[Mangling] Add a mangling for macro declarations.

Although macro declarations never produce any symbols in the compiled
binary, they can be referenced via USR, so introduce a mangling for
them.

Author: DougGregor

docs/ABI/Mangling.rst

@@ -362,6 +362,7 @@ Entities
   entity-spec ::= decl-name label-list? type 'v' ACCESSOR                           // variable
   entity-spec ::= decl-name type 'fp'                                               // generic type parameter
   entity-spec ::= decl-name type 'fo'                                               // enum element (currently not used)
+  entity-spec ::= decl-name label-list? type generic-signature? 'fm'   // macro
   entity-spec ::= identifier 'Qa'                                                   // associated type declaration
 
   ACCESSOR ::= 'm'                           // materializeForSet

include/swift/Demangling/DemangleNodes.def

@@ -147,6 +147,7 @@ NODE(KeyPathHashThunkHelper)
 NODE(LazyProtocolWitnessTableAccessor)
 NODE(LazyProtocolWitnessTableCacheVariable)
 NODE(LocalDeclName)
+NODE(Macro)
 CONTEXT_NODE(MaterializeForSet)
 NODE(MergedFunction)
 NODE(Metatype)

lib/AST/ASTMangler.cpp

@@ -3339,6 +3339,8 @@ void ASTMangler::appendEntity(const ValueDecl *decl) {
     return appendAccessorEntity("p", storageDecl, decl->isStatic());
   if (isa<GenericTypeParamDecl>(decl))
     return appendEntity(decl, "fp", decl->isStatic());
+  if (auto macro = dyn_cast<MacroDecl>(decl))
+    return appendEntity(decl, "fm", false);
 
   assert(isa<AbstractFunctionDecl>(decl) || isa<EnumElementDecl>(decl));
 

lib/Demangling/Demangler.cpp

@@ -3545,6 +3545,7 @@ NodePointer Demangler::demangleFunctionEntity() {
     case 'U': Args = TypeAndIndex; Kind = Node::Kind::ExplicitClosure; break;
     case 'u': Args = TypeAndIndex; Kind = Node::Kind::ImplicitClosure; break;
     case 'A': Args = Index; Kind = Node::Kind::DefaultArgumentInitializer; break;
+    case 'm': return demangleEntity(Node::Kind::Macro);
     case 'p': return demangleEntity(Node::Kind::GenericTypeParamDecl);
     case 'P':
       Args = None;

lib/Demangling/NodePrinter.cpp

@@ -438,6 +438,7 @@ class NodePrinter {
     case Node::Kind::LazyProtocolWitnessTableAccessor:
     case Node::Kind::LazyProtocolWitnessTableCacheVariable:
     case Node::Kind::LocalDeclName:
+    case Node::Kind::Macro:
     case Node::Kind::MaterializeForSet:
     case Node::Kind::MergedFunction:
     case Node::Kind::Metaclass:
@@ -1327,6 +1328,11 @@ NodePointer NodePrinter::print(NodePointer Node, unsigned depth,
     return printEntity(
         Node, depth, asPrefixContext, TypePrinting::FunctionStyle,
         /*hasName*/ false, /*ExtraName*/ "", /*ExtraIndex*/ -1, "subscript");
+  case Node::Kind::Macro:
+    return printEntity(Node, depth, asPrefixContext,
+                       Node->getNumChildren() == 3? TypePrinting::WithColon
+                                                  : TypePrinting::FunctionStyle,
+                       /*hasName*/ true);
   case Node::Kind::GenericTypeParamDecl:
     return printEntity(Node, depth, asPrefixContext, TypePrinting::NoType,
                        /*hasName*/ true);

lib/Demangling/OldRemangler.cpp

@@ -1058,6 +1058,11 @@ ManglingError Remangler::mangleSubscript(Node *node, EntityContext &ctx,
   return ManglingError::Success;
 }
 
+ManglingError Remangler::mangleMacro(Node *node, unsigned depth) {
+  Buffer << "fm";
+  return mangleChildNodes(node, depth + 1);
+}
+
 ManglingError Remangler::mangleAccessor(Node *storageNode,
                                         StringRef accessorCode,
                                         EntityContext &ctx, unsigned depth) {

lib/Demangling/Remangler.cpp

@@ -2859,6 +2859,12 @@ ManglingError Remangler::mangleSubscript(Node *node, unsigned depth) {
   return mangleAbstractStorage(node, "p", depth + 1);
 }
 
+ManglingError Remangler::mangleMacro(Node *node, unsigned depth) {
+  RETURN_IF_ERROR(mangleChildNodes(node, depth + 1));
+  Buffer << "fm";
+  return ManglingError::Success;
+}
+
 ManglingError Remangler::mangleSuffix(Node *node, unsigned depth) {
   // Just add the suffix back on.
   Buffer << node->getText();

test/Demangle/Inputs/manglings.txt

@@ -441,3 +441,5 @@ $sxIeghHr_xs5Error_pIegHrzo_s8SendableRzs5NeverORs_r0_lTRTY_ ---> {T:} (0) suspe
 $sxIeghHr_xs5Error_pIegHrzo_s8SendableRzs5NeverORs_r0_lTRTQ12_ ---> {T:} (13) await resume partial function for reabstraction thunk helper <A, B where A: Swift.Sendable, B == Swift.Never> from @escaping @callee_guaranteed @Sendable @async () -> (@out A) to @escaping @callee_guaranteed @async () -> (@out A, @error @owned Swift.Error)
 $s7Library3fooyyFTwS ---> #_hasSymbol query for Library.foo() -> ()
 $s7Library5KlassCTwS ---> #_hasSymbol query for Library.Klass
+$s14swift_ide_test14myColorLiteral3red5green4blue5alphaAA0E0VSf_S3ftcfm ---> swift_ide_test.myColorLiteral(red: Swift.Float, green: Swift.Float, blue: Swift.Float, alpha: Swift.Float) -> swift_ide_test.Color
+$s14swift_ide_test10myFilenamexfm ---> swift_ide_test.myFilename : A