Use std::error_code instead of llvm::error_code.

The idea of this patch is to turn llvm/Support/system_error.h into a
transitional header that just brings in the erorr_code api to the llvm
namespace. I will remove it shortly afterwards.

The cases where the general idea needed some tweaking:

* std::errc is a namespace in msvc, so we cannot use "using std::errc". I could
add an #ifdef, but there were not that many uses, so I just added std:: to
them in this patch.

* Template specialization had to be moved to the std namespace in this
patch set already.

* The msvc implementation of default_error_condition doesn't seem to
provide the same transformations as we need. Not too surprising since
the standard doesn't actually say what "equivalent" means. I fixed the
problem by keeping our old mapping and using it at error_code
construction time.

Despite these shortcomings I think this is still a good thing. Some reasons:

* The different implementations of system_error might improve over time.
* It removes 925 lines of code from llvm already.
* It removes 6313 bytes from the text segment of the clang binary when
it is built with gcc and 2816 bytes when building with clang and
libstdc++.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210687 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 5 insertions, 3 deletions

diff --git a/tools/obj2yaml/Error.cpp b/tools/obj2yaml/Error.cpp
index 3aa472fc3d..ab615ee193 100644
--- a/tools/obj2yaml/Error.cpp
+++ b/tools/obj2yaml/Error.cpp
@@ -42,7 +42,7 @@ error_condition
 _obj2yaml_error_category::default_error_condition(int ev) const {
   if (static_cast<obj2yaml_error>(ev) == obj2yaml_error::success)
     return error_condition();
-  return errc::invalid_argument;
+  return std::errc::invalid_argument;
 }
 
 namespace llvm {
diff --git a/tools/obj2yaml/Error.h b/tools/obj2yaml/Error.h
index 4aaf5c7942..7180d54307 100644
--- a/tools/obj2yaml/Error.h
+++ b/tools/obj2yaml/Error.h
@@ -27,8 +27,10 @@ inline error_code make_error_code(obj2yaml_error e) {
   return error_code(static_cast<int>(e), obj2yaml_category());
 }
 
-template <> struct is_error_code_enum<obj2yaml_error> : std::true_type { };
-
 } // namespace llvm
 
+namespace std {
+template <> struct is_error_code_enum<llvm::obj2yaml_error> : std::true_type {};
+}
+
 #endif