tree f165ad9fb1d924e4c6f49c2d684b0805eaf13090
parent 1ef88828146c23bfc6d81042c6d6ecd61ccc983b
author Cosmin Truta <ctruta@gmail.com> 1534646836 -0400
committer Cosmin Truta <ctruta@gmail.com> 1534646836 -0400

Remove top-level const from function-scope variables

As per the const correctness rules, top-level const-ness of data
in automatic scopes does not propagate outside of these scopes
(unlike const-ness at lower levels, such as pointers to const data).

Previously, const was used liberally, but inconsistently across the
libpng codebase. Using const wherever applicable is not incorrect.
However, _consistent_ use of const is difficult to maintain in such
conditions.

In conclusion, we shall continue to use const only where doing so is
strictly necessary:

1. If a function guarantees that it will not modify an argument
   passed by pointer, the corresponding function parameter should be
   a pointer-to-const (const T *).

2. Static data should not be modified, therefore it should be const.

Reference:
Google C++ Style Guide
https://google.github.io/styleguide/cppguide.html#Use_of_const