fatal error at GetCXXRecordDclFromBaseType in Parser.cpp

[r-schmitt]

Brief Description

We are attempting to use CppSharp to bind Pixar's USD library to C# to hopefully enable a great development environment for USD in C#

On first pass, we got about a 50% success rate, almost all the failures were here:
Parser.cpp line 884

These fatal parsing errors prevent us from generating any output, but I have unable to identify what specifically is breaking at this point. Any help identifying how we can avoid this error would be awesome! I've been very happy with what we've been able to generate successfully...

OS: Windows 10

Used headers

pxr/usd/sdf/path.h
pxr/usd/usd/prim.h
pxr/usd/usd/stage.h

these are three examples, representing a lot of core USD functionality

Used settings

DriverOptions options = driver.Options;
options.GeneratorKind = GeneratorKind.CSharp;
options.Verbose = true;
options.GenerationOutputMode = GenerationOutputMode.FilePerUnit;

Other settings
USD was exported with the cmake flag set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON) which is important for getting all the mangled names exported for bindings, but not needed for these parsing errors

[tritao]

Sounds like an interesting bindings.

Don't have time right now to properly repro and test this, but based on looking where the code fails, I've pushed some changes that hopefully will help with the crash: #1751

Let me know how it goes with the new version.

[r-schmitt]

thanks, unfortunately that has just pushed the error to a new location:

Exception thrown: read access violation.
*(clang::TemplateName::getAsTemplateDecl(...)) was nullptr.

at Parser.cpp line 901

[tritao]

thanks, unfortunately that has just pushed the error to a new location:

Exception thrown: read access violation. *(clang::TemplateName::getAsTemplateDecl(...)) was nullptr.

at Parser.cpp line 901

Can you try making the following changes to Parser.cpp:GetCXXRecordDeclFromTemplateName:

First try adding Name.dump(); to the start of the function, hopefully when you run it it will give you the offending piece of code that makes it crash and we can take a look at what's going on.

Then try replacing the case clang::TemplateName::Template case:

    case clang::TemplateName::Template:
    {
        if (auto TD = Name.getAsTemplateDecl())
            return dyn_cast<clang::CXXRecordDecl>(TD->getTemplatedDecl());
        else
            return nullptr;
    }

Hopefully that works around it / fixes it.

[r-schmitt]

Name.dump() was helpful, it looks like its coming from std::enable_if which is being used for several template functions. is there a way to ignore functions that use std::enable_if or ignore all template functions?

still hitting the error though with the code change

[r-schmitt]

update, after trying to bind std::optional which hits the same error, it looks like the error is actually during the parsing of Allocator

[r-schmitt]

@tritao do you have any updates? we're blocked at the moment due to this, but would still very much like to use this if we can

[tritao]

@tritao do you have any updates? we're blocked at the moment due to this, but would still very much like to use this if we can

No updates on my side, I can try to take a look next time I got some free time, but I need a test case. It would really help if you can help get me an isolated test case that can trigger this issue.

[r-schmitt]

thanks, any of the three headers listed in my fist post will trigger it

[tritao]

Ok, those are not self contained tests, ideally we have something that is only a dozen lines or so and can be included in the test suite. Usually we would start with a self-contained header (after using the preprocessing option on the compiler, so no further includes are needed), then start removing code until we as minimal repro as possible.

[r-schmitt]

float getOptionalFloat(std::optional<float> optionalFloat)
{
    if(optionalFloat.has_value())
    {
        return optionalFloat.value();
    }
    else
    {
        return 0.0f;
    }
}

that should trigger it

also if we cannot fix the error, any guidance on ignoring template functions during parsing would be great

[tritao]

Ok cool, thanks, I will try to repro that later.

[tritao]

@r-schmitt Btw which VS version are you using?

[r-schmitt]

i built cppsharp with 2019, but im running the bindings in 2022

[tritao]

float getOptionalFloat(std::optional<float> optionalFloat)
{
    if(optionalFloat.has_value())
    {
        return optionalFloat.value();
    }
    else
    {
        return 0.0f;
    }
}

that should trigger it

also if we cannot fix the error, any guidance on ignoring template functions during parsing would be great

Just tried to parse this with latest CppSharp in VS2019 and can't repro it.

[r-schmitt]

could you outline your build process/MSVC version/LLVM version and cppsharp settings/.net version? i still get this error, so maybe its a mis-configuration somwhere in my build process