<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </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 - Extend IndentPPDirectives with a LeaveAsIs option"
   href="https://bugs.llvm.org/show_bug.cgi?id=39163">39163</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Extend IndentPPDirectives with a LeaveAsIs option
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </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>Formatter
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>niklas.frykholm@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>djasper@google.com, klimek@google.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Currently IndentPPDirectives can have values None or AfterHash. There has
also been a suggestion of a BeforeHash option.

I suggest adding another option Leave, which would leave preprocessor
directives alone (i.e. not change the indentation at all).

Motivation:

    Indenting pre-processor directives can be really tricky with lots of
    edge cases. There maybe certain directives you do not want indented,
    for example. clang-format already has some detection of include guards
    as I understand it, but we also use platform macros around entire
    files:

    #ifdef OSX
    ...
    #endif

    These are not recognized and cause the entire file to be indented.

    Further complications arise from interaction between macros and C
    code, when you want macros to be indented to the scope of the C code
    and the C code to be indented to the scope of the macros, i.e.:

    if (x) {
        #ifdef OSX
           bla();
        #endif
    }

    While it is possible to come up with decent indentation for simple
    cases like this, it can get hairy, since the macros don't follow the
    C syntax and vice versa. For example, the scopes in C code and the
    preprocessor don't have to nest nicely. It may be hard to come up with
    good consistent rules for how C/preprocessor interactions should be
    handled.

    A Leave option would sidestep these thorny issues and leave the
    indentation of preprocessor macros to the code author. It should also
    be easy to implement.

References:

* <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - preprocessor directives indentation"
   href="show_bug.cgi?id=17362">https://bugs.llvm.org/show_bug.cgi?id=17362</a>
* <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Extend IndentPPDirectives with a BeforeHash option"
   href="show_bug.cgi?id=36019">https://bugs.llvm.org/show_bug.cgi?id=36019</a>
* <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Add option to IndentPPDirectives to respect indentation of context"
   href="show_bug.cgi?id=36020">https://bugs.llvm.org/show_bug.cgi?id=36020</a></pre>
        </div>
      </p>


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