State of Windows x64 COFF support?

[Etienne via Digitalmars-d-learn]

On 2015-02-19 1:41 PM, ketmar wrote:
>
> i remember that DMD creates one section for each function (to allow
> smartlink feature). with templates this can be alot. maybe it needs new
> cli flag "--collapse-sections" or something like it.
>

I watched the section names and discovered over 20,000 sections named : 
.debug$S

According to the code, a new .debug$S section is created every time it 
is searched with the flag IMAGE_SCN_LNK_COMDAT in:

https://github.com/D-Programming-Language/dmd/blob/de6fccf8391b1dfdb959fa0f089920c2c8e6aff8/src/backend/mscoffobj.c#L1724

I deleted this flag and now the program links correctly with COFF with 
<50k sections.

It would have been easier to debug with an error in mscoffobj.c:1591:

assert(scnhdr_cnt < 65536, "Too many symbols for COFF format");

https://github.com/D-Programming-Language/dmd/blob/de6fccf8391b1dfdb959fa0f089920c2c8e6aff8/src/backend/mscoffobj.c#L1591

With this simple patch on the compiler, there are stil some errors 
compiling Botan on win64, but they are not related to the COFF format 
anymore.