Commit Graph
55 Commits
Author SHA1 Message Date
Richard Smith 05cc09daca Fix cross-package signature mismatches. (#7232)
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.
2026-05-21 00:02:29 +00:00
Richard Smith f9ab963bd6 Add a type_literal instruction to represent syntactic type literals. (#6781)
This allows us to capture the location at which a type literal was used,
even in the cases where we don't otherwise need to create a new
instruction to represent the type such as for `char` or `str`.

The logic used to build the underlying type is now marked as desugaring.
For cases such as `iN`, this causes the call to `Core.Int` to no longer
be added as a dedicated IR instruction, and instead its constant value
is used directly as the value of the `type_literal`. This results in
this being on balance a reduction in the size of the IR.

This also fixes a crash in C++ interop when using a `char` literal as a
template argument. The crash was caused by the template argument not
having an associated location when mapping to a C++ location. See
changes to check/testdata/interop/cpp/template/type_param.carbon for an
example that used to crash before this change.

Update alias handling to allow an alias to point at any type literal,
reinstating support for aliases for type literals such as `bool` and
`i32` that had previously worked but stopped working when we
transitioned those types to being defined in the prelude. See changes to
toolchain/check/testdata/alias/builtins.carbon.

All the test changes other than the two mentioned above are mechanical
autoupdate changes switching to the new instruction.
2026-02-26 20:10:50 +00:00
Geoff Romer 09710d102f Separate binding insts for refs and values (#6235)
This resolves a TODO in `expr_info.cpp` by using the inst kind rather
than the bound value to track the binding's category.

Since we're churning all the `bind_name` insts in testdata anyway, I'm
also taking this opportunity to align the inst naming with the design's
terminology, by calling these insts "bindings" (this aspect of the PR is
dependent on #6231 resolving an ambiguity in that terminology). For
consistency we'll need to rename several other insts as well (see the
TODO on `RefBinding`); I'm deferring that to a separate PR to minimize
the review load, but I think those name changes are in-scope for this
review.
2025-10-23 01:46:24 +00:00
Dana Jansens 07aec169e1 Add min-preludes to more slow tests (#5681)
Adds min-preludes more tests which were seen as slow and their
surrounding neighbours. This drops the file_test runtime on my machine
from about 7s to about 6s.

For a few files that are clearly only testing diagnostics, we drop the
if-present semir ranges and the associated TODO.
2025-06-17 20:55:48 +00:00
Jon Ross-Perkins 59cb7183b2 Add range flag settings to pointer files (#5571)
Where `--no-dump-sem-ir` is used, change to `--dump-sem-ir-ranges=only`.
Otherwise, add `--dump-sem-ir-ranges=if-present` with a TODO to change
to `only`.

Note, SemIR is affected just because the extra comments change line
numbers in files where splits aren't in use.
2025-05-29 20:25:46 +00:00
a23631f360 Support for lowering references to imported vars. (#5513)
Previously we walked the global variables defined by the current file
and emitted an LLVM global variable definition for each of them. Now
instead, when emitting a constant reference to a global variable, we
emit an LLVM global variable declaration, and we then subsequently walk
the global variables defined by the current file and convert each of
them from a declaration to a definition.

In order to make import of names of global variables work, add support
for import of `var`, as well as support for importing `tuple_access` and
`tuple_pattern` in the case where the `var` has a tuple pattern in its
declaration. Also treat `bind_name`s that are reference bindings to
`var`s as having the same constant reference value as their `var` so
that we can properly import and lower them.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
2025-05-29 19:48:16 +00:00
Richard Smith 797b14eb8e Import ImplWitnessTable into the imports block instead of the constants block. (#5374)
Don't import `ImplWitnessTable` into the `constants` block, because we
generally don't put `Unique` constants there. This matches the handling
of the other kinds of `Unique` constants. In order to keep the
instruction visible in formatted SemIR, add it to the `imports` block
instead.

Also fix a bug in the instruction formatter that resulted in
instructions in the `imports` block being omitted from the output if
they were only referenced by earlier instructions in the `imports` block
and by instructions in the `constants` block. This was already resulting
in some referenced instructions being omitted from the output, but also
occurred frequently for `impl_witness_table` instructions after this
change because it is common for the only reference to those instructions
to be from `impl_witness` instructions in the `constants` block.
2025-05-01 00:08:43 +00:00
Geoff Romer 34887403ab Model patterns as constant values (#5385)
This will enable us to simplify support for parameter and return
patterns in import, which operates primarily on constants.
2025-04-30 22:32:41 +00:00
Geoff Romer fafb655d39 Separate pattern types from expression types (#5360)
This is a step toward treating patterns as compile-time constants, so
that we can import them more easily.
2025-04-28 16:54:37 +00:00
Richard Smith 0d2f364f39 Split evaluation up into one function per instruction kind (#5008)
Replace the large and growing `TryEvalInstInContext` function with one
function per kind. While we still have special-case handling for a small
number of instruction kinds, most instructions are now handled either
fully automatically or use a common codepath that evaluates the
instruction operands and then performs an eval-context-independent
evaluation of the instruction.

To support this, `InstConstantKind` is expanded to describe more
fine-grained details about how each kind of instruction interacts with
constant evaluation. Also, the operand kinds of instructions become
slightly more fine-grained: we now distinguish between operands that
describe the destination of an initializing expression (`DestInstId`)
from other `InstId` operands, because `DestInstId` operands need
different treatment during constant evaluation. In particular, an
initializing expression can have a constant value even if its
destination is non-constant or has not yet been set, because evaluation
of an initializing expression doesn't include the store to the
destination.

Some minor test changes:

- We now more consistently propagate errors into the results of constant
evaluation, so more instructions that depend on errors have a constant
value of `<error>`.
- Diagnostic location for invalid array types now point at the whole
array type rather than the array index expression, because
`EvalConstantinst` doesn't have access to the original expression.
- Diagnostic for failed `RequireCompleteType` doesn't print the original
type any more because `EvalConstantInst` doesn't have access to the
original expression.

As a follow-up, some of this -- in particular, the `EvalConstantInst`
overloads -- will be moved to a separate file, in an effort to split the
overall constant evaluation machinery apart from the logic to evaluate
each individual kind of instruction.
2025-02-27 01:31:26 +00:00
Boaz Brickner 986a2a064c Add poisoned names to the format (#4961)
Part of #4622.
2025-02-14 19:18:51 +00:00
Richard Smith c6d35e1c4a Rename template constant -> concrete constant. (#4939)
This implements a direction decided in a
[recent
discussion](https://docs.google.com/document/d/1Iut5f2TQBrtBNIduF4vJYOKfw7MbS8xH_J01_Q4e6Rk/edit?resourcekey=0-mc_vh5UzrzXfU4kO-3tOjA&tab=t.0#heading=h.mas1g68xx9ct)
to switch away from "template constant" when naming a constant that
doesn't depend on any generic parameters, because that creates confusion
with template-dependent constant values that depend on a template
parameter.
2025-02-12 21:24:51 +00:00
Calvin 3f4de65ad8 Improve SemIR naming of import_refs (#4824)
Changes the name of SemIR `import_ref`s to use the format
`<package>.<entity>`.

<table>
<tr><th>Before</th><th>After</th></tr>
<tr>
<td><code>%import_ref.05a: type</code></td>
<td><code>%Main.D: type</code></td>
</tr>
<tr>
<td><code>%import_ref.8f2: &lt;witness&gt;</code></td>
<td><code>%Main.import_ref.8f2: &lt;witness&gt;</code></td>
</tr>
</table>

* [Discord discussion in
#toolchain](https://discord.com/channels/655572317891461132/655578254970716160/1330253540999827577)
* Closes #4769
2025-01-22 07:22:07 +00:00
Geoff RomerandRichard Smith 13434f0e8a Model var as a pattern operator (#4720)
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2025-01-17 17:51:34 +00:00
David BlaikieandJon Ross-Perkins e6c1f0630a Add a newline after diagnostic output when testing (#4818)
This removes some churn when adding new diagnostic cases to test files
(where previous to this change the newly added newline would cause the
previous diagnostic CHECKs to be updated including changes to the line
number because the CHECK for the blank line meant an extra line between
CHECK and source line).

A few alternatives discussed here:
https://discord.com/channels/655572317891461132/655578254970716160/1329573358475673723

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2025-01-16 23:23:57 +00:00
Richard Smith b1230218d5 Make fingerprinting stable across compatible source changes. (#4789)
Include the index rather than the name in the fingerprint of a symbolic
binding. While both the index and the name contribute to the canonical
identity, using either one of them in the fingerprint is sufficient to
ensure that distinct entities get different fingerprints. Changing the
name of a symbolic binding should ideally not result in fingerprint
changes, so exclude the name from the fingerprint when we have an index.

Use the canonical type and constraint when fingerprinting an impl, so
that uses of names in `name_ref` instructions aren't considered, only
the entity the name resolves to, and different ways of spelling the same
type have the same fingerprint. This similarly allows compatible changes
to be made to impls without changing the fingerprint.

Exclude the declaration block when determining the fingerprint of a
declaration. The declaration block contains the declarations of
parameters of the declaration, which do affect whether two declarations
are identical, but not whether they denote the same entity, because it
would be invalid to have different declaration blocks for declarations
with the same name in the same scope. Therefore changes to the
declaration block are compatible, and it's useful for such changes to
not affect the fingerprint.

This is not easy to test in isolation with our current testing
machinery. However, a follow-on PR will change the name of a parameter
in the prelude, and with this in place, will not cause any changes to
occur elsewhere in the toolchain tests.
2025-01-10 22:30:22 +00:00
Richard SmithandDana Jansens 19182f08aa Compute a fingerprint for constants and import_ref instructions. (#4763)
Use it in the instruction namer to make instruction names more stable
across unrelated changes to the toolchain or the prelude.

---------

Co-authored-by: Dana Jansens <danakj@orodu.net>
2025-01-07 20:41:44 +00:00
Geoff RomerandRichard Smith a112cbde5c Model type expressions as regions (#4698)
This is a precondition for enabling the new pattern-matching subsystem
to support binding patterns that have `if` expressions in the type
position.

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2024-12-19 21:41:06 +00:00
Richard Smith a10c79569e Model Core.Int as a class type (#4644)
Instead of treating `Core.Int` as the toolchain's builtin `IntType`,
model it as a class that adapts the builtin type. This aligns us better
with the intended language model, gives an associated library for
`impl`s involving `Core.Int` to live within, and opens the door adding
member functions to `Core.Int` if we decide that is desirable.
Remarkably it also seems to make the formatted SemIR a little smaller,
because a call to a generic class generates less IR than a call to a
function.
2024-12-16 22:19:23 +00:00
josh11bandJosh L 5d1b39e1f2 More instructions get named (#4615)
Goal is to reduce churn in names in test updates (by churning a lot of
them in this PR).

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
2024-12-03 20:47:53 +00:00
Richard SmithandJon Ross-Perkins e2ae5f212c Remove the special case for i32. (#4543)
For the few remaining uses of the builtin `i32` type, manually build an
`IntType(Signed, 32)` value instead. These are:

- The return type of `Run`.
- The type that int literals in an `if` expression are converted into.
- The type of an array index expression.

We should consider converting those three cases away from `i32` over
time.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-11-18 23:19:36 +00:00
Richard Smith 145f878ce8 Allow extend adapt of non-class types. (#4544)
Stop rejecting `extend adapt` of non-class types such as struct and
tuple. These don't actually work just yet because name lookup into
struct and tuple types is a special case that doesn't handle adapters,
but this gets us a bit closer.

This also slightly improves error recovery for name lookup into an
invalid scope.
2024-11-18 16:01:44 +00:00
4ee65ef58a Reduce the size of formatted SemIR. (#4534)
- Do not include entities imported from files that we are not dumping.
- Do not include constants and import_refs that are not referenced by
something that we are including in the formatted output.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
2024-11-15 21:00:26 +00:00
Jon Ross-Perkins 10e256a241 Name empty tuples distinctly in SemIR. (#4503)
Building on #4502, give empty tuple values a distinct name, and also
explicitly name tuple types (previously values but not types were
named).
2024-11-08 17:14:52 +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
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
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 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
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
Jon Ross-Perkins b8ceb8dd8b Print a blank line after a diagnostic. (#3806)
The purpose of the newline is to make it clearer where a given
diagnostic begins and ends, particularly as the first message of a
diagnostic may not be the error.

This is a trivial code change, but ripples edits through test files.
2024-03-22 18:10:49 +00:00
CJ Johnson d0e8afc51b Handle arrow operator (#3768)
This change implements the check behavior for the arrow operator.

`ptr->Foo()` is rewritten as `(*ptr).Foo()` and `ptr->(X.y)` is
rewritten as `(*ptr).(X.y)`
2024-03-18 17:40:00 +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 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
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