[libc] Build fixes for widechar characterconverter (#143805)

Build fixes for wchar CharacterConverter class

libc/hdr/CMakeLists.txt

@@ -221,6 +221,8 @@ add_proxy_header_library(
 
 add_header_library(wchar_overlay HDRS wchar_overlay.h)
 
+add_header_library(uchar_overlay HDRS uchar_overlay.h)
+
 add_proxy_header_library(
   wchar_macros
   HDRS

libc/hdr/types/CMakeLists.txt

@@ -1,3 +1,25 @@
+add_proxy_header_library(
+  char8_t 
+  HDRS
+    char8_t.h
+  DEPENDS
+    libc.hdr.uchar_overlay
+  FULL_BUILD_DEPENDS
+    libc.include.llvm-libc-types.char8_t
+    libc.include.uchar
+)
+
+add_proxy_header_library(
+  char32_t 
+  HDRS
+    char32_t.h
+  DEPENDS
+    libc.hdr.uchar_overlay
+  FULL_BUILD_DEPENDS
+    libc.include.llvm-libc-types.char32_t
+    libc.include.uchar
+)
+
 add_proxy_header_library(
   div_t
   HDRS

libc/include/llvm-libc-types/char8_t.h

@@ -9,8 +9,7 @@
 #ifndef LLVM_LIBC_TYPES_CHAR8_T_H
 #define LLVM_LIBC_TYPES_CHAR8_T_H
 
-#if !defined(__cplusplus) && defined(__STDC_VERSION__) &&                      \
-    __STDC_VERSION__ >= 202311L
+#if !(defined(__cplusplus) && defined(__cpp_char8_t))
 typedef unsigned char char8_t;
 #endif
 

libc/src/__support/CMakeLists.txt

@@ -391,4 +391,6 @@ add_subdirectory(fixed_point)
 
 add_subdirectory(time)
 
+add_subdirectory(wchar)
+
 add_subdirectory(math)

libc/src/__support/wchar/mbstate.h

@@ -10,6 +10,7 @@
 #define LLVM_LIBC_SRC___SUPPORT_MBSTATE_H
 
 #include "hdr/types/char32_t.h"
+#include "src/__support/common.h"
 #include <stdint.h>
 
 namespace LIBC_NAMESPACE_DECL {

libc/src/__support/wchar/utf_ret.h

@@ -9,13 +9,16 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_UTF_RET_H
 #define LLVM_LIBC_SRC___SUPPORT_UTF_RET_H
 
-namespace LIBC_NAMESPACE_DECL {
+#include "src/__support/common.h"
 
+namespace LIBC_NAMESPACE_DECL {
+namespace internal {
 template <typename T> struct utf_ret {
   T out;
   int error;
 };
 
+} // namespace internal
 } // namespace LIBC_NAMESPACE_DECL
 
 #endif // LLVM_LIBC_SRC___SUPPORT_UTF_RET_H