The new checker searches for those for loops which has a loop variable with a "too small" type which means this type can't represent all values which are part of the iteration range.
For example:
```
int main() {
long size = 300000;
for( short int i = 0; i < size; ++i) {}
}
```
The short type leads to infinite loop here because it can't store all values in the `[0..size]` interval. In a real use case, size means a container's size which depends on the user input. Which means for small amount of objects the algorithm works, but with a larger user input the software will freeze.
The idea of the checker comes from the LibreOffice project, where the same check was implemented as a clang compiler plugin, called `LoopVarTooSmall` (LLVM licensed).
The idea is the same behind this check, but the code is different because of the different framework.
Patch by ztamas.
Reviewers: alexfh, hokein, aaron.ballman, JonasToth, xazax.hun, whisperity
Reviewed By: JonasToth, whisperity
Differential Revision: https://reviews.llvm.org/D53974
llvm-svn: 346665
Jonas Toth