Compilation problems with GDC/GCC

[DRex via Digitalmars-d-learn]

On Saturday, 15 April 2017 at 12:45:47 UTC, DRex wrote:
> On Friday, 14 April 2017 at 18:00:22 UTC, Johannes Pfau wrote:
>> Am Fri, 14 Apr 2017 13:03:22 +0000
>> schrieb DRex <armstronga94 at hotmail.com>:
>>
>>
>> GDC should generally only need to link to -lgdruntime (and 
>> -lgphobos if you need it). However, if you really link using 
>> ld you'll have to provide the C startup files, -lc and similar 
>> stuff for C as well, which gets quite complicated.
>>
>> You'll have to post the exact commands you used and some
>> of the missing symbol names so we can give better answers.
>>
>> -- Johannes
>
> okay so here is an outline of the situation:
>
> The project is a rather large C project that is being ported to 
> D (small pieces at a time) and as I said before, it's make 
> files are simply way too complicated t unravel and rewrite (the 
> main make file has 5000 some lines of code).
>
> I have re-written some small elements of C code so far in D.  I 
> need to compile the D code into object (*.o) files, and simply 
> including them as references in the make files doesn't work 
> because ld on its own doesn't know how to link D files (as I 
> assume it doesn't by default know to link the object files with 
> the D runtime).
>
> On small projects with C and D (test projects for including D 
> with C) showed that I can simply replace ld with gdc when I go 
> to link, i.e. instead of `ld cfile.o dfile.o -o foo` I can use 
> `gdc cfile.o dfile.o -o foo` and it will link the objects 
> together and make the program.  However this is not a viable 
> solution to the project without navigating through the make 
> files, as there are some options that are passed to the linker 
> that GDC doesn't seem to recognize, and this build fails.
>
> After reading the above comment, I have tried linking with `ld 
> *options* -lgdruntime`, which failed, I also tried specifying 
> the druntime lib with its full path 
> '-l:/usr/gcc/x86_64-linux-gnu/5/libgdruntime.a' and derivatives 
> thereof and ld says it cannot find it.  UPDATE: using -L 
> instead of -l seems to have worked, but I am now recieveing a 
> lot of 'undefined referece' errors, so many that I wont write 
> them here, but some of them are:
>
> `test.o: In function `main':
> test.d:(.text+0x21): undefined reference to `_d_run_main'
>
> `test.o: In function `_D4test9__modinitFZv':
> test.d:(.text+0xaa): undefined reference to `_Dmodule_ref'`
>
> `test.o:(.data+0x10): undefined reference to 
> `_D3std5stdio12__ModuleInfoZ'`

Update: using the --verbose option of ld, it has printed out 
attempts to open the library (when using `-lgdruntime` the output 
is as follows:

attempt to open //usr/local/lib/x86_64-linux-gnu/libgdruntime.so 
failed
attempt to open //usr/local/lib/x86_64-linux-gnu/libgdruntime.a 
failed
attempt to open //lib/x86_64-linux-gnu/libgdruntime.so failed
attempt to open //lib/x86_64-linux-gnu/libgdruntime.a failed
attempt to open //usr/lib/x86_64-linux-gnu/libgdruntime.so failed
attempt to open //usr/lib/x86_64-linux-gnu/libgdruntime.a failed
attempt to open //usr/local/lib64/libgdruntime.so failed
attempt to open //usr/local/lib64/libgdruntime.a failed
attempt to open //lib64/libgdruntime.so failed
attempt to open //lib64/libgdruntime.a failed
attempt to open //usr/lib64/libgdruntime.so failed
attempt to open //usr/lib64/libgdruntime.a failed
attempt to open //usr/local/lib/libgdruntime.so failed
attempt to open //usr/local/lib/libgdruntime.a failed
attempt to open //lib/libgdruntime.so failed
attempt to open //lib/libgdruntime.a failed
attempt to open //usr/lib/libgdruntime.so failed
attempt to open //usr/lib/libgdruntime.a failed
attempt to open //usr/x86_64-linux-gnu/lib64/libgdruntime.so 
failed
attempt to open //usr/x86_64-linux-gnu/lib64/libgdruntime.a failed
attempt to open //usr/x86_64-linux-gnu/lib/libgdruntime.so failed
attempt to open //usr/x86_64-linux-gnu/lib/libgdruntime.a failed

I don't see why it is failing, because the second attempt is the 
right path, the libgdruntime.a file is exactly at 
"/usr/local/lib/x86_64-linux-gnu/libgdruntime.a", although I do 
not know why it is using double forward slash as the root :s, 
which I cannot seem to stop it from doing.