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      <base href="https://bugs.llvm.org/">
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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 - Lvalue reference types appear in the signature of __builtin_va_start when compiled as C and targeting Windows"
   href="https://bugs.llvm.org/show_bug.cgi?id=37122">37122</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Lvalue reference types appear in the signature of __builtin_va_start when compiled as C and targeting Windows
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>6.0
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Windows NT
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>-New Bugs
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>thonerma@synopsys.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>It seems that the signature of __builtin_va_start contains a C++ lvalue
reference type when targeting Windows, even when compiling as C:

$ cat t.c
void f(int n, ...) {
  __builtin_va_list v;
  __builtin_va_start(v, n);
}

$ clang --version
clang version 6.0.0 (tags/RELEASE_600/final)
Target: x86_64-unknown-linux-gnu
...

$ clang -c -Xclang -ast-dump -target x86_64-pc-windows-gnu t.c
...
`-FunctionDecl 0x4c89578 <col:3> col:3 implicit used __builtin_va_start 'void
(__builtin_va_list &, ...)' extern
  |-ParmVarDecl 0x4c89618 <<invalid sloc>> <invalid sloc> '__builtin_va_list &'
  `-NoThrowAttr 0x4c89680 <col:3> Implicit

Note the presence of '__builtin_va_list &' as a parameter type.

The lvalue reference is a surprise for AST consumers that do not expect to
encounter C++ reference types in code compiled as C.</pre>
        </div>
      </p>


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