For now, hide `override fn`s from name lookup, so that the base class
version is always used, as the derived-class version does not have its
own vptr entry and so would not do the right thing if a further-derived
class adds a new override. This is implemented via a new access kind of
`Hidden`.
When checking the overriding function, pass in the expected `Self` type
and check the `self` parameter against that; the signature that we
generate for the thunk in the derived class is the base class signature
with the `self` parameter's type changed to the derived class.
When we generate a thunk for a virtual function, the thunk is assigned a
`virtual_index`, and the virtual function itself is not. When the thunk
makes a direct call to the virtual function, recognize this situation by
checking for a `virtual_index`, and perform a non-virtual call if there
isn't one.
Assisted-by: Gemini via Antigravity
This uses the `CARBON_KIND_ANY(AnyImportRef, auto import_ref):` syntax
that seemed to be favored [on
Discord](https://discord.com/channels/655572317891461132/655578254970716160/1478486848207720478).
This converted uses in the `sem_ir` directory to show it works
initially, then added `check` for full coverage plus validating the
`SemIR::` namespace discard.
Note in inst_namer.cpp, AnyBindingPattern includes FormBindingPattern
which wasn't previously handled.
I'm disabling clang-format because I think it formats with readability
issues, e.g.:
```
#define CARBON_KIND_ANY_EXPAND_AnyBinding(X, SEP) \
X(::Carbon::SemIR::AliasBinding) \
SEP X(::Carbon::SemIR::FormBinding) SEP X(::Carbon::SemIR::RefBinding) \
SEP X(::Carbon::SemIR::SymbolicBinding) \
SEP X(::Carbon::SemIR::ValueBinding)
```
Since `SEP` is typically a comma, it's also a nuisance to treat as an
argument to `X` (which could get better results).
Assisted-by: Google Antigravity with Gemini 3 Flash
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>
Every test that used `addr` before #6283 should be using `ref` after
this PR. In most cases that was done in #6283, but this PR transitions a
few that I missed in that first pass. In addition, #6283 cloned the old
`addr` tests from `foo.carbon` to `foo_addr.carbon` in order to maintain
test coverage during the transition; this PR removes those cloned tests.
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.
This restructures the import and merge logic to support parameter
patterns in a more scalable way.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
When checking whether we can use the function in an impl directly to
satisfy a signature in an interface, allow the parameter names to differ
between the two declarations.
We frequently want to operate on singletons. Per discussion, drop
`Singleton` to make the code shorter.
This started off as wanting to write `inst_id.is_error()`, but the
dependency relationship between ids.h and singleton_insts.h would
require some kind of delayed evaluation to allow the implementation to
remain in headers (which I suspect is helpful to have for inlining). I
could have added something like `IsErrorInst`, forward declared in ids.h
and defined in singleton_insts.h (which would always be included by
typed_insts.h), but the template approach felt like a decent balance
between (a) removing the boilerplate `::SingletonInstId`, (b)
understandability, (c) still visually mirroring if we immediately return
a singleton, and (d) flexibility for more than just `ErrorInst`. But TBH
I'd probably still have written `is_error()` if it didn't require
addressing the cross-header cycle.
Then I tried `SemIR::InstId::Is<SemIR::ErrorInst>`, which generally
worked with types but generated the complaint that it didn't shorten
*all* singleton uses. So pulling back on `::Is`, and instead just
dropping `Singleton`.
Reduce usage of `GetConstantInSpecific` to a single caller in constant
evaluation, with a TODO to remove that.
This gets us closer to being able to fully perform type-checking against
abstract types instead of types anchored within a particular generic.
What this really does is avoids shadowing names, so that we can
comfortable have things like `Check::DiagnosticEmitter` or
`Check::DiagnosticLoc` without shadowing being a concern.
Note, down this path I'm also thinking about:
- Renaming misc DiagnosticConsumer/DiagnosticEmitter classes, possibly
just to DiagnosticConsumer/DiagnosticEmitter (so
`Check::DiagnosticEmitter` instead of `SemIRLocDiagnosticEmitter`).
- Dropping `Diagnostic` from `Emitter::DiagnosticBuilder`.
- But not for `Check::DiagnosticBuilder`, because `Check::Builder` would
be ambiguous.
- Renaming diagnostics/diagnostic_* to drop "diagnostic".
[Discussion about SemIRLoc ->
DiagnosticLoc](https://discord.com/channels/655572317891461132/655578254970716160/1353771570463768698)
reminded me of this (in particular the older [Check::DiagnosticBuilder
discussion](https://discord.com/channels/655572317891461132/655578254970716160/1344363562608627763)),
but I'd only do that rename if there's matching consensus about a path
forward where we keep SemIRLoc, and in a way that it's only ever used
for diagnostics (the divergence from which is at the root of current
LocId discussion).
I'm trying to keep that separate from a namespace addition for clarity.
I've found myself cleaning up other cases of this, so moving to disallow
it.
```
In file included from toolchain/check/merge.cpp:5:
In file included from ./toolchain/check/merge.h:8:
In file included from ./toolchain/check/context.h:13:
In file included from ./toolchain/check/decl_introducer_state.h:8:
In file included from ./toolchain/check/keyword_modifier_set.h:11:
In file included from ./toolchain/sem_ir/name_scope.h:10:
In file included from ./toolchain/sem_ir/ids.h:12:
./toolchain/diagnostics/diagnostic_emitter.h:95:11: error: static assertion failed: Use `emitter.Emit(...)` or `emitter.Build(...).Note(...).Emit(...)` instead of `emitter.Build(...).Emit(...)`
95 | false,
| ^~~~~
toolchain/check/merge.cpp:92:61: note: in instantiation of function template specialization 'Carbon::DiagnosticEmitter<Carbon::Check::SemIRLoc>::DiagnosticBuilder::Emit<>' requested here
92 | context.emitter().Build(loc, ExternRequiresDeclInApiFile).Emit();
| ^
1 error generated.
```
- Explicitly document that `*Param` and `*ParamPattern` insts represent
`Call` parameters.
- Stop wrapping compile-time parameter patterns in `ValueParamPattern`
insts (because they aren't `Call` parameters).
- Document how `MatchContext::results_` relates to the `Call`
parameters, and be more consistent about when it's written to.
- Remove `RuntimeParamIndex::Unknown`: we no longer need to distinguish
"this `Param`'s runtime index is unknown" from "this `Param` isn't a
runtime param", because we no longer use `Param`s at all in the latter
case.
- Rename `RuntimeParamIndex` to `CallParamIndex`.
As a side effect of removing the `ValueParamPattern` insts, this fixes a
minor diagnostic bug where `NoteInitializingParam` didn't identify the
specific parameter that led to a deduction failure, because it expects
generic parameters to only be represented by `SymbolicBindingPattern`s,
but before this change they could be wrapped in `ValueParamPattern`s.
This tripped over a lowering crash when a member function with self was
declared-but-not-defined, so that's why some test cases were updated to
have (empty) function definitions.
I'll follow-up with/look into a fix for the
self-declared-but-not-defined cases separately.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
Note this mirrors parse_tree().packaging_decl().is_impl, but I'm
preferring to keep the version that doesn't access the parse tree so
that we could change tree storage without hurting as much.
Benefits:
* Provide a proper API for accessing lookup information.
* Make assumptions on whether the result is poisoned or not and how we
can use `InstId` explicit.
* Allow safely reusing the `InstId` value for pointing to the poisoning
entity for poisoned results (in a future PR).
* Consolidate `LookupNameInExactScopeResult`, `std::pair<SemIR::InstId,
bool>` and part of `LookupResult`.
Part of #4622.
This is a followup from #4834, I searched for "invalid" uses in our
codebase. This is mostly changing comments, and a couple debug
functions, but shouldn't affect testable behavior.
Note a couple things I'll highlight as not changing (but could) are:
- `ReturnTypeInfo::is_valid`
- `"invalid"` uses in the formatter
- `AddInvalid` for `!has_value` in `inst_fingerprinter` (because the
cases it's called sound invalid-ish)
High level, replacing `Id::Invalid` with `Id::None` and `Id::is_valid`
with `Id::has_value` for clarity, as discussed
[here](https://discord.com/channels/655572317891461132/655578254970716160/1331664574545395794).
The `IntId` refactoring is needed together with `AnyIdBase` because it's
also used with `ValueStore`.
Note, trying to be careful not to rewrite `EnumBase::InvalidIndex`, or
`is_valid` in general (e.g., `IdKind::is_valid`).
I've tried to sequence commits here:
1. Automatic replacements:
- `((?:Id|Index)(?: |::|\(|Base(?:\(|::)))Invalid((?:Index)?\W)` ->
`$1None$2`
- `<invalid>` -> `<none>`
- `InvalidNodeId` -> `NoneNodeId`
- `/\*invalid\*/` -> `/*none*/`
- `id((?:_|\(\))(?:\.|->))is_valid` -> `id$1has_value`
2. Manual edits:
- In `int.h` and `int_test.cpp`
- `IntT` has `is_value`, which I'm renaming to `is_embedded_value`.
- Manual edits to comments in this file.
- `AnyIdBase` and `IdBase`
- Declaration of `is_valid` -> `has_value`, `InvalidIndex` ->
`NoneIndex`.
- In `ids.h` and `ids.cpp`
- `is_valid` -> `has_value`
- `// An explicitly invalid ID.` -> `// An ID with no value.`; similar
for index
- Various math on `InvalidIndex` -> `NoneIndex`
- Various mentions of "valid" in comments
- In `value_store.h`, for `IdT::Invalid`, plus one comment
- In `impl.h` and `tokenized_buffer.h`, we had different initialization
of `::None` values (versus `ids.h` syntax) that I fixed manually.
- Spot checks to compile
- Particularly where `is_valid` replacements didn't catch spots due to
different naming.
3. Autoupdate tests
4. verbose.carbon (NOAUTOUPDATE)
5. Comment spot checks
Note there are probably other mentions of "Invalid" that should be swept
up, but I'd like to argue for merging and separating out remaining
cleanup since this is so sweeping (and likely to hit merge conflicts
from churn). We'll probably have lingering mentions of "invalid" for a
bit regardless, just because there are uses of "invalid" in non-Id APIs.
Rename `CheckIsAllowedRedecl` to `DiagnoseIfInvalidRedecl` to try to
better document behavior, and clean up comments.
This extends the no-merge-if-defined behavior to functions. It was
already the case for class/interface, and just added for impl, so if
anything functions were now inconsistent. I was kind of tempted to make
a helper for it, but I didn't think of a great structure/name to get
there: `DiagnoseRedef` isn't always called when it's a redefinition, for
example due to `extern` diagnostics, it's hard to combine.
Cleans up `is_defined` calls to rely more on `has_definition_started`,
removing some code paths that are unused since definitions aren't
merged.
* Implement ignoring the difference between `Self as` and `as`, as well
as `where` clauses at the end of an `impl` declaration when checking
whether `impl` declarations match, from #3763.
* Allow impl declarations with different constraint ids to match, as
long as the facet type of the constraint has the same interface_id and
specific_id.
* Add some TODOs reflecting future facet type resolution.
---------
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
This is a preparation change for adding name poisoning support
(https://github.com/carbon-language/carbon-lang/issues/4622), which is
expected to require more elaborate logic around NameScope since a name
can be not defined yet, defined, or poisoned.
The API separates looking up a name from getting the full entry since we
have cases where the entries are invalidated between the time we're
looking for the name and when we access (and sometimes modify) the
entry.
This change has the following benefits:
* `names` and `name_map` are internal to `NameScope` and are guaranteed
to match.
* `extended_scopes` and `import_ir_scopes` can not be manipulated (only
new scopes can be added).
* `inst_id`, `name_id` and `parent_scope_id` are constants.
* `has_error` can only be mutated from false to true.
---------
Co-authored-by: jonmeow <jperkins@google.com>
`ids.h` and `ids.cpp` are the manual edits, everything else is
search-and-replace.
The full list of things moved is:
- `TypeId::TypeType`
- `TypeId::AutoType`
- `TypeId::Error`
- `ConstantId::Error`
This is to unblock removing `InstId::Builtin*`.
The new `FacetValue` instruction represents `C as I` for some type `C`
and facet type `I`. It is named `FacetValue` instead of just `Facet` to
parallel the `FacetType` instruction.
This PR uses this instruction represent the facet value `Self` in an
`impl` declaration. This instruction will be used in the future to also
support things like:
* `C as I` where `C` is a class; and
* forming a specific for a generic with a `T:! I` parameter where `T` is
being given a concrete value.
(Here `I` is an interface or other non-`type` facet type.)
Also do some renaming and add some comments to make things a bit more
clear.
* `FacetTypeAccess` -> `FacetAccessType` to clarify this is not access
of a facet type, but access of the type of a facet
* `.facet_id` -> `.facet_value_inst_id` to parallel the `FacetValue`
instruction
`FacetAccessWitness` will be in a future PR.
---------
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Note, this supports plurals, but doesn't apply it anywhere. I'm mainly
doing that to demonstrate the approach regarding syntax. See
format_providers.h for details.
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>
Update impl handling to more closely match other kinds of declaration,
including support for declaring and defining gneeric `impl`s.
When of performing redeclaration lookup for impls by looking for the
self and constraint type, produce a list of impls rather than a single
impl because it's possible for there to be multiple impls with different
deduced parameters but the same self type and constraint. Following
#3763, only consider impls to be redeclarations if they're spelled the
same, not just if they have the same self and constraint types.
No support yet for impl selection to deduce the arguments of a generic
impl.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
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>
This switches `DCHECK` and `FATAL` as well.
The goal is to reduce the code size impact of these assertions so that
we can keep more of them enabled. Currently, the largest cost I see from
`CHECK` is not the actual check or the cold code itself, but actually
the failure to inline trivial functions due to the presence of the cold
code. This means that our goal isn't to reduce apparent code size in the
final binary but the LLVM IR cost assessed for these routines in the
inliner, which closely correlates with code size but is a bit different.
As discussed in #4283, experimentation shows that a single function call
with a minimal number of arguments is the lowest cost model for these.
This is easily achieved with a format-string API that internally uses
`llvm::formatv`. This PR is essentially the `CHECK` version of #4283.
However, the check macros are substantially harder to make work with
both format strings and streaming because they also take a condition.
Also, unexpectedly, I was very successful at devising a regular
expression based automated rewrite from the streaming to the format
string form with only low 10s of manual fixes. This includes compacting
strings broken up across lines, etc. Given how well that went, I've
prepared this PR which just directly switches to the format string API
and migrate everything to use it.
One nice side-effect is that the format string approach ends up greatly
simplifying the implementation here as well.
This is ... *shockingly* effective. Parsing speeds up by more than 3%
with just this change. And checking speeds up by **8%** with this change
alone:
```
BM_CompileAPIFileDenseDecls<Phase::Parse>/256 86.3µs ± 1% 82.9µs ± 1% -3.94% (p=0.000 n=17+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 431µs ± 1% 415µs ± 1% -3.76% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 1.77ms ± 1% 1.71ms ± 1% -3.18% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 7.44ms ± 1% 7.17ms ± 2% -3.56% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 30.7ms ± 1% 29.7ms ± 1% -3.15% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 131ms ± 1% 127ms ± 1% -2.81% (p=0.000 n=18+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/256 878µs ± 2% 800µs ± 1% -8.91% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/1024 1.88ms ± 2% 1.72ms ± 1% -8.56% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/4096 5.78ms ± 2% 5.28ms ± 1% -8.70% (p=0.000 n=20+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/16384 21.9ms ± 1% 20.1ms ± 1% -8.02% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/65536 90.4ms ± 2% 83.1ms ± 1% -8.04% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/262144 381ms ± 2% 352ms ± 1% -7.79% (p=0.000 n=19+19)
```
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
The particular test this focused on is indirect_two_file in
toolchain/check/testdata/function/definition/no_prelude/extern_library.carbon.
This removes `parent_scope_id_for_new_inst` because I think it's
returning unhelpful results. The use was at the root of incorrect
results for the indirect import chain. `name_id_for_new_inst` is
actually wrapping a union, so it's more important.
The merging of `is_extern` and `first_owning_decl_id` in
`handle_function.cpp` feels like it's less correct with the changes
that've been made to `extern`. This ripples in tests, because the error
recovery shifts.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Support for types (particularly classes) is left as a TODO.
There's also an issue I'm observing with a "define in impl" test, but
this is probably an issue with resolving the prior declaration which is
imported indirectly. The PR was already feeling big, so I'm choosing to
cut here.
Note, this does not implement the rule "The owning library's API file
must import the `extern` declaration, and must also contain a
declaration."
Allow directly constructing a PostorderIterator, to get rid of
`tree.postorder(node_id).end()` indirect construction. For ranges that
don't need tree data, make it clearer that they're not validated.
Note, this subtly gets rid of a subtree size use in the
`tree.postorder(node_id).end()` case (to get the discarded `begin()`
value).
Note this isn't implementing checking through imports. The parse node
there is harder to access through the context, so would require
examining the entity in order to get the import declaration, to get at
the ImportIR. We also don't have a parse tree attached in that case, and
would need to add one to SemIR::File. But I believe we do want to add
that, so it's explicitly a TODO.
Note GetTokenText re-lexes literal values, so there's a bit of potential
overhead there. Not sure if we want a more efficient manner for
comparing in cases like this.
For each generic, build a list of instructions describing the
computations we need to do when resolving an instance of the generic:
this is a list of the instance-specific constants and types that the
generic uses. Another way of viewing this list is as a block of Carbon
SemIR code that is evaluated in order to form an instance of the generic
-- this is referenced in the code as the "eval block" for the generic.
For each instruction in the generic whose type or value is a symbolic
constant, replace that type or constant value with a symbolic reference
that says "to find the actual type or value, look at index N in the list
of values for the generic instance".
For an instruction with a symbolic constant value, we can just add that
instruction to our list. For an instruction with a symbolic constant
type, however, we may not have a corresponding instruction computing the
type within the generic and may need to build a new instruction, but
will reuse one where possible. In the case where we build a new
instruction, we use the existing substitution code to build the type
within the eval block.
For now, this transformation is only done in the declaration region of
the generic, not in the definition region. Also, we map back from the
symbolic references to the underlying constant value in a few places
where we will eventually need to do a lookup into a generic instance, in
order to avoid regressing the tests.
This works to leverage the capabilities of the hashtable as much as
possible, for example using the key context in the value stores.
However, there may still be opportunities to refactor more deeply and
use the functionality even better. Hopefully this is at least
a reasonable start and gets us a clean baseline.
On an Arm M1, this is a 15% improvement on my large lexing stress test,
but ends up a wash on my x86-64 server. This is a smaller benefit than
I expected, and it's because we're using a set-of-IDs and looking up
values with a key context for things like identifiers. This pattern has
a surprising tradeoff. The new hashtable uses significantly less memory,
a 10% peak RSS reduction just from the hashtable change. But indirecting
through the vector of values makes growing the hashtable dramatically
less cache-friendly: it causes growth to randomly access every key when
rehashing. On x86, everything gained by the faster hashtable is lost in
even slower growth. And even on Arm, this eats into the benefits.
But I have a plan to tweak how identifiers specifically work to avoid
most of the growth, and so I suspect this is the right tradeoff on the
whole. It gives us significant working set size reduction and we can
likely avoid the regressed operation (growth with rehash) in most cases
by clever reserving and if necessary by adding a hash caching layer to
the table infrastructure.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Name scopes store the names in their scope in a `DenseMap`. Several
places reasonably avoid depending on the iteration order by sorting the
names -- they're in the formatting code path where that's a solid
approach.
Unfortunately, when we're importing one scope into another, we also need
to walk the entire scope and do something for each name. =[ This doesn't
seem like a great place to sort things to stabilize them.
I've switched to a fairly simplistic solution of having a vector of name
entries that can be iterated stably, and a separate map for lookups. I
didn't use the set-of-indices trick here because it's not clear that's
the right trade-off for a scope: likely a lot of small scopes here with
relatively hot name lookups. And the key here isn't a large or
dynamically sized thing that we're canonicalizing, it's a `NameId`. That
made me lean towards duplicating the name in the hashtable for lookup
and the vector for iteration.
I thought about a fancy approach of sorting the hashtable keys by their
values (the indices), but that would still require a bit of copying and
more code.
I also thought a bit about other optimizations, but decided to leave a
comment for now -- it's not obvious to me exactly how hot this is and
whether it's better served by faster lookups, being more memory dense,
etc. And that might involve more of an SOA layout change or some other
approach. Rather than do that here, and especially before switching
hashtables, I stuck with a simple approach to address the ordering.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Adds access to the name lookup table in name scopes. This is so that we
can quickly check access during name lookup without resolving the entity
itself. Does this for names in general, but does not implement handling
for entity-scoped names, only namespace-scoped names (where they're
essentially just not exported).
Excludes `private` names from exports. Although names should be
accessible to `impl` files, that's not implemented here because we'll
probably want to do it by directly copying name lookup tables.
Check the parameters specified in a name qualifier against the
parameters of the entity that the qualifier refers to.
For interfaces, this required adding minimal support for parameterized
interface names.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
I'd split out the decl-specific handlers so that import_ref.cpp could
also call them. However, with the current model for imports and
constants, we shouldn't use them there. As a consequence, merge them
back into individual files for greater consistency with other helper
functions (and better visibility when making related code changes).
This addresses the const reliance of ResolvePrevInstForMerge by checking
the imported instruction, testing with `alias` name conflicts. Given the
need to examine structure, the helper function feels like it now gets in
the way, so I'm just removing it.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This was to track use of a declaration after import, prior to a
redeclaration. Per [discussion on
Discord](https://discord.com/channels/655572317891461132/1217182321933815820/1236016521059237962),
we likely don't need this check due to the change in behavior of
`extern`.
Rather than potentially getting one of many `extern` decls and depending
on it by accident, it is now planned to be _required_ to be imported,
and the library doing a non-`extern` decl must _know_ it's importing the
`extern` decl. The stricter requirement on the library means it now
seems more reasonable to use the `extern` decl.
So kind of rolling back #3831, though keeping `ImportIRInstId` (at least
for now) and keeping `Loaded`/`Unloaded` terminology (seems a nicer
fit).
Richard Smith
Geoff Romer
Jon Ross-Perkins
Dana Jansens
Boaz Brickner
josh11bandJosh L
