Merge pull request #70602 from ApolloZhu/macro/expression-as-default-argument

[Macros] Expression macro as caller-side default argument

Author: DougGregor

include/swift/AST/DefaultArgumentKind.h

@@ -51,6 +51,8 @@ enum class DefaultArgumentKind : uint8_t {
   // Magic identifier literals expanded at the call site:
 #define MAGIC_IDENTIFIER(NAME, STRING, SYNTAX_KIND) NAME,
 #include "swift/AST/MagicIdentifierKinds.def"
+  /// An expression macro.
+  ExpressionMacro
 };
 enum { NumDefaultArgumentKindBits = 4 };
 

include/swift/AST/Module.h

@@ -106,6 +106,7 @@ enum class SourceFileKind {
   SIL,      ///< Came from a .sil file.
   Interface, ///< Came from a .swiftinterface file, representing another module.
   MacroExpansion, ///< Came from a macro expansion.
+  DefaultArgument, ///< Came from default argument at caller side
 };
 
 /// Contains information about where a particular path is used in

include/swift/AST/SourceFile.h

@@ -674,6 +674,7 @@ class SourceFile final : public FileUnit {
     case SourceFileKind::Interface:
     case SourceFileKind::SIL:
     case SourceFileKind::MacroExpansion:
+    case SourceFileKind::DefaultArgument:
       return false;
     }
     llvm_unreachable("bad SourceFileKind");

include/swift/Basic/Features.def

@@ -135,6 +135,7 @@ EXPERIMENTAL_FEATURE(NamedOpaqueTypes, false)
 EXPERIMENTAL_FEATURE(FlowSensitiveConcurrencyCaptures, false)
 EXPERIMENTAL_FEATURE(CodeItemMacros, false)
 EXPERIMENTAL_FEATURE(BodyMacros, true)
+EXPERIMENTAL_FEATURE(ExpressionMacroDefaultArguments, false)
 EXPERIMENTAL_FEATURE(TupleConformances, false)
 
 // Whether to enable @_used and @_section attributes

include/swift/Basic/SourceManager.h

@@ -43,6 +43,9 @@ class GeneratedSourceInfo {
 
     /// Pretty-printed declarations that have no source location.
     PrettyPrinted,
+
+    /// The expansion of default argument at caller side
+    DefaultArgument,
   } kind;
 
   /// The source range in the enclosing buffer where this source was generated.

include/swift/Bridging/ASTGen.h

@@ -68,6 +68,10 @@ void *_Nonnull swift_ASTGen_resolveExecutableMacro(
     void *_Nonnull opaquePluginHandle);
 void swift_ASTGen_destroyExecutableMacro(void *_Nonnull macro);
 
+bool swift_ASTGen_checkDefaultArgumentMacroExpression(
+    void *_Nonnull diagEngine, void *_Nonnull sourceFile,
+    const void *_Nonnull macroSourceLocation);
+
 ptrdiff_t swift_ASTGen_checkMacroDefinition(
     void *_Nonnull diagEngine, void *_Nonnull sourceFile,
     const void *_Nonnull macroSourceLocation,

include/swift/Sema/ConstraintSystem.h

@@ -85,7 +85,7 @@ llvm::Optional<constraints::SyntacticElementTarget>
 typeCheckTarget(constraints::SyntacticElementTarget &target,
                 OptionSet<TypeCheckExprFlags> options);
 
-Type typeCheckParameterDefault(Expr *&, DeclContext *, Type, bool);
+Type typeCheckParameterDefault(Expr *&, DeclContext *, Type, bool, bool);
 
 } // end namespace TypeChecker
 
@@ -3019,7 +3019,7 @@ class ConstraintSystem {
 
   friend Type swift::TypeChecker::typeCheckParameterDefault(Expr *&,
                                                             DeclContext *, Type,
-                                                            bool);
+                                                            bool, bool);
 
   /// Emit the fixes computed as part of the solution, returning true if we were
   /// able to emit an error message, or false if none of the fixits worked out.

lib/AST/ASTDumper.cpp

@@ -309,6 +309,8 @@ static StringRef getDumpString(DefaultArgumentKind value) {
     case DefaultArgumentKind::EmptyDictionary: return "[:]";
     case DefaultArgumentKind::Normal: return "normal";
     case DefaultArgumentKind::StoredProperty: return "stored property";
+    case DefaultArgumentKind::ExpressionMacro:
+    return "expression macro";
   }
 
   llvm_unreachable("Unhandled DefaultArgumentKind in switch.");

lib/AST/ASTMangler.cpp

@@ -3885,6 +3885,7 @@ void ASTMangler::appendMacroExpansionContext(
 
   case GeneratedSourceInfo::PrettyPrinted:
   case GeneratedSourceInfo::ReplacedFunctionBody:
+  case GeneratedSourceInfo::DefaultArgument:
     return appendContext(origDC, StringRef());
   }
 
@@ -3935,6 +3936,7 @@ void ASTMangler::appendMacroExpansionContext(
 
   case GeneratedSourceInfo::PrettyPrinted:
   case GeneratedSourceInfo::ReplacedFunctionBody:
+  case GeneratedSourceInfo::DefaultArgument:
     llvm_unreachable("Exited above");
   }
 

lib/AST/ASTPrinter.cpp

@@ -3043,6 +3043,18 @@ static bool usesFeatureFreestandingMacros(Decl *decl) {
   return macro->getMacroRoles().contains(MacroRole::Declaration);
 }
 
+static bool usesFeatureExpressionMacroDefaultArguments(Decl *decl) {
+  if (auto func = dyn_cast<AbstractFunctionDecl>(decl)) {
+    for (auto param : *func->getParameters()) {
+      if (param->getDefaultArgumentKind() ==
+          DefaultArgumentKind::ExpressionMacro)
+        return true;
+    }
+  }
+
+  return false;
+}
+
 static bool usesFeatureCodeItemMacros(Decl *decl) {
   auto macro = dyn_cast<MacroDecl>(decl);
   if (!macro)