Hello !
I've been following the dmd2 trunk for months and today it was
the first time the it could compile vibe.d library cleanly (with
deimos/openssl trunk).

But when try to compile an application that uses vibe.d then the
compiler gives errors inside vibe.d (lazy template instantiation
?).

---------------
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
getUserList, false).UDA is not accessible from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(getUserList) error
instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
deleteUser, false).UDA is not accessible from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(deleteUser) error
instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
deleteUserByFieldNameFieldValue, false).UDA is not accessible
from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(deleteUserByFieldNameFieldValue)
error instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
getUserByFieldNameFieldValue, false).UDA is not accessible from
module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(getUserByFieldNameFieldValue)
error instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
getCustomerLast, false).UDA is not accessible from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(getCustomerLast) error
instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
getCustomerList, false).UDA is not accessible from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(getCustomerList) error
instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
deleteCustomer, false).UDA is not accessible from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(deleteCustomer) error
instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
deleteCustomerByFieldNameFieldValue, false).UDA is not accessible
from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(deleteCustomerByFieldNameFieldValue)
error instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
getCustomerByFieldNameFieldValue, false).UDA is not accessible
from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(getCustomerByFieldNameFieldValue)
error instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
getIspList, false).UDA is not accessible from module common
../../dLib/vibe-d-0.7.20/source/vibe/web/web.d(130): Error:
template instance
vibe.web.common.extractHTTPMethodAndName!(getIspList) error
instantiating
../../dLib/inhouse-code/vibed_common.d(464):        instantiated
from here: registerWebInterface!(ApakauHttpRequestHandler,
cast(MethodStyle)5)
source/app.d(80):        instantiated from here:
setupHttpServer!(ApakauHttpRequestHandler)
../../dLib/vibe-d-0.7.20/source/vibe/web/common.d(181): Error:
variable vibe.internal.meta.uda.findFirstUDA!(PathAttribute,
deleteIsp, false).UDA is not accessible from module common
-----------

Also after posting this I tried to make vibe.d with unittest and then dmd2 trunk gives errors that it gave on previous builds.

---------
source/vibe/core/concurrency.d(254): Error: template vibe.core.concurrency.send cannot deduce function from argument types !()(Tid, IsolatedArray!double), candidates are:
source/vibe/core/concurrency.d(1175):        vibe.core.concurrency.send(ARGS...)(Task task, ARGS args)
source/vibe/core/core.d(248): Error: static assert  "Argument type Tid is not safe to pass between threads."
source/vibe/core/concurrency.d(271):        instantiated from here: runWorkerTaskH!(void function(Tid tid, IsolatedArray!double array, ulong start_index), Tid, IsolatedArray!double, ulong)

tl; dr: try 0.7.21-rc.4 instead of 0.7.20

I don't know what exactly got broken in vibe.d 0.7.20 by last DMD releases but Sonke has mentioned it is too much of an effort to fix and relase 0.7.20.1