The previous API of returning two `unsigned`s was ambiguous when accessing the second member of a union that is the first member of a struct, where both output were set to zero.
It now returns one `unsigned` and an output `bool` to determine if it should be used as either a field or byte offset.
Make -linkonce-templates *not* tamper with the general template
emission algorithm anymore (so on top of default non-allinst or
-allinst modes), and keep those tweaks as experimental
-linkonce-templates-aggressive.
Compiling the druntime/Phobos unittests is only marginally slowed
down compared to the more aggressive variant (~1.5% for debug,
~2.5% for release). It does show some rough 10% increase in required
memory, but that's in line with non-linkonce-templates.
The more aggressive variant has the advantage of skipping
needsCodegen() and potentially codegen'ing less symbols. The problem
is that if an instantiated symbol isn't explicitly referenced, for
instance a CRT ctor, it might not be codegen'd at all.
The linkage now (2.098) also affects the size of empty structs - e.g.,
1 for extern(C++), 0 for Posix extern(C), 4 for MSVC extern(C).
This also affects beauties like `extern(C) struct S { double[0] a; }`,
as tested by dmd-testsuite's runnable/ldc_cabi1.d, which is hereby
fixed for Posix - don't try to GEP into an empty LL struct.
A clean way of directly accessing struct and class init symbols. It
yields a `const(void[])` slice; the length reflecting the struct/class
instance size, and the pointer either pointing to the init symbol or
being null for zero-initialized structs.
Paves the way for resolving #3773 in druntime as well as accessing class
init symbols without `TypeInfo_Class.initializer()` indirection, and so
with -betterC as well.
* Newly require `-link-defaultlib-shared` for implicit dllimport.
E.g., this enables to compile druntime DLL with `-fvisibility=public`
for pure exports and no (local) imports (such as builtin TypeInfos).
* `-link-defaultlib-shared` alone now only implicitly imports symbols
from druntime/Phobos.
This simplifies building complex DLLs linked against a bunch of
static libs (dub only supports static lib dependencies!); the static
libs don't need to be compiled with `-fvisibility=public` anymore
(if the DLL itself isn't either), `-link-defaultlib-shared` is
sufficient.
This is mainly useful for existing DLLs with explicit exports, to make
them link against *shared* druntime/Phobos and so end up with a single
druntime/Phobos for the whole process.
Init symbols, TypeInfos (classes only) & vtables - unless defined in a
root module. For explicitly exported aggregates, or, with
`-fvisibility=public`, all aggregates.
This fixes an issue where any instantiation of TypeInfo in the final
output would lead to a cryptic error with no file or line information.
This change brings ldc in line with dmd's reporting of the same error,
which at least gives file and line information to discover the problem.
