[Windows] Set the console output page to UTF-8

[rnk]

Summary

Remove the Windows-specific logic that restricted us to printing only
printable ASCII characters. Use the normal UTF-8 isPrintable check
instead.

Fixes PR36267.

It's possible that older versions of the Windows console don't handle
CP_UTF8 correctly, but I think it's better to print UTF-8 for users of
modern OSs and gibberish on older installs.

[rnk]

Maybe we shouldn't do this, I wrote in the bug:

Unfortunately, it sounds like forcibly setting the user's console to the UTF8 codepage is hostile: https://github.com/stedolan/jq/issues/1121 Apparently it can cause window resizing, and I was able to confirm that the setting persists after exiting clang, which is really unclean. I want a solution where clang just prints UTF-8 and it works.

[amccarth]

llvm/lib/Support/Windows/Process.inc

273

I agree that we should _not_ change the console's code page, but if we do, we should make an effort to change it back. That would still be less than ideal if the program crashes, and you might have two resize events.

llvm/lib/Support/Locale.cpp

 #include "llvm/Support/Locale.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/Unicode.h"
 
 namespace llvm {
 namespace sys {
 namespace locale {
 
 int columnWidth(StringRef Text) {
-#if LLVM_ON_WIN32
-  return Text.size();
-#else
   return llvm::sys::unicode::columnWidthUTF8(Text);
-#endif
 }
 
 bool isPrint(int UCS) {
-#if LLVM_ON_WIN32
-  // Restrict characters that we'll try to print to the lower part of ASCII
-  // except for the control characters (0x20 - 0x7E). In general one can not
-  // reliably output code points U+0080 and higher using narrow character C/C++
-  // output functions in Windows, because the meaning of the upper 128 codes is
-  // determined by the active code page in the console.
-  return ' ' <= UCS && UCS <= '~';
-#else
   return llvm::sys::unicode::isPrintable(UCS);
-#endif
 }
 
 } // namespace locale
 } // namespace sys
 } // namespace llvm

llvm/lib/Support/Windows/Process.inc

if (ec)
       break;
   }
 
   LocalFree(UnicodeCommandLine);
   return ec;
 }
 
 std::error_code Process::FixupStandardFileDescriptors() {
+  // Set the console to output UTF-8.
+  ::SetConsoleOutputCP(CP_UTF8);
   return std::error_code();
 }
 
 std::error_code Process::SafelyCloseFileDescriptor(int FD) {
   if (::close(FD) < 0)
     return std::error_code(errno, std::generic_category());
   return std::error_code();
 }