Make SemIR::TypeType be an empty FacetType instruction (#7813)

The type `type` is now a `FacetType` inst with no constraints. This
brings the model implemented in the toolchain into better alignment with
the language design. The `SemIR::TypeType` struct remains as a scope for
holding the `TypeInstId`, `ConstantId`, and `TypeId` constants, but is
not an `InstKind` anymore.

The `TypeType` inst looks a lot like singletons, but there are many
`FacetType` insts so it doesn't quite fit that model. So we put it
alongside singletons with a fixed inst id but refer to it as a more
general "builtin" inst that is not a singleton.
`Namespace::PackageInstId` is similar, and we group it with `TypeType`
conceptually as another builtin instruction with a fixed id.

No conversion is needed anymore to use a `type` as a facet, since types
also have a `FacetType` type. This simplifies and removes a number of
helpers and branches throughout the code.

The `TypeType` inst is now part of the constant store, so we end up
printing it in the constants block in every test. But it's also named
`type` rather than `%type` to preserve the majority of existing
formatting behaviour, though this does look different from other
constants.

Assisted-by: Opus 5 was used to generate a first draft and validate the
refactoring. Though nearly everything non-trivial the tool wrote has
been modified or rewritten.
This commit is contained in:
Dana Jansens
2026-09-22 15:04:40 +00:00
committed by GitHub
parent 83ca5b71e3
commit fcae9610bd
795 changed files with 9505 additions and 8048 deletions
@@ -23,10 +23,10 @@ fn Class(T: type).F(unused self, unused n: T) {}
// CHECK:STDOUT: --- generic_method.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %type: type = facet_type <type> [concrete]
// CHECK:STDOUT: %.Self.frozen: %type = symbolic_binding .Self [symbolic_self]
// CHECK:STDOUT: %pattern_type.98f: type = pattern_type type [concrete]
// CHECK:STDOUT: %T.patt: %pattern_type.98f = symbolic_binding_pattern T, 0 [symbolic]
// CHECK:STDOUT: type: type = facet_type <type> [concrete]
// CHECK:STDOUT: %.Self.frozen: type = symbolic_binding .Self [symbolic_self]
// CHECK:STDOUT: %pattern_type.9a5: type = pattern_type type [concrete]
// CHECK:STDOUT: %T.patt: %pattern_type.9a5 = symbolic_binding_pattern T, 0 [symbolic]
// CHECK:STDOUT: %T: type = symbolic_binding T, 0 [symbolic]
// CHECK:STDOUT: %Class.type: type = generic_class_type @Class [concrete]
// CHECK:STDOUT: %Class.generic: %Class.type = struct_value () [concrete]
@@ -60,10 +60,10 @@ fn Class(T: type).F(unused self, unused n: T) {}
// CHECK:STDOUT: }
// CHECK:STDOUT: %Core.import = import Core
// CHECK:STDOUT: %Class.decl: %Class.type = class_decl @Class [concrete = constants.%Class.generic] {
// CHECK:STDOUT: %T.patt.loc15_14.1: %pattern_type.98f = symbolic_binding_pattern T, 0 [symbolic = %T.patt.loc15_14.2 (constants.%T.patt)]
// CHECK:STDOUT: %T.patt.loc15_14.1: %pattern_type.9a5 = symbolic_binding_pattern T, 0 [symbolic = %T.patt.loc15_14.2 (constants.%T.patt)]
// CHECK:STDOUT: } {
// CHECK:STDOUT: %.loc15_16.1: type = splice_block %.loc15_16.2 [concrete = type] {
// CHECK:STDOUT: %.Self.frozen: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %.Self.frozen: type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %.loc15_16.2: type = type_literal type [concrete = type]
// CHECK:STDOUT: }
// CHECK:STDOUT: %T.loc15_14.2: type = symbolic_binding T, 0 [symbolic = %T.loc15_14.1 (constants.%T)]
@@ -75,7 +75,7 @@ fn Class(T: type).F(unused self, unused n: T) {}
// CHECK:STDOUT: %n.patt.loc20: @Class.F.%pattern_type.loc17_15 (%pattern_type.51d) = wrapper_binding_pattern n, %n.param_patt.loc20 [symbolic = %n.patt.loc17 (constants.%n.patt)]
// CHECK:STDOUT: } {
// CHECK:STDOUT: %.loc20_13.1: type = splice_block %.loc20_13.2 [concrete = type] {
// CHECK:STDOUT: %.Self.frozen: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %.Self.frozen: type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %.loc20_13.2: type = type_literal type [concrete = type]
// CHECK:STDOUT: }
// CHECK:STDOUT: %T.loc20: type = symbolic_binding T, 0 [symbolic = @Class.%T.loc15_14.1 (constants.%T)]
@@ -92,7 +92,7 @@ fn Class(T: type).F(unused self, unused n: T) {}
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: generic class @Class(%T.loc15_14.2: type) {
// CHECK:STDOUT: %T.patt.loc15_14.2: %pattern_type.98f = symbolic_binding_pattern T, 0 [symbolic = %T.patt.loc15_14.2 (constants.%T.patt)]
// CHECK:STDOUT: %T.patt.loc15_14.2: %pattern_type.9a5 = symbolic_binding_pattern T, 0 [symbolic = %T.patt.loc15_14.2 (constants.%T.patt)]
// CHECK:STDOUT: %T.loc15_14.1: type = symbolic_binding T, 0 [symbolic = %T.loc15_14.1 (constants.%T)]
// CHECK:STDOUT:
// CHECK:STDOUT: !definition: