Improve pre-commit githook

[SamBent]

Fixes Issue

Main PR

Description

Improvements to the hook that deters users from changing generated files:

1. The hook calls a file-comparison tool that expects its inputs to be sorted, but doesn't sort the inputs ("comm: file 1 is not in sorted order"). Fixed that by (a) sorting the dynamic list of staged files, and (b) pre-sorting the fixed list of generated files.
2. Revised the error output to give a better suggestion about what to do next.

To get the full benefit of this change, copy eng\WpfArcadeSdk\tools\pre-commit.githook to .git\hooks\pre-commit, overwriting the existing file (both paths are relative to your repo's root). There's probably some way to cause this to happen automatically, but I couldn't find it.

Customer Impact

No change to product code. Developer experience is improved.

Regression

No.

Testing

It works for me.

Risk

No risk.

[dipeshmsft]

The eng\WpfArcadeSdk\tools\pre-commit.githook file is compied to .git\hooks\pre-commit at the time when build.cmd is run. It executes restore-toolset.ps1 which copies the pre-commit hook file.

[SamBent]

@dipeshmsft

The eng\WpfArcadeSdk\tools\pre-commit.githook file is compied to .git\hooks\pre-commit at the time when build.cmd is run. It executes restore-toolset.ps1 which copies the pre-commit hook file.

No it doesn't. This only happens the very first time you build the repo. After that, restore-toolset says:

Detecting WPF Git hooks...
Detected existing WPF Git pre-commit hook.

However, deleting .git\hooks\pre-commit will install the new one the next time you build:

Detecting WPF Git hooks...
Installing WPF Git pre-commit hook...

BTW, I pushed the wrong version of pre-commit.githook, lacking the sort (step 1a). Fixed in latest commit.