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      <base href="https://llvm.org/bugs/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - Option -module-dependency-dir reported by -help, but not supported by clang driver"
   href="https://llvm.org/bugs/show_bug.cgi?id=26318">26318</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Option -module-dependency-dir reported by -help, but not supported by clang driver
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

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

        <tr>
          <th>OS</th>
          <td>Linux
          </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>Driver
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>jeremy.bennett@embecosm.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=15720" name="attach_15720" title="Example program from source tree attached for convenience">attachment 15720</a> <a href="attachment.cgi?id=15720&action=edit" title="Example program from source tree attached for convenience">[details]</a></span>
Example program from source tree attached for convenience

clang --help reports -module-dependency-dir as one of its options:

  -module-dependency-dir <value>
                          Directory to dump module dependencies to

However the option is not supported by the clang driver. Taking the clang
test/Modules/dependency-dump.m (attached for convenience), we run:

  $ clang -fmodules -module-dependency-dir `pwd` dependency-dump.m 
  clang-3.9: warning: argument unused during compilation:
'-module-dependency-dir /tmp'

However, if CC1 is invoked explicitly, the option is accepted:

  $ clang -cc1 -fmodules -module-dependency-dir `pwd` dependency-dump.m 
  dependency-dump.m:15:9: fatal error: module 'Module' not found
  @import Module;
  ...

The option should either be removed from the list reported by clang --help, or
be promoted to be accepted by the top level clang driver (which would seem more
consistent).

This is a similar issue to that reported in <a class="bz_bug_link 
          bz_status_ASSIGNED "
   title="ASSIGNED --- - Option -fno-math-builtin reported by -help, but not supported by clang driver"
   href="show_bug.cgi?id=26317">Bug 26317</a>.

Issue identified with commit 7506929a38783ed7038f893c8f1f59f6a4ccfd20,
git-svn-id: <a href="https://llvm.org/svn/llvm-project/cfe/trunk@258290">https://llvm.org/svn/llvm-project/cfe/trunk@258290</a>
91177308-0d34-0410-b5e6-96231b3b80d8</pre>
        </div>
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