Avoid collissions with extension names in namespaced code (#199)

Author: janedbal

src/UsedSymbolExtractor.php

@@ -163,6 +163,11 @@ public function parseUsedSymbols(
                         } elseif (isset($extensionSymbols[$lowerName])) {
                             $symbolName = $name;
                             $kind = $extensionSymbols[$lowerName];
+
+                            if (!$inGlobalScope && $kind === SymbolKind::CLASSLIKE) {
+                                break; // cannot use class-like symbols in non-global scope when not imported
+                            }
+
                             $usedSymbols[$kind][$symbolName][] = $token[2];
                         }
 
@@ -211,6 +216,11 @@ public function parseUsedSymbols(
                         } elseif (isset($extensionSymbols[$lowerName])) {
                             $symbolName = $name;
                             $kind = $extensionSymbols[$lowerName];
+
+                            if (!$inGlobalScope && $kind === SymbolKind::CLASSLIKE) {
+                                break; // cannot use class-like symbols in non-global scope when not imported
+                            }
+
                             $usedSymbols[$kind][$symbolName][] = $token[2];
 
                         } else {

tests/data/not-autoloaded/used-symbols/extensions.php

@@ -3,7 +3,7 @@
 
 use { DDTrace, DDTrace\Integrations };
 use function DDTrace\active_span;
-use My\App\XMLReader;
+use My\App\XMLReader, PDO;
 
 json_encode('');
 LIBXML_ERR_FATAL;
@@ -23,3 +23,5 @@
 
 function foo($normalizer) {}
 foo(normalizer: 1);
+
+class Normalizer {}