Instead of trying to fit a stub file into the frame of a Dylib struct,
I think it makes more sense to keep them as separate entities with
possibly shared interface (which would be added in the future).
This cleaned up a lot of logic in Dylib as well as Stub. Also, while
here I've made creating actual *Symbols lazy in the sense Dylib and
Stub only store hash maps of symbol names that they expose but we
defer create and referencing given dylib/stub until link time when
a symbol is actually referenced. This should reduce memory usage
and speed things up a bit.
NetBSD expects 2 PT_LOAD segments in a shared object, otherwise
ld.elf_so fails to load, emitting a general "not found" error.
Workaround issue by adding args `--no-rosegment` and `-znorelro`.
see #9109
We will silently ignore expected section that are either won't take
part in linking such as any `__DWARF` section, or are known but are
not yet implemented such as `__TEXT,__eh_frame`. For any other
we will throw an error and exit.
Also, inform the caller that we currently are unable to handle
frameworks.
Up until now, we only expected old-fashioned objects which carried
two basic segments by name: __TEXT and __DATA. Since macOS 11.1,
there is a new segment __DATA_CONST, and we should expect and
correctly parse sections designated to that segment explicitly
as is the case in golang.
The only allowed system libraries that we can link are libraries
that are part of the sysroot such as libc or WASI emulated
subcomponents. This is required as Wasm allows to defer symbol
resolution until load time.
For example, the following import in Zig
```zig
extern "wasi_snapshot_preview1" fn proc_exit() void;
```
would normally result in appending `-lwasi_snapshot_preview1` flag
to the linker line. However, for Wasm/WASI, the symbol is provided
at load rather than link time, therefore, the linker should not be
concerned with resolving the symbol. As a result, we should not
consider system libs by the Wasm linker.
* then, in `link/Wasm.zig` map `CRTFile` to full emulated libs name
* move logic for removing any mention of WASI snapshot
`wasi_snapshot_preview1` from `Compilation.zig` into `link/Wasm.zig`
Move parsing of system libs into `main.zig` next to where we decide
if we should link libC, and, if targeting WASI, if the specified
libname equals one of the emulated components, save it on the side
and remove it from the system libs. Then, build *only* those parts
of WASI libc that were preserved in the previous step.
This also fixes building of different crt1 bits needed to support
reactors and commands.
This replicates the expected behavior when using `clang` with
upstream `wasi-libc` sysroot: linking emulated subcomponents
such as process clocks or signals requires an explicit link flag
in the compiler invocation, for example:
```
zig cc -target wasm32-wasi -lwasi-emulated-process-clocks main.c -o main.wasm
```
