warnings.cmake

# Our principle is to enable as many warnings as possible and always do it with "warnings as errors" flag.
#
# But it comes with some cost:
# - we have to disable some warnings in 3rd party libraries (they are located in "contrib" directory)
# - we have to include headers of these libraries as -isystem to avoid warnings from headers
#   (this is the same behaviour as if these libraries were located in /usr/include)
# - sometimes warnings from 3rd party libraries may come from macro substitutions in our code
#   and we have to wrap them with #pragma GCC/clang diagnostic ignored

set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra")

# Control maximum size of stack frames. It can be important if the code is run in fibers with small stack size.
# Only in release build because debug has too large stack frames.
if ((NOT CMAKE_BUILD_TYPE_UC STREQUAL "DEBUG") AND (NOT SANITIZE) AND (NOT CMAKE_CXX_COMPILER_ID MATCHES "AppleClang"))
    add_warning(frame-larger-than=65536)
endif ()

if (COMPILER_CLANG)
    # Add some warnings that are not available even with -Wall -Wextra -Wpedantic.
    # We want to get everything out of the compiler for code quality.
    add_warning(everything)
    add_warning(pedantic)
    no_warning(zero-length-array)
    no_warning(c++98-compat-pedantic)
    no_warning(c++98-compat)
    no_warning(c++20-compat) # Use constinit in C++20 without warnings
    no_warning(sign-conversion)
    no_warning(implicit-int-conversion)
    no_warning(implicit-int-float-conversion)
    no_warning(shorten-64-to-32)
    no_warning(ctad-maybe-unsupported) # clang 9+, linux-only
    no_warning(disabled-macro-expansion)
    no_warning(documentation-unknown-command)
    no_warning(double-promotion)
    no_warning(exit-time-destructors)
    no_warning(float-equal)
    no_warning(global-constructors)
    no_warning(missing-prototypes)
    no_warning(missing-variable-declarations)
    no_warning(padded)
    no_warning(switch-enum)
    no_warning(undefined-func-template)
    no_warning(unused-template)
    no_warning(vla)
    no_warning(weak-template-vtables)
    no_warning(weak-vtables)
    no_warning(thread-safety-negative) # experimental flag, too many false positives
    no_warning(enum-constexpr-conversion) # breaks magic-enum library in clang-16
    no_warning(unsafe-buffer-usage) # too aggressive
    # TODO Enable conversion, sign-conversion, double-promotion warnings.
endif ()