Base classes will be destroyed in a dedicated change, so we can
trivially confirm that the base is being destroyed.
This is a partial implementation of #7362.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
A specific's definition block may contain `InstId::None`, indicating it
has no constant value. Display this as `<not constant>` instead of
`invalid`, to avoid it sounding like an error.
Removes support for unspecified default values. Fixes canonicalization
of the `DefaultValuePattern` instruction by making them immutable after
they are issued, and by removing the `DefaultValueId` operand which
wasn't being canonicalized.
Add support for deferring initialization as a template action, and
performing the deferred initialization during template instantiation.
This is substantially more complex than other conversion actions, for
two primary reasons:
* The initializer in the generic may have storage arguments as inputs.
We model an initializing expression as having a "slot" where
initialization writes the location that should be initialized by that
initializing expression, and that needs to be an output of the
initialization action.
* Initialization from a tuple or struct literal needs to recurse into
that literal, and the literal will have been spelled in the generic,
meaning we don't have an `InstId` that can be used to name the specific
version of the initializer as input for nested conversions.
These issues are addressed by introducing two new features to the action
machinery:
In addition to `InstAction`, we now have `MultiInstAction`, which is an
action that produces a tuple of instruction values instead of a single
instruction value. Initialization actions produce one instruction for
the final result, which is spliced at the point of initialization, plus
one instruction for each storage argument, which are spliced into the
storage argument slots in the original generic. During initialization,
if we find one of those splices in the storage argument of an
initializing expression, we return the new storage argument back to the
initialization action to be included in the specific, instead of
overwriting the storage argument in the generic.
Actions whose `PerforrmAction` takes a `SpecificId` as input no longer
perform automatic refinement of their operands to specific instructions.
Instead, the action is given control over when and where it performs
that refinement. In `InitializeAction`, we use this freedom to form a
`SpecificInst` for the initializer in the primary output block, and form
a `SpecificInst` for the target in the target block. When detecting
whether we are initializing from a tuple or struct literal, we step over
the `SpecificInst` and track its `SpecificId`, and if necessary create a
new `SpecificInst` wrapping the sub-initializer when we recurse into the
nested element conversion.
Assisted-by: Claude and Gemini via Antigravity
This change partially implements [PR #7362], which revises how objects
are destroyed. It is a partial implementation for two reasons:
1. This change moves `Destroy.Op`'s current behaviour into
`Destroy.SubobjectDestroy`, but it doesn't add support for objects with
non-trivial destruction.
2. `Destroy.SubobjectDestroy` is a workaround for `require impls
SubobjectDestroy`. We aren't able to use the latter until the dependents
add their requirements' implementations to their own witness tables.
[PR #7362]: https://github.com/carbon-language/carbon-lang/pulls/7362
The type `type` is now a `FacetType` inst with no constraints. This
brings the model implemented in the toolchain into better alignment with
the language design. The `SemIR::TypeType` struct remains as a scope for
holding the `TypeInstId`, `ConstantId`, and `TypeId` constants, but is
not an `InstKind` anymore.
The `TypeType` inst looks a lot like singletons, but there are many
`FacetType` insts so it doesn't quite fit that model. So we put it
alongside singletons with a fixed inst id but refer to it as a more
general "builtin" inst that is not a singleton.
`Namespace::PackageInstId` is similar, and we group it with `TypeType`
conceptually as another builtin instruction with a fixed id.
No conversion is needed anymore to use a `type` as a facet, since types
also have a `FacetType` type. This simplifies and removes a number of
helpers and branches throughout the code.
The `TypeType` inst is now part of the constant store, so we end up
printing it in the constants block in every test. But it's also named
`type` rather than `%type` to preserve the majority of existing
formatting behaviour, though this does look different from other
constants.
Assisted-by: Opus 5 was used to generate a first draft and validate the
refactoring. Though nearly everything non-trivial the tool wrote has
been modified or rewritten.
When evaluating a deferred member access action, the scope stack cannot
be relied on, so `LookupUnqualifiedName` cannot be used in
`GetHighestAllowedAccess` to get the `Self` type.
Instead, store the `Self` type in the `Context` when evaluating a
method, and use that in `GetHighestAllowedAccess`.
This action was created to wrap any `MetaInstId` operand of an action
instruction. This served two purposes:
1) It had a special hook in `OperandIsDependent` to allow it to be
performed while it had a dependent operand (the reference to the
instruction in the generic).
2) It created a `specific_inst` so that the downstream action saw an
instruction in the specific instead of one in the generic.
These are both replaced: the special case in `OperandIsDependent` for
`RefineInstAction` is replaced by a special case for `MetaInstId`s in
general, and the `SpecificInst` is now created as part of performing the
downstream action, rather than as a separate step carried out
beforehand.
This simplifies the produced SemIR and reduces the number of splices
significantly. It also prepares us to handle actions like
initialization, where we don't actually want to create `SpecificInst`s
immediately in the location where the action is performed, because they
actually belong somewhere else in the IR.
Assisted-by: Claude Opus 5 and Gemini via Antigravity
We use the same conversion codepath to handle both qualification
conversions and derived-to-base conversions, because we allow both to be
performed at once. However, we were previously modeling the
qualification conversion as happening *first*, and producing a result
whose type is the target type of the overall conversion (that is, the
base class type). That led to bogus SemIR, where a `Derived` -> `const
Base` conversion would first have a "compatible" conversion from
`Derived` to `const Base`, *then* an access of the base subobject (of
type `const Base`, within an object of type `const Base`).
We now reverse the order: first we do a derived-to-base conversion,
which already has logic to preserve qualifiers, and then we do any
necessary qualification conversions on the result to reach the overall
target type.
In passing, we now skip forming the `as_compatible` instruction at all
for a pure derived-to-base conversion that has no qualification
conversion, simplifying the SemIR by one instruction in the common case.
Use a single `SemIR::Function` per `Core` interface method, whether it's
generated locally or imported. This prevents generating duplicate
functions, which lead to different types when the witness appears in a
`FacetValue` as part of a specific for a class.
We use a `CanonicalValueStore` of `GeneratedFunction` objects that allow
finding an existing FunctionId for a `Generated` special function before
(re-)generating it. Mangling for `Generated` functions is also moved to
use the values from the `GeneratedFunction`'s canonicalization key, so
that we have a consistent source of truth for the unique ID of a
`Generated` function across all files.
New tests are in
`toolchain/check/testdata/impl/custom_witness/destroy.carbon`.
Test passing a template argument or a symbolic argument to a template.
Fix a bug in the template case where we'd crash when instantiating a
dependent discarded expression, because conversion produced an
`InstId::None` which the actions machinery did not expect and crashed
on.
Add basic support for lowering templates: we can now lower `SpliceInst`
in the case where the generic and specific are from the same file (and
we don't support importing templates from other files yet in general).
In order for this to work, lowering needs to be able to query the
expression category, and to handle instructions that appear to be
(template) constants in the generic but turn out to be non-constant in
the specific, so support for that is added.
Switch `type_of_inst` from being added as an action inst to being added
as a normal inst, since it's not an action and the old approach led to a
crash in lowering.
Replace `refine_type_action` with `refine_inst_action`, and generate a
`specific_inst` instead of an `as_compatible` to represent the specific
version of an instruction that's used as an input to a template action.
This gives us a place to handle other properties of the instruction that
might vary from generic to specific beyond its type, such as its
constant value and its expression category.
For now, we provide a non-template-dependent constant value to the
`specific_inst` in addition to the non-template-dependent type we have
traditionally provided. This doesn't seem to matter for any current
actions, but sets us up to better handle future actions. The
`specific_inst` representation also allows downstream consumers of the
instruction to track which specific they should be requesting
information from. Providing a correct expression category for
`specific_inst` will be handled in a future PR.
Two somewhat related fixes. The first is call-specific for now (because
it's the first action to take a `MetaInstId`), and the second is general
across all actions, but it seems like calls are the easiest place to hit
it.
1) Add support for refining inst blocks as action operands. Refine all
the insts in the block, using the appropriate InstId-derived type.
2) When an action operand is a `MetaInstId` referring to an unattached
constant, form a corresponding attached constant. This comes up when
forming (for example) an implicit `AddWith(%T)` call, where the `%T`
operand is an unattached constant.
This causes us to form correct specifics in more cases, where previously
we formed specifics that contained values that were still
template-dependent.
This unfortunately causes some existing template tests to produce more
errors, but those errors reflect cases where we were previously silently
doing the wrong thing.
`GetCallee` is sometimes called on a spliced instruction, and is
checking its exact inst operand to see if it's a `BoundMethod`. This
fails if the `BoundMethod` is wrapped in another instruction, such as a
splice. Normally our approach for such a situation would be to
constant-evaluate the operand, but that doesn't work here because the
`BoundMethod` will be non-constant if its bound `self` is. So instead we
now step through splice instructions manually when looking for the
`BoundMethod`.
Calls with template callee or args can now be deferred via an
InstAction. This allows code like this to check:
```carbon
import Cpp inline '''
template<typename T>
struct C {};
''';
fn F(generic T: type) {
let unused c: Cpp.C(T) = Cpp.C(T).C();
}
```
Treat `InstConstantKind::InstAction` the same as
`InstConstantKind::ConstInstAction`. Drop `ConstInstAction`, since the
two now behave the same.
Fix eval for specifics in a couple places to handle `InstId::None`.
When a template action is created, any (non-meta) instruction operand
will refer to instructions in the corresponding generic, or possibly to
a constant. This means that when the action is eventually executed when
forming a specific, it would see the generic value for that operand
rather than the intended specific value.
Fix this by refining `InstId` operands to refer to a corresponding value
in the specific, much like we would when rebuilding a constant in the
eval block.
Generalize ConvertToValue template action to handle other kinds of
conversion target that don't perform initialization. Initializing
conversions will need more work since they also need to use a splice to
form the storage block.
This allows various templated constructs to get further through
checking, but typically we hit another unsupported action such as a
conversion or call, so it's not enough to make much work.
Implementing interface modifiers causes an infinite loop when generating
fingerprints because the witness value generates a fingerprint that's
dependent on something dependent on the witness value. We've debugged
this to the witness table's `elements_id` field.
This hack is a workaround for creating a new block type whose value is
not codependent with its identity.
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
During impl lookup, for each (generic) impl candidate, we form a
specific for that impl by deducing its generic arguments. Then we
compare the query interface against the impl's specific interface. That
comparison needs the deduced arguments applied to the impl's specific
interface. Previously we were doing this by getting the impl's
constraint facet type with the impl's specific applied (via
`GetConstantValueInSpecific()`) and then identifying that facet type
with the impl's deduced self.
Identify is a fairly expensive operation. It runs subst, trying to
replace `.Self` references. It walks named constraints. It collects
require declarations. We're looking at making it do _more_ in the future
too, including rewrite constraint resolution and collecting rewrite and
same-type constraints. For this reason we have a cache to make it cheap
on the second run, but it's still a very heavyweight operation to
involve in impl lookup, when all we want is to apply the impl's specific
to its target interface.
We almost have all the information we need to avoid the identification
step. We have the impl's specific after deduction. And we have the
SpecificInterface that the impl is targeting in the `Impl` struct. When
we form the specific for the impl itself, we resolve the declaration
block and form new constant values for all instructions in there, but
that does not cover the SpecificInterface that we're storing in the
`Impl` struct. So we add a new instruction to the impl's eval block,
which will be symbolic when the impl is generic and the target interface
depends on a generic parameter. And we store the `InstId` in the `Impl`
struct. This allows us to gets its constant value later with the impl's
specific applied. From that constant value we can then pull out the
SpecificInterface that the impl is targeting.
Implement the toolchain side of proposal #7254, removing the `:!`
binding
syntax for generic and template parameters in favor of the keywords
`generic`,
`template`, and `runtime` plus contextual defaults for phase.
For valid programs this is semantics-preserving: each binding resolves
to the
same phase, and produces the same SemIR, as it did under `:!`/`:`. The
parser
derives a binding's phase from its syntactic context plus any explicit
phase
keyword; new diagnostics and error recovery for misused keywords are
described
below.
Implementation details for each component:
- Lexer: remove the `:!` (`ColonExclaim`) token, move its virtual
parse-node
budget onto `:`, and add the `generic` and `runtime` keywords.
- Parser: thread a `BindingContext` (`ExplicitParam`, `DeducedParam`, or
`CompileTimeEntityParam`) from declaration introducers down through
parameter
lists to each binding pattern, using a one-token lookahead to
distinguish a
name-qualifier parameter list from a declaration's own final list.
Parameters
of a compile-time entity (`class`, `interface`, `constraint`, `choice`,
`alias`, `export`, `namespace`) and deduced `[]` parameters default to
checked
generic; explicit function parameters and local bindings default to
runtime.
`HandleBindingPattern` resolves the phase from that context plus the
keyword: a
`generic` keyword needs no node of its own (the phase is carried by the
binding's node kind), while a `runtime` keyword is preserved as a
`RuntimeBindingName` node so `check` can name it in a diagnostic. A
phase
keyword that is merely redundant with the contextual default is
diagnosed
here, without invalidating the parse tree.
- Check: a phase keyword that is invalid for its context (for example
`runtime`
on a checked-generic parameter) is diagnosed here, and recovers by
building an
error binding that still introduces the name so that later uses of it do
not
produce cascading errors.
The removed `:!` syntax is now rejected as an ordinary parse error.
The `form`/`:?`/`->?` ("extended types") portion of proposal #7254 is
left for a
separate change.
Assisted-by: Claude Code
In #7436 we stopped substituting `.Self` when collecting witnesses out
of a facet type. While this was correct, it did not capture all the
cases that need to avoid substituting `.Self`. And it poisoned the
`IdentifiedFacetType` cache by not replacing `.Self` but storing the
result in the cache. This led to incoherent behaviour, where the result
of an impl lookup would change depending on which ones had been done
previously.
Now we use a flag to track for each `.Self` if we're currently
type-checking inside the scope where it was introduced in a facet type.
While inside that scope, identify should not replace the `.Self`. Any
use of it should remain as-is since we don't yet know what value will
replace it. We call this state "frozen" since it should not be modified
by identify. This requires a substitution step when we leave the scope
that introduced the `.Self`, to remove the flag. The flag is set in the
`EntityName` of the `SymbolicBinding`, and is part of the canonical
value, since `.Self` can become part of types, which are constants, and
the flag needs to follow it for correct behaviour.
We also have to ensure the flag is the same when doing comparison with
constants from inside a facet type and constants from outside. For
instance in `(Z where .Z1 = ()) where .Z2 = .Z1`, when we arrive at the
second `.Z1` its `.Self` will be frozen, while the `.Z1 = ()` contains a
non-frozen `.Self`. So we add the frozen flag to the first when storing
it in `where_stack` in order to compare the constant values of the two
`.Z1`.
The `WhereExpr` requirement inst kinds now have an `InstConstantKind` of
`AlwaysUnique` instead of `Never`. This allows us to add them to the
usual InstBlocks, and in an `eval fn` body they have a constant value,
so eval does not fail when trying to call that function. We have to be
careful to not consider `AlwaysUnique` as being actually concrete
though, since their constant value erases `.Self`-dependence. This
allows us to stop special casing them when thawing the requirements
block in a `WhereExpr`, and we can just thaw each `InstId` in the block
in a straightforward manner.
We add the new flag to the instruction's fingerprint and name in
formatted semir.
This adds SemIR structs and implements building `observe` lists, as well
as naming, formatting, and importing `observe` declarations.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
In some cases the pattern block can depend on the initializer, so it
must be sequenced after it. See #7469 for a more detailed explanation of
why this is necessary.
If the deduction fails while forming the parameter type, ensure that we
print an actual diagnostic saying what went wrong.
And always ensure that an invalid array bounds error points at a
location. The `inst_id` given to `EvalConstantInst` always has a
location, but the `bounds_id` instruction inside it may be canonical
when it's coming from inside a larger type. So when it is, fall back to
using the location of the whole array inst.
Depending on the order in which type completion identifies things in the
facet type, it may try to replace `.Self` with a facet that fails to
convert to the type of `.Self` due to a monomorphization error. We
should fail gracefully, not crash.
The bulk of this change is changing most pattern insts to be `Always`
rather than `AlwaysUnique` constants, so that they can be wrapped in
`SpecificConstant`s to perform substitution. That then lets thunking
rely much more on `SpecificConstant` wrappers instead of deep-copying
the inst tree with modified types.
This approach to thunking should scale better, particularly as things
like form generics make function signatures more complex, because we can
leverage the existing support for constant evaluation and substitution.
Unfortunately, applying this approach to binding patterns will require
more work; see the TODO near the top of `thunk.cpp` for details.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Implements proposal #7016: `self` moves from the deduced implicit list
(`fn F[self: Self]()`) to the front of the explicit list. Its type may
be written explicitly (`fn F(self: Self)`) or omitted, in which case it
defaults to `Self` (`fn F(self)`, `fn F(ref self)`); `self` in the
implicit list is rejected.
Throughout checking, `self` is modeled as the first explicit parameter.
Because a method is just a function whose first parameter is `self`, it
can also be called as an ordinary function with the receiver passed
explicitly (`Type.M(obj, ...)`), not only as `obj.M(...)`. A new
`SemIR::CallArgParamPatterns` helper chooses the parameters matched
against the explicit arguments, excluding a leading `self` only when it
is supplied as a method-call receiver; arity checking, conversion, and
generic deduction use it. The resulting SemIR and lowering are
unchanged: `self` is still `call_param0`, and witnesses, thunks, and
vtables are unaffected.
An omitted `self` type is parsed as a `SelfBindingPattern` node with no
type expression; checking synthesizes the `Self` type so it behaves
exactly like `self: Self`. However, the exact spelling used must match
between a forward declaration and a definition, following #3763's rules
around declaration matching.
Generated functions, thunks, and C++ interop import/export build `self`
as the first explicit parameter, and the `self`-type override (e.g.
Derived->Base for a virtual override) applies to the explicit `self`.
Placement is validated by new diagnostics: `SelfInImplicitParamList`,
`SelfNotFirstParam`, and `SelfOutsideParamList`. The benchmark source
generator and the documentation adopt the `(self)` shorthand; the
prelude, the examples, and the test data are migrated in the following
commits.
Assisted-by: Claude Code with Claude Opus 4.7
---------
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
Fix import logic to make all imported packages be children of the
`NameScopeId::Package` scope. Previously, indirectly-imported packages
would end up as children of their importing package's scope, which
resulted in them not being treated as packages at all, and in particular
not being fingerprinted as packages.
Fixing that caused a failure in the fingerprinting logic as we started
to encounter packages with no correspoding import scopes. Instead of
looking for import scopes, use a simpler mechanism to map packages to
their package names, and clean up.
Unfortunately the latter change churns all the fingerprints again :(
Hopefully this is the last time for a while.
When we import from another library in the same package, its entities
end up with our library as their parent scope, resulting in cross-file
fingerprint mismatches. Instead, only include the library ID when
fingerprinting either a package-private entity or an `ImportIRId` that
refers to a particular `SemIR::File`.
Pass a function's self specific in `ScopeStack::PushForFunctionBody` and
remove assertion preventing lexical scopes from having specific IDs.
This allows lexical lookup within the function to find entities
associated with its self specific.
Closes#6793
As suggested in [1], replace `FieldInitializerMap` with a `FieldStore`.
The corresponding `FieldId` is now stored in `FieldDecl`. To make room
for the `FieldId`, the `ElementIndex` is now stored in the `Field`,
along with the initializer.
In import_ref.cpp, resolving `FieldDecl` initializers is now supported,
and in convert.cpp `LoadImportRef` is called to do so. The
`field_initializer_import.carbon` test now passes.
Printing a `FieldDecl` instruction now prints the initializer as well,
if present. See field_initializer.carbon for an example.
[1]:
https://github.com/carbon-language/carbon-lang/pull/7238#discussion_r3283217158
Fixes link failures when referencing a symbol involving a fingerprint
from a different package.
Previously we included the `Namespace`'s `import_id` as part of its
fingerprint, which caused local and imported namespaces to get different
fingerprints. We now store the `import_id` on the `NameScope` instead of
on the `Namespace` inst to avoid this problem.
Also, when we reach a package-level `NameScopeId`, consistently
fingerprint it as a (package name, library name) pair. Previously the
fingerprinting depended on whether it was imported or not, as an
imported `NameScopeId` had a parent scope (the current package). We need
to include the library name here so that private entities with the same
name in different libraries have different fingerprints.
Christopher Di BellaandRichard Smith
Nicholas Bishop
Geoff Romer
Lucile Rose Nihlen
Dana Jansens
Chandler Carruth
Özgür T. ÖnsoyandDana Jansens
antangelo