Ignore system headers in clang-tidy

Question

tldr;> How do I hide warnings from system headers in clang-tidy?

I have the following minimal example source file, which triggers a clang-tidy warning in the system headers:

#include <future>  int main() {   std::promise<int> p;   p.set_value(3); } 

Calling it with libstdc++ 7.0.1 using clang-tidy 4.0.0 on Ubuntu 17.04:

$ clang-tidy main.cpp -extra-arg=-std=c++14 

yields

Running without flags. 1 warning generated. /usr/lib/gcc/x86_64-linux-gnu/7.0.1/../../../../include/c++/7.0.1/mutex:693:5: warning: Address of stack memory associated with local variable '__callable' is still referred to by the global variable '__once_callable' upon returning to the caller.  This will be a dangling reference [clang-analyzer-core.StackAddressEscape]     }     ^ /home/user/main.cpp:5:3: note: Calling 'promise::set_value'   p.set_value(3);   ^ /usr/lib/gcc/x86_64-linux-gnu/7.0.1/../../../../include/c++/7.0.1/future:1094:9: note: Calling '_State_baseV2::_M_set_result'       { _M_future->_M_set_result(_State::__setter(this, std::move(__r))); }         ^ /usr/lib/gcc/x86_64-linux-gnu/7.0.1/../../../../include/c++/7.0.1/future:401:2: note: Calling 'call_once'         call_once(_M_once, &_State_baseV2::_M_do_set, this,         ^ /usr/lib/gcc/x86_64-linux-gnu/7.0.1/../../../../include/c++/7.0.1/mutex:691:11: note: Assuming '__e' is 0       if (__e)           ^ /usr/lib/gcc/x86_64-linux-gnu/7.0.1/../../../../include/c++/7.0.1/mutex:691:7: note: Taking false branch       if (__e)       ^ /usr/lib/gcc/x86_64-linux-gnu/7.0.1/../../../../include/c++/7.0.1/mutex:693:5: note: Address of stack memory associated with local variable '__callable' is still referred to by the global variable '__once_callable' upon returning to the caller.  This will be a dangling reference     } 

I want to hide warnings in system headers. I tried the following:

$ clang-tidy -extra-arg=-std=c++14 main.cpp -header-filter=$(realpath .) -system-headers=0 

but the warning still shows.

Answer 1

I ran into this issue as well, and spent some time trying to figure it out, but I could not see a way to disable this type of warning in clang-tidy.

From reading this discussion on the LLVM issue tracker regarding a similar issue, I get the impression that the problem is that from clang-tidy's perspective, the warning is actually located in main.cpp, because the call to set_value is from there.

My workaround has been to disable the static analysis checks in clang-tidy, and use the scan-build utility to run clang's static analysis, which seems to avoid these problems. For example, using your main.cpp:

$ scan-build-3.9 clang++ -std=c++14 main.cpp  scan-build: Using '/usr/lib/llvm-3.9/bin/clang' for static analysis In file included from main.cpp:1: In file included from /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/future:39: /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/mutex:621:11: warning: Address of stack memory associated with local variable '__callable' is still referred to by the global variable '__once_callable' upon returning to the caller.  This will be a dangling reference       if (__e)           ^~~ 1 warning generated. scan-build: Removing directory '/tmp/scan-build-2017-12-02-112018-13035-1' because it contains no reports. scan-build: No bugs found. 

The analyzer finds the same error in a system header, but it's smart enough not to include it in the final report. ("No bugs found")

You'll still need to run clang-tidy separately if you are interested in the style guide type warnings, like modernize-* or readability-*.