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c++boostqt-creatorboost-beastclangd

Boost Beast 1.84 server example and clangd warning in QT Creator 13

When I load the following original boost beast 1.84.0 server example into my IDE QT Creator 13.0 (C++20), I get the following warning with clang-tools 17.0.1. How can I fix/work around this and is this a bug/warning in the boost library/example that will be fixed?

Example: https://www.boost.org/doc/libs/1_84_0/libs/beast/example/advanced/server/

Warning in Line 167 in original example file (my line is different in 161): enter image description here

Compiler-Call (cmake generated) (Ubuntu 13.2.0-4ubuntu3):
/usr/bin/x86_64-linux-gnu-g++-13 -DBOOST_SYSTEM_NO_LIB -DBOOST_THREAD_NO_LIB -isystem /home/xxx/projects_cpp/boost_beast_server/extlibs/boost/include -O3 -DNDEBUG -std=c++20 -fdiagnostics-color=always -Wall -Wextra -Wconversion -Wsign-conversion -Wfloat-equal -Wunreachable-code -Wunused-variable -Wshadow -Wcast-align -Werror -MD -MT CMakeFiles/BoostBeastServer.dir/main.cpp.o -MF CMakeFiles/BoostBeastServer.dir/main.cpp.o.d -o CMakeFiles/BoostBeastServer.dir/main.cpp.o -c /home/xxx/projects_cpp/boost_beast_server/main.cpp

Note that it compiles with gcc (-Werror active), only clangd thinks there is still a problem (Why does clangd consider the boost header code?).

CMake (Used version 3.29.1):

cmake_minimum_required(VERSION 3.20)
project(BoostBeastServer)

set(CMAKE_VERBOSE_MAKEFILE ON)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

set(BOOST_ROOT "${CMAKE_SOURCE_DIR}/extlibs/boost")

if(POLICY CMP0144)
  cmake_policy(SET CMP0144 NEW)
endif()

set(Boost_NO_SYSTEM_PATHS ON)

find_package(Boost 1.84.0 REQUIRED COMPONENTS system thread)

if(NOT Boost_FOUND)
    message(FATAL_ERROR "Boost not found")
endif()

message(STATUS "Boost_LIBRARIES: ${Boost_LIBRARIES}")

add_executable(${PROJECT_NAME} main.cpp)

target_compile_options(${PROJECT_NAME} PRIVATE
    -Wall
    -Wextra
    -Wconversion
    -Wsign-conversion
    -Wfloat-equal
    -Wunreachable-code
    -Wunused-variable
    -Wshadow
    -Wcast-align
    -Werror
)

target_include_directories(${PROJECT_NAME} SYSTEM PRIVATE ${Boost_INCLUDE_DIRS})

target_link_libraries(${PROJECT_NAME} PRIVATE ${Boost_LIBRARIES})

Possible solution:
To get rid of the warning, the following could help, but please review, as I only have dangerous half-knowledge here. After this at least the warning will go away:
[include/boost/core/detail/string_view.hpp]

enter image description here

Opened the following issue for this: https://github.com/boostorg/core/issues/170

Solution

  • @AlanBirtles's analysis is spot on, the warning is due to a sloppy conversion inside Boost Core std::string_view. Note that this is not a real issue unless you can deal with strings over 2^63 characters long.

    You can make a PR like https://github.com/sehe/core/commit/0d757123f136aff8f8ebed2c876ce7a2ccd28445 or just report the issue.

    Another solution is to make the include a system include, which makes the warnings silent.