1 files changed, 15 insertions, 0 deletions
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 2c0bb11cc4b..49e8321953c 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -1846,6 +1846,8 @@ Decl *ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
   if (ToD)
     return ToD;
 
+  const FunctionDecl *FoundWithoutBody = nullptr;
+
   // Try to find a function in our own ("to") context with the same name, same
   // type, and in the same context as the function we're importing.
   if (!LexicalDC->isFunctionOrMethod()) {
@@ -1863,6 +1865,13 @@ Decl *ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
           if (Importer.IsStructurallyEquivalent(D->getType(), 
                                                 FoundFunction->getType())) {
             // FIXME: Actually try to merge the body and other attributes.
+            const FunctionDecl *FromBodyDecl = nullptr;
+            D->hasBody(FromBodyDecl);
+            if (D == FromBodyDecl && !FoundFunction->hasBody()) {
+              // This function is needed to merge completely.
+              FoundWithoutBody = FoundFunction;
+              break;
+            }
             return Importer.Imported(D, FoundFunction);
           }
 
@@ -2013,6 +2022,12 @@ Decl *ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
   }
   ToFunction->setParams(Parameters);
 
+  if (FoundWithoutBody) {
+    auto *Recent = const_cast<FunctionDecl *>(
+          FoundWithoutBody->getMostRecentDecl());
+    ToFunction->setPreviousDecl(Recent);
+  }
+
   if (usedDifferentExceptionSpec) {
     // Update FunctionProtoType::ExtProtoInfo.
     QualType T = Importer.Import(D->getType());