[Macros] Macro-metaprogram macro roles

Introduce X-macros for the various macro roles, and use them to
macro-metaprogram a lot of boilerplate involved with introducing new
macro roles.

Author: DougGregor

include/swift/AST/MacroDeclaration.h

@@ -32,37 +32,17 @@ enum class MacroSyntax: uint8_t {
   Attached,
 };
 
+enum class MacroRoleBits: uint8_t {
+#define MACRO_ROLE(Name, Description) Name,
+#include "swift/Basic/MacroRoles.def"
+};
+
 /// The context in which a macro can be used, which determines the syntax it
 /// uses.
 enum class MacroRole: uint32_t {
-  /// An expression macro, referenced explicitly via "#stringify" or similar
-  /// in the source code.
-  Expression = 0x01,
-  /// A freestanding declaration macro.
-  Declaration = 0x02,
-  /// An attached macro that declares accessors for a variable or subscript
-  /// declaration.
-  Accessor = 0x04,
-  /// An attached macro that generates attributes for the
-  /// members inside the declaration.
-  MemberAttribute = 0x08,
-  /// An attached macro that generates synthesized members
-  /// inside the declaration.
-  Member = 0x10,
-  /// An attached macro that generates declarations that are peers
-  /// of the declaration the macro is attached to.
-  Peer = 0x20,
-  /// An attached macro that adds conformances to the declaration the
-  /// macro is attached to.
-  Conformance = 0x40,
-  /// A freestanding macro that expands to expressions, statements and
-  /// declarations in a code block.
-  CodeItem = 0x80,
-  /// An attached macro that adds extensions to the declaration the
-  /// macro is attached to.
-  Extension = 0x100,
-
-  // NOTE: When adding a new macro role, also add it to `getAllMacroRoles`.
+#define MACRO_ROLE(Name, Description) \
+    Name = 1 << static_cast<uint8_t>(MacroRoleBits::Name),
+#include "swift/Basic/MacroRoles.def"
 };
 
 /// Returns an enumeratable list of all macro roles.

include/swift/Basic/MacroRoles.def

@@ -0,0 +1,79 @@
+//===--- MacroRoles.def - Known macro roles --*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines all of the kinds of macro roles. Clients should define
+// either MACRO_ROLE or both ATTACHED_MACRO_ROLE and FREESTANDING_MACRO_ROLE.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef ATTACHED_MACRO_ROLE
+#  define ATTACHED_MACRO_ROLE(Name, Description) MACRO_ROLE(Name, Description)
+#endif
+
+#ifndef FREESTANDING_MACRO_ROLE
+#  define FREESTANDING_MACRO_ROLE(Name, Description) MACRO_ROLE(Name, Description)
+#endif
+
+#ifndef EXPERIMENTAL_ATTACHED_MACRO_ROLE
+#  define EXPERIMENTAL_ATTACHED_MACRO_ROLE(Name, Description, Feature) \
+     ATTACHED_MACRO_ROLE(Name, Description)
+#endif
+
+#ifndef EXPERIMENTAL_FREESTANDING_MACRO_ROLE
+#  define EXPERIMENTAL_FREESTANDING_MACRO_ROLE(Name, Description, Feature) \
+     FREESTANDING_MACRO_ROLE(Name, Description)
+#endif
+
+/// An expression macro, referenced explicitly via "#stringify" or similar
+/// in the source code.
+FREESTANDING_MACRO_ROLE(Expression, "expression")
+
+/// A freestanding declaration macro.
+FREESTANDING_MACRO_ROLE(Declaration, "declaration")
+
+
+/// An attached macro that declares accessors for a variable or subscript
+/// declaration.
+ATTACHED_MACRO_ROLE(Accessor, "accessor")
+
+/// An attached macro that generates attributes for the
+/// members inside the declaration.
+ATTACHED_MACRO_ROLE(MemberAttribute, "memberAttribute")
+
+/// An attached macro that generates synthesized members
+/// inside the declaration.
+ATTACHED_MACRO_ROLE(Member, "member")
+
+/// An attached macro that generates declarations that are peers
+/// of the declaration the macro is attached to.
+ATTACHED_MACRO_ROLE(Peer, "peer")
+
+/// An attached macro that adds conformances to the declaration the
+/// macro is attached to.
+ATTACHED_MACRO_ROLE(Conformance, "conformance")
+
+/// A freestanding macro that expands to expressions, statements and
+/// declarations in a code block.
+EXPERIMENTAL_FREESTANDING_MACRO_ROLE(CodeItem, "codeItem", CodeItemMacros)
+
+/// An attached macro that adds extensions to the declaration the
+/// macro is attached to.
+ATTACHED_MACRO_ROLE(Extension, "extension")
+
+#undef ATTACHED_MACRO_ROLE
+#undef FREESTANDING_MACRO_ROLE
+#undef EXPERIMENTAL_ATTACHED_MACRO_ROLE
+#undef EXPERIMENTAL_FREESTANDING_MACRO_ROLE
+
+#ifdef MACRO_ROLE
+#  undef MACRO_ROLE
+#endif

include/swift/Basic/SourceManager.h

@@ -34,29 +34,8 @@ class GeneratedSourceInfo {
 public:
   /// The kind of generated source code.
   enum Kind {
-    /// The expansion of a freestanding expression macro.
-    ExpressionMacroExpansion,
-
-    /// The expansion of a freestanding declaration macro.
-    FreestandingDeclMacroExpansion,
-
-    /// The expansion of an accessor attached macro.
-    AccessorMacroExpansion,
-
-    /// The expansion of a member attribute attached macro.
-    MemberAttributeMacroExpansion,
-
-    /// The expansion of an attached member macro.
-    MemberMacroExpansion,
-
-    /// The expansion of an attached peer macro.
-    PeerMacroExpansion,
-
-    /// The expansion of an attached conformance macro.
-    ConformanceMacroExpansion,
-
-    /// The expansion of an attached extension macro.
-    ExtensionMacroExpansion,
+#define MACRO_ROLE(Name, Description) Name##MacroExpansion,
+#include "swift/Basic/MacroRoles.def"
 
     /// A new function body that is replacing an existing function body.
     ReplacedFunctionBody,

lib/AST/ASTMangler.cpp

@@ -3873,80 +3873,54 @@ void ASTMangler::appendMacroExpansionContext(
   DeclContext *outerExpansionDC;
   DeclBaseName baseName;
   unsigned discriminator;
+
+  // Determine the macro role.
   MacroRole role;
   switch (generatedSourceInfo->kind) {
-  case GeneratedSourceInfo::ExpressionMacroExpansion: {
+#define MACRO_ROLE(Name, Description)               \
+  case GeneratedSourceInfo::Name##MacroExpansion: \
+    role = MacroRole::Name;                       \
+    break;
+#include "swift/Basic/MacroRoles.def"
+
+  case GeneratedSourceInfo::PrettyPrinted:
+  case GeneratedSourceInfo::ReplacedFunctionBody:
+    return appendContext(origDC, StringRef());
+  }
+  
+  switch (generatedSourceInfo->kind) {
+  // Freestanding macros
+#define FREESTANDING_MACRO_ROLE(Name, Description) \
+  case GeneratedSourceInfo::Name##MacroExpansion:
+#define ATTACHED_MACRO_ROLE(Name, Description)
+#include "swift/Basic/MacroRoles.def"
+  {
     auto parent = ASTNode::getFromOpaqueValue(generatedSourceInfo->astNode);
     if (auto expr =
             cast_or_null<MacroExpansionExpr>(parent.dyn_cast<Expr *>())) {
       outerExpansionLoc = expr->getLoc();
       baseName = expr->getMacroName().getBaseName();
       discriminator = expr->getDiscriminator();
-      role = MacroRole::Expression;
       outerExpansionDC = expr->getDeclContext();
     } else {
       auto decl = cast<MacroExpansionDecl>(parent.get<Decl *>());
       outerExpansionLoc = decl->getLoc();
       baseName = decl->getMacroName().getBaseName();
       discriminator = decl->getDiscriminator();
-      role = MacroRole::Declaration;
       outerExpansionDC = decl->getDeclContext();
     }
     break;
   }
 
-  case GeneratedSourceInfo::FreestandingDeclMacroExpansion: {
-    auto expansion =
-        cast<MacroExpansionDecl>(
-          ASTNode::getFromOpaqueValue(generatedSourceInfo->astNode)
-            .get<Decl *>());
-    outerExpansionLoc = expansion->getLoc();
-    outerExpansionDC = expansion->getDeclContext();
-    discriminator = expansion->getDiscriminator();
-    role = MacroRole::Declaration;
-    baseName = expansion->getMacroName().getBaseName();
-    break;
-  }
-
-  case GeneratedSourceInfo::AccessorMacroExpansion:
-  case GeneratedSourceInfo::MemberAttributeMacroExpansion:
-  case GeneratedSourceInfo::MemberMacroExpansion:
-  case GeneratedSourceInfo::PeerMacroExpansion:
-  case GeneratedSourceInfo::ConformanceMacroExpansion:
-  case GeneratedSourceInfo::ExtensionMacroExpansion: {
+  // Attached macros
+#define FREESTANDING_MACRO_ROLE(Name, Description)
+#define ATTACHED_MACRO_ROLE(Name, Description)      \
+    case GeneratedSourceInfo::Name##MacroExpansion:
+#include "swift/Basic/MacroRoles.def"
+  {
     auto decl = ASTNode::getFromOpaqueValue(generatedSourceInfo->astNode)
       .get<Decl *>();
     auto attr = generatedSourceInfo->attachedMacroCustomAttr;
-
-    switch (generatedSourceInfo->kind) {
-    case GeneratedSourceInfo::AccessorMacroExpansion:
-      role = MacroRole::Accessor;
-      break;
-
-    case GeneratedSourceInfo::MemberAttributeMacroExpansion:
-      role = MacroRole::MemberAttribute;
-      break;
-
-    case GeneratedSourceInfo::MemberMacroExpansion:
-      role = MacroRole::Member;
-      break;
-
-    case GeneratedSourceInfo::PeerMacroExpansion:
-      role = MacroRole::Peer;
-      break;
-
-    case GeneratedSourceInfo::ConformanceMacroExpansion:
-      role = MacroRole::Conformance;
-      break;
-
-    case GeneratedSourceInfo::ExtensionMacroExpansion:
-      role = MacroRole::Extension;
-      break;
-
-    default:
-      llvm_unreachable("Unhandled macro role");
-    }
-
     outerExpansionLoc = decl->getLoc();
     outerExpansionDC = decl->getDeclContext();
 
@@ -3956,13 +3930,12 @@ void ASTMangler::appendMacroExpansionContext(
       baseName = ctx.getIdentifier("__unknown_macro__");
 
     discriminator = decl->getAttachedMacroDiscriminator(baseName, role, attr);
-
     break;
   }
 
   case GeneratedSourceInfo::PrettyPrinted:
   case GeneratedSourceInfo::ReplacedFunctionBody:
-    return appendContext(origDC, StringRef());
+    llvm_unreachable("Exited above");
   }
 
   // If we hit the point where the structure is represented as a DeclContext,
@@ -3982,9 +3955,9 @@ void ASTMangler::appendMacroExpansionOperator(
   appendIdentifier(macroName);
 
   switch (role) {
-  case MacroRole::Expression:
-  case MacroRole::Declaration:
-  case MacroRole::CodeItem:
+#define FREESTANDING_MACRO_ROLE(Name, Description) case MacroRole::Name:
+#define ATTACHED_MACRO_ROLE(Name, Description)
+#include "swift/Basic/MacroRoles.def"
     appendOperator("fMf", Index(discriminator));
     break;