This commit separates semantic analysis of the annotated type vs value
of a global declaration, therefore allowing recursive and mutually
recursive values to be declared.
Every `Nav` which undergoes analysis now has *two* corresponding
`AnalUnit`s: `.{ .nav_val = n }` and `.{ .nav_ty = n }`. The `nav_val`
unit is responsible for *fully resolving* the `Nav`: determining its
value, linksection, addrspace, etc. The `nav_ty` unit, on the other
hand, resolves only the information necessary to construct a *pointer*
to the `Nav`: its type, addrspace, etc. (It does also analyze its
linksection, but that could be moved to `nav_val` I think; it doesn't
make any difference).
Analyzing a `nav_ty` for a declaration with no type annotation will just
mark a dependency on the `nav_val`, analyze it, and finish. Conversely,
analyzing a `nav_val` for a declaration *with* a type annotation will
first mark a dependency on the `nav_ty` and analyze it, using this as
the result type when evaluating the value body.
The `nav_val` and `nav_ty` units always have references to one another:
so, if a `Nav`'s type is referenced, its value implicitly is too, and
vice versa. However, these dependencies are trivial, so, to save memory,
are only known implicitly by logic in `resolveReferences`.
In general, analyzing ZIR `decl_val` will only analyze `nav_ty` of the
corresponding `Nav`. There are two exceptions to this. If the
declaration is an `extern` declaration, then we immediately ensure the
`Nav` value is resolved (which doesn't actually require any more
analysis, since such a declaration has no value body anyway).
Additionally, if the resolved type has type tag `.@"fn"`, we again
immediately resolve the `Nav` value. The latter restriction is in place
for two reasons:
* Functions are special, in that their externs are allowed to trivially
alias; i.e. with a declaration `extern fn foo(...)`, you can write
`const bar = foo;`. This is not allowed for non-function externs, and
it means that function types are the only place where it is possible
for a declaration `Nav` to have a `.@"extern"` value without actually
being declared `extern`. We need to identify this situation
immediately so that the `decl_ref` can create a pointer to the *real*
extern `Nav`, not this alias.
* In certain situations, such as taking a pointer to a `Nav`, Sema needs
to queue analysis of a runtime function if the value is a function. To
do this, the function value needs to be known, so we need to resolve
the value immediately upon `&foo` where `foo` is a function.
This restriction is simple to codify into the eventual language
specification, and doesn't limit the utility of this feature in
practice.
A consequence of this commit is that codegen and linking logic needs to
be more careful when looking at `Nav`s. In general:
* When `updateNav` or `updateFunc` is called, it is safe to assume that
the `Nav` being updated (the owner `Nav` for `updateFunc`) is fully
resolved.
* Any `Nav` whose value is/will be an `@"extern"` or a function is fully
resolved; see `Nav.getExtern` for a helper for a common case here.
* Any other `Nav` may only have its type resolved.
This didn't seem to be too tricky to satisfy in any of the existing
codegen/linker backends.
Resolves: #131
The new representation is often more compact. It is also more
straightforward to understand: for instance, `extern` is represented on
the `declaration` instruction itself rather than using a special
instruction. The same applies to `var`, making both of these far more
compact.
This commit also separates the type and value bodies of a `declaration`
instruction. This is a prerequisite for #131.
In general, `declaration` now directly encodes details of the syntax
form used, and the embedded ZIR bodies are for actual expressions. The
only exception to this is functions, where ZIR is effectively designed
as if we had #1717. `extern fn` declarations are modeled as
`extern const` with a function type, and normal `fn` definitions are
modeled as `const` with a `func{,_fancy,_inferred}` instruction. This
may change in the future, but improving on this was out of scope for
this commit.
This includes function aliases, but not function declarations.
Also, re-introduce a target check for function alignment which was
inadvertently removed in the prior commit.
This commit changes the `root_module` field of `std.Build.Step.Compile`
to be a `*Module` rather than a `Module`. This is a breaking change, but
an incredibly minor one (the full potential extent of the breakage can
be seen in the modified standalone test).
This change will be necessary for an upcoming improvement, so it was
convenient to make it here.
The error messages here aren't amazing yet, but this is an improvement
on status quo, because the current behavior allows false negative
compile errors, so effectively miscompiles.
Resolves: #15874
There are several test decls inside `/src` that are not currently being
tested and have bitrotted as a result. This commit revives those tests
and adds the `test-compiler-internals` set of tests which tests
everything reachable from `/src/main.zig`.
The goal here is to support both levels of unwind tables (sync and async) in
zig cc and zig build. Previously, the LLVM backend always used async tables
while zig cc was partially influenced by whatever was Clang's default.
Both of these instructions were previously under a special case in
`rvalue` which resulted in every reference to such an instruction adding
a new `ref` instruction. This had the effect that, for instance,
`&a != &a` for parameters. Deduplicating these `ref` instructions was
problematic for different reasons.
For `alloc_inferred`, the problem was that it's not valid to `ref` the
alloc until the allocation has been resolved (`resolve_inferred_alloc`),
but `AstGen.appendBodyWithFixups` would place the `ref` directly after
the `alloc_inferred`. This is solved by bringing
`resolve_inferred_alloc` in line with `make_ptr_const` by having it
*return* the final pointer, rather than modifying `sema.inst_map` of the
original `alloc_inferred`. That way, the `ref` refers to the
`resolve_inferred_alloc` instruction, so is placed immediately after it,
avoiding this issue.
For `param`, the problem is a bit trickier: `param` instructions live in
a body which must contain only `param` instructions, then a
`func{,_inferred,_fancy}`, then a `break_inline`. Moreover, `param`
instructions may be referenced not only by the function body, but also
by other parameters, the return type expression, etc. Each of these
bodies requires separate `ref` instructions. This is solved by pulling
entries out of `ref_table` after evaluating each component of the
function declaration, and appending the refs later on when actually
putting the bodies together. This gives way to another issue: if you
write `fn f(x: T) @TypeOf(x.foo())`, then since `x.foo()` takes a
reference to `x`, this `ref` instruction is now in a comptime context
(outside of the `@TypeOf` ZIR body), so emits a compile error. This is
solved by loosening the rules around `ref` instructions; because they
are not side-effecting, it is okay to allow `ref` of runtime values at
comptime, resulting in a runtime-known value in a comptime scope. We
already apply this mechanism in some cases; for instance, it's why
`runtime_array.len` works in a `comptime` context. In future, we will
want to give similar treatment to many operations in Sema: in general,
it's fine to apply runtime operations at comptime provided they don't
have side effects!
Resolves: #22140
This commit enhances AstGen to introduce a form of error resilience
which allows valid ZIR to be emitted even when AstGen errors occur.
When a non-fatal AstGen error (e.g. `appendErrorNode`) occurs, ZIR
generation is not affected; the error is added to `astgen.errors` and
ultimately to the errors stored in `extra`, but that doesn't stop us
getting valid ZIR. Fatal AstGen errors (e.g. `failNode`) are a bit
trickier. These errors return `error.AnalysisFail`, which is propagated
up the stack. In theory, any parent expression can catch this error and
handle it, continuing ZIR generation whilst throwing away whatever was
lost. For now, we only do this in one place: when creating declarations.
If a call to `fnDecl`, `comptimeDecl`, `globalVarDecl`, etc, returns
`error.AnalysisFail`, the `declaration` instruction is still created,
but its body simply contains the new `extended(astgen_error())`
instruction, which instructs Sema to terminate semantic analysis with a
transitive error. This means that a fatal AstGen error causes the
innermost declaration containing the error to fail, but the rest of the
file remains intact.
If a source file contains parse errors, or an `error.AnalysisFail`
happens when lowering the top-level struct (e.g. there is an error in
one of its fields, or a name has multiple declarations), then lowering
for the entire file fails. Alongside the existing `Zir.hasCompileErrors`
query, this commit introduces `Zir.loweringFailed`, which returns `true`
only in this case.
The end result here is that files with AstGen failures will almost
always still emit valid ZIR, and hence can undergo semantic analysis on
the parts of the file which are (from AstGen's perspective) valid. This
is a noteworthy improvement to UX, but the main motivation here is
actually incremental compilation. Previously, AstGen failures caused
lots of semantic analysis work to be thrown out, because all `AnalUnit`s
in the file required re-analysis so as to trigger necessary transitive
failures and remove stored compile errors which would no longer make
sense (because a fresh compilation of this code would not emit those
errors, as the units those errors applied to would fail sooner due to
referencing a failed file). Now, this case only applies when a file has
severe top-level errors, which is far less common than something like
having an unused variable.
Lastly, this commit changes a few errors in `AstGen` to become fatal
when they were previously non-fatal and vice versa. If there is still a
reasonable way to continue AstGen and lower to ZIR after an error, it is
non-fatal; otherwise, it is fatal. For instance, `comptime const`, while
redundant syntax, has a clear meaning we can lower; on the other hand,
using an undeclared identifer has no sane lowering, so must trigger a
fatal error.
It doesn't appear that targeting bridgeOS is meaningfully supported by Apple.
Even LLVM/Clang appear to have incomplete support for it, suggesting that Apple
never bothered to upstream that support. So there's really no sense in us
pretending to support this.
The freestanding and other OS targets by default need to just @trap in the
default Panic implementation.
And `isValidMemory` won't work with freestanding or other targets.
Update the unwind_freestanding.zig test case to also run on the 'other' OS
target, too. This should keep the Zig's stacktrace generation from
regressing on the standalone targets.
Without doing this, we don't actually test whether the data layout string we
generate matches LLVM's.
A number of targets had to be commented out due to this change:
* Some are using a non-working experimental LLVM backend (arc, csky, ...).
* Some don't have working LLD support (lanai, sparc, ...).
* Some don't have working self-hosted linker support (nvptx).
* Some are using ABIs that haven't been standardized (loongarch32).
Finally, all non-x86 uefi targets are hopelessly broken and can't really be
fixed until we change our emit logic to lower *-uefi-* verbatim rather than to
*-windows-*. See: https://github.com/ziglang/zig/issues/21630
