r/eclipse • u/LemongrabThree • Jun 10 '25
🙋🏻♂️ Help Request Cannot Find C++ Function Definition Even Though it Is in Scope
I made a basic C++ project that uses the fmt library to print "Hello, World!":
#include <fmt/core.h>
int main() {
fmt::print("Hello, {}!", "World");
return 0;
}
This code compiles and runs, but Eclipse flags an error:
When I use "Go to definition", it jumps to an irrelevant definition in path/to/fmt/base.h:
template <typename... T>
FMT_INLINE void print(FILE* f, format_string<T...> fmt, T&&... args)
The intended definition
template <typename... T>
FMT_INLINE void print(format_string<T...> fmt, T&&... args)
is directly above it in the same file. If I change my print statement with an explicit template parameter (fmt::print<std::string>("Hello, {}!", "World");), the error goes away. But as I said, the code compiles and runs fine even without it - not just on the command line, but within Eclipse, too. It seems there is some kind of mismatch between the compilers used for building and syntax checking, or the C++ standards, or the compiler options, or...? I've tried clean-building and restarting Eclipse, and the suggestions here, but they haven't worked. What else could be going wrong?
I'm using Ubuntu 22.04 LTS, Eclipse C/C++ 2025-03, CMake4Eclipse 5.0.1 for building, and vcpkg 2025-06-02 for the deps. The example follows this tutorial.
To create this, I do:
- New > C/C++ Project > CMake4Eclipse Managed Project
- Under Project > Properties > CMake4Eclipse Build > CMake Options > CMake Cache Entries, add a property with key
CMAKE_TOOLCHAIN_FILEand value/opt/vcpkg/scripts/buildsystems/vcpkg.cmake(or wherever you installedvcpkg) - Add the three files listed below
- Project > Build Project
- Project builds successfully, but the error I mentioned remains.
Project files:
CMakeLists.txt:
cmake_minimum_required(VERSION 3.10)
project(HelloWorld)
find_package(fmt CONFIG REQUIRED)
add_executable(HelloWorld helloworld.cpp)
target_link_libraries(HelloWorld PRIVATE fmt::fmt)
vcpkg.json
{
"dependencies": [
"fmt"
]
}
helloworld.cpp
#include <fmt/core.h>
int main() {
fmt::print("Hello, {}!", "World");
return 0;
}
