-var array<string, string[]>
      */
-    private array $groups;
+    private array $groups = [];
 
     /**
      * @psalm-param array<string, string|string[]> $groups
      */
     public function __construct(array $groups)
     {
-        $this->groups = [];
         foreach ($groups as $package => $groupNames) {
             $this->groups[$package] = (array) $groupNames;
         }
diff --git a/src/Modifier/ReverseMerge.php b/src/Modifier/ReverseMerge.php
index 1770998..7b1e557 100644
--- a/src/Modifier/ReverseMerge.php
+++ b/src/Modifier/ReverseMerge.php
@@ -68,17 +68,12 @@
  */
 final class ReverseMerge
 {
-    /**
-     * @var string[]
-     */
-    private array $groups;
-
     /**
      * @param string[] $groups
      */
-    private function __construct(array $groups)
-    {
-        $this->groups = $groups;
+    private function __construct(
+        private array $groups,
+    ) {
     }
 
     public static function groups(string ...$groups): self
diff --git a/src/Options.php b/src/Options.php
index 4d5e33b..f1eeaf1 100644
--- a/src/Options.php
+++ b/src/Options.php
@@ -6,7 +6,6 @@
 
 use function is_array;
 use function str_replace;
-use function strpos;
 use function trim;
 
 /**
@@ -48,17 +47,17 @@ public function __construct(array $extra)
 
     public static function containsWildcard(string $file): bool
     {
-        return strpos($file, '*') !== false;
+        return str_contains($file, '*');
     }
 
     public static function isOptional(string $file): bool
     {
-        return strpos($file, '?') === 0;
+        return str_starts_with($file, '?');
     }
 
     public static function isVariable(string $file): bool
     {
-        return strpos($file, '$') === 0;
+        return str_starts_with($file, '$');
     }
 
     public function buildMergePlan(): bool
diff --git a/tests/ConfigPathsTest.php b/tests/ConfigPathsTest.php
index fece431..8b9150b 100644
--- a/tests/ConfigPathsTest.php
+++ b/tests/ConfigPathsTest.php
@@ -27,10 +27,6 @@ public function absolutePathsDataProvider(): array
 
     /**
      * @dataProvider absolutePathsDataProvider
-     *
-     * @param string $file
-     * @param string $package
-     * @param string $expected
      */
     public function testAbsolute(string $file, string $package, string $expected): void
     {
diff --git a/tests/OptionsTest.php b/tests/OptionsTest.php
index d2b6f7d..3dbe7a3 100644
--- a/tests/OptionsTest.php
+++ b/tests/OptionsTest.php
@@ -22,10 +22,8 @@ public function buildMergePlanDataProvider(): array
 
     /**
      * @dataProvider buildMergePlanDataProvider
-     *
-     * @param mixed $value
      */
-    public function testBuildMergePlanTrue($value): void
+    public function testBuildMergePlanTrue(mixed $value): void
     {
         $options = new Options([
             'config-plugin-options' => [
@@ -48,10 +46,8 @@ public function noBuildMergePlanDataProvider(): array
 
     /**
      * @dataProvider noBuildMergePlanDataProvider
-     *
-     * @param mixed $value
      */
-    public function testBuildMergePlanFalse($value): void
+    public function testBuildMergePlanFalse(mixed $value): void
     {
         $options = new Options([
             'config-plugin-options' => [
@@ -71,10 +67,8 @@ public function packagePatternDataProvider(): array
 
     /**
      * @dataProvider packagePatternDataProvider
-     *
-     * @param array|string $packages
      */
-    public function testVendorOverrideLayerPackages($packages): void
+    public function testVendorOverrideLayerPackages(array|string $packages): void
     {
         $options = new Options([
             'config-plugin-options' => [