[raw_fd_ostream] report actual error in error messages

Summary:
Previously, we would emit error messages like "IO failure on output
stream". This change causes use to include information about what
actually went wrong, e.g. "No space left on device".

Reviewers: sunfish, rnk

Reviewed By: rnk

Subscribers: mehdi_amini, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D39203

llvm-svn: 316404

1 files changed, 5 insertions, 3 deletions

diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index 9693a7c254c..ba5c04d5b1a 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -218,7 +218,7 @@ bool LTOCodeGenerator::writeMergedModules(StringRef Path) {
   ToolOutputFile Out(Path, EC, sys::fs::F_None);
   if (EC) {
     std::string ErrMsg = "could not open bitcode file for writing: ";
-    ErrMsg += Path;
+    ErrMsg += Path.str() + ": " + EC.message();
     emitError(ErrMsg);
     return false;
   }
@@ -229,7 +229,7 @@ bool LTOCodeGenerator::writeMergedModules(StringRef Path) {
 
   if (Out.os().has_error()) {
     std::string ErrMsg = "could not write bitcode file: ";
-    ErrMsg += Path;
+    ErrMsg += Path.str() + ": " + Out.os().error().message();
     emitError(ErrMsg);
     Out.os().clear_error();
     return false;
@@ -260,7 +260,9 @@ bool LTOCodeGenerator::compileOptimizedToFile(const char **Name) {
   bool genResult = compileOptimized(&objFile.os());
   objFile.os().close();
   if (objFile.os().has_error()) {
-    emitError((Twine("could not write object file: ") + Filename).str());
+    emitError((Twine("could not write object file: ") + Filename + ": " +
+               objFile.os().error().message())
+                  .str());
     objFile.os().clear_error();
     sys::fs::remove(Twine(Filename));
     return false;