mixin template test(A...){
        __gshared a = A;
        a++;
}

extern(C) void main(){
        mixin test!123;
}

-------------

I dont want to use string mixin to intro a lot un want symbol,  try with mixin template find this not work.

I know if mixin test on global it should not working, but why not make the limit for function scope ?


I try use D for a WASM project then find so much limitation with no good reason.  or I missing some thing here ?

On Friday, 10 August 2018 at 12:38:55 UTC, learnfirst1 wrote:
> mixin template test(A...){


mixin template test(A...){
        __gshared a = A;
}

extern(C) void main(){
        mixin test!123;
}

---------------

duplicate symbol __D4test4mainUZ8__mixin111__a_field_0i in:
    test.o
ld: 1 duplicate symbol for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Error: linker exited with status 1


this really make no sense,  what is wrong with it?    (same code build with ldc2)

Mixim template can only introduce declarations, not statements, a workaround is a lambda called in place.

mixin template test(A...){
        __gshared a = A;
        int dummy = (){ a++; return 0; }();
}

extern(C) void main(){
        mixin test!123;
}

On Friday, 10 August 2018 at 13:05:24 UTC, Kagamin wrote:
> Mixim template can only introduce declarations, not statements, a workaround is a lambda called in place.
>
> mixin template test(A...){
>         __gshared a = A;
>         int dummy = (){ a++; return 0; }();
> }
>
> extern(C) void main(){
>         mixin test!123;
> }

Except that you can't use tuples for that, a working sample:

mixin template test(alias A){
        __gshared a = A;
        int dummy = (){ a++; return 0; }();
}

extern(C) void main(){
    mixin test!123;

    import core.stdc.stdio;
    printf("%d", a);
}

On Friday, 10 August 2018 at 13:05:24 UTC, Kagamin wrote:
> Mixim template can only introduce declarations, not statements, a workaround is a lambda called in place.
>
> mixin template test(A...){
>         __gshared a = A;
>         int dummy = (){ a++; return 0; }();
> }
>
> extern(C) void main(){
>         mixin test!123;
> }

Thanks, this work for me.   my second example should be a dmd bug ? (ldc work)

On Friday, 10 August 2018 at 13:01:21 UTC, learnfirst1 wrote:
> duplicate symbol __D4test4mainUZ8__mixin111__a_field_0i in:
>     test.o
> ld: 1 duplicate symbol for architecture x86_64
> clang: error: linker command failed with exit code 1 (use -v to see invocation)
> Error: linker exited with status 1
>
>
> this really make no sense,  what is wrong with it?    (same code build with ldc2)

Looks like some problem with tuple, try __gshared a = A[0];

On Friday, 10 August 2018 at 13:10:57 UTC, Kagamin wrote:
> On Friday, 10 August 2018 at 13:01:21 UTC, learnfirst1 wrote:
> Looks like some problem with tuple, try __gshared a = A[0];

this work,  it report no error but give  a link problem.  (this could be a bug ?)

On Friday, 10 August 2018 at 13:17:13 UTC, learnfirst1 wrote:
> this work,  it report no error but give  a link problem.  (this could be a bug ?)

mixin template test(A...){
        __gshared int a = A[0];
        pragma(inline, true) // remove this will work
        static extern(C) int test(){
                a++;
                return 0;
        }
        int dummy = test();
}

import core.stdc.stdio;
extern(C) void main(){
    mixin test!1;
    printf("a=%d\n", a);
}

-----------------------
Undefined symbols for architecture x86_64:
  "__D4test4mainUZ8__mixin1QvUNbNiZi", referenced from:
      _main in test.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Error: linker exited with status 1

try this:

mixin template test(A...){
        __gshared int a = A[0];
        int dummy = (){
                a++;
                return 0;
        }();
}

import core.stdc.stdio;
int main(){
    mixin test!1;
    printf("a=%d\n", a);
    return 0;
}