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[CPP][Questions]No effective API to qeury macro used in function parameter declaration

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Descrição

Hello all,

Recently I'm interested in writing queries to detect common vulnerability pattern specific for Linux kernel codebase. I find that `__user` marco is used to indicate parameter is user mode pointer, for example
```cpp
#define __user //empty macro body

static int sg_scsi_ioctl(struct request_queue *q, fmode_t mode,
struct scsi_ioctl_command __user *sic) //sic is a user mode pointer
```

I want to write a query to get all user mode pointer defined in function parameter declaration, I tried to find avaliable API defined in `Marco/MacroAccess/MarcoInovation/Function/Function/FunctionDeclarationEntry/ParameterDeclarationEntry`, but I can not find one can be used for my purpose.

I have no way but to query macro used in function parameter declaration by combining `MacroAccess` and `Location`, the following code may be work, but it prone to be false positive and ugly:(

```ql
class UserParameterDeclarationEntry extends ParameterDeclarationEntry{
UserParameterDeclarationEntry(){
exists(MacroAccess m|
m.getMacroName() = "__user"
and m.getFile() = this.getFile()
and m.getLocation().getEndLine() = this.getLocation().getEndLine()
)
}
}
```

So I hope you guys can be kind enougth to help me find a more effective way to query specific macro in function parameter declaration, thank you:)

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