I'm getting an unhelpful linker error, what've I got wrong?

[tcak via Digitalmars-d-learn]

On Wednesday, 28 October 2015 at 11:11:01 UTC, pineapple wrote:
> When I attempt to compile my code I get the same linker error 
> with both dmd and ldc2. I know where the problematic code is, 
> as I don't get the error when I comment out lines 102 through 
> 107, but I don't understand why it's bad. I must have some 
> misconceptions about how templates work? Is there any way to 
> get more descriptive errors out of the compiler if this sort of 
> thing happens again in the future?
>
> Here's the code:
>
>     http://pastebin.com/kGUPVa59
>
> Here's the problematic lines:
>
>     final streamint writestring(in char[] str){
>         return this.writebuffer!char(str.ptr, str.length);
>     }
>     final streamint writestring(in string str){
>         return this.writebuffer!char(str.ptr, str.length);
>     }
>
> And the linker error:
>
>     Undefined symbols for architecture x86_64:
>       
> "_D6stream6Stream19__T11writebufferTaZ11writebufferMFxPaxlZl", 
> referenced from:
>           _D6stream6Stream11writestringMFxAaZl in stream.o
>           _D6stream6Stream11writestringMFxAyaZl in stream.o
>     ld: symbol(s) not found for architecture x86_64
>     clang: error: linker command failed with exit code 1 (use 
> -v to see invocation)
>     --- errorlevel 1

The "writebuffer" is defined to take an array as parameter. Yet, 
you are passing a pointer and a length to it. Instead, pass the 
parameter "str" to it directly. Also, you do not have to put 
"!char" to there. Compiler will solve it out by itself.