Executable compiled with Visual Studio 2019 and NuGet package 1.9.8 in Debug configuration throws exception

[DonChunior]

Description

I'm using following simple example code:

#include <cpr/cpr.h>

int main() {
    cpr::Response r = cpr::Get(cpr::Url{"https://example.com/"});
}

Building the executable works with all combinations:

• Debug + x86 = 🆗
• Debug + x64 = 🆗
• Release + x86 = 🆗
• Release + x64 = 🆗

But executing does only work for the Release builds.
The Debug builds throw an error:

Exception thrown at 0x00007FFD9A0B3240 (msvcp140d.dll) in my_example.exe: 0xC0000005: Access violation reading location 0x0000000000000000.

When the exception is thrown, Visual Studio jumps to line 58 of the file ...\packages\libcpr.1.9.8\build\native\x64\Debug\include\cpr\api.h:

template <typename... Ts>                               // Line 56
Response Get(Ts&&... ts) {                              // Line 57
    Session session;                                    // Line 58 <-- Visual Studio jumps to here when exception is thrown
    priv::set_option(session, std::forward<Ts>(ts)...); // Line 59
    return session.Get();                               // Line 60
}                                                       // Line 61

Example/How to Reproduce

1. Create new, empty C++ project in Visual Studio 2019.
2. Add a C++ file with the example code above.
3. Install version 1.9.8 of the libcpr NuGet package.
4. Choose Debug as configuration and x64 as platform.
5. Press the key F7 to build the executable.
6. Press the key F5 to start debugging.

Possible Fix

No response

Where did you get it from?

NuGet

Additional Context/Your Environment

• OS: Windows 10
• OS Version: Version 22H2 (Build 19045.5131)
• IDE: Visual Studio Professional 2019
• IDE Version: Version 16.11.42

[DonChunior]

Today I tested the behaviour on my private home computer:

• OS: Windows 10
• OS Version: 22H2 (Build 19045.5131)
• IDE: Visual Studio Community 2019
• IDE Version: 16.11.42

Building the executable again works with all combinations of configurations and platforms.

But executing only works for the Release x64 build.
Debug x86, Debug x64 and Release x86 throw the previously mentioned exception.

[COM8]

@DonChunior thanks for reporting! I will try to look into this.

[DonChunior]

Hello @COM8,

thanks, I would appreciate it very much if there would be a fix for my problem in the 1.9.x version, because I am bound to the standard C++14 due to dependencies to other libraries.
Therefore I can't use a newer cpr version which already relies on C++17 features.

[COM8]

@DonChunior I can not reproduce your issue in VS 2022.

I used:

Microsoft Visual Studio Community 2022 (64-bit) - Current
Version 17.11.6

Bot, Release and Debug compile and execute with cpr 1.9.8. Do you mind sharing an example solution for me to reproduce this?

[DonChunior]

Hello @COM8,

When developing plugins for a CAD system, I am bound to Visual Studio version 2019 by the software manufacturer of the CAD system.
Otherwise, I will not receive any technical support for problems with the CAD API.
Therefore, unfortunately, I cannot update to a newer Visual Studio version until further notice.

[COM8]

@DonChunior thanks for clarifying! Let me see if I can install VS2019 and retest...

[COM8]

OK, finally I was able to install VS2019...
Luckily I found an old VS2019 Community installer in my downloads archive else I would have failed to find a way how to download the VS2019 Community installer...

Looks like there is no community version for old releases available any more...

I would have had to subscribe to professional or enterprise. WTF?!

Well... I released 1.9.9-alpha1 which is build using VS2019.
I tried all kind of combinations like c++ standard, runtime version, compiler version, ...
Nothing worked. Looks like it needs to be build with VS2019.

Please let me know if it works.

[COM8]

#1160

[DonChunior]

Hi @COM8,

I'm glad to tell you, that with 1.9.9-alpha1 the problem I had is solved and the exceptions don't appear anymore! 😃

[COM8]

Awesome! Glad to hear. I will make a final 1.9.9 release over the next couple of days. This will most likely also be ported to master.