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D.gnu - Strange Multiple Definition Error using makefile

reply LeqxLeqx <mitchelldlarson protonmail.ch> writes:
Hello,

When compiling a simple project with makefile, I'm getting the 
error:
myclass.d:(.text+0x88): multiple definition of 
`_DT16_D15myabstractclass15MyAbstractClass11firstMethodMFZv'

I'm not certain what's actually wrong with my code. The error 
occurs when the all of the original object (*.o) files are linked 
together to make the executable. According to `nm', both the 
files `myabstractclass.o' and `myclass.o' contain a definition of:

0000000000XXXXXX T 
_DT16_D15myabstractclass15MyAbstractClass11firstMethodMFZv

(where the X's are replaced by their offset in the file)

I've distilled the error to the smallest number of files and 
lines that seem to induce it. The 4 source files are as follows:

============ main.d ==============

     module main;
     import myclass;

     int main(string[] args)
     {
       MyClass myClass;
       myClass = new MyClass;
       myClass.firstMethod;
       myClass.secondMethod;
       return 0;
     }


======== myinterface.d ============

     module myinterface;

     interface MyInterface
     {
       void firstMethod();
       void secondMethod();
     }

======= myabstractclass.d =========

     module myabstractclass;
     import myinterface;

     abstract class MyAbstractClass : MyInterface
     {
       void firstMethod()
       {
         import std.stdio : writefln;
         writefln("hello from firstMethod");
       }
     }

============ myclass.d ==========

     module myclass;

     import myabstractclass;

     class MyClass : MyAbstractClass
     {
       void secondMethod()
       {

       }
     }

===== and my simple makefile ======

     O_FILES=myinterface.o myabstractclass.o myclass.o main.o
     CC=gdc

     .PHONY : all
     all : $(O_FILES)
             $(CC) $(O_FILES) -o test.bin

     %.o : %.d
             $(CC) -c -o $  $<

     .PHONY : clean
     clean :
             rm -f $(O_FILES) test.bin

=================================

I'm using GDC version: `gdc (Ubuntu 8.2.0-1ubuntu2~18.04) 8.2.0'

So ultimately, my question is: What am i doing wrong here?
Any and all help is appreciated.
Dec 26 2018
next sibling parent Sebastien Alaiwan <ace17 free.fr> writes:
Could you please post the console output (the exact commands 
invoked by make) ?
Dec 27 2018
prev sibling parent reply Iain Buclaw <ibuclaw gdcproject.org> writes:
On Wed, 26 Dec 2018 at 22:25, LeqxLeqx via D.gnu <d.gnu puremagic.com> wrote:

 ===== and my simple makefile ======

      O_FILES=myinterface.o myabstractclass.o myclass.o main.o
      CC=gdc


Ahem, CC means "C Compiler", you should be using another variable name here. ;-)


 I'm using GDC version: `gdc (Ubuntu 8.2.0-1ubuntu2~18.04) 8.2.0'

 So ultimately, my question is: What am i doing wrong here?
 Any and all help is appreciated.


Two object files are claiming to have the one true copy of the thunk
to firstMethod.

Switching from separate compilation to compiling all sources in one
compilation command will sort that out.

---
D_FILES=myinterface.d myabstractclass.d myclass.d myderived.d main.d
CC=gdc

.PHONY : all
all : test.bin

test.bin: $(D_FILES)
        $(CC) -o $  $^
---

There should be better spec over how thunks (particularly to methods
outside the compilation unit) are handled.  Maybe this can be
addressed before version 9 release.

-- 
Iain
Dec 28 2018
parent LeqxLeqx <mitchelldlarson protonmail.ch> writes:
On Friday, 28 December 2018 at 13:41:14 UTC, Iain Buclaw wrote:

 On Wed, 26 Dec 2018 at 22:25, LeqxLeqx via D.gnu 
 <d.gnu puremagic.com> wrote:

 ===== and my simple makefile ======

      O_FILES=myinterface.o myabstractclass.o myclass.o main.o
      CC=gdc


 Ahem, CC means "C Compiler", you should be using another 
 variable name here. ;-)


 I'm using GDC version: `gdc (Ubuntu 8.2.0-1ubuntu2~18.04) 
 8.2.0'

 So ultimately, my question is: What am i doing wrong here? Any 
 and all help is appreciated.


 Two object files are claiming to have the one true copy of the 
 thunk to firstMethod.

 Switching from separate compilation to compiling all sources in 
 one compilation command will sort that out.

 ---
 D_FILES=myinterface.d myabstractclass.d myclass.d myderived.d 
 main.d CC=gdc

 .PHONY : all
 all : test.bin

 test.bin: $(D_FILES)
         $(CC) -o $  $^
 ---

 There should be better spec over how thunks (particularly to 
 methods outside the compilation unit) are handled.  Maybe this 
 can be addressed before version 9 release.


Okay, I'll switch to the all-source-code way for the moment. For 
some reason, I never had a problem with this when I was using 
GDC-6, but with the newer GDC, it suddenly became a problem.

Thank you!
Jan 04 2019