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Remove top-level const from function-scope variables

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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
This commit is contained in:
Cosmin Truta
2018-08-18 22:47:16 -04:00
parent 1ef8882814
commit ceb327789b
22 changed files with 196 additions and 205 deletions
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4
contrib/examples/pngpixel.c
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@@ -73,7 +73,7 @@ static void
print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
png_uint_32 x)
{
const unsigned int bit_depth = png_get_bit_depth(png_ptr, info_ptr);
unsigned int bit_depth = png_get_bit_depth(png_ptr, info_ptr);
switch (png_get_color_type(png_ptr, info_ptr))
{
@@ -87,7 +87,7 @@ print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
*/
case PNG_COLOR_TYPE_PALETTE:
{
const int index = component(row, x, 0, bit_depth, 1);
int index = component(row, x, 0, bit_depth, 1);
png_colorp palette = NULL;
int num_palette = 0;