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      <base href="http://llvm.org/bugs/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - ##__VA_ARGS__ does not expand inner macros, whereas __VA_ARGS__ works as expected"
   href="http://llvm.org/bugs/show_bug.cgi?id=19141">19141</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>##__VA_ARGS__ does not expand inner macros, whereas __VA_ARGS__ works as expected
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>3.4
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Macintosh
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>MacOS X
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Frontend
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>jeffery.thomas@gm.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>##__VA_ARGS__ does not expand inner macros, whereas __VA_ARGS__ works as
expected.

This input file (foo.m):

[--
#define F1(...) [NSString stringWithFormat:__VA_ARGS__]
#define F2(format, ...) [NSString stringWithFormat:(format), ##__VA_ARGS__]

    NSLog(F1(@"%@", F1(@"%@", @"a")));
    NSLog(F2(@"%@", F2(@"%@", @"a")));
--]

when processed with `clang -E -o foo.i foo.m`, produces the following output:

[--
# 1 "foo.m"
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 178 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "foo.m" 2



    NSLog([NSString stringWithFormat:@"%@", [NSString stringWithFormat:@"%@",
@"a"]]);
    NSLog([NSString stringWithFormat:(@"%@"), F2(@"%@", @"a")]);
--]

Version Details:

[--
$ clang --version
Apple LLVM version 5.1 (clang-503.0.38) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.1.0
Thread model: posix
--]</pre>
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