Bug 19640 – Linker error when compiling delegate with betterC

**a.d**: ``` int call(int delegate() d) { return d(); } int foo(int i) { return call(() => i); } void main() { foo(0); } ``` **dub.json**: ``` { "name": "test", "buildOptions": ["betterC"], } ``` Output of `dub build`: ``` Performing "debug" build using /usr/bin/dmd for x86_64. test ~master: building configuration "application"... Linking... /usr/bin/ld: error: /usr/lib/x86_64-linux-gnu/libphobos2.a(dmain2_6f5_47b.o): size of section .dtors.d_dso_dtor[.data.d_dso_rec] is not multiple of address size /usr/bin/ld: final link failed: Error reading (null): No error collect2: error: ld returned 1 exit status Error: linker exited with status 1 /usr/bin/dmd failed with exit code 1. ```

There are multiple issues with the code you've written. First of all you cannot have a main function with betterC because dmd creates a d_run_main function which is the entrypoint of d programs. Typically, you just create the object file with betterC and then you link it with some C code. This is a minor aspect, regarding the test code. The main issue with the code is that the delegate (() => i) requires a closure that is allocated with the GC. Since you are compiling with -betterC, the GC is not available.

As Razvan pointed out, that delegate will create a closure and allocate on the GC heap. This is fixable by changing `call` to look like ``` int call(scope int delegate() d) ``` Note the scope keyword. Also, main should look like ``` extern(C) void main() ``` Please use the learn forums (https://forum.dlang.org/group/learn) before adding a bug, this kind of information is easily available there.