<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/67943>67943</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Dollar sign ('$') can not be encoded as a UCN inside an identifier
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          mattmanj17
      </td>
    </tr>
</table>

<pre>
    Dollar signs are supported in identifiers as an extension,  
but dollar signs encoded with a UCN do not work in identifiers.  

For example, the file... 
`gcc/testsuite/gcc.dg/ucnid-5.c`  
...from the gcc test suite, does not compile.

Here is the contents of that file:

```
/* { dg-do run } */
/* { dg-skip-if "No dollar in identifiers" { avr-*-* powerpc-ibm-aix* } } */
/* { dg-options "-std=c99 -fdollars-in-identifiers -g" } */
void abort (void);

int a$b(void) { return 1; }

int main (void)
{
  
  if (a\u0024b() != 1)
    abort ();
  
  return 0;
}
```

Godbolt link of it not compiling in clang 17.0.1 
https://godbolt.org/z/TGdd9PoYx

Godbolt links for it compiling in gcc (and a previous clang version)  
GCC 13.2 https://godbolt.org/z/TGdd9PoYx  
clang 16 https://godbolt.org/z/xWfvKqvxz

Neither the C or C++ standards forbid using a UCN to encode '$'.  
As far as I can tell they just forbid control chars, surrogates,   
and chars in the 'basic character set', which does not include '$'.

</pre>
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