Consider code:
#include <stdio.h>
int main() {
int a = 4;
#if 1
printf("Hello world\n");
#endif a++;
printf("a is %d\n", a);
}
Inadvertently, statement a++; is on the same line as a #endif and is not evaluated. As a result, the final output is:
Hello world
a is 4
On x86-64 clang 12, this is captured as a warning with using option -Wextra-tokens. See here.
I tried compiling this on Visual Studio 2019 MSVC, with command line options:
/JMC /permissive- /ifcOutput "Debug\" /GS /analyze- /W3 /Zc:wchar_t /I"../include/" /ZI /Gm- /Od /sdl /Fd"Debug\vc142.pdb" /Zc:inline /D "WIN32" /D "_DEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX- /Zc:forScope /RTC1 /Gd /Oy- /MDd /FC /Fa"Debug\" /EHsc /nologo /Fo"Debug\" /Fp"Debug\windows.pch" /diagnostics:column
There is no warning of any sort on compilation. Is there a setting that can be passed to the compiler in MSVC that detects extra tokens?
Edited to add:
As answered by user Nathan Pierson, it was indeed option /Za that worked. It does not seem to be on by default. I was also unable to use the Visual Studio Project Properties dialog to find out the option to set. Yet, one can feed in extra options manually thus:
There's compiler warning C4067. It looks like you need to set the flag /Za for it to apply to #endif directives.
In the Visual Studio properties page, this flag is controlled by the setting "Disable Language Extensions" in the Language subsection of the C/C++ section.
Related
I have a solution with two one-source-file projects in it. Each file is:
#include <mosquitto.h>
The first compiles fine. The second says it cannot find a header. The source code in the second is identical to the first, so it is a mystery why it cannot compile.
Pre-compiled headers are not being used in either, so it is curious that the /Fp option is issued, I don't see how it can be playing a role.
/permissive- /ifcOutput "x64\Release\" /GS /GL /W3 /Gy /Zc:wchar_t /I"C:\Program Files\mosquitto2.0.14\devel" /Zi /Gm- /Od /sdl /Fd"x64\Release\vc143.pdb" /Zc:inline /fp:precise /D "NDEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX- /Zc:forScope /Gd /Oi /MD /FC /Fa"x64\Release\" /EHsc /nologo /Fo"x64\Release\" /Fp"x64\Release\Good.pch" /diagnostics:column
/permissive- /ifcOutput "x64\Release\" /GS /GL /W3 /Gy /Zc:wchar_t /I"C:\Program Files\mosquitto2.0.14\devel" /Zi /Gm- /O2 /sdl /Fd"x64\Release\vc143.pdb" /Zc:inline /fp:precise /D "NDEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX- /Zc:forScope /Gd /Oi /MD /FC /Fa"x64\Release\" /EHsc /nologo /Fo"x64\Release\" /Fp"x64\Release\Bad.pch" /diagnostics:column
Another user suggests posting the actual failed output.
Build started...
1>------ Build started: Project: Bad, Configuration: Debug x64 ------
1>Bad.cpp
1>T:\MyFirm\dev\MinorProjects\Bad\Bad.cpp(55,10): fatal error C1083: Cannot open include file: 'mosquitto.h': No such file or directory
1>Done building project "Bad.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
I turned on Tools->Options->Projects and Solutions->Build and Run->verbosity=Detailed, and compared the CL.exe commands issued.
To my surprise, the /I include option was NOT present on the failed build command, despite being in the Properties dialog "Command Line" page as pasted above.
The issue was that I was building in Debug, but for some reason the Properties dialog was editing Release options. So, while the "Command Line" page was showing the options that would be used were I building Release, they weren't used while building Debug.
According to Microsoft ( https://learn.microsoft.com/en-us/cpp/overview/visual-cpp-language-conformance?view=msvc-160 ), it implemented P1502R1 Standard library header units for C++20:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1502r1.html
in the latest Visual Studio 2019.
So one can write, e.g.:
import <vector>;
But if I do it in my Visual Studio 2019 16.10.3 (with /std:c++latest switch), the following compilation error arises:
error C7612: could not find header unit for 'C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector'
The complete command-line in Debug configuration:
/JMC /experimental:module /external:env:"EXTERNAL_INCLUDE" /permissive- /ifcOutput "x64\Debug\" /GS /W4 /Zc:wchar_t /ZI /Gm- /Od /sdl /Fd"x64\Debug\vc142.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\Project1.pch" /diagnostics:column
Please help how to activate this new feature in MSVC?
I downloaded the source code for a library that resembles the processing library but for c++ called libxd. I used CMake to generate project files for Visual Studio 2019 which worked successfully. When trying to compile the solution for all of the provided build modes, I get the following errors:
The first error invlaid numeric argument '/Wno-narrowing' is what I'm concerned about for now. I'm trying to figure out why this argument is being provided to the compiler. When looking in the properties window for the xd project in the solution I can see the command line arguments that are supposed to be provided to the compiler in the C/C++ > Command Line tab. I verified that there is no /Wno-narrowing option provided. When looking at the build output it can be seen that the option -Wno-narrowing is being provided to the compiler. Can someone help me figure out why this argument is being passed? I looked throughout the compiler properties window to see if I could see anything that would be affecting it but I can't see anything that would affect this.
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29910\bin\HostX64\x64\CL.exe /c /IC:\dev\libxd\include /IC:\dev\libxd\lib\glad\include /IC:\dev\libxd\lib\glm /IC:\dev\libxd\lib\stb\include /IC:\dev\libxd\lib\glfw\include /Zi /nologo /W3 /WX- /diagnostics:column /Od /Ob0 /D WIN32 /D _WINDOWS /D "CMAKE_INTDIR=\"Debug\"" /D _MBCS /Gm- /EHsc /RTC1 /MDd /GS /fp:precise /Zc:wchar_t /Zc:forScope /Zc:inline /GR /Fo"xd.dir\Debug\\" /Fd"xd.dir\Debug\xd.pdb" /Gd /TP /errorReport:prompt -Wno-narrowing C:\dev\libxd\src\opensans.cpp
Tracking command:
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Current\Bin\Tracker.exe /d "C:\Program Files (x86)\MSBuild\15.0\FileTracker\FileTracker32.dll" /i C:\dev\libxd\build\xd.dir\Debug\xd.tlog /r C:\DEV\LIBXD\SRC\OPENSANS.CPP /b MSBuildConsole_CancelEventfa83e1bb599743cfa0c02eb67d579e28 /c "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29910\bin\HostX64\x64\CL.exe" /c /IC:\dev\Users\olive\Downloads\libxd\include /IC:\dev\libxd\lib\glad\include /IC:\dev\libxd\lib\glm /IC:\dev\libxd\lib\stb\include /IC:\dev\libxd\lib\glfw\include /Zi /nologo /W3 /WX- /diagnostics:column /Od /Ob0 /D WIN32 /D _WINDOWS /D "CMAKE_INTDIR=\"Debug\"" /D _MBCS /Gm- /EHsc /RTC1 /MDd /GS /fp:precise /Zc:wchar_t /Zc:forScope /Zc:inline /GR /Fo"xd.dir\Debug\\" /Fd"xd.dir\Debug\xd.pdb" /Gd /TP /errorReport:prompt -Wno-narrowing C:\dev\libxd\src\opensans.cpp
cl : command line error D8021: invalid numeric argument '/Wno-narrowing'
The command exited with code 2.
The error is caused because that's not a valid MSVC flag. The flag is there because the CMakeLists.txt file demands it:
set_source_files_properties(src/opensans.cpp PROPERTIES COMPILE_FLAGS -Wno-narrowing)
That project specifies what it supports for building under Windows and it's not MSVC.
Windows Prerequisites: mingw-w64 version >= 4.8.1
So you either need to build it in the supported way, or modify the build scripts to allow for MSVC.
That would entail figuring out what the flag does in gcc (disables diagnostic messages about narrowing issues) and finding the equivalent in MSVC, probably a /disable:nnnn variant, once you figure out the nnnn. Figuring that out should be relatively painless since MSVC will tell you that when you compile it - lots of Cnnnn - something to do with narrowing warning messages.
Or you could just disable the line that adds the flag (for MSVC builds only) and see if it still builds. Of course, in the spirit of open source, you should then notify the author what it took to get it going, they may be happy to support MSVC if the effort is not too high.
I'm trying to build my dll file as x64, here are the configurations I have done on VisualStudio:
I have set solution and project platform to x64:
According to this answer, I have changed naming convention from __cdecl to __fastcall:
According to this comment I have added the argument _WIN64 to Preprocessor Definitions:
But still, when I rebuild my project and open my dll file using notepad, I see PE L which means my dll file is 32 bit.
Here's the command line options of the C/C++ settings (for better reading, I put a couple of line breaks in there):
/JMC /permissive- /GS /W3 /Zc:wchar_t /ZI /Gm- /Od /sdl
/Fd"x64\Debug\vc142.pdb" /Zc:inline /fp:precise /D "_WIN64" /D "_DEBUG" /D
"_CONSOLE" /D "_WINDLL" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX-
/Zc:forScope /RTC1 /Gr /MDd /FC /Fa"x64\Debug\" /EHsc /nologo /Fo"x64\Debug\"
/Fp"x64\Debug\DllCall-CppConsoleApp-1.pch" /diagnostics:column
Linker settings:
What should I do?
I'm trying the code example for resumable functions in Visual Studio 2015 RC from this MSDN link.
#include<iostream>
#include<experimental/generator>
auto hello()
{
for (auto ch : "Hello, world\n")
yield ch;
}
int main()
{
for (auto ch : hello())
std::cout << ch;
}
So far, no matter what my compiler settings are, the code causes an access violation exception when run.
Here are my compiler flags:
/Yu"stdafx.h" /GS- /W3 /Zc:wchar_t /ZI /Gm /Od /sdl- /Fd"x64\Debug\vc140.pdb" /Zc:inline /fp:precise /D "WIN32" /D "_DEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX- /Zc:forScope /Gd /MDd /Fa"x64\Debug\" /EHsc /nologo /Fo"x64\Debug\" /Fp"x64\Debug\Test.pch"
Anyone figure out how to get it working?
I got a response from a comment on the original MSDN link. The problem is with the /ZI flag (program database for edit and continue) which is not supported yet. Switching to /Zi works.