[Macros] Diagnose conformance macros as being replaced by extension macros.

Author: hborla

include/swift/AST/DiagnosticsSema.def

@@ -7277,6 +7277,9 @@ ERROR(extension_macro_invalid_conformance,none,
 ERROR(macro_attached_to_invalid_decl,none,
       "'%0' macro cannot be attached to %1",
       (StringRef, DescriptiveDeclKind))
+ERROR(conformance_macro,none,
+      "conformance macros are replaced by extension macros",
+      ())
 
 ERROR(macro_resolve_circular_reference, none,
       "circular reference resolving %select{freestanding|attached}0 macro %1",

lib/Sema/TypeCheckAttr.cpp

@@ -7152,9 +7152,9 @@ void AttributeChecker::visitMacroRoleAttr(MacroRoleAttr *attr) {
     case MacroRole::Peer:
       break;
     case MacroRole::Conformance:
-      if (!attr->getNames().empty())
-        diagnoseAndRemoveAttr(attr, diag::macro_cannot_introduce_names,
-                              getMacroRoleString(attr->getMacroRole()));
+      diagnoseAndRemoveAttr(attr, diag::conformance_macro)
+          .fixItReplace(attr->getRange(),
+                        "@attached(extension, conformances: <#Protocol#>)");
       break;
     case MacroRole::Extension:
       break;

test/Macros/macro_expand_conformances.swift

@@ -14,10 +14,15 @@
 // RUN: %target-codesign %t/main
 // RUN: %target-run %t/main | %FileCheck %s
 
-@attached(conformance)
+#if TEST_DIAGNOSTICS
+@attached(conformance) // expected-error{{conformance macros are replaced by extension macros}}
+macro InvalidEquatable() = #externalMacro(module: "MacroDefinition", type: "EquatableMacro")
+#endif
+
+@attached(extension, conformances: Equatable)
 macro Equatable() = #externalMacro(module: "MacroDefinition", type: "EquatableMacro")
 
-@attached(conformance)
+@attached(extension, conformances: Hashable)
 macro Hashable() = #externalMacro(module: "MacroDefinition", type: "HashableMacro")
 
 #if MODULE_EXPORTING_TYPE
@@ -52,7 +57,7 @@ enum E {
   @Equatable struct Nested {}
 }
 
-// CHECK-DUMP: @__swiftmacro_25macro_expand_conformances1S9EquatablefMc_.swift
+// CHECK-DUMP: @__swiftmacro_25macro_expand_conformances1S9EquatablefMe_.swift
 // CHECK-DUMP: extension S: Equatable  {
 // CHECK-DUMP: }
 
@@ -77,7 +82,7 @@ requireHashable(PublicEquatable())
 //expected-error@-1{{global function 'requireHashable' requires that 'PublicEquatable' conform to 'Hashable'}}
 #endif
 
-@attached(conformance)
+@attached(extension, conformances: P)
 @attached(member, names: named(requirement))
 macro DelegatedConformance() = #externalMacro(module: "MacroDefinition", type: "DelegatedConformanceMacro")
 
@@ -94,7 +99,7 @@ struct Wrapped: P {
 @DelegatedConformance
 struct Generic<Element> {}
 
-// CHECK-DUMP: @__swiftmacro_25macro_expand_conformances7Generic20DelegatedConformancefMc_.swift
+// CHECK-DUMP: @__swiftmacro_25macro_expand_conformances7Generic20DelegatedConformancefMe_.swift
 // CHECK-DUMP: extension Generic: P where Element: P {
 // CHECK-DUMP: }
 

test/Macros/option_set.swift

@@ -5,7 +5,7 @@
 import Swift
 
 @attached(member, names: named(RawValue), named(rawValue), named(`init`), arbitrary)
-@attached(conformance)
+@attached(extension, conformances: OptionSet)
 public macro OptionSet<RawType>() =
   #externalMacro(module: "SwiftMacros", type: "OptionSetMacro")
 

test/Macros/top_level_freestanding.swift

@@ -117,7 +117,7 @@ macro Empty<T>(_ closure: () -> T) = #externalMacro(module: "MacroDefinition", t
   S(a: 10, b: 10)
 }
 
-@attached(conformance)
+@attached(extension, conformances: Initializable)
 @attached(member, names: named(init))
 macro Initializable() = #externalMacro(module: "MacroDefinition", type: "InitializableMacro")