Details
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Suggestion
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Resolution: Done
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Not Evaluated
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Qt Creator 4.13.3
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None
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- Ubuntu 20.04
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Linux/X11
Description
The Clang Code Model backend needs continuously restarting when using C++20 template lambdas. Here's a simple example:
CMakeLists.txt
cmake_minimum_required(VERSION 3.12)
project(scratch)
add_executable(scratch ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp)
target_compile_features(scratch PUBLIC cxx_std_20)
set_target_properties(scratch PROPERTIES CXX_EXTENSIONS OFF)
target_compile_options(scratch PRIVATE
$<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>,$<CXX_COMPILER_ID:GNU>>:
-Werror -Wall -Wextra>
$<$<CXX_COMPILER_ID:MSVC>:
/W4>
)
main.cpp:
#include <boost/mp11/algorithm.hpp> #include <tuple> #include <string> namespace { template <typename Tuple, typename F> constexpr void tuple_type_iterator(F&& f) { constexpr auto N = std::tuple_size_v<std::decay_t<Tuple>>; boost::mp11::mp_for_each<boost::mp11::mp_iota_c<N>>([&](auto i) { f.template operator()<std::tuple_element_t<i, Tuple>>(i); }); } } int main() { using Tuple = std::tuple<std::string, double, int>; tuple_type_iterator<Tuple>([]<typename T>(auto i) { static_assert(std::is_same_v<std::tuple_element_t<i, Tuple>, T>); }); return 0; }
Results in this kind of output in the 'General Messages' Pane:
2020-12-06T15:00:12 Clang Code Model: Error: The clangbackend process has finished unexpectedly and was restarted. 2020-12-06T15:00:13 Clang Code Model: Error: The clangbackend process has finished unexpectedly and was restarted. 2020-12-06T15:01:05 Clang Code Model: Error: The clangbackend process has finished unexpectedly and was restarted. 2020-12-06T15:01:06 Clang Code Model: Error: The clangbackend process has finished unexpectedly and was restarted. 2020-12-06T15:01:07 Clang Code Model: Error: The clangbackend process has finished unexpectedly and was restarted. 2020-12-06T15:01:08 Clang Code Model: Error: The clangbackend process has finished unexpectedly and was restarted.
Switching the code to use a non-template lambda allows it restart and run successfully.