C++ Extractor freezes when reading specific code pattern #16094
Description
We've had trouble with CodeQL freezing when reading some old C++ code.
Here is a very minimalist example of code that can trigger this behavior:
char *Foo(size_t &size, char *target)
{
return target ? target : (char *)(size = 0, 0);
}If you compile this with the MSVC compiler (cl /c test.cpp), everything is fine.
But when running it in the database create command, extractor.exe seems to get stuck in a busy loop.
e.g:
.\codeql\codeql database create db --language=cpp --command="cl /c test.cpp"
A process with path: \codeql\cpp\tools\win64\extractor.exe and args --mimic "c:\program files\microsoft visual studio\2022\professional\vc\tools\msvc\14.39.33519\bin\hostx86\x86\cl.exe" /c test.cpp
is running indefinitely, using exactly 1 CPU core, and is not performing any operations that show up in "Process Monitor".
This is not a new issue. We have observed the same problem with older versions of the compiler and of CodeQL ever since we started using it, so I cannot say when this issue was introduced.
I have attached the log files from the CodeQL database:
log.zip
OS: Windows 10
Compiler: MSVC 14.39 (As part of Visual Studio Professional 17.9.5)
CodeQL Version: 2.16.6 (https://github.com/github/codeql-action/releases/download/codeql-bundle-v2.16.6/codeql-bundle-win64.tar.gz)
Please let me know if you need any more info.