tests/test-fix-clang-format.t

documentation: add some internals documentation about bid merge

This is an important algorithm that was only documented on the wiki so far.

Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.

Differential Revision: https://phab.mercurial-scm.org/D8711

#require clang-format

Test that a simple "hg fix" configuration for clang-format works.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > fix =
  > [experimental]
  > evolution.createmarkers=True
  > evolution.allowunstable=True
  > [fix]
  > clang-format:command=clang-format --style=Google --assume-filename={rootpath}
  > clang-format:linerange=--lines={first}:{last}
  > clang-format:pattern=set:**.cpp or **.hpp
  > EOF

  $ hg init repo
  $ cd repo

  $ printf "void foo(){int x=2;}\n" > foo.cpp
  $ printf "void\nfoo();\n" > foo.hpp
  $ hg commit -Am "foo commit"
  adding foo.cpp
  adding foo.hpp
  $ hg cat -r tip *
  void foo(){int x=2;}
  void
  foo();
  $ hg fix -r tip
  $ hg cat -r tip *
  void foo() { int x = 2; }
  void foo();

  $ cd ..