[Macros] Fix visiting nested conformance macro declarations in SIL and IRGen.

lib/IRGen/GenDecl.cpp

@@ -5501,6 +5501,11 @@ void IRGenModule::emitNestedTypeDecls(DeclRange members) {
       continue;
 
     member->visitAuxiliaryDecls([&](Decl *decl) {
+      // FIXME: Conformance macros can generate extension decls. These
+      // are visited as top-level decls; skip them here.
+      if (isa<ExtensionDecl>(decl))
+        return;
+
       emitNestedTypeDecls({decl, nullptr});
     });
     switch (member->getKind()) {

lib/SILGen/SILGen.cpp

@@ -2196,6 +2196,10 @@ class SILGenModuleRAII {
     for (auto *D : sf->getTopLevelDecls()) {
       // Emit auxiliary decls.
       D->visitAuxiliaryDecls([&](Decl *auxiliaryDecl) {
+        // Skip extensions decls; they are visited below.
+        if (isa<ExtensionDecl>(auxiliaryDecl))
+          return;
+
         FrontendStatsTracer StatsTracer(SGM.getASTContext().Stats,
                                         "SILgen-decl", auxiliaryDecl);
         SGM.visit(auxiliaryDecl);
@@ -2206,6 +2210,34 @@ class SILGenModuleRAII {
       SGM.visit(D);
     }
 
+    // FIXME: Visit macro-generated extensions separately.
+    //
+    // The code below that visits auxiliary decls of the top-level
+    // decls in the source file does not work for nested types with
+    // attached conformance macros:
+    // ```
+    // struct Outer {
+    //   @AddConformance struct Inner {}
+    // }
+    // ```
+    // Because the attached-to decl is not at the top-level. To fix this,
+    // visit the macro-generated conformances that are recorded in the
+    // synthesized file unit to cover all macro-generated extension decls.
+    if (auto *synthesizedFile = sf->getSynthesizedFile()) {
+      for (auto *D : synthesizedFile->getTopLevelDecls()) {
+        if (!isa<ExtensionDecl>(D))
+          continue;
+
+        auto *sf = D->getInnermostDeclContext()->getParentSourceFile();
+        if (sf->getFulfilledMacroRole() != MacroRole::Conformance)
+          continue;
+
+        FrontendStatsTracer StatsTracer(SGM.getASTContext().Stats,
+                                        "SILgen-decl", D);
+        SGM.visit(D);
+      }
+    }
+
     for (Decl *D : sf->getHoistedDecls()) {
       FrontendStatsTracer StatsTracer(SGM.getASTContext().Stats,
                                       "SILgen-decl", D);

lib/SILGen/SILGenType.cpp

@@ -1086,6 +1086,11 @@ class SILGenType : public TypeMemberVisitor<SILGenType> {
     SGM.emitLazyConformancesForType(theType);
 
     forEachMemberToLower(theType, [&](Decl *member) {
+      // FIXME: Conformance macros can generate extension decls. These
+      // are visited as top-level decls; skip them here.
+      if (isa<ExtensionDecl>(member))
+        return;
+
       visit(member);
     });
 

test/Macros/macro_expand_conformances.swift

@@ -29,6 +29,10 @@ struct S {}
 @Hashable
 struct S2 {}
 
+enum E {
+  @Equatable struct Nested {}
+}
+
 // CHECK-DUMP: @__swiftmacro_25macro_expand_conformances1S9EquatablefMc_.swift
 // CHECK-DUMP: extension S : Equatable  {}
 
@@ -38,6 +42,8 @@ requireEquatable(S())
 requireEquatable(S2())
 requireHashable(S2())
 
+requireEquatable(E.Nested())
+
 @attached(conformance)
 @attached(member, names: named(requirement))
 macro DelegatedConformance() = #externalMacro(module: "MacroDefinition", type: "DelegatedConformanceMacro")