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Drop Singleton from ErrorInst::SingletonInstId and similar (#5304)

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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`.
This commit is contained in:
Jon Ross-Perkins
2025-04-15 22:40:29 +00:00
committed by GitHub
parent 838417e358
commit 4923445e3a
64 changed files with 489 additions and 539 deletions
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toolchain/check/handle_binding_pattern.cpp
+5 -6
View File
@@ -142,8 +142,8 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
return context.emitter().Build(type_node, AbstractTypeInFieldDecl,
cast_type_id);
});
if (cast_type_id == SemIR::ErrorInst::SingletonTypeId) {
cast_type_inst_id = SemIR::ErrorInst::SingletonTypeInstId;
if (cast_type_id == SemIR::ErrorInst::TypeId) {
cast_type_inst_id = SemIR::ErrorInst::TypeInstId;
}
auto binding_id =
context.parse_tree().As<Parse::VarBindingPatternId>(node_id);
@@ -266,11 +266,11 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
auto result_inst_id = SemIR::InstId::None;
if (had_error) {
if (name_id != SemIR::NameId::Underscore) {
AddNameToLookup(context, name_id, SemIR::ErrorInst::SingletonInstId);
AddNameToLookup(context, name_id, SemIR::ErrorInst::InstId);
}
// Replace the parameter with `ErrorInst` so that we don't try
// constructing a generic based on it.
result_inst_id = SemIR::ErrorInst::SingletonInstId;
result_inst_id = SemIR::ErrorInst::InstId;
} else {
result_inst_id = make_binding_pattern();
if (node_kind == Parse::NodeKind::LetBindingPattern) {
@@ -381,8 +381,7 @@ auto HandleParseNode(Context& context, Parse::AddrId node_id) -> bool {
if (pointer_type) {
auto addr_pattern_id = AddPatternInst<SemIR::AddrPattern>(
context, node_id,
{.type_id = SemIR::AutoType::SingletonTypeId,
.inner_id = param_pattern_id});
{.type_id = SemIR::AutoType::TypeId, .inner_id = param_pattern_id});
context.node_stack().Push(node_id, addr_pattern_id);
} else {
CARBON_DIAGNOSTIC(