考虑这个程序:
#include <iostream>
template<bool Debug = false, int Line = __LINE__>
constexpr int adds(const int& a, const int& b) {
if (Debug)
std::cout << __FUNCTION__ << " called on line " << Line << '\n';
return (a + b);
}
int main() {
std::cout << adds(3, 7) << '\n';
std::cout << adds<true, __LINE__> (5, 9) << '\n';
return 0;
}
当我尝试编译并构建它时Debug
模式 Visual Studio 2017 正在生成以下编译器错误:
1>------ Build started: Project: Simulator, Configuration: Debug x64 ------
1>main2.cpp
1>c:\***\main2.cpp(12): error C2672: 'adds': no matching overloaded function found
1>c:\***\main2.cpp(12): error C2975: 'Line': invalid template argument for 'adds', expected compile-time constant expression
1>c:\***\main2.cpp(3): note: see declaration of 'Line'
1>Done building project "Simulator.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
但是,当我在下面尝试这个时Release
mode:它编译、构建、运行并产生适当的输出:
10
adds called on line 12
14
这是 Visual Studio 2017 的潜在错误吗?如果不是,为什么它可以在一种模式下工作,而不能在另一种模式下工作?
你可以在这里看到它的编译结果:编译器资源管理器 https://godbolt.org/z/rvxnhK
以下是调试和发布模式的命令行标志的副本:
Debug
/JMC /permissive- /GS /W3 /Zc:wchar_t /Qspectre /ZI /Gm- /Od /sdl /Fd"x64\Debug\vc141.pdb" /Zc:inline /fp:precise /D "_DEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX- /Zc:forScope /RTC1 /Gd /MDd /std:c++latest /FC /Fa"x64\Debug\" /EHsc /nologo /Fo"x64\Debug\" /Fp"x64\Debug\Simulator.pch" /diagnostics:classic
Release
/permissive- /GS /GL /W3 /Gy /Zc:wchar_t /Qspectre /Zi /Gm- /O2 /sdl /Fd"x64\Release\vc141.pdb" /Zc:inline /fp:precise /D "NDEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX- /Zc:forScope /Gd /Oi /MD /std:c++latest /FC /Fa"x64\Release\" /EHsc /nologo /Fo"x64\Release\" /Fp"x64\Release\Simulator.pch" /diagnostics:classic