After merging `populateMetadata` with `populateMissingMetadata`,
it is imperative we clear the number of symbols in `writeSymbolTable`.
However, this is hopefully just a temp measure until the convergence
of incremental with traditional is complete.
* AstGen: use coerced_ty ResultLoc on array types and rely on Sema
doing type coercion, to reduce the size of the ZIR for these
instructions.
* Sema: implement `@ptrCast`.
* Sema: implement coercion from `T` to `?T` with an intermediate
coercion rather than equality check.
instead of globally storing unresolved and tentative defs,
store indices to actual symbols in the functions that are responsible
for symbol resolution.
This is now no longer limited to targeting macOS natively but also
tries to detect the sysroot when targeting different Apple platforms
from macOS; for instance targeting iPhone Simulator from macOS. In
this case, Zig will try detecting the SDK path by invoking
`xcrun --sdk iphonesimulator --show-sdk-path`, and if the command
fails because the SDK doesn't exist (case when having CLT installed only)
or not having either Xcode or CLT installed, we simply return null
signaling that the user has to provide the sysroot themselves.
For example, in order to run a binary on an iPhone Simulator,
you need to specify that explicitly as part of the target as
`aarch64-ios-simulator` rather than `aarch64-ios-gnu` or
`aarch64-ios` for short.
* ensure we correctly transfer `-iwithsysroot` and
`-iframeworkwithsysroot` flags with values from `build.zig` and that
they are correctly transferred forward to `zig cc`
* try to look for `libSystem.tbd` in the provided syslibroot - one
caveat that the user will have to specify library search paths too
Previously, I have incorrectly assumed that with two-level namespace
we only need to link in dylibs/frameworks that actually export symbols
which are undefined in the linked image. Turns out, regardless of
whether we link with two-level namespace (default on macOS) or a
flat namespace (more common on other platforms), we always need to
put the dylibs/frameworks as specified by the user from the linker
line into the final linked image.
* Value: rename `error_union` to `eu_payload` and clarify the intended
usage in the doc comments. The way error unions is represented with
Value is fixed to not have ambiguous values.
* Fix codegen for error union constants in all the backends.
* Implement the AIR instructions having to do with error unions in the
LLVM backend.
* New AIR instructions: ptr_add, ptr_sub, ptr_elem_val, ptr_ptr_elem_val
- See the doc comments for details.
* Sema: implement runtime pointer arithmetic.
* Sema: implement elem_val for many-pointers.
* Sema: support coercion from `*[N:s]T` to `[*]T`.
* Type: isIndexable handles many-pointers.
* Introduce `ret_load` ZIR instruction which does return semantics
based on a corresponding `ret_ptr` instruction. If the return type of
the function has storage for the return type, it simply returns.
However if the return type of the function is by-value, it loads the
return value from the `ret_ptr` allocation and returns that.
* AstGen: improve `finishThenElseBlock` to not emit break instructions
after a return instruction in the same block.
* Sema: `ret_ptr` instruction works correctly in comptime contexts.
Same with `alloc_mut`.
The test case with a recursive inline function having an implicitly
comptime return value now has a runtime return value because of the fact
that it calls a function in a non-comptime context.
This commit solves the problem in a much simpler way: putting
runtime-known values in place of non-comptime arguments when
instantiating a generic function.
The `comptime_args` field of Fn has a clarified purpose:
For generic function instantiations, there is a `TypedValue` here
for each parameter of the function:
* Non-comptime parameters are marked with a `generic_poison` for the value.
* Non-anytype parameters are marked with a `generic_poison` for the type.
Sema now has a `fn_ret_ty` field. Doc comments reproduced here:
> When semantic analysis needs to know the return type of the function whose body
> is being analyzed, this `Type` should be used instead of going through `func`.
> This will correctly handle the case of a comptime/inline function call of a
> generic function which uses a type expression for the return type.
> The type will be `void` in the case that `func` is `null`.
Various places in Sema are modified in accordance with this guidance.
Fixed `resolveMaybeUndefVal` not returning `error.GenericPoison` when
Value Tag of `generic_poison` is encountered.
Fixed generic function memoization incorrect equality checking. The
logic now clearly deals properly with any combination of anytype and
comptime parameters.
Fixed not removing generic function instantiation from the table in case
a compile errors in the rest of `call` semantic analysis. This required
introduction of yet another adapter which I have called
`GenericRemoveAdapter`. This one is nice and simple - it's the same hash
function (the same precomputed hash is passed in) but the equality
function checks pointers rather than doing any logic.
Inline/comptime function calls coerce each argument in accordance with
the function parameter type expressions. Likewise the return type
expression is evaluated and provided (see `fn_ret_ty` above).
There's a new compile error "unable to monomorphize function". It's
pretty unhelpful and will need to get improved in the future. It happens
when a type expression in a generic function did not end up getting
resolved at a callsite. This can happen, for example, if a runtime
parameter is attempted to be used where it needed to be comptime known:
```zig
fn foo(x: anytype) [x]u8 { _ = x; }
```
In this example, even if we pass a number such as `10` for `x`, it is
not marked `comptime`, so `x` will have a runtime known value, making
the return type unable to resolve.
In the LLVM backend I implement cmp instructions for float types to pass
some behavior tests that used floats.
When doing a function call, if the return type requires comptime, the
function is analyzed as an inline/comptime call.
There is an important TODO here. I will reproduce the comment from this
commit:
> In the case of a comptime/inline function call of a generic function,
> the function return type needs to be the resolved return type based on
> the function parameter type expressions being evaluated with comptime arguments
> passed in. Otherwise, it ends up being .generic_poison and failing the
> comptime/inline function call analysis.
For now these errors are handled via `@panic` rather than `unreachable`.
These are relatively likely bugs to occur at this early stage of
development, and handling them as panics lets us ship release builds
of the compiler without worrying about undefined behavior.
Furthermore, in stage1, `@panic` is implemented to include an error
return trace, while `unreachable` is not. In this case, the error return
traces are extremely helpful in debugging the compiler.
