[Importer] Ensure that we can see macro-expanded declarations in C++ namespaces

Lookup into C++ namespaces uses a different path from C++ record declarations.
Augment the C++ namespace lookup path to also account for the auxiliary
declarations introduced by peer macro expansions.

Author: DougGregor

lib/AST/ASTPrinter.cpp

@@ -2750,8 +2750,24 @@ static void addNamespaceMembers(Decl *decl,
           auto clangMember = found.get<clang::NamedDecl *>();
           if (auto importedDecl =
                   ctx.getClangModuleLoader()->importDeclDirectly(clangMember)) {
-            if (addedMembers.insert(importedDecl).second)
+            if (addedMembers.insert(importedDecl).second) {
               members.push_back(importedDecl);
+
+              // Handle macro-expanded declarations.
+              importedDecl->visitAuxiliaryDecls([&](Decl *decl) {
+                auto valueDecl = dyn_cast<ValueDecl>(decl);
+                if (!valueDecl)
+                  return;
+
+                // Bail out if the auxiliary decl was not produced by a macro.
+                auto module = decl->getDeclContext()->getParentModule();
+                auto *sf = module->getSourceFileContainingLocation(decl->getLoc());
+                if (!sf || sf->Kind != SourceFileKind::MacroExpansion)
+                  return;
+
+                members.push_back(valueDecl);
+              });
+            }
           }
         }
       };

lib/ClangImporter/ClangImporter.cpp

@@ -5078,6 +5078,42 @@ ClangDirectLookupRequest::evaluate(Evaluator &evaluator,
   return filteredDecls;
 }
 
+namespace {
+  /// Collects name lookup results into the given tiny vector, for use in the
+  /// various Clang importer lookup routines.
+  class CollectLookupResults {
+    DeclName name;
+    TinyPtrVector<ValueDecl *> &result;
+
+  public:
+    CollectLookupResults(DeclName name, TinyPtrVector<ValueDecl *> &result)
+      : name(name), result(result) { }
+
+    void add(ValueDecl *imported) {
+      result.push_back(imported);
+
+      // Expand any macros introduced by the Clang importer.
+      imported->visitAuxiliaryDecls([&](Decl *decl) {
+        auto valueDecl = dyn_cast<ValueDecl>(decl);
+        if (!valueDecl)
+          return;
+
+        // Bail out if the auxiliary decl was not produced by a macro.
+        auto module = decl->getDeclContext()->getParentModule();
+        auto *sf = module->getSourceFileContainingLocation(decl->getLoc());
+        if (!sf || sf->Kind != SourceFileKind::MacroExpansion)
+          return;
+
+        // Only produce results that match the requested name.
+        if (!valueDecl->getName().matchesRef(name))
+          return;
+
+        result.push_back(valueDecl);
+      });
+    }
+  };
+}
+
 TinyPtrVector<ValueDecl *> CXXNamespaceMemberLookup::evaluate(
     Evaluator &evaluator, CXXNamespaceMemberLookupDescriptor desc) const {
   EnumDecl *namespaceDecl = desc.namespaceDecl;
@@ -5087,6 +5123,8 @@ TinyPtrVector<ValueDecl *> CXXNamespaceMemberLookup::evaluate(
   auto &ctx = namespaceDecl->getASTContext();
 
   TinyPtrVector<ValueDecl *> result;
+  CollectLookupResults collector(name, result);
+
   llvm::SmallPtrSet<clang::NamedDecl *, 8> importedDecls;
   for (auto redecl : clangNamespaceDecl->redecls()) {
     auto allResults = evaluateOrDefault(
@@ -5102,7 +5140,7 @@ TinyPtrVector<ValueDecl *> CXXNamespaceMemberLookup::evaluate(
         continue;
       if (auto import =
               ctx.getClangModuleLoader()->importDeclDirectly(clangMember))
-        result.push_back(cast<ValueDecl>(import));
+        collector.add(cast<ValueDecl>(import));
     }
   }
 
@@ -6202,28 +6240,7 @@ TinyPtrVector<ValueDecl *> ClangRecordMemberLookup::evaluate(
 
   // The set of declarations we found.
   TinyPtrVector<ValueDecl *> result;
-  auto addResult = [&result, name](ValueDecl *imported) {
-    result.push_back(imported);
-
-    // Expand any macros introduced by the Clang importer.
-    imported->visitAuxiliaryDecls([&](Decl *decl) {
-      auto valueDecl = dyn_cast<ValueDecl>(decl);
-      if (!valueDecl)
-        return;
-
-      // Bail out if the auxiliary decl was not produced by a macro.
-      auto module = decl->getDeclContext()->getParentModule();
-      auto *sf = module->getSourceFileContainingLocation(decl->getLoc());
-      if (!sf || sf->Kind != SourceFileKind::MacroExpansion)
-        return;
-
-      // Only produce results that match the requested name.
-      if (!valueDecl->getName().matchesRef(name))
-        return;
-
-      result.push_back(valueDecl);
-    });
-  };
+  CollectLookupResults collector(name, result);
 
   // Find the results that are actually a member of "recordDecl".
   ClangModuleLoader *clangModuleLoader = ctx.getClangModuleLoader();
@@ -6261,7 +6278,7 @@ TinyPtrVector<ValueDecl *> ClangRecordMemberLookup::evaluate(
         continue;
     }
 
-    addResult(cast<ValueDecl>(imported));
+    collector.add(cast<ValueDecl>(imported));
   }
 
   if (inheritance) {
@@ -6280,7 +6297,7 @@ TinyPtrVector<ValueDecl *> ClangRecordMemberLookup::evaluate(
       if (!imported)
         continue;
 
-      addResult(imported);
+      collector.add(imported);
     }
   }
 
@@ -6329,7 +6346,7 @@ TinyPtrVector<ValueDecl *> ClangRecordMemberLookup::evaluate(
           if (foundNameArities.count(getArity(foundInBase)))
             continue;
 
-          addResult(foundInBase);
+          collector.add(foundInBase);
         }
       }
     }

lib/Sema/ImportResolution.cpp

@@ -329,6 +329,11 @@ void swift::performImportResolutionForClangMacroBuffer(
   ImportResolver resolver(SF);
   resolver.addImplicitImport(clangModule);
 
+  // FIXME: This is a hack that we shouldn't need, but be sure that we can
+  // see the Swift standard library.
+  if (auto stdlib = SF.getASTContext().getStdlibModule())
+    resolver.addImplicitImport(stdlib);
+
   SF.setImports(resolver.getFinishedImports());
   SF.setImportedUnderlyingModule(resolver.getUnderlyingClangModule());
 

test/Interop/Cxx/swiftify-import/counted-by-in-namespace.swift

@@ -0,0 +1,28 @@
+// REQUIRES: swift_feature_SafeInteropWrappers
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: %target-swift-ide-test -plugin-path %swift-plugin-dir -I %t/Inputs -cxx-interoperability-mode=upcoming-swift -enable-experimental-feature SafeInteropWrappers -print-module -module-to-print=Namespace -source-filename=x | %FileCheck %s
+// RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -I %t/Inputs -cxx-interoperability-mode=default -enable-experimental-feature SafeInteropWrappers %t/namespace.swift -dump-macro-expansions -typecheck -verify
+
+// CHECK: enum foo {
+// CHECK:  static func bar(_ p: UnsafeMutableBufferPointer<Float>)
+
+//--- Inputs/module.modulemap
+module Namespace {
+    header "namespace.h"
+    requires cplusplus
+}
+
+//--- Inputs/namespace.h
+
+namespace foo {
+   __attribute__((swift_attr("@_SwiftifyImport(.countedBy(pointer: .param(1), count: \"len\"))"))) void bar(float *p, int len);
+}
+
+//--- namespace.swift
+import Namespace
+  
+func test(s: UnsafeMutableBufferPointer<Float>) {
+  foo.bar(s)
+}    

test/Interop/Cxx/swiftify-import/counted-by-method.swift

@@ -2,11 +2,11 @@
 
 // RUN: rm -rf %t
 // RUN: split-file %s %t
-// RUNx: %target-swift-ide-test -plugin-path %swift-plugin-dir -I %t/Inputs -cxx-interoperability-mode=upcoming-swift -enable-experimental-feature SafeInteropWrappers -print-module -module-to-print=Method -source-filename=x | %FileCheck %s
+// RUN: %target-swift-ide-test -plugin-path %swift-plugin-dir -I %t/Inputs -cxx-interoperability-mode=upcoming-swift -enable-experimental-feature SafeInteropWrappers -print-module -module-to-print=Method -source-filename=x | %FileCheck %s
 // RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -I %t/Inputs -cxx-interoperability-mode=default -enable-experimental-feature SafeInteropWrappers %t/method.swift -dump-macro-expansions -typecheck -verify
 
 // CHECK: @_alwaysEmitIntoClient 
-// CHECK:  public mutating func bar(_ p: UnsafeMutableBufferPointer<Int32>)
+// CHECK-SAME: public mutating func bar(_ p: UnsafeMutableBufferPointer<Float>)
 
 //--- Inputs/module.modulemap
 module Method {