Running ament_clang_tidy results in Could not find 'clang-tidy-6.0' executable

[RFRIEDM-Trimble]

Hello,

I would like to start using clang-tidy in all my ROS2 packages.

I am using the OSRF supplied ROS2 galactic docker image that comes with clang-tidy

root@rfriedm-us-dl01:~/tas-ros2-system# clang-tidy --version
LLVM (http://llvm.org/):
  LLVM version 10.0.0
  
  Optimized build.
  Default target: x86_64-pc-linux-gnu
  Host CPU: skylake-avx512

Docs recommends to use clang-tidy-6.0. but I don't have that version. I can install it directly with

apt install clang-tidy-6.0

I have built my package according to documentation.

colcon build --packages-up-to tas_tn_002 --mixin compile-commands --cmake-args -DBUILD_TESTING=ON

Now, I can run ament_clang_tidy successfully.

ament_clang_tidy build

If I don't go out and install ament-clang-tidy-6.0, I get this error:

Could not find 'clang-tidy-6.0' executable

Now, if I try using the cmake integration,with the appropriate calls package.xml and CMakeLists.txt, rosdep still doesn't install the depenency.

rosdep install -i path/to/tas_tn_002
...

1. Is there a reason it is tied to clang-tidy-6, or can you support the version installed by OSRF for galactic?
2. If version 6.0 is required, should I submit a PR with the command to install it?
3. If I am using rosdep to install dependencies, why does it not install clang-tidy-6.0 as a dependency?