Linker error regarding importing and unit tests. Is this a bug?

[Daniel Davidson]

On Friday, 1 November 2013 at 12:59:24 UTC, Gary Willoughby wrote:
> I have a small test case that displays a linker error. I 
> wondered if this is an issue with the tool chain or whether i'm 
> doing something wrong.
>
> I have a simple directory structure like this:
>
> test/methods.d
> test/test1.d
> test/test2.d
>
> Here is the source code for the above modules:
>
> methods.d:
>
> 	module test.methods;
>
> 	import std.array;
>
> 	public bool nothing(int[] x)
> 	{
> 		return x.empty();
> 	}
>
> test1.d:
>
> 	module test.test1;
>
> 	struct S
> 	{
> 		int x[];
> 	}
>
> 	unittest
> 	{
> 		import test.methods;
> 		import std.stdio;
>
> 		writeln("test1 unit test");
>
> 		S s;
>
> 		assert(s.x.nothing());
> 	}
>
> test2.d:
>
> 	module test.test2;
>
> 	import test.test1;
>
> 	struct T
> 	{
> 		int x[];
> 	}
>
> I compile the following sources like this:
>
> 	rdmd --force -de -debug -I~/Desktop -m64 -main -property 
> -unittest -w <file>
>
> Where <file> is an individual file above. I do this because i 
> like to compile and tests each module in isolation running the 
> unit tests. When i try and compile `test2.d` i get the 
> following error:
>
> Undefined symbols for architecture x86_64:
>   "_D4test7methods12__ModuleInfoZ", referenced from:
>       _D4test5test112__ModuleInfoZ in test2.o
>   "_D4test7methods7nothingFAiZb", referenced from:
>       _D4test5test114__unittestL8_1FZv in test2.o
> ld: symbol(s) not found for architecture x86_64
> clang: error: linker command failed with exit code 1 (use -v to 
> see invocation)
>
> If i add the following to the bottom of `test2.d` it all 
> compiles fine:
>
> 	unittest
> 	{
> 		import test.methods;
> 	}
>
> Any idea what's going on here?

An alternative is to move the import statements in test1.d out of 
the unittest block, which becomes a function, to file scope. Then 
if you have multiple unittests in test1.d all are covered and the 
symbols are available.

...
version(unittest) {
   import methods;
}
unittest
{
   import std.stdio;
   writeln("test1 unit test");
   S s;
   assert(s.x.nothing());
}

Thanks
Dan