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

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
+4 -4
View File
@@ -40,8 +40,8 @@ auto BuildUnaryOperator(Context& context, SemIR::LocId loc_id, Operator op,
// Form `operand.(Op)`.
auto bound_op_id = PerformCompoundMemberAccess(context, loc_id, operand_id,
op_fn, missing_impl_diagnoser);
if (bound_op_id == SemIR::ErrorInst::SingletonInstId) {
return SemIR::ErrorInst::SingletonInstId;
if (bound_op_id == SemIR::ErrorInst::InstId) {
return SemIR::ErrorInst::InstId;
}
// Form `bound_op()`.
@@ -58,8 +58,8 @@ auto BuildBinaryOperator(Context& context, SemIR::LocId loc_id, Operator op,
// Form `lhs.(Op)`.
auto bound_op_id = PerformCompoundMemberAccess(context, loc_id, lhs_id, op_fn,
missing_impl_diagnoser);
if (bound_op_id == SemIR::ErrorInst::SingletonInstId) {
return SemIR::ErrorInst::SingletonInstId;
if (bound_op_id == SemIR::ErrorInst::InstId) {
return SemIR::ErrorInst::InstId;
}
// Form `bound_op(rhs)`.