[PATCH] Add readability-redundant-include check to clang-tidy

[Alexander Kornienko]

In http://reviews.llvm.org/D7982#132666, @LegalizeAdulthood wrote:

> I think there is benefit to checking for redundant includes separately from include order.
>
> On many code bases where I've worked the include order is all over the place.  The main barrier in my experience to having a consistent include order hasn't been one of tools, but getting agreement from the team.  For the llvm/clang code bases the team has already decided on the order of includes, but for many teams that can start a big political battle.
>
> However, noone is going to disagree with eliminating redundant includes.


Makes sense. See a couple of initial comments below.

I have a feeling that some common machinery could be pulled from the llvm-include-order check which could benefit this check as well. I'll try to come up with a specific idea later.


================
Comment at: clang-tidy/readability/CMakeLists.txt:10
@@ -9,2 +9,3 @@
   ReadabilityTidyModule.cpp
+  RedundantInclude.cpp
   RedundantSmartptrGet.cpp
----------------
I'm not a native speaker, but I have a feeling that "duplicate" is a more suitable word here than "redundant". WDYT?

================
Comment at: clang-tidy/readability/RedundantInclude.h:22
@@ +21,3 @@
+///
+/// Any change in the defined macros in the main file between \c #include
+/// directives resets the list of includes used to check for duplicates.
----------------
This description is somewhat confusing. Maybe something along the lines of "Only consecutive #include directives without any other preprocessor directives between them are analyzed"?

http://reviews.llvm.org/D7982

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