[PATCH] D53974: [clang-tidy] new checker: bugprone-too-small-loop-variable

[Tamás Zolnai via Phabricator via cfe-commits]

ztamas created this revision.
Herald added subscribers: cfe-commits, xazax.hun, mgorny.

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.


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D53974

Files:
  clang-tidy/bugprone/BugproneTidyModule.cpp
  clang-tidy/bugprone/CMakeLists.txt
  clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
  clang-tidy/bugprone/TooSmallLoopVariableCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/bugprone-too-small-loop-variable.rst
  docs/clang-tidy/checks/list.rst
  test/clang-tidy/bugprone-too-small-loop-variable.cpp

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