Open andylizf opened 1 year ago
Maybe related to #3974 and fixed by #3975.
Is it fixed now? BTW, how to use the new version in xmake?
it's not fixed, I got this compilation error as well with single include and modules. It looks kinda weird, not sure why this line in particular errors but not the one above which is almost identical.
same issue in version 3.11.3
I have the issue, 3.11.3, Visual Studio, using C++20 modules.
The issue is not an issue with nlohmann/json, but rather MSVC compiler. I get the same issue with c42f/tinyformat. The compiler does not like something in the header and I just have not yet figured out what it is.
You can work around it if you add a "compilation firewall" by defining an interface in a header and shoving the include in a regular cpp. Too bad both libraries rely heavily on template to make the client code nice and small.
I'm having a similar issue when trying to include nlohmann/json.hpp
within a C++ module file.
Dev Attribube | Value |
---|---|
Visual Studio Version: | 17.10.0 Preview 7.0 |
Windows SDK Version: | 10.0 |
Platform Toolset: | Visual Studio 2022 (v143) |
C++ Language Standard: | Preview - Features from the Latest C++ Working Draft (/std:c++latest) |
nlohmann-json | Version: 3.11.3 |
The following section of my code:
nlohmann::json config = {
{"Version", "x.x.x.d"}
};
Provides the error:
>Main.cpp
> *\vcpkg_installed\x64 - windows\x64 - windows\include\nlohmann\json.hpp(120, 38) : error C2039 : 'json_sax_dom_callback_parser' : is not a member of 'nlohmann::json_abi_v3_11_3::detail'
I'm in a greenfield project and would love to be able to use this library to parse and export json data.
@rioki, are you able to expand on your temporary fix until either this library or MSVC have a solution?
Many thanks.
For my project I moved to jsoncpp, which has been working fine with a module wrapper that I made.
@JamieSharpe I dropped modules altogether for the time being. I ran into 1001 issues like this. I will revisit modules in a year or two. Looks promising, not there yet.
The issue is not an issue with nlohmann/json, but rather MSVC compiler. I get the same issue with c42f/tinyformat. The compiler does not like something in the header and I just have not yet figured out what it is.
You can work around it if you add a "compilation firewall" by defining an interface in a header and shoving the include in a regular cpp. Too bad both libraries rely heavily on template to make the client code nice and small.
Exactly how did you implement the compilation firewall? Perhaps you can show some code. I'm getting compilation errors when I try to do it. :/
Exactly how did you implement the compilation firewall? Perhaps you can show some code. I'm getting compilation errors when I try to do it. :/
For me the following works:
JSONTools.ixx
module;
#include <filesystem>
export module JSONTools;
import DataDefs; // defines A
namespace myns
{
export class JSONTools final
{
public:
static A readA(const std::filesystem::path& filePath);
static void writeA(const std::filesystem::path& filePath, const A& a);
private:
JSONTools() = delete;
JSONTools(const JSONTools&) = delete;
JSONTools(JSONTools&&) = delete;
};
} // namespace myns
DataDefs.cpp
module;
#include <fstream>
#include <nlohmann/json.hpp>
module JSONTools;
import DataDefs;
namespace myns
{
A JSONTools::readA(const std::filesystem::path& filePath);
{
std::string fileContent = readTxt(filePath); // readTxt defined somewhere else
nlohmann::json jsonContent = nlohmann::json::parse(fileContent);
A result{};
A.setVersion(jsonContent["version"].get<int>());
// Fill A with the data read from the json
return result;
}
void JSONTools::writeA(const std::filesystem::path& filePath, const A& a);
{
auto oFile = std::make_unique<std::ofstream>(filePath, std::ios::ate);
nlohmann::json jsonOutput;
jsonOutput["version"] = 1;
// add some more content to json file
(*oFile) << jsonOutput;
}
} // myns
CMakeLists.txt
project(JSONTools CXX)
find_package(nlohmann_json CONFIG REQUIRED)
set(INTERFACE_LIST
JSONTools.ixx
)
set(SOURCE_LIST
DataDefs.cpp
)
add_library(${PROJECT_NAME})
target_sources(${PROJECT_NAME}
PRIVATE
${SOURCE_LIST}
PUBLIC
FILE_SET CXX_MODULES
FILES ${INTERFACE_LIST}
)
target_link_libraries(${PROJECT_NAME}
PRIVATE
DataDefs
nlohmann_json::nlohmann_json
)
For every other module I am just importing JSONTools
in the target_link_libraries
section of the corresponding CMakeLists.txt
Description
Importing a module file using the lib will cause a compilation error.
Reproduction steps
Codes below.
Expected vs. actual results
To compile successfully.
Minimal code example
network.ixx:
main.cpp:
Error messages
Compiler and operating system
Visual Studio 17 2022 MSVC 19.36.32323; Windows-10.0.22624
Library version
3.11.2
Validation
develop
branch is used.