[PATCH] D19451: [clang-tidy] New checker for redundant expressions.

[Etienne Bergeron via cfe-commits]

etienneb created this revision.
etienneb added a reviewer: alexfh.
etienneb added a subscriber: cfe-commits.

This checker finds redundant expression on both side of a binary operator.

The current implementation provide a function to check whether expression
are the equivalent. This implementation is able to recognize the frequent 
subset encounter in C++ program. Side-effects like "x++" are not considered
to be equivalent.

There are many False Positives related to macros and to floating point
computations (detecting NaN). The checker is ignoring these cases.

Example:
```
    if( !dst || dst->depth != desired_depth ||
        dst->nChannels != desired_num_channels ||
        dst_size.width != src_size.width ||
        dst_size.height != dst_size.height )    <<--- bug
    {
```

http://reviews.llvm.org/D19451

Files:
  clang-tidy/misc/CMakeLists.txt
  clang-tidy/misc/MiscTidyModule.cpp
  clang-tidy/misc/RedundantExpressionCheck.cpp
  clang-tidy/misc/RedundantExpressionCheck.h
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/misc-redundant-expression.rst
  test/clang-tidy/misc-redundant-expression.cpp

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