Improve error message for "function is not callable using argument"

[Paul Backus]

On Sunday, 2 April 2023 at 13:43:59 UTC, ryuukk_ wrote:
> ```
> Error: function `proxy.injector.RemoteLibraryFunction(void* 
> hProcess, const(wchar)* lpModuleName, const(wchar)* lpProcName, 
> void* lpParameters, ulong dwParamSize, void** ppReturn)` is not 
> callable using argument
> types `(void*, const(wchar)*, wchar[512], void*, int, void**)`
> ```
>
> While writing this post i just remembered that i attempted a PR 
> few years ago: https://github.com/dlang/dmd/pull/13366
>
> This is always painful to read/decipher, can this error be 
> improved?
>
> At least colors/arrows to tell me wich argument(s) are wrong
>
> Perhaps on a new line?
>
> Unfortunately, I have no ideas how to improve it, anyone mind 
> helping me?
>
> Thanks!

I attempted to reproduce your issue using the following example 
code:

```d
void RemoteLibraryFunction(
     void* hProcess,
     const(wchar)* lpModuleName,
     const(wchar)* lpProcName,
     void* lpParameters,
     ulong dwParamSize,
     void** ppReturn
);

void main()
{
     void* vp;
     const(wchar)* cwcp;
     wchar[512] wca;
     int n;
     void** vpp;

     RemoteLibraryFunction(vp, cwcp, wca, vp, n, vpp);
}
```

Attempting to compile this code with DMD v2.102.2 produced the 
following output:

```
example.d(18): Error: function 
`example.RemoteLibraryFunction(void* hProcess, const(wchar)* 
lpModuleName, const(wchar)* lpProcName, void* lpParameters, ulong 
dwParamSize, void** ppReturn)` is not callable using argument 
types `(void*, const(wchar)*, wchar[512], void*, int, void**)`
example.d(18):        cannot pass argument `wca` of type 
`wchar[512]` to parameter `const(wchar)* lpProcName`
```

Note the last line, which points out the specific argument that 
does not match. According to the changelog, that line was added 
in DMD v2.079.0:

https://dlang.org/changelog/2.079.0.html#argument-mismatch

So, unless you are using an extremely old D compiler, you should 
be seeing that line in your compiler's output.