[libc-commits] [libc] [libc] Support %lc in printf (PR #169983)

[Shubh Pachchigar via libc-commits]

================
@@ -33,7 +39,21 @@ LIBC_INLINE int convert_char(Writer<write_mode> *writer,
     RET_IF_RESULT_NEGATIVE(writer->write(' ', padding_spaces));
   }
 
-  RET_IF_RESULT_NEGATIVE(writer->write(c));
+  if (to_conv.length_modifier == LengthModifier::l) {
+    wc = static_cast<wchar_t>(static_cast<unsigned int>(to_conv.conv_val_raw));
----------------
shubhe25p wrote:

Thanks this makes sense, what I was referring to was that naively casting from `conv_val_raw` (BigInt) to `wchar_t` leads to an error in `BigInt to()`, as the casting has a guard clause that essentially checks:

```
struct BigInt {
...
template <typename T>
  LIBC_INLINE constexpr cpp::enable_if_t<
      cpp::is_integral_v<T> && !cpp::is_same_v<T, bool>, T>
  to() const { 
       ... }
```
  
`  is_integral_v ` will return false if the type is not one of:
  
``` 
char, signed char, unsigned char, short, unsigned short, int,
      unsigned int, long, unsigned long, long long, unsigned long long, bool
```
      
That is the reason why I cast to `unsigned int` first. Let me know your thoughts

https://github.com/llvm/llvm-project/pull/169983