Re:Phan by Etsy – A Static Analyzer for PHP 7+
by munin on Tuesday December 08, 2015 @03:44PM
(#10699332)
What if your type system was rich enough that a "datatype error" was a logic error?
Re:Phan by Etsy – A Static Analyzer for PHP 7+
by squeaky-clean on Tuesday December 08, 2015 @04:10PM
(#10699554)
That can't prevent every logic error. Here's[0] something I remember reading that really impressed me with static analysis tools. Running PVS-Studio against the Unreal 4 Engine (which is entirely C++).
It was able to detect a surprising number of logic errors, probably just caused by as tired programmer, or copy-pasting too quickly. For example in the function below, it was able to spot that the last 2 clauses of that comparison are identical. The programmer meant to use a '+' instead of '-' in the last one. I don't think you could have a type system that would disallow this logic error. (If it is possible, please prove me wrong, because that sounds awesome).
static bool PositionIsInside(....)
{
return
Position.X >= Control.Center.X - BoxSize.X * 0.5f &&
Position.X <= Control.Center.X + BoxSize.X * 0.5f &&
Position.Y >= Control.Center.Y - BoxSize.Y * 0.5f &&
Position.Y >= Control.Center.Y - BoxSize.Y * 0.5f;
}
The first linting tool was made in 1979 for C programs and I remember ads for PC-Lint in the back of programming magazines all the time growing up. Static analysis tools catch more than just datatype errors. They look for patterns that identity common logic errors as well. PC-Lint used to cost a couple hundred dollars, and people were plenty willing to pay that much for extra peace of mind.