minor #54447 Remove unnecessary empty usages (ostrolucky)

This PR was merged into the 7.1 branch.

Discussion
----------

Remove unnecessary empty usages

| Q             | A
| ------------- | ---
| Branch?       | 7.1
| Bug fix?      | no
| New feature?  |no
| Deprecations? |  no
| Issues        |
| License       | MIT

I've written a rector for this rectorphp/rector-src#5783 and decided to apply it on Symfony src here.

As for motivation for removing empty where possible, in my and several other prominent devs opinions, using `empty()` is a bad practice for several reasons:
- it's misleading. It doesn't work with collection or stringable objects. Its meaning is more like `isset($foo) && (bool) $foo` rather than `count($foo) === 0` or `strlen($foo) === 0`, contrary to name of this function.
- it decreases safety of the code, because it's doing implicit `isset` call, so once you remove variable assignment, `empty()` call that references it continues silently working
- it increases complexity because of having to negate the call in most cases (there is no `nonempty()` function)
- it's unnecessary in most cases and hence adds extra opcodes and increases length of code for no good reason

There were also several articles written on this topic, I know about these 2:
- https://www.contextualcode.com/Blog/php-micro-optimization.-variable-boolean-cast-vs-!empty
- https://www.beberlei.de/2021/02/19/when_to_use_empty_in_php_i_say_never.html (this one is from `@beberlei`)

However, personally I'm not in a super strict camp. I like that I don't have to explicitly specify `[] === $foo` or `'' === $foo` or `null === $foo` (and so on and on)  and I think Symfony shares the similar opinion.

Commits
-------

ccc813c65f Remove unnecessary empty usages

Author: fabpot

Application.php

@@ -620,7 +620,7 @@ public function findNamespace(string $namespace): string
         $expr = implode('[^:]*:', array_map('preg_quote', explode(':', $namespace))).'[^:]*';
         $namespaces = preg_grep('{^'.$expr.'}', $allNamespaces);
 
-        if (empty($namespaces)) {
+        if (!$namespaces) {
             $message = sprintf('There are no commands defined in the "%s" namespace.', $namespace);
 
             if ($alternatives = $this->findAlternatives($namespace, $allNamespaces)) {
@@ -674,12 +674,12 @@ public function find(string $name): Command
         $expr = implode('[^:]*:', array_map('preg_quote', explode(':', $name))).'[^:]*';
         $commands = preg_grep('{^'.$expr.'}', $allCommands);
 
-        if (empty($commands)) {
+        if (!$commands) {
             $commands = preg_grep('{^'.$expr.'}i', $allCommands);
         }
 
         // if no commands matched or we just matched namespaces
-        if (empty($commands) || \count(preg_grep('{^'.$expr.'$}i', $commands)) < 1) {
+        if (!$commands || \count(preg_grep('{^'.$expr.'$}i', $commands)) < 1) {
             if (false !== $pos = strrpos($name, ':')) {
                 // check if a namespace exists and contains commands
                 $this->findNamespace(substr($name, 0, $pos));

Descriptor/XmlDescriptor.php

@@ -208,7 +208,7 @@ private function getInputOptionDocument(InputOption $option): \DOMDocument
             $defaults = \is_array($option->getDefault()) ? $option->getDefault() : (\is_bool($option->getDefault()) ? [var_export($option->getDefault(), true)] : ($option->getDefault() ? [$option->getDefault()] : []));
             $objectXML->appendChild($defaultsXML = $dom->createElement('defaults'));
 
-            if (!empty($defaults)) {
+            if ($defaults) {
                 foreach ($defaults as $default) {
                     $defaultsXML->appendChild($defaultXML = $dom->createElement('default'));
                     $defaultXML->appendChild($dom->createTextNode($default));

Helper/Table.php

@@ -727,7 +727,7 @@ private function fillNextRows(array $rows, int $line): array
             } else {
                 $row = $this->copyRow($rows, $unmergedRowKey - 1);
                 foreach ($unmergedRow as $column => $cell) {
-                    if (!empty($cell)) {
+                    if ($cell) {
                         $row[$column] = $cell;
                     }
                 }

Input/InputOption.php

@@ -75,7 +75,7 @@ public function __construct(
             $name = substr($name, 2);
         }
 
-        if (empty($name)) {
+        if (!$name) {
             throw new InvalidArgumentException('An option name cannot be empty.');
         }
 

Output/ConsoleSectionOutput.php

@@ -63,7 +63,7 @@ public function setMaxHeight(int $maxHeight): void
      */
     public function clear(?int $lines = null): void
     {
-        if (empty($this->content) || !$this->isDecorated()) {
+        if (!$this->content || !$this->isDecorated()) {
             return;
         }