Support: ensure proper state in ErrorOr copy ctors before calling 'get'

Some paths through the copy constructors for 'ErrorOr' were calling
'get' when 'HasError' and 'IsValid' were not properly initialized.
Depending on what happened to be in memory for those member variables
the asserts in 'get' might incorrectly fire.  Fixed by ensuring that
the member variables in question are always initialized before calling
'get'.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174381 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/ErrorOr.h

@@ -204,18 +204,17 @@ class ErrorOr {
     // Construct an invalid ErrorOr if other is invalid.
     if (!Other.IsValid)
       return;
+    IsValid = true;
     if (!Other.HasError) {
       // Get the other value.
-      new (get()) storage_type(*Other.get());
       HasError = false;
+      new (get()) storage_type(*Other.get());
     } else {
       // Get other's error.
       Error = Other.Error;
       HasError = true;
       Error->aquire();
     }
-
-    IsValid = true;
   }
 
   ErrorOr &operator =(const ErrorOr &Other) {
@@ -234,11 +233,11 @@ class ErrorOr {
     // Construct an invalid ErrorOr if other is invalid.
     if (!Other.IsValid)
       return;
+    IsValid = true;
     if (!Other.HasError) {
       // Get the other value.
-      IsValid = true;
-      new (get()) storage_type(std::move(*Other.get()));
       HasError = false;
+      new (get()) storage_type(std::move(*Other.get()));
       // Tell other not to do any destruction.
       Other.IsValid = false;
     } else {
@@ -248,8 +247,6 @@ class ErrorOr {
       // Tell other not to do any destruction.
       Other.IsValid = false;
     }
-
-    IsValid = true;
   }
 
   ErrorOr &operator =(ErrorOr &&Other) {