I've been looking at the objects etcetera produced by dmd, and using D's function demangle in std.demangle to decrypt some of the symbols found in such objects by nm.

http://sourceware.org/binutils/docs-2.22/binutils/nm.html

While demangle does produce a demangled version of some symbols, it does not in other cases where they nevertheless look as if they may be mangled names of some kind. I considered that perhaps they are C++ mangled names, but have been unable to get nm to unmangle them, even though it nominally knows about C++ name mangling.

Is there a better analog of demangle I can use to translate back some of these more intractable mangled names? I tried the one in core.demangle but it did no better. Or is there somewhere I could determine the demangling rules and implement them for myself? Any suggestions will be gratefully received.

Here are some examples that are not demangled by std.demangle.demangle :

_D13libd_demangle12__ModuleInfoZ
_D15TypeInfo_Struct6__vtblZ
_D3std5stdio12__ModuleInfoZ
_D3std6traits15__T8DemangleTkZ8Demangle6__initZ
_D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ

On Aug 20, 2012, at 1:45 PM, Carl Sturtivant <sturtivant@gmail.com> wrote:

> I've been looking at the objects etcetera produced by dmd, and using D's function demangle in std.demangle to decrypt some of the symbols found in such objects by nm.
> 
> http://sourceware.org/binutils/docs-2.22/binutils/nm.html
> 
> While demangle does produce a demangled version of some symbols, it does not in other cases where they nevertheless look as if they may be mangled names of some kind. I considered that perhaps they are C++ mangled names, but have been unable to get nm to unmangle them, even though it nominally knows about C++ name mangling.
> 
> Is there a better analog of demangle I can use to translate back some of these more intractable mangled names? I tried the one in core.demangle but it did no better. Or is there somewhere I could determine the demangling rules and implement them for myself? Any suggestions will be gratefully received.

std.demangle calls core.demangle, so it's no surprise that you got the same result.


> Here are some examples that are not demangled by std.demangle.demangle :
> 
> _D13libd_demangle12__ModuleInfoZ
> _D15TypeInfo_Struct6__vtblZ
> _D3std5stdio12__ModuleInfoZ
> _D3std6traits15__T8DemangleTkZ8Demangle6__initZ
> _D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ

demangle is currently designed to demangle functions names, while the strings above are types.  During parsing, demangle sees the string as a qualified name and then expects a type, and when it doesn't find one it figures the symbol isn't valid.  It sounds like we either need a separate function for demangling types or if the demangle function encounters a 'Z' when it expects a type name it should realize it's demangling a type name, back up, and try again according to that logic.  I suggest submitting a ticket.

To learn how the demangler works, the easiest thing is to copy core.demangle into your workspace and compile a small app with it directly, turning on the debug info.  For example:

module abc;
import demangle_;
import std.stdio;

void main() {
	writeln(decodeDmdString("_D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ"));
}

$ dmd abc -debug=trace -debug=info demangle

>> _D13libd_demangle12__ModuleInfoZ
>> _D15TypeInfo_Struct6__vtblZ
>> _D3std5stdio12__ModuleInfoZ
>> _D3std6traits15__T8DemangleTkZ8Demangle6__initZ
>> _D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ
>
> demangle is currently designed to demangle functions names, while the strings above are types.  During parsing, demangle sees the string as a qualified name and then expects a type, and when it doesn't find one it figures the symbol isn't valid.
>  It sounds like we either need a separate function for demangling types or if the demangle function encounters a 'Z' when it expects a type name it should realize it's demangling a type name, back up, and try again according to that logic.  I suggest submitting a ticket.
>
> To learn how the demangler works, the easiest thing is to copy core.demangle into your workspace and compile a small app with it directly, turning on the debug info.  For example:
>
> module abc;
> import demangle_;
> import std.stdio;
>
> void main() {
> 	writeln(decodeDmdString("_D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ"));
> }
>
> $ dmd abc -debug=trace -debug=info demangle

Thanks, I'll do that. (Odd, my original post vanished from the thread.)

> demangle is currently designed to demangle functions names, while the strings above are types.  During parsing, demangle sees the string as a qualified name and then expects a type, and when it doesn't find one it figures the symbol isn't valid.
>  It sounds like we either need a separate function for demangling types or if the demangle function encounters a 'Z' when it expects a type name it should realize it's demangling a type name, back up, and try again according to that logic.  I suggest submitting a ticket.

I submitted a ticket along these lines.

>> Here are some examples that are not demangled by std.demangle.demangle :
>> 
>> _D13libd_demangle12__ModuleInfoZ
>> _D15TypeInfo_Struct6__vtblZ
>> _D3std5stdio12__ModuleInfoZ
>> _D3std6traits15__T8DemangleTkZ8Demangle6__initZ
>> _D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ
>
> demangle is currently designed to demangle functions names, while the strings above are types.  During parsing, demangle sees the string as a qualified name and then expects a type, and when it doesn't find one it figures the symbol isn't valid.
>  It sounds like we either need a separate function for demangling types or if the demangle function encounters a 'Z' when it expects a type name it should realize it's demangling a type name, back up, and try again according to that logic.

OK, so as a practical matter, I'd like to be able to demangle these types that appear as symbols in object &c. files. Is there a simple way I can modify a mangled type such as

_D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ

into a mangled qualified name so it can be demangled by the existing demangle function and the result then modified into a string representing a type?

On Sunday, 26 August 2012 at 19:24:03 UTC, Carl Sturtivant wrote:
>>> Here are some examples that are not demangled by std.demangle.demangle :
>>> 
>>> _D13libd_demangle12__ModuleInfoZ
>>> _D15TypeInfo_Struct6__vtblZ
>>> _D3std5stdio12__ModuleInfoZ
>>> _D3std6traits15__T8DemangleTkZ8Demangle6__initZ
>>> _D47TypeInfo_S3std6traits15__T8DemangleTkZ8Demangle6__initZ
>>

Ah, just what I needed all along: this D ABI definition
http://dlang.org/abi.html
contains the exact definition of mangling.