Thread overview
[Issue 8856] New: import inside function sometimes causes link errors
Oct 20, 2012
Andrej Mitrovic
Oct 20, 2012
Andrej Mitrovic
Jan 12, 2013
Andrej Mitrovic
October 20, 2012
http://d.puremagic.com/issues/show_bug.cgi?id=8856

           Summary: import inside function sometimes causes link errors
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: thelastmammoth@gmail.com


--- Comment #0 from thelastmammoth@gmail.com 2012-10-19 18:18:13 PDT ---
I sometimes get link errors eg:

void fun(){
    import mypackage.mymodule;
    mypackage.mymodule.myfun(); //might cause link error, depending on contents
of myfun
}

(cf http://forum.dlang.org/thread/xdonaxnahmonhyafhmvd@forum.dlang.org)

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-19 18:44:09 PDT ---
We'll need a failing test-case. What contents cause the linker error?

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--- Comment #2 from thelastmammoth@gmail.com 2012-10-19 20:18:49 PDT ---
(In reply to comment #1)
> We'll need a failing test-case. What contents cause the linker error?

here's a failure case which I simplified to the maximum.
Note that link error occurs with rdmd, not with dmd, as shown below. So that is
a problem with rdmd failing to find dependencies in some cases.

----
rdmd ${DFLAGS} main

=>Undefined symbols for architecture x86_64:
"_D9main_aux24fun1FZv", referenced from:
_D8main_aux4testFZv in main.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status

----
dmd ${DFLAGS} main main_aux main_aux2
=> works
----

Here are the files:

.
├── main.d
├── main_aux.d
└── main_aux2.d

cat  main.d

import main_aux;
void main(){
    test;
}
cat main_aux.d
module main_aux;
//putting the main function here removes link error
//void main(){
//    test;
//}

//import main_aux2; //uncomment removes link error
void test(){
    import main_aux2;
    fun1();
}

cat main_aux2.d
module main_aux2;
void fun1() {
}

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--- Comment #3 from thelastmammoth@gmail.com 2012-10-19 20:20:57 PDT ---
In the above post, DFLAGS is just the usual import path to dmdroot/phobos, druntime/import and phobos library path.

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--- Comment #4 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-19 20:34:14 PDT ---
(In reply to comment #2)
> snip

The problem is DMD's -v option doesn't output dependencies when an import is function local.

test.d:
module test;
import foo;
void main() { }

foo.d:
module foo;
import bar;

bar.d is empty

$ dmd -c -v test.d
> import    foo   (foo.d)
> import    bar   (bar.d)

Now use a local import in foo.d:

foo.d:
module foo;
void loc() { import bar; }

$ dmd -c -v test.d
> import    foo   (foo.d)

DMD doesn't output the import to bar.d when using -v. That has to be fixed.

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE


--- Comment #5 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-01-11 19:15:13 PST ---
Caused by same issue as in Issue 7016.

*** This issue has been marked as a duplicate of issue 7016 ***

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