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.
In the `EntityName` for a binding, preserve the `TypeInstId` describing
how the type was written. When a diagnostic refers to that type via
`TypeOfInstId`, use the type-as-written in the diagnostic rather than
the canonical type.
Assisted-by: Claude Opus via Antigravity
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`.
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>
If we find an overload set containing mulitple methods, discard any
non-const methods and try again. This allows libc++'s `std::vector` to
be iterated with range-based for.
Split up the CppRange interface into smaller parts, with the intent of
improving the diagnostic quality and making the implementation easier to
understand.
This also makes the implementation details of the CppRange machinery
private, which breaks one of the existing tests; that test is split into
two files, one which tests the low-level machinery works, and another
that tests the resulting prelude behavior.
This change exposes a crash in `where` expression handling, where we
would perform a substitution that creates a new `SpecificConstant` that
refers into a region of a generic that has never been resolved. Fix that
by resolving the definition region of a generic if eval sees a
`SpecificConstant` that refers into it. This is usually not necessary
because something else should have resolved that region first, but that
doesn't happen here.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
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
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.
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>
Because we now support calling a function with a `self` parameter
directly, we can unconditionally call `operator$(lhs, rhs)` rather than
calling `lhs.operator$(rhs)` if the selected operator function happens
to be a member function.
This makes the logic a bit simpler and the SemIR a bit smaller.
We can't do the same for Carbon operators, unfortunately, as we use the
member access to trigger impl lookup.
Adapters were erroneously satisfying `Core.Destroy` because we were
directly getting the object's representation without consideration for
abstract and adapted types. This change ensures that adapted types'
representations are used instead of the adapter types.
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`.
Carbon-side thunks (for example the `Copy`/`Destroy` witness thunks
generated for imported C++ types) are mangled by Carbon, and their names
incorporate a fingerprint of the involved types. The instruction
fingerprinter identifies a class only by its name and parent scope,
which is sufficient for Carbon classes but not for imported C++ classes:
different specializations of one class template (and other cases such as
types in anonymous namespaces) share a Carbon name and parent scope. As
a result, the thunks for two distinct specializations could mangle to
the same name, producing a single LLVM function with two definitions and
failing `verifyModule` during lowering.
When fingerprinting a class imported from C++, also include the Clang
mangled name of its type.
Test: toolchain/lower/testdata/interop/cpp/thunks.carbon gains a split
with two specializations of one class template, each requiring a thunk;
their thunks now get distinct mangled names instead of colliding.
Assisted-by: Claude Code
---------
Co-authored-by: Christopher Di Bella <cjdb.ns@gmail.com>
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.
Fixes mangling collisions when two thunks with the same name (eg, `Op`)
are created in the same context, which in turn would lead to LLVM
verifier failures and miscompiles.
To support this, add a new value store to track a little more
information about thunks beyond what's in the `Function`.
See
[here](https://docs.google.com/document/d/1rWcueFwIfZox6GKVGxiUG4cBzjrZ6djXiIDGyJDtrE4/edit?tab=t.0)
for the design doc.
This also removes the default value of the `result_type_inst_id`
parameter of `HandleAction`, moves it before the action in the parameter
list, and documents it. This solves two problems:
- The default made it easy to forget, leading to unnecessary
`TypeOfInst` instructions.
- When it was present, putting it after the fairly "bulky" action
argument tended to make the callsite harder to read.
When importing a C++ function with an rvalue reference parameter, we
previously produced a Carbon value parameter. This would lead to the
toolchain believing it could pass the address of a non-expiring object
to the function, which would lead to a use-after-move.
Instead, we now map non-const rvalue reference parameters to Carbon
`var` parameters. This forces the object passed into C++ to be unique
and owned by the call. While that's not an exact match for C++ rvalue
reference parameters, given that it provides "always move" not
"conditionally move", it's the closest match we have at the moment.
This is only fixing the decision about *whether* to produce a witness.
Implementation of the witness is still a TODO, though where a body is
generated, it should also precisely reflect where one _needs_ to be
generated.
Note the tests:
- toolchain/lower/testdata/function/generic/import_core_witness.carbon
- toolchain/lower/testdata/function/generic/import_unused_def.carbon
These tests can probably be produced _without_ Core.Destroy, but I found
the essence of them while trying to build //examples with Core.Destroy
and a simpler minimization wasn't striking me.
Assisted-by: Google Antigravity with Gemini
---------
Co-authored-by: jonmeow <jperkins@google.com>
In C++ overload resolution, when mapping a Carbon value expression into
a C++ argument, produce a const-qualified argument where possible. This
has two effects:
* Overload resolution does not consider non-const-qualified member
functions to be viable for a prvalue self any more. This is desirable
since such functions are not actually callable with a prvalue self, and
permits overload resolution to pick a const-qualified overload instead.
* Overload resolution does not allow a Carbon value expression to be
passed to a C++ `T&&` parameter any more. This is desirable since it's
not correct to move from a value expression. Previously we allowed this
and moved from the value!
This case is redundant: when deducing against a runtime parameter
pattern, the type is all that matters, and the type is added to the
deduction earlier. Additionally deducing the same argument against
parameter's subpattern just creates duplicate work, because the
subpattern has the same type.
This is a step toward removing the index from `InitForm`, so that equal
form values always have equal representations.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This is iterating on how `Destroy.Op` generates, to start adding body
capabilities. This changes the way the signature is created, and adds a
`CoreWitness` function kind so that mangling can prevent name
collisions. The result is that what _was_ `DestroyOp` is now
`Core.Destroy.Op` or, as can be seen in
toolchain/lower/testdata/interop/cpp/nullptr.carbon,
`_COp.<hash>:core.Destroy.Core` where `:core` is indicating that it's a
core witness (taking a note from `:thunk`).
Assisted-by: Google Antigravity with Gemini 3 Flash
When initializing `.base` in class initialization, use `partial Base` as
the destination type rather than `Base`. Treat `partial Base` as not
being abstract even when `Base` is.
Allow conversion from a `partial T` initializer to a `T` initializer.
Store the vptr while performing the conversion. Do not store the vptr
when performing a `partial T` initialization, only when performing a
non-partial `T` initialization.
Introduces `Context` and `SoftContext` messages, which can be introduced
through a `ContextBuilder`:
- The `Context` messages come before the diagnostic in the output.
- The first `Context` message steals the diagnostic level from the main
diagnostic, and turns the main diagnostic into a Note attached to the
context.
- A `SoftContext` message works similarly, but if it's preceeded by a
`Context` or `SoftContext` message, then it is dropped. This can be used
as a default/backup scope when nothing more interesting is provided up
the stack, such as in `TryEvalBlockForSpecific`.
The `ContextBuilder` is provided to a callback through
`Diagnostics::ContextScope`, an RAII type `AnnotationScope` but for
context messages.
This allows a high level operation to provide a context message like
"failed to identify facet type {0}" which will then be used as the error
if a diagnostic is produced during identification, with the latter
diagnostic attached as a note to explain why the contextual operation
failed.
In particular, this allows monomorphization errors (such as an array
bound being negative) to be attached to a higher lever operation instead
of being top-level diagnostics themselves, with the monomorphization
site being a note. This inverts the source code locations that appear in
the diagnostic, so that the top-level diagnostic points to the "user
code" which causes the monomorphization.
This is presented as an alternative strategy to #6753, which plumbed
diagnoser callbacks around to achieve the same goals.
We replace the diagnoser callbacks in type completion and operators with
ContextScope callbacks instead, which now provide better diagnostics for
monomorphization errors. Other callers to MakeSpecific do not yet have
ContextScopes introduced in order to turn monomorphization errors into
more interesting diagnostics.
This shifts logic a little so that empty top-level scopes are printed
less often. This affects imports mainly for now, but should be expected
to affect the soon-to-be-added generated scope more significantly.
Assisted-by: Google Antigravity with Gemini 3 Flash
## Summary
Fixes the toolchain incorrectly allowing `{}` initialization for
non-aggregate C++ classes.
## Problem
When importing an empty C++ class, the toolchain was treating it as a
Carbon empty struct, which allowed initialization from `{}`. This is
incorrect for non-aggregate classes (e.g., those with user-declared
constructors).
```carbon
import Cpp inline '''
struct X { X(); }; // non-aggregate (has user-declared constructor)
''';
fn Make() {
var x: Cpp.X = {}; // incorrectly accepted, should be rejected
}
```
## Solution
Added a check for `clang_def->isAggregate()` in `ImportClassObjectRepr`
so that only aggregate classes get the empty struct representation.
**Before:**
```cpp
if (clang_def->isEmpty() && !clang_def->getNumBases()) {
```
**After:**
```cpp
if (clang_def->isEmpty() && !clang_def->getNumBases() &&
clang_def->isAggregate()) {
```
## Testing
Added test file
`toolchain/check/testdata/interop/cpp/class/non_aggregate_init.carbon`
with:
- Non-aggregate class (`struct X { X(); }`) - should reject `{}`
initialization
- Aggregate class (`struct Y {}`) - should accept `{}` initialization
Note: I couldn't run tests locally due to clang version requirements
(needs >= 19, have 17). The CI should validate the changes.
Closes#6669
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Implementation of unused pattern bindings #2022, continued.
Whereas previous PR #6460 took care of parsing, and PR #6479 prepared
the stage by using _ in some test cases, this PR has the the actual
implementation, using a simple dataflow analysis.
---------
Co-authored-by: Burak Emir <bqe@google.com>
Co-authored-by: jonmeow <jperkins@google.com>
Currently each interface has a `Self` facet internally that becomes a
binding to every entity inside the interface: associated constants,
functions, and require decls. Each of these has to be independently
generic as a result. This makes is challenging in extended name lookup
to move into an extended scope of an interface, as we have a specific
for the interface, but the names within require a different specific
that includes a `Self` facet value.
We generalize this relationship by adding a second generic to Interface,
called `generic_with_self`. When we want to work with entities inside
the interface, we move from the interface-without-specific to the
interface-with-self specific by adding a Self to the specific. This is
done independently of any particular entity inside the Interface, as
those entities are now all members of the interface-with-self generic.
Associated constants no longer need a generic of their own, as they do
not have separate generic bindings. Functions retain a generic, but if
the function has no generic arguments, it will have no bindings of its
own now.
Require decls retain a generic so that their specific can be
instantiated separately from the interface. Requiring the interface to
be complete does not require the types in a require decl to be complete
unless it is modified by `extend`. So we allow them to be completed
later by keeping them in a separate generic.
Named constraints look like interfaces and gain the additional inner
generic-with-self, with the same relationship to require decls.
This removes the need for name lookup to perform Substitution of a Self
facet into the extended scope instruction. Instead, the
`SpecificConstant` instruction inserted by a `require` decl is part of
the interface-with-self generic. When looking through a FacetType for
extended scopes, for each interface, we push the scope with the specific
for the interface-with-self. Then the constant value of the
`SpecificConstant` is correctly modified by the provided self
automatically through applying that specific.
This TODO had been written before C++ types were generating destroy
implementations, which is resolved now.
Assisted-by: Google Antigravity with Gemini 3 Flash
The primary change in this PR is to split the `Initializing` expression
category into separate `ReprInitializing` and `InPlaceInitializing`
categories, depending on whether initialization uses the types
initializing representation, or is guaranteed to be in place. It also
rationalizes and documents the SemIR-level semantics of those categories
(including where #5545's "ephemeral entire reference" category will
fit), and introduces two new inst kinds to close gaps exposed in the
process.
Some additional secondary changes:
- Consistently format the storage arguments of initializers with `to`,
regardless of whether initialization is in-place, and document the `to`
notation.
- Rename some inst kinds and functions, and restructure some of the
code, for clarity and consistency with the new documentation.
- Resolve a TODO to handle more category conversions in
`CategoryConverter`, in order to make it easier to reason about category
conversions.
See #6588 and the review history of this PR for background.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Add a new builtin function `cpp.std.initializer_list.make` that takes an
array and returns a `std::initializer_list`, initialized to refer to
that array. When C++ initialization wants to perform a
`std::initializer_list`-from-array construction, synthesize a
declaration of a matching builtin function and use that to perform the
initialization.
Ideally we would specify this conversion as an impl of `ImplicitAs` in
the prelude instead of hardcoding it in the interop layer, but
unfortunately that's not currently possible, for various reasons -- we
can't make the conversion form-generic, we can't deduce the array length
from the initializer, and we can't deduce against the arguments of
imported C++ class templates yet -- so for now synthesizing a builtin
function on demand is the best we can do.
Assisted-by: Gemini 3 Pro via Antigravity
The general strategy here is to import the constructor with a signature
that directly matches the argument. The intent is that the imported
function will eventually be usable directly as the `ImplicitAs.Convert`
function in a generated `impl`.
For initialization from a tuple, for example `(1, 2)`, we import the
selected constructor with a signature that takes a tuple pattern:
`fn Class.Class((a: i32, b: i32)) -> Class;`
In order to support that, this PR also adds support in general for tuple
patterns in function signatures. It turns out the implementation was
already very close to allowing this.
Assisted-by: Gemini 3 Pro via Antigravity
When performing an implicit conversion to or from a C++ class type, look
for a C++ implicit conversion, and if that conversion involves a
function call (to a constructor or conversion function), call that
function to perform the conversion.
Note that this is just a first pass at supporting implicit conversions.
There are a lot of other things that can happen in a C++ implicit
conversion, such as aggregate initialization or `std::initializer_list`
initialization that aren't handled here. In addition, we intentionally
leave all standard conversions to Carbon to perform, so that we will
reject conversions such as `i32 -> unsigned` that C++ would select but
Carbon considers to be invalid.
Also support `as` conversions. These are treated analogously, but
perform direct-initialization instead of copy-initialization, so they
also find `explicit` constructors and conversion functions.
In order to give good diagnostics, also track the original C++ source
location for imported C++ functions on the imported version of the
function.
Assisted-by: Gemini 3 Pro via Antigravity
The key changes are:
- Function output parameters are now prefixed with `out`, and more
consistently formatted as named parameters.
- Function and inst output arguments are now written as part of the inst
form, rather than as one of the inst arguments.
As a drive-by fix, this also changes `Temporary::storage_id` from
`DestInstId` to `InstId`, because it doesn't represent an output
parameter of the `Temporary` inst itself.
See the review of
[#6532](https://github.com/carbon-language/carbon-lang/pull/6532) and
[this Discord
discussion](https://discord.com/channels/655572317891461132/999638000126394370/1458268977020141589)
for additional background.
Also clarify and enforce that `ConversionTarget::init_id` is used only
as storage for in-place initialization, and correspondingly rename it to
`storage_id`.
Not all functions have a return slot, and once we have composite forms,
functions will be able to have any number of return slots. Obtaining a
unique return slot for a function only makes sense in `returned var`
handling.
This avoids us trying to produce a reference to the C++ destructor,
which Clang won't emit because it believes it's unnecessary. This
previously led to link errors.
Fixe #6502.
Christopher Di Bella
Dana Jansens
Richard Smith
Geoff Romer
Chandler Carruth
Özgür T. ÖnsoyandDana Jansens
Jon Ross-Perkinsandjonmeow
Nicholas Bishop
little KitchenandRichard Smith
