swiftlang · DougGregor · Mar 29, 2023 · Mar 27, 2023
diff --git a/include/swift/AST/DiagnosticsParse.def b/include/swift/AST/DiagnosticsParse.def
@@ -2028,8 +2028,6 @@ ERROR(foreign_diagnostic,none,
 //------------------------------------------------------------------------------
 ERROR(expected_macro_value_type,PointsToFirstBadToken,
       "expected macro value type following ':'", ())
-ERROR(no_default_arg_macro,none,
-      "default arguments are not allowed in macros", ())
 ERROR(expected_lparen_macro,PointsToFirstBadToken,
       "expected '(' for macro parameters or ':' for a value-like macro", ())
 ERROR(expected_type_macro_result,PointsToFirstBadToken,

diff --git a/include/swift/AST/DiagnosticsSema.def b/include/swift/AST/DiagnosticsSema.def
@@ -6970,8 +6970,6 @@ ERROR(macro_definition_unsupported,none,
 ERROR(external_macro_arg_not_type_name,none,
       "argument to `#externalMacro` must be a string literal naming "
       "the external macro's %select{module|type}0", (unsigned))
-ERROR(attached_declaration_macro_not_supported,none,
-      "attached declaration macros are not yet supported", ())
 ERROR(invalid_decl_in_macro_expansion,none,
       "macro expansion cannot introduce %0",
       (DescriptiveDeclKind))

diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
@@ -9595,9 +9595,10 @@ ParserResult<MacroDecl> Parser::parseDeclMacro(DeclAttributes &attributes) {
   DeclName macroFullName;
 
   // Parameter list.
+  DefaultArgumentInfo defaultArgs;
   SmallVector<Identifier, 2> namePieces;
   auto parameterResult = parseSingleParameterClause(
-      ParameterContextKind::Macro, &namePieces, nullptr);
+      ParameterContextKind::Macro, &namePieces, &defaultArgs);
   status |= parameterResult;
   parameterList = parameterResult.getPtrOrNull();
 
@@ -9640,6 +9641,8 @@ ParserResult<MacroDecl> Parser::parseDeclMacro(DeclAttributes &attributes) {
     status |= whereStatus;
   }
 
+  defaultArgs.setFunctionContext(macro, macro->getParameterList());
+
   return dcc.fixupParserResult(status, macro);
 }
 

diff --git a/lib/Parse/ParsePattern.cpp b/lib/Parse/ParsePattern.cpp
@@ -109,16 +109,14 @@ static ParserStatus parseDefaultArgument(
   case Parser::ParameterContextKind::Initializer:
   case Parser::ParameterContextKind::EnumElement:
   case Parser::ParameterContextKind::Subscript:
+  case Parser::ParameterContextKind::Macro:
     break;
   case Parser::ParameterContextKind::Closure:
     diagID = diag::no_default_arg_closure;
     break;
   case Parser::ParameterContextKind::Curried:
     diagID = diag::no_default_arg_curried;
     break;
-  case Parser::ParameterContextKind::Macro:
-    diagID = diag::no_default_arg_macro;
-    break;
   }
 
   assert((diagID.ID != DiagID()) == !defaultArgs &&
@@ -704,7 +702,8 @@ mapParsedParameters(Parser &parser,
              paramContext == Parser::ParameterContextKind::Operator ||
              paramContext == Parser::ParameterContextKind::Initializer ||
              paramContext == Parser::ParameterContextKind::EnumElement ||
-             paramContext == Parser::ParameterContextKind::Subscript) &&
+             paramContext == Parser::ParameterContextKind::Subscript ||
+             paramContext == Parser::ParameterContextKind::Macro) &&
             "Default arguments are only permitted on the first param clause");
 
     if (param.DefaultArg) {

diff --git a/lib/Sema/TypeCheckDeclPrimary.cpp b/lib/Sema/TypeCheckDeclPrimary.cpp
@@ -2043,6 +2043,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       MD->diagnose(diag::macro_without_role, MD->getName());
 
     TypeChecker::checkParameterList(MD->getParameterList(), MD);
+    checkDefaultArguments(MD->getParameterList());
 
     // Check the macro definition.
     switch (auto macroDef = MD->getDefinition()) {

diff --git a/test/Macros/macros_diagnostics.swift b/test/Macros/macros_diagnostics.swift
@@ -146,8 +146,13 @@ func testExternalMacroOutOfPlace() {
 
 @freestanding(expression)
 public macro macroWithDefaults(_: Int = 17) = #externalMacro(module: "A", type: "B")
-// expected-error@-1{{default arguments are not allowed in macros}}
-// expected-warning@-2{{external macro implementation type 'A.B' could not be found for macro 'macroWithDefaults'}}
+// expected-warning@-1{{external macro implementation type 'A.B' could not be found for macro 'macroWithDefaults'}}
+// expected-note@-2{{'macroWithDefaults' declared here}}
+
+func callMacroWithDefaults() {
+  _ = #macroWithDefaults()
+  // expected-error@-1 {{external macro implementation type 'A.B' could not be found for macro 'macroWithDefaults'}}
+}
 
 // Make sure we don't allow macros to prevent type folding.
 @attached(member)

diff --git a/test/Serialization/Inputs/def_macros.swift b/test/Serialization/Inputs/def_macros.swift
@@ -1,4 +1,4 @@
-@freestanding(expression) public macro publicStringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
+@freestanding(expression) public macro publicStringify<T>(_ value: T, label: String? = nil) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
 
 @freestanding(expression) macro internalStringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
 

diff --git a/test/Serialization/macros.swift b/test/Serialization/macros.swift
@@ -13,6 +13,7 @@ import def_macros
 
 func test(a: Int, b: Int) {
   _ = #publicStringify(a + b)
+  _ = #publicStringify(a + b, label: "hello")
 
   _ = #internalStringify(a + b)
   // expected-error@-1{{no macro named 'internalStringify'}}