feature #39352 [TwigBridge] export concatenated translations (Stephen)

This PR was submitted for the 4.4 branch but it was squashed and merged into the 5.3-dev branch instead.

Discussion
----------

[TwigBridge] export concatenated translations

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #39351
| License       | MIT
| Doc PR        |

This PR will fix that concatenated strings are ignored by the translation:update command. Suppose you have a twig file like this:
```
{{ ('aa' ~ 'bb') | trans }}
```
This is not exported when using the command. This PR will fix that.

Commits
-------

122eaba746 [TwigBridge] export concatenated translations

src/Symfony/Bridge/Twig/NodeVisitor/TranslationNodeVisitor.php

@@ -13,6 +13,7 @@ namespace Symfony\Bridge\Twig\NodeVisitor;
 
 use Symfony\Bridge\Twig\Node\TransNode;
 use Twig\Environment;
+use Twig\Node\Expression\Binary\ConcatBinary;
 use Twig\Node\Expression\ConstantExpression;
 use Twig\Node\Expression\FilterExpression;
 use Twig\Node\Expression\FunctionExpression;
@@ -87,6 +88,16 @@ final class TranslationNodeVisitor extends AbstractNodeVisitor
                 $node->getNode('body')->getAttribute('data'),
                 $node->hasNode('domain') ? $this->getReadDomainFromNode($node->getNode('domain')) : null,
             ];
+        } elseif (
+            $node instanceof FilterExpression &&
+            'trans' === $node->getNode('filter')->getAttribute('value') &&
+            $node->getNode('node') instanceof ConcatBinary &&
+            $message = $this->getConcatValueFromNode($node->getNode('node'), null)
+        ) {
+            $this->messages[] = [
+                $message,
+                $this->getReadDomainFromArguments($node->getNode('arguments'), 1),
+            ];
         }
 
         return $node;
@@ -151,4 +162,28 @@ final class TranslationNodeVisitor extends AbstractNodeVisitor
 
         return self::UNDEFINED_DOMAIN;
     }
+
+    private function getConcatValueFromNode(Node $node, ?string $value): ?string
+    {
+        if ($node instanceof ConcatBinary) {
+            foreach ($node as $nextNode) {
+                if ($nextNode instanceof ConcatBinary) {
+                    $nextValue = $this->getConcatValueFromNode($nextNode, $value);
+                    if (null === $nextValue) {
+                        return null;
+                    }
+                    $value .= $nextValue;
+                } elseif ($nextNode instanceof ConstantExpression) {
+                    $value .= $nextNode->getAttribute('value');
+                } else {
+                    // this is a node we cannot process (variable, or translation in translation)
+                    return null;
+                }
+            }
+        } elseif ($node instanceof ConstantExpression) {
+            $value .= $node->getAttribute('value');
+        }
+
+        return $value;
+    }
 }

src/Symfony/Bridge/Twig/Tests/Translation/TwigExtractorTest.php

@@ -43,6 +43,10 @@ class TwigExtractorTest extends TestCase
         $m->setAccessible(true);
         $m->invoke($extractor, $template, $catalogue);
 
+        if (0 === \count($messages)) {
+            $this->assertSame($catalogue->all(), $messages);
+        }
+
         foreach ($messages as $key => $domain) {
             $this->assertTrue($catalogue->has($key, $domain));
             $this->assertEquals('prefix'.$key, $catalogue->get($key, $domain));
@@ -70,6 +74,15 @@ class TwigExtractorTest extends TestCase
 
             // make sure this works with twig's named arguments
             ['{{ "new key" | trans(domain="domain") }}', ['new key' => 'domain']],
+
+            // concat translations
+            ['{{ ("new" ~ " key") | trans() }}', ['new key' => 'messages']],
+            ['{{ ("another " ~ "new " ~ "key") | trans() }}', ['another new key' => 'messages']],
+            ['{{ ("new" ~ " key") | trans(domain="domain") }}', ['new key' => 'domain']],
+            ['{{ ("another " ~ "new " ~ "key") | trans(domain="domain") }}', ['another new key' => 'domain']],
+            // if it has a variable or other expression, we can not extract it
+            ['{% set foo = "new" %} {{ ("new " ~ foo ~ "key") | trans() }}', []],
+            ['{{ ("foo " ~ "new"|trans ~ "key") | trans() }}', ['new' => 'messages']],
         ];
     }