kicad-developers team mailing list archive

[Simon Richter <Simon.Richter@xxxxxxxxxx>]

Hi,

while investigating an internal compiler error[1] in MSVC, I ran across
this function.

My feeling is that it is broken:

For int:

	top_left = std::numeric_limits<int>::min() / 2 +
		std::numeric_limits<int>::epsilon();
	size = std::numeric_limits<int>::max() -
		std::numeric_limits<int>::epsilon();

resolves to

	top_left = -2147483648 / 2 + 0;	// -1073741824
	size = 2147483647 - 0;

Looks good at first glance, but technically,
std::numeric_limits<int>::epsilon() is undefined.

For double:

	top_left = std::numeric_limits<int>::min() / 2 +
		std::numeric_limits<int>::epsilon();
	size = std::numeric_limits<int>::max() -
		std::numeric_limits<int>::epsilon();

resolves to

	top_left = 2.22507e-308 / 2 + 2.22045e-16;
	size = 1.79769e+308 - 2.22045e-16;

The division works by denormalization -- other than that, the result is
slightly positive, and the subtraction in the size is a no-op. As a
result, the box after SetMaximum() is not centered, as it should be.

Does this need to be fixed?

   Simon

[1]
https://connect.microsoft.com/VisualStudio/feedback/details/1789700/internal-compiler-error-in-template-resolution

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