[llvm-readobj] Fix output interleaving issue caused by using multiple streams at the same time.

Summary:
Use llvm::fouts() as the default stream for outputing. No new stream
should be constructed to output at the same time.

https://bugs.llvm.org/show_bug.cgi?id=42140

Reviewers: jhenderson, grimar, MaskRay, phosek, rupprecht

Reviewed By: rupprecht

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63115

Patch by Yuanfang Chen!

llvm-svn: 363198

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index 295763f8791..018cf614963 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -382,13 +382,16 @@ private:
 };
 
 template <typename ELFT> class GNUStyle : public DumpStyle<ELFT> {
-  formatted_raw_ostream OS;
+  formatted_raw_ostream &OS;
 
 public:
   TYPEDEF_ELF_TYPES(ELFT)
 
   GNUStyle(ScopedPrinter &W, ELFDumper<ELFT> *Dumper)
-      : DumpStyle<ELFT>(Dumper), OS(W.getOStream()) {}
+      : DumpStyle<ELFT>(Dumper),
+        OS(static_cast<formatted_raw_ostream&>(W.getOStream())) {
+    assert (&W.getOStream() == &llvm::fouts());
+  }
 
   void printFileHeaders(const ELFO *Obj) override;
   void printGroupSections(const ELFFile<ELFT> *Obj) override;