Suppress clang warnings when using ROOT as third party library with CMake

ROOT
, ,
1

I am using ROOT as third party library in a CMake project as follows

find_package(ROOT 6.30 CONFIG REQUIRED)
target_link_libraries(myLibrary PUBLIC ROOT::Core)
target_include_directories(myLibrary PRIVATE  ${CMAKE_SOURCE_DIR}/include/myLibrary)
ROOT_GENERATE_DICTIONARY(myLibrary_dict myLibrary.h MODULE myLibrary LINKDEF include/myLibrary/LinkDef.h)

This seems to work fine, but I am getting a long list of compiler warnings from A) the dictionary generated, e.g.

/build/myLibrary_dict.cxx:76:38: warning: use of old-style cast [clang-diagnostic-old-style-cast]
   if (!fgIsA.load()) { R__LOCKGUARD(gInterpreterMutex); fgIsA = ::ROOT::GenerateInitInstanceLocal((const ::MLogging*)nullptr)->GetClass(); }

and B) ROOT itself, e.g.:

/root/include/THashTable.h:48:73: warning: conversion to ‘Int_t’ {aka ‘int’} from ‘UInt_t’ {aka ‘unsigned int’} may change the sign of the result [-Wsign-conversion]
   48 |    Int_t       GetHashValue(const char *str) const { return ::Hash(str) % fSize; }

What is the recommended way of suppressing these warnings in the CMake configuration? It would be great if this could be added to the documentation!

Cheers

2

Your question seems more related to cmake and not directly to ROOT.
Nevertheless @bellenot might have an idea about it.

3

You can try to disable the warnings for specific source files using something like: set_source_files_properties(myLibrary_dict.cxx PROPERTIES COMPILE_FLAGS "-Wno-old-style-cast")
And possibly the same for source files using ROOT headers (-Wno-sign-conversion)
(check for the correct flags)
You can also disable the warnings for the whole project, but I would advise not to.
And FYI, I’m just trying to guess here…

4

Hi @couet and @bellenot,

I think your suggestion works for compiler warnings but not for clang-tidy. What I finally found to work was

set_target_properties(myLibrary_dict PROPERTIES COMPILE_FLAGS "-w" CXX_CLANG_TIDY "")

Interestingly, one (real) error message remains

Checking /workspaces/build/myLibrary_dict.cxx ...
/root/include/ROOT/span.hxx:18:0: error: failed to evaluate #if condition [preprocessorErrorDirective]
# if __has_include(<span>)

Everyting compiles fine, but I am wondering whether you are aware of this and where this comes from. I am using ROOT Version: 6.30/06.

I also think its worth putting this in the documentation (e.g. Integrating ROOT into CMake projects - ROOT) as people will likely always want to disable warnings from third-party libaries and we definitely should not encourage them to disable the warnings on a project level.

5

Thanks for the feedback and for the solution. We’ll see where to add add a clang-tidy specific paragraph in the doc. Note that you can also open a GH pull request if you want…

I’m not aware, but I’m working on Windows… I’ll check on other platforms, but I think we would have seen it in our CI if it was the case…

6

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.