input-validate: add CATEGORIES make variable

[hirooih]

This PR lets validate-input make target support the CATEGORIES variable as units make target does.

Some minor fixes of input validation are also included.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (a423dce) 83.04% compared to head (f2f0703) 83.04%.

Additional details and impacted files

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##           master    #3793   +/-   ##
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  Coverage   83.04%   83.04%           
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  Files         227      227           
  Lines       55203    55203           
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  Hits        45843    45843           
  Misses       9360     9360           

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[hirooih]

@masatake san,

Thank you for your approval.

BTW I have a question after reading the section, Input validation for Units.

With VALIDATORS variable passed via command-line, you can specify validators to run. Multiple validators can be specified using a comma-separated list. If you don’t give VALIDATORS, the make target tries to use all available validators.

What is a use-case of the VALIDATORS variable?
make validate-input works fine. On what situation this variable is needed?

[masatake]

@hirooih As you implemented, CATEGORIES may cover most of all use cases.
VALIDATORS is mainly designed for C++.
Some languages like C++ have generations of standards like C++-11 and C++-23.
Even if an input is valid as C++11, the input can be invalid as C++-23.
For validating only C++-23 input but not C++-11 ([or vice versa]), the VALIDATORS may help you.