[llvm] [libc] [libc][math] Implement nan(f|l) functions (PR #76690)

[via llvm-commits]

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@@ -1055,6 +1056,37 @@ hexadecimal_string_to_float(const char *__restrict src,
   return output;
 }
 
+struct NanMantissaResult {
+  uint64_t value;
+  int error;
+
+  LIBC_INLINE constexpr NanMantissaResult(uint64_t value, int error)
+      : value(value), error(0) {}
+};
+
+LIBC_INLINE NanMantissaResult
+nan_mantissa_from_ncharseq(const cpp::string_view ncharseq) {
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lntue wrote:

`const` qualifier for value type in the function signature is not needed / effective.

https://github.com/llvm/llvm-project/pull/76690