Reland rL341509: "[llvm-dwp] Use buffer_stream if output file is not seekable (e.g. "-")"

It caused ambiguity between llvm::cl::Optional and llvm::Optional, which
has been fixed by dropping `using namespace cl;` in favor of explicit
cl:: qualified names.

llvm-svn: 341586

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/tools/llvm-dwp/llvm-dwp.cpp b/llvm/tools/llvm-dwp/llvm-dwp.cpp
index 176c470dd02..8a0744cf1e0 100644
--- a/llvm/tools/llvm-dwp/llvm-dwp.cpp
+++ b/llvm/tools/llvm-dwp/llvm-dwp.cpp
@@ -697,13 +697,21 @@ int main(int argc, char **argv) {
   // Create the output file.
   std::error_code EC;
   raw_fd_ostream OutFile(OutputFilename, EC, sys::fs::F_None);
+  Optional<buffer_ostream> BOS;
+  raw_pwrite_stream *OS;
   if (EC)
     return error(Twine(OutputFilename) + ": " + EC.message(), Context);
+  if (OutFile.supportsSeeking()) {
+    OS = &OutFile;
+  } else {
+    BOS.emplace(OutFile);
+    OS = BOS.getPointer();
+  }
 
   MCTargetOptions MCOptions = InitMCTargetOptionsFromFlags();
   std::unique_ptr<MCStreamer> MS(TheTarget->createMCObjectStreamer(
       TheTriple, MC, std::unique_ptr<MCAsmBackend>(MAB),
-      MAB->createObjectWriter(OutFile), std::unique_ptr<MCCodeEmitter>(MCE),
+      MAB->createObjectWriter(*OS), std::unique_ptr<MCCodeEmitter>(MCE),
       *MSTI, MCOptions.MCRelaxAll, MCOptions.MCIncrementalLinkerCompatible,
       /*DWARFMustBeAtTheEnd*/ false));
   if (!MS)