nmap / nmap/npcap

Compiling 'Packet32.cpp' with '-std:c++20'

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Dominant language
C
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Description

The default C++ standard in cl is C++14. And using that for packetWin7/Dll/Packet32.cpp works fine.
But using -std:c++20 or -std:c++latest does not. This is what I did:

cd packetWin7\Dll\Project
set CL=-std:c++20
msbuild -nologo -p:Configuration=Release -p:Platform="x64" Packet.sln

The errors generated by MSVC version 19.42.34321.1 for x64 (the latest):

Packet32.cpp(414): error C2362: initialization of 'nFields' is skipped by 'goto Exit'
Packet32.cpp(422): note: see declaration of 'Exit'
Packet32.cpp(3369): error C2362: initialization of 'numEntries' is skipped by 'goto END_PacketGetNetInfoEx'
Packet32.cpp(3417): note: see declaration of 'END_PacketGetNetInfoEx'
Packet32.cpp(3368): error C2362: initialization of 'pAddr' is skipped by 'goto END_PacketGetNetInfoEx'
Packet32.cpp(3417): note: see declaration of 'END_PacketGetNetInfoEx'
Packet32.cpp(3314): error C2362: initialization of 'RetVal' is skipped by 'goto END_PacketGetNetInfoEx'
Packet32.cpp(3417): note: see declaration of 'END_PacketGetNetInfoEx'
Packet32.cpp(3301): error C2362: initialization of 'AdapterGuid' is skipped by 'goto END_PacketGetNetInfoEx'
Packet32.cpp(3417): note: see declaration of 'END_PacketGetNetInfoEx'

Googling this issue seems to be related to option /Za which is not in use.

And further, using -std:c++20 or -std:c++latest with clang-cl ver. 18.1 works just fine.
So I'm not sure what is the real issue with the Packet32.cpp code.

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Research direction

Reproduce the failure from packetWin7\Dll\Project with MSBuild and MSVC 19.42 using CL=-std:c++20, then inspect the reported declarations and goto labels in packetWin7/Dll/Packet32.cpp. Compare the MSVC result with clang-cl 18.1. Done means Packet.sln builds for x64 Release under C++20 or C++latest without the listed C2362 errors.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
networking, operating-systems
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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