<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/118002>118002</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [ClangFormat] Adjusting Include Order for Main Headers by Prefix Match
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          thirumurugan-git
      </td>
    </tr>
</table>

<pre>
    Does the `IncludeIsMainRegex` option in the Clang format file only search for the suffix in the header stem? Is there an option to check the header prefix to identify it as "not a main file"? For example, consider the following code:

```cpp
// file: a.cc
#include "b.h"
#include "../a.h"

// some code
```

When formatting this, `a.h` is prioritized as `0` (default) and always appears first. However, I want it to be placed last. Does Clang-Format support any option in the `.clang-format` file to address this, or would I need to use `clang-off` for the include section? 

**Note:** The include must retain the relative path. Alternate approaches are not feasible. Could such an option be introduced in the future?"
</pre>
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