Make llvm-ar behave like ar, if you create an empty archive, ar creates an empty archive. llvm-ar would not generate an output file in this case

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47733 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 2 insertions, 1 deletions

diff --git a/lib/Archive/ArchiveWriter.cpp b/lib/Archive/ArchiveWriter.cpp
index 07f7d88dd8..04cc981f79 100644
--- a/lib/Archive/ArchiveWriter.cpp
+++ b/lib/Archive/ArchiveWriter.cpp
@@ -348,7 +348,7 @@ Archive::writeToDisk(bool CreateSymbolTable, bool TruncateNames, bool Compress,
 {
   // Make sure they haven't opened up the file, not loaded it,
   // but are now trying to write it which would wipe out the file.
-  if (members.empty() && mapfile->size() > 8) {
+  if (members.empty() && mapfile && mapfile->size() > 8) {
     if (ErrMsg)
       *ErrMsg = "Can't write an archive not opened for writing";
     return true;
diff --git a/tools/llvm-ar/llvm-ar.cpp b/tools/llvm-ar/llvm-ar.cpp
index a72a4c0019..a6611a3e80 100644
--- a/tools/llvm-ar/llvm-ar.cpp
+++ b/tools/llvm-ar/llvm-ar.cpp
@@ -717,6 +717,7 @@ int main(int argc, char **argv) {
       if (!Create)
         std::cerr << argv[0] << ": creating " << ArchivePath.toString() << "\n";
       TheArchive = Archive::CreateEmpty(ArchivePath);
+      TheArchive->writeToDisk();
     } else {
       std::string Error;
       TheArchive = Archive::OpenAndLoad(ArchivePath, &Error);