feat(completion): complete class aliases when the target does not exist

fixtures/completion/used_class.php

@@ -2,8 +2,10 @@
 
 namespace Whatever;
 
-use TestNamespace\{TestClass, TestInterface};
+use TestNamespace\{TestClass, TestInterface, IDontExist};
 
-TestC
+TestC;
+
+IDont;
 
 class OtherClass {}

src/CompletionProvider.php

@@ -408,7 +408,8 @@ class CompletionProvider
         yield from $this->getCompletionsForAliases(
             $prefix,
             $namespaceAliases,
-            $requireCanBeInstantiated
+            $requireCanBeInstantiated,
+            CompletionItemKind::CLASS_
         );
 
         // Completions from the current namespace
@@ -471,13 +472,15 @@ class CompletionProvider
      *
      * @param string $prefix Non-qualified name being completed for
      * @param QualifiedName[] $aliases Array of alias FQNs indexed by the alias.
+     * @param int $defaultSymbolKind The SymbolKind:: constant to use when the definition for the alias is not found.
      * @return \Generator|CompletionItem[]
      *   Yields CompletionItems.
      */
     private function getCompletionsForAliases(
         string $prefix,
         array $aliases,
-        bool $requireCanBeInstantiated
+        bool $requireCanBeInstantiated,
+        int $defaultCompletionItemKind
     ): \Generator {
         foreach ($aliases as $alias => $aliasFqn) {
             if (!nameStartsWith($alias, $prefix)) {
@@ -491,6 +494,11 @@ class CompletionProvider
                 $completionItem = CompletionItem::fromDefinition($definition);
                 $completionItem->insertText = $alias;
                 yield (string)$aliasFqn => $completionItem;
+            } else {
+                // Use clause referred to a symbol which was not indexed.
+                $completionItem = new CompletionItem($alias, $defaultCompletionItemKind);
+                $completionItem->detail = nameGetParent((string)$aliasFqn);
+                yield (string)$aliasFqn => $completionItem;
             }
         }
     }

tests/Server/TextDocument/CompletionTest.php

@@ -271,6 +271,29 @@ class CompletionTest extends TestCase
         $this->assertCompletionsListDoesNotContainLabel('TestInterface', $items);
     }
 
+    /**
+     * Tests completion at `IDontE|` with `use TestNamespace\IDontExist`
+     */
+    public function testUsedClassNonExistent()
+    {
+        $completionUri = pathToUri(__DIR__ . '/../../../fixtures/completion/used_class.php');
+        $this->loader->open($completionUri, file_get_contents($completionUri));
+        $items = $this->textDocument->completion(
+            new TextDocumentIdentifier($completionUri),
+            new Position(8, 5)
+        )->wait();
+        $this->assertEquals(new CompletionList([
+            new CompletionItem(
+                'IDontExist',
+                CompletionItemKind::CLASS_,
+                'TestNamespace'
+            )
+        ], true), $items);
+
+        $this->assertCompletionsListDoesNotContainLabel('OtherClass', $items);
+        $this->assertCompletionsListDoesNotContainLabel('TestInterface', $items);
+    }
+
     /**
      * Tests completion at `AliasNamespace\I|` with `use TestNamespace\InnerNamespace as AliasNamespace`
      */