Just a thought. Can dmd demangle the symbols before spitting the output of ld to stderr?

On Thursday, 31 August 2017 at 02:20:00 UTC, Arun Chandrasekaran wrote:
> Just a thought. Can dmd demangle the symbols before spitting the output of ld to stderr?

dmd doesn't print the output of ld to stderr, ld does.

I believe binutils has some support for D symbol demangling thanks to the GDC folks.  I tried it once:  http://forum.dlang.org/post/bdmsrcczmizevhxorquo@forum.dlang.org

So I think you need to find a way to pass --demangle=dlang to ld.  Maybe `dmd program.d -L--demangle=dlang`?

Mike

Arun Chandrasekaran wrote:

> Just a thought. Can dmd demangle the symbols before spitting the output of ld to stderr?

no need to ;-) just add this to DFLAGS in dmd.conf, "Envirnment" section:

-L--demangle=dlang

so, it should look something like this:

..
[Environment]
DFLAGS=<your flags here> -L--demangle=dlang
..

due to hard work of Iain Buclaw, gdb and binutils (ld, objdump, etc.) are able to demangle DMD names.

note that new DMD version *may* include slightly changed mangling scheme, so the latest betas *may* produce "undecipherable" names.

Arun Chandrasekaran wrote:

> Just a thought. Can dmd demangle the symbols before spitting the output of ld to stderr?

p.s.: redirecting output to ddemangle may work too, as ddemange will try to detect mangled DMD names, and won't modify other text. this way you can, for example, demangle names in valgrind output.

On Thursday, 31 August 2017 at 02:31:24 UTC, Michael V. Franklin wrote:
> On Thursday, 31 August 2017 at 02:20:00 UTC, Arun Chandrasekaran wrote:
>> Just a thought. Can dmd demangle the symbols before spitting the output of ld to stderr?
>
> dmd doesn't print the output of ld to stderr, ld does.
>
> I believe binutils has some support for D symbol demangling thanks to the GDC folks.  I tried it once:  http://forum.dlang.org/post/bdmsrcczmizevhxorquo@forum.dlang.org
>
> So I think you need to find a way to pass --demangle=dlang to ld.
>  Maybe `dmd program.d -L--demangle=dlang`?
>
> Mike

Thanks Mike.

I was looking at src/ddmd/link.d, has the below that reads the output of ld. So I was wondering if we can plugin the demangle logic in this function. Nevertheless, good to know the linker already supports it.

```
    private int findNoMainError(int fd)
    {
        version (OSX)
        {
            static __gshared const(char)* nmeErrorMessage = "\"__Dmain\", referenced from:";
        }
        else
        {
            static __gshared const(char)* nmeErrorMessage = "undefined reference to `_Dmain'";
        }
        FILE* stream = fdopen(fd, "r");
        if (stream is null)
            return -1;
        const(size_t) len = 64 * 1024 - 1;
        char[len + 1] buffer; // + '\0'
        size_t beg = 0, end = len;
        bool nmeFound = false;
        for (;;)
        {
            // read linker output
            const(size_t) n = fread(&buffer[beg], 1, len - beg, stream);
            if (beg + n < len && ferror(stream))
                return -1;
            buffer[(end = beg + n)] = '\0';
            // search error message, stop at last complete line
            const(char)* lastSep = strrchr(buffer.ptr, '\n');
            if (lastSep)
                buffer[(end = lastSep - &buffer[0])] = '\0';
            if (strstr(&buffer[0], nmeErrorMessage))
                nmeFound = true;
            if (lastSep)
                buffer[end++] = '\n';
            if (fwrite(&buffer[0], 1, end, stderr) < end)
                return -1;
            if (beg + n < len && feof(stream))
                break;
            // copy over truncated last line
            memcpy(&buffer[0], &buffer[end], (beg = len - end));
        }
        return nmeFound ? 1 : 0;
    }
```

On Thursday, 31 August 2017 at 02:51:25 UTC, Arun Chandrasekaran wrote:

> I was looking at src/ddmd/link.d, has the below that reads the output of ld.

Ah, right you are.  My apologies.

It'd probably be simple enough to have that demangling on by default.  Maybe I'll give it a go later today.  What's your use case? Just getting unresolved symbols?

Mike

On Thursday, 31 August 2017 at 03:58:14 UTC, Michael V. Franklin wrote:

> Just getting unresolved symbols?

Yeah, I was just wondering what if the output can be readable, given that dmd is the one that invokes ld. Would be much more human readable without piping through ddemangle. Thanks.