<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/113236>113236</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Assertion Error when expanding macro with consecutive ## tokens and empty parameters.
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          mrolle45
      </td>
    </tr>
</table>

<pre>
    `Assertion failed: (!NonEmptyPasteBefore || PasteBefore || VCtx.isInVAOpt()) && "unexpected ## in ResultToks", file D:\GitHub\Repos\LLVM\llvm-project\clang\lib\Lex\TokenLexer.cpp, line 414`

I got this while running clang on this code:
``` c
#define FOO(a,b,c) ;b########c,b##########c,a########a,a##########a, (more...)
FOO (,y,z)
```
I set a breakpoint at this line, condition being `I == 22`. `Tokens[22]` is the comma after the fourth `a`.  Thus `PasteBefore` is false. However, `ResultToks` ends with
▶ | [15] | comma | clang::Token
▶ | [16] | hashhash | clang::Token
▶ | [17] | hashhash | clang::Token
```
</pre>
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