wip: take a quoted string in @_documentation(metadata:)

Author: QuietMisdreavus

include/swift/AST/DiagnosticsParse.def

@@ -1777,8 +1777,9 @@ ERROR(documentation_attr_unknown_access_level,none,
       (StringRef))
 ERROR(documentation_attr_duplicate_visibility,none,
       "cannot give more than one visibility to the same item", ())
-ERROR(documentation_attr_metadata_expected_identifier,none,
-      "@_documentation attribute's 'metadata' argument expected a plain identifier",
+ERROR(documentation_attr_metadata_expected_text,none,
+      "@_documentation attribute's 'metadata' argument expected an identifier or "
+      "quoted string",
       ())
 ERROR(documentation_attr_duplicate_metadata,none,
       "cannot give more than one metadata argument to the same item", ())

lib/Parse/ParseDecl.cpp

@@ -1985,8 +1985,8 @@ bool Parser::parseDocumentationAttributeArgument(Optional<StringRef> &Metadata,
     consumeToken();
     Visibility = ParsedVisibility;
   } else if (ArgumentName == "metadata") {
-    if (Tok.isNot(tok::identifier)) {
-      diagnose(Tok.getLoc(), diag::documentation_attr_metadata_expected_identifier);
+    if (!Tok.isAny(tok::identifier, tok::string_literal)) {
+      diagnose(Tok.getLoc(), diag::documentation_attr_metadata_expected_text);
       return false;
     }
     auto ArgumentValue = Tok.getText();
@@ -1996,7 +1996,7 @@ bool Parser::parseDocumentationAttributeArgument(Optional<StringRef> &Metadata,
       return false;
     }
 
-    consumeToken(tok::identifier);
+    consumeToken();
     Metadata = ArgumentValue;
   } else {
     llvm_unreachable("unimplemented @_documentation attr argument");

test/SymbolGraph/Symbols/DocumentationMetadata.swift

@@ -6,3 +6,5 @@
 // CHECK: "metadata": "cool_stuff"
 @_documentation(metadata: cool_stuff) public class SomeClass {}
 
+@_documentation(metadata: "this is a longer string") public class OtherClass {}
+