Commit Graph
72 Commits
Author SHA1 Message Date
Richard Smith 26d7717d60 Insert a value_of_initializer after a call to ImplicitAs where possible. (#4473)
This avoids going through memory when performing an implicit conversion
to a type with a by-copy value representation, such as i32.
2024-11-04 16:06:19 +00:00
Richard Smith db76e81630 Rename IntLiteral to IntValue. (#4475)
This instruction represents integer values, whether they come from
literals or calculations, so it the old name is inaccurate. I also plan
to rename `BigInt` to `IntLiteral` based on recent discussion and this
change aims to avoid confusion stemming from the same name being used
for two different things.

I'm not renaming `FloatLiteral` because recent discussion suggests we
may want distinct `FloatLiteral` versus `FloatValue` representations in
SemIR.
2024-11-02 01:19:39 +00:00
Jon Ross-Perkins d944347e7b Elide prelude components in the IR formatter. (#4453)
This is in particular to avoid churn from changes such as #4370. I think
the import list can be helpful (particularly to understand what the
library is aware of), but it's a different trade-off for the prelude
package due to the implicit imports.
2024-10-30 22:45:26 +00:00
Brymer MenesesandJon Ross-Perkins 89eed4220f Expose indexing as a language interface (#4370)
This PR makes it so that types can implement the `IndexWith` interface
so that they can provide their custom indexing behavior.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-10-29 21:25:02 +00:00
Geoff Romer b67d03126e Separate inst kind for out params (#4442) 2024-10-24 15:22:32 +00:00
Richard Smith 2e63da1a40 Move diagnostic kind name to the end of the diagnostic. (#4437)
Also surround it in square brackets rather than parentheses. This
matches the format used by Clang and GCC, and means diagnostics will
still match the `file:line:col: error: ` pattern used by some IDE tools.

Before:
```console
fail_builtins.carbon:11:11: error(AliasRequiresNameRef): alias initializer must be a name reference
```

After:
```console
fail_builtins.carbon:11:11: error: alias initializer must be a name reference [AliasRequiresNameRef]
```

Also tighten up test regex to only match on `STDERR` lines that list a
file name.
2024-10-23 16:56:23 +00:00
Geoff Romer 9266f867f9 Model the return slot as an output parameter (#4432)
Also fix `Param` insts to have meaningful names in pretty-printing, to
help clarify relationship with return slot.
2024-10-23 16:53:34 +00:00
Jon Ross-Perkins 62c36eceda Support printing the diagnostic kind for verification. (#4425)
This is to help identify which diagnostics we're actually using.

Note that driver/testdata still has tests which don't pass this flag,
and so continue to test the kind-less (default) behavior.
2024-10-18 22:33:56 +00:00
Richard Smith a02dfe0226 Superficial support for Core.BigInt type (#4414)
Add a `Core.BigInt` type and a corresponding builtin type in the
toolchain. See [corresponding section of the
design](https://docs.carbon-lang.dev/docs/design/expressions/literals.html#defined-types).

So far this type is not used for anything, and there is no way to create
an instance of it.
2024-10-16 23:27:01 +00:00
Geoff RomerandJon Ross-Perkins 9d942f4633 Generate parameter pattern-match IR from pattern IR (#4388)
Also propagate the pattern IR along with the pattern-match IR, and use
it where appropriate.

Strictly speaking, some parts of the pattern-match IR are allocated
eagerly, while traversing the pattern's parse tree, but they still
aren't actually emitted until we traverse the associated pattern insts.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-10-16 19:15:29 +00:00
Richard Smith 17411c5e78 Assign a name to interface_type instructions. (#4369)
This matches what we do for `class_type` and `function_type`.
2024-10-04 23:06:24 +00:00
Richard Smith 568ad197d1 Track the instruction used to name the type and constraint in an impl. (#4368)
This is necessary in order to have access to the specific versions of
their constant values in a generic impl.

Stub out impl deduction.
2024-10-04 00:06:55 +00:00
josh11bandJosh L 49e0c186fc Add comma between the arguments to the bind_symbolic_name instruction (#4358)
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
2024-10-01 23:58:30 +00:00
Richard Smith 5ab957d012 Make ImplDecls evaluate to themselves. (#4352)
Change ImplDecls so they evaluate to themselves in general, rather than
having a special case in import handling that pretends that they do.
2024-09-27 22:39:56 +00:00
Geoff RomerandJon Ross-Perkins dc32aa2690 Initial support for binding patterns in SemIR (#4221)
Introduces the `BindingPattern` and `SymbolicBindingPattern` insts, and
a separate stack of pattern blocks that they are emitted into. The
intent is to generate the corresponding pattern-matching insts (like
`BindName`) from them in a separate pass, but that is deferred to future
PRs.

See
[here](https://docs.google.com/document/d/1U_vQH17V893J9aF1LJXUnFYBNSs2MjKl4bJPaWCB2zo/edit?usp=sharing&resourcekey=0-w0xGYZ0An31Kpz-wvzSXwQ)
for the design this is based on, but note that during review we have
chosen to deviate from that design by putting the patterns in separate
blocks, and omitting the "forward references" from a `BindingPattern` to
its corresponding `BindName`. This in turn necessitates having separate
inst kinds for symbolic and non-symbolic binding patterns.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-09-25 19:12:58 +00:00
Richard Smith 8d45530c5f Add a note: prefix to all notes. (#4330)
Omit the `note: ` prefix and the snippet from the "in import" note that
precedes a diagnostic.

This makes our diagnostic output more closely match that of Clang and
GCC.
2024-09-23 23:59:25 +00:00
Jon Ross-PerkinsandRichard Smith e7aebbe581 Update basic diagnostic capitalization/punctuation (#4328)
This is a primarily automated change:

- Search & replace for capitalization
-
`(CARBON_DIAGNOSTIC\((?:\n\s+)?\w+,(?:\n\s+)?\s\w+,(?:\n\s+)?\s")([A-Z])`
    - `$1\L$2`
- Search & replace for period
-
`(CARBON_DIAGNOSTIC\((?:\n\s+)?\w+,(?:\n\s+)?\s\w+,(?:\n\s+)?\s"(?:[^)]|\n)+)\.("[,)])`
    - `$1$2`
- Limited search & replace for `ERROR: ` -> `error: ` in streamed things
- Leaving a TODO for command_line because there's more cleanup that can
be done there
- Modify diagnostic_consumer.cpp
    - ERROR -> error
    - WARNING -> warning

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2024-09-19 21:32:53 +00:00
Richard Smith 2044366652 Support initialization of specific classes from struct literals (#4320)
Add support for initializing types like `GenericClass(i32)` from a
struct literal. A new kind of instruction, `complete_type_witness`, is
added to the class definition to track the object representation type so
that it's visible to the generics machinery. Accesses to the object
representation of a class have all been updated to pass in the class's
`SpecificId` so that the types of the fields of the specific class are
used instead of the types of the fields of the generic class in places
that look at the object representation -- primarily class
initialization.
2024-09-19 19:18:32 +00:00
Richard Smith 0354efa1fc Rework how we check calls to support deduced implicit parameters (#4302)
Instead of the `call` instruction having a block with one argument per
explicit argument, preceded optionally by `self` and followed optionally
by a return slot, change the `call` to store only the *runtime*
arguments. Store an index on the runtime parameters to make it easier to
determine the correspondence between arguments and parameters in a call.
Compile-time parameters, whether implicit or explicit, are no longer
included in the call argument list. Instead, they're tracked only in the
`specific_id` on the callee.

For calls to generic classes and generic interfaces, it no longer makes
sense to form a `call` instruction, given that the entirety of the
result is determined by the `specific_id`, which is now formed when
checking the call. Instead, the `call` instruction now only models
function calls, and not calls to other kinds of parameterized entity
names, and we create a `class_type` or `interface_type` instead of a
`call` instruction to model these kinds of calls. Notionally the model
here is that we're following the #3720 approach for calls, but for now
we inline the `Call.Op` function when forming SemIR.

We now also track the enclosing specific for a generic class or generic
interface that appears within an enclosing generic. This is necessary in
order for deduction of the inner generic parameters to not get confused
by the outer generic parameters being absent.

In order to not regress diagnostics, the template argument deduction
mechanism has been extended to specify the name of the parameter we're
deducing against when possible, and call arity mismatch errors are now
diagnosed before performing deduction rather than afterwards.
2024-09-13 21:31:43 +00:00
Jon Ross-Perkins d4c7743d18 Update tests to use [[@TEST_NAME]] (#4293)
Applies #4278 TEST_NAME substitution to tests. Note I've tried to
structure commits as:

1. Do all the replacements.
2. autoupdate (nothing else) -- this shows incorrect updates.
3. Fix up manually, including autoupdates to get back to original
output.
2024-09-10 22:52:23 +00:00
Richard SmithandJon Ross-Perkins 187a3608df Use As and ImplicitAs interfaces for conversions. (#4209)
Add these interfaces to the core library. For now, they're two separate
interfaces because we don't yet support one interface extending another.

This collapses a lot of the layering in check: for example, the call
building logic depends on implicit conversions, conversions now depend
on the overloaded operator machinery, and that machinery depends on
building calls.

In passing, improve the diagnostics for failing to find a name required
from the prelude. Also convert all the transitively-called code from
`NodeId` to `LocId` given the latter is what the conversion machinery
has available.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-09-05 23:39:58 +00:00
Jon Ross-PerkinsandRichard Smith 7ded56ef35 Improve namespace handling in imports. (#4153)
This implements a few closely related features:

- Starts merging namespaces discovered inside imports.
- Stores results of cross-package name lookup as an entry inside the
scope.
  - Note this is particularly visible with `i32`.
- Moves more of the imported instructions to the import scope.

Note this is primarily for executing the namespace TODO in check.cpp,
which is removed here.
`testdata/namespace/merging_with_indirections.carbon` tests key
behavior.

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2024-07-24 19:56:17 +00:00
Jon Ross-PerkinsandGeoff Romer 07c286e3cb Use the package/library name in ImportIRId formatting. (#4154)
Also adds import_ir_scope to namespace formatting. I'd done this as an
aid for #4153, and am splitting it out.

---------

Co-authored-by: Geoff Romer <gromer@google.com>
2024-07-22 22:43:36 +00:00
Jon Ross-Perkins 9581a1867d Move import refs to their own block. (#4103)
This executes on a TODO in AddImportRef to add instructions to their own
block instead of the File block. This has an important consequence of
removing a pattern from InstBlockStack that added to blocks not
currently at the top, cleaning up an issue for ArrayStack. The delta
here is then mostly in different formatting of the import refs, a
consequence of the separation.
2024-07-03 18:21:12 +00:00
Jon Ross-Perkins 5ebcbae2e8 Add a location to indirect imports. (#4098)
By adding an `ImportDecl` instruction, this creates something that can
be referenced through `ImportIRInst`.
packages/no_prelude/implicit_imports_entities.carbon is getting a test
of this (import_conflict and import_conflict_reverse).

Also re-packs ImportIR from 24 bytes to 16 on 64-bit, since I'm touching
everywhere that makes one anyways.
2024-07-03 17:34:39 +00:00
Jon Ross-Perkins ac2428acaf Start unifying let/var handling. (#4032)
Merges handle_let.cpp and handle_variable.cpp into a single file in
order to take better advantage of commonalities.

Both still have a bunch of kludges, and there's still divergent handling
in handle_binding_pattern that will yield different results. However,
this fixes some things about `let` like starting to make use of
global_init (imperfectly, due to how VarStorage works, I grant), and in
particular adding `let` names to a name scope, not just lexical lookup.
2024-06-07 20:08:31 +00:00
Richard Smith 1c07f959a8 Format types in SemIR using the formatting for their instruction. (#4035)
Don't use the pretty-printed type name, because that's intended for
diagnostics, not for a theoretically machine-readable format like SemIR.

Types are always constants, so omit the leading `constant.` on the type
instruction name.
2024-06-06 15:12:48 +00:00
Richard Smith 9a11e977b3 Improve formatting of the type of a function or generic class name. (#4033)
Don't format the *type of* the function `F` as `"F"`. Instead use
`"<type of F>"`.

Also improve instruction naming for function and generic class name
values: name the value after the function or generic class, and add a
`.type` suffix to the type.
2024-06-06 00:40:43 +00:00
Jon Ross-Perkins 83413479d7 Move some of the test information to TIP lines (#4007)
This has is a nice-to-have for me. Frequently I want to run a specific
test, and end up digging through output to be able to copy-paste the run
line. This uses TIP lines to inject the command into the file when using
AUTOUPDATE.

Note, one of the reasons I want this is because "bazel test
//toolchain/testing:file_test --test_output=all" has been regularly
exceeding bazel's output limit for me (workaround is either opening the
output file or specifying an obscure output limit flag), making it a
little harder for me to get the commands. However, frequently I'm adding
a file and want to iterate on it, so that's really the use case I have
in mind here.
2024-06-04 17:57:23 +00:00
Jon Ross-Perkins 55300d1ebb Switch type literals to use builtin functions. (#3978)
Modifies the core package and literal handling to use factory functions
for standard type literals.

Updates function/builtin/import.carbon to stop depending on the prelude,
since it would list all the impls in the core file. Updates
alias/builtins.carbon to be failing (the type values cannot be aliased).
2024-05-23 16:00:08 +00:00
Richard Smith 23f9065949 Implement proposal #3927. (#3963)
Change syntax for package declaration to put the `impl` keyword at the
start and remove the `api` keyword.

To support this, rearrange processing of package, library, and import
declarations to use the general modifier handling support in declaration
parsing rather than special-case logic.

There is an ambiguity in `impl package.Foo as Bar`, which we resolve by
treating `package` as an introducer after a modifier only if it's not
followed by `.`.
2024-05-21 00:36:03 +00:00
Jon Ross-PerkinsandRichard Smith 76ed3c73cb Promote FunctionType to a standard instruction. (#3931)
This removes the builtin FunctionType, replacing it with a FunctionType
instruction. The constant for a FunctionDecl is now a StructValue with
type of FunctionType.

Note this means a function declaration produces _both_ a type, and a
value of the type. This has some consequences in terms of circularity,
and makes the importing of function declarations a little more complex.

It'll get particularly peculiar for imports because of the behavior of
the reference, but that's a known issue due to other things such as
`alias`. The impact will hopefully be contained to
ResolvePrevInstForMerge (and ImportRefs).

To note a small formatting change in diagnostics:

```
-  // CHECK:STDERR: fail_member_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated <function> in Interface>` is not callable.
+  // CHECK:STDERR: fail_member_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated F in Interface>` is not callable.

-  // CHECK:STDERR: fail_todo_facet_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated <function> in Interface>` is not callable.
+  // CHECK:STDERR: fail_todo_facet_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated F in Interface>` is not callable.
```

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2024-05-03 15:18:04 +00:00
Richard Smith 008d41d7f3 Move instruction names for struct and tuple values from lower to InstNamer. (#3918)
Change the names for emitted globals for constants with storage to
include both the name of the constant and the name of the use.

This causes the instructions to also be named in SemIR and in LLVM IR
constants.
2024-04-26 23:47:08 +00:00
Jon Ross-Perkins de4c32beb5 Split apart some tests which don't need the prelude. (#3904)
This could probably go further, but I'm just trying to get the ability
to run some significant tests without the prelude. This already requires
some migration of `i32` and `bool` to non-prelude-dependent types
(technically not at the moment, but I'm trying to stick with the
philosophical model of the prelude).

Note this undoes part of #3895 which had made all lex/parse tests depend
on the prelude -- I don't think that was a necessary change. Rather, it
seems better to isolate individual lex/parse tests from the prelude. I'd
been on the fence in that PR (it was fixing one of the issues that
contributed to wanting to not include the prelude), but now it feels
more consistent. The prelude could have a parse error and we shouldn't
break every parse test on that.
2024-04-24 20:16:48 +00:00
Richard Smith ccf87f0a38 Use computed constants in lowering rather than lowering instructions (#3905)
First steps towards using constant values in lowering.

For now, we reuse the regular instruction lowering to lower constants.
This mostly works, because we don't actually need an `llvm::Function` or
a current basic block when lowering a constant most of the time.
However, a special case is needed for lowering aggregate value constants
because they would otherwise create a stack alloca to store the
constant. Separate constant lowering code will be added in a future
change to clean this up.

When lowering a constant initializing expression, the result is a value
of the destination type, rather than code to initialize the destination,
so a separate copy step is required when finishing initialization from a
constant for a type that uses in-place initialization. Handling this
required extending `ReturnExpr` to track its destination location.

We currently often create non-constant `*_access` SemIR instructions
that are only used by constant `*_init` instructions. These cause
lowering to leave behind `getelementptr` instructions in the lowered IR
that are now unused. It should be possible to detect this case and avoid
producing these instructions, or to produce them lazily, but for now
we're just leaving them around for LLVM to clean up.
2024-04-23 16:23:24 +00:00
Richard Smith 3776c068de Unify instruction naming between SemIR and LLVM IR (#3898)
Factor out `SemIR::InstNamer` and also use it when lowering to LLVM IR.
Automatically name all instructions created with our `IRBuilder` based
on the name computed by the `InstNamer`, and likewise name basic blocks
using the label generated by the `InstNamer`.

Move some of the existing naming logic out from lower into `InstNamer`
so that it's also used in SemIR. In particular, we now name call
instructions after their callee, or after the builtin name for calls to
builtins.

Computing and adding these names isn't completely free. This instruction
naming is designed to be optional, so that we can turn it off for builds
where the LLVM IR will only be converted to assembly and won't be seen
by a human, but so far it's enabled unconditionally. We can tune that
later as needed.
2024-04-19 02:19:30 +00:00
Richard Smithandjosh11b 462bcd9f6e Support explicit conversion between adapters and their adapted types. (#3889)
Allow an explicit `as` conversion to convert between adapters and their
adapted types. Also make the value representation of an adapter be the
same as the value representation of the adapted type so that the
conversion is always possible.

---------

Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
2024-04-17 18:11:27 +00:00
Richard Smith 015c7c780c Fix location of converted inst for explicit as conversion. (#3887)
Use the complete location of the `as` conversion rather than the
location of the first operand, so diagnostics referring to the result
point at the whole thing.
2024-04-15 23:22:44 +00:00
Richard Smith 1b335402d1 Allow incomplete return types in function declarations. (#3875)
Move completeness check to the point where the function is defined or
first called. This means we also defer deciding whether the function has
a return slot until that point. Instead of storing a return slot per
function, store the location of the return storage, which may or may not
be used, and compute and store a separate flag saying whether to use it
at the point of first use or definition.

This is the final piece in supporting simple `Make` functions in classes
as a replacement for constructors.
2024-04-11 07:23:56 +00:00
Jon Ross-Perkins 895e90e791 Start including the prelude for testing. (#3861)
- Adds an empty prelude.carbon file
- Imports that file in any non-Core package file
  - Adds --disable-prelude-import to avoid that
- Adds --exclude-dump-file-prefix to be able to hide files from dumping
- Used to hide core files (we can't do this by package name due to lex
dumps, for example)
- Restructures some tests to not rely on `i32`, particularly `alias`
tests (which rely on a name ref) and tests with no prelude.

I'm adding the framework for switching i32 to calling Int32 in the
prelude, but I'm running into a separate error actually switching over.
So that *mostly* works, but isn't quite ready for prime time. However,
maybe the current state of this PR is still useful to review since it
does a lot of the infrastructure work and adds the %Core everywhere?
2024-04-07 17:11:42 +00:00
Richard Smith 5665660677 Remove special-case formatting for class and interface LHS. (#3744)
These now have a type_id, so we can use the normal formatting.
2024-03-06 23:32:33 +00:00
Richard Smith 064123d93f If a SemIR instruction has a braced block and a constant value, print the constant value first. (#3734) 2024-02-29 23:51:32 +00:00
Richard Smith 67d5446b03 Add Self to the name scope for a class. (#3736)
Rather than just adding `Self` to the lexical scope, add it to the
class's name scope so that it is visible in later lexical scopes for the
same class -- in particular, for out-of-line definitions of members.
Also switch some tests in `check/testdata/class` over to making
idiomatic use of `Self` both inside a class and out-of-line, now that it
works more consistently.

Note that this does not permit using `Class.Self`, but only because we
don't yet support keyword names after `.` at all. If that changed, one
could use `Class.Self` to redundantly refer to `Class`. Whether we allow
that is left to a future decision.
2024-02-29 21:33:47 +00:00
Richard Smith a6f4752a7b Collapse empty braces onto a single line. (#3733)
Don't write out `.members` section at all if it's empty.
2024-02-28 23:21:43 +00:00
Richard Smith 5543602a50 Make namespace formatting more consistent with other declaration block instructions. (#3732)
List names vertically rather than horizontally.
2024-02-28 22:20:37 +00:00
Richard Smith 5f4e6c768a Format the decl block for a declaration as a trailing block. (#3731)
Previously we used the default inst block formatting, which writes out a
parenthesized list of references, which would always be 'unexpected
instref's because nothing else prints the instructions in the decl
block.

In addition, track the decl block for function declarations like we do
for other kinds of declaration. This means that the parameter
declarations for a function are now properly rendered into the formatted
IR. Note that this adds a lot of verbosity to `function_decl`, but it
does accurately reflect the IR, and we'll probably want this information
to be printed once we start supporting more complex generic function
declarations.

This removes almost all the 'unexpected instref's in our formatted
output. There are remaining cases when a declarative scope contains
multiple blocks, where we only track one of those blocks. That happens
when there is control flow within declarative scopes, and for error
recovery when a class or interface or similar is defined more than once.

As requested in #3730.
2024-02-28 21:28:59 +00:00
Jon Ross-Perkins 364ea5d3f2 Assign a constant to ClassDecl/InterfaceDecl for name references. (#3722)
By adding a constant to ClassDecl/InterfaceDecl, we're able to remove
name reference special-casing. Use TryEvalInst on the Decl to generate
the Type. For ClassDecl, then use the generated constant for
self_type_id.
2024-02-24 00:00:18 +00:00
Jon Ross-Perkins 91f0c23124 Provide diagnostic locations for imported namespaces. (#3640)
Building on #3636 which handles the general import case, add special
casing for namespaces. Namespaces can be combined cross-IR, so it's a
little more complex.

The implementation adds import_id to the Namespace instruction as a
reference to find the original using the normal structure. This is
achieved by moving the name_id to NameScope to free up space.

---

I considered a few alternatives...

I considered adding import_id to NameScope, but:

1. It's more consistent with things such as Function or Class that
provide name_id on the info object rather than the instruction.
2. I thought it more likely that there would be more NameScope cases
that might want a name_id rather than the import_id, since ImportRef
will typically be used.

I considered putting the import source (cross-ref IR id + inst id) on
the NameScope versus a separate ImportRef, which seems like the
strongest argument towards the NameScope approach because it removes an
instruction. That just felt inconsistent though, and the overhead of
instruction-per-imported-namespace should be low (theoretically few
namespaces should be used). Plus I feel a bit odd adding two
generally-unused ids to NameScope.

A specialized Namespace structure could also have been created to store
the import_id, but that would add an indirection to the NameScope.
2024-01-24 18:00:32 +00:00
Richard Smith afd194de9d Runtime : name bindings are not constants. (#3639)
Do not create runtime name bindings for `FieldDecl`s even though they're
declared with `:`, so that we can still constant-evaluate references to
fields.
2024-01-23 17:02:08 +00:00
Richard Smith b138c90c9e Use constant evaluation to determine the identity of types. (#3617)
Remove the type canonicalization mechanism and instead rely on constant
canonicalization to deduplicate types.

Rename the `Canonicalize*Type` functions to reflect that they're no
longer performing canonicalization. Switch code that creates types due
to semantic checking, rather than due to source syntax, to directly
create type constants through evaluation rather than creating an
instruction and evaluating it to produce a separate constant
representation.

The mapping from `const (const T)` that was previously performed by type
canonicalization is now implemented in expression evaluation instead.

The value `<error>` is now treated as a constant value, with a special
property that an instruction involving `<error>` that could possibly be
constant evaluates to `<error>`. This helps avoid producing follow-on
errors when an error occurs as a subexpression of an expression, such as
a type, that is intended to be constant.
2024-01-19 00:47:37 +00:00