clang-format.el: Make clang-format work in indirect buffers.

[phst]

Summary

In an indirect buffer, buffer-file-name is nil, so check the base buffer
instead. This works fine in direct buffers where buffer-base-buffer returns
nil.

[sammccall]

Makes sense, thanks!

[phst]

Thanks for the review! I think you have to commit this (I don't have commit access).

clang/tools/clang-format/clang-format.el

uses the function `buffer-file-name'."
    (if (use-region-p)
        (list (region-beginning) (region-end))
      (list (point) (point))))
 
   (unless style
     (setq style clang-format-style))
 
   (unless assume-file-name
-    (setq assume-file-name buffer-file-name))
+    (setq assume-file-name (buffer-file-name (buffer-base-buffer))))
 
   (let ((file-start (clang-format--bufferpos-to-filepos start 'approximate
                                                         'utf-8-unix))
         (file-end (clang-format--bufferpos-to-filepos end 'approximate
                                                       'utf-8-unix))
         (cursor (clang-format--bufferpos-to-filepos (point) 'exact 'utf-8-unix))
         (temp-buffer (generate-new-buffer " *clang-format-temp*"))
         (temp-file (make-temp-file "clang-format"))