Use `GetWithAttachedType` consistently in import (#5483)

This unblocks merging #5400.

toolchain/check/import_ref.cpp

@@ -892,7 +892,8 @@ static auto GetLocalConstantId(ImportRefResolver& resolver,
     return SemIR::ConstantId::None;
   }
   auto import_decl_inst_id = resolver.import_generics().Get(generic_id).decl_id;
-  auto import_decl_inst = resolver.import_insts().Get(import_decl_inst_id);
+  auto import_decl_inst =
+      resolver.import_insts().GetWithAttachedType(import_decl_inst_id);
   if (import_decl_inst.Is<SemIR::ImplDecl>()) {
     // For an impl declaration, the imported entity can be found via the
     // declaration.
@@ -1370,6 +1371,8 @@ static auto AddAssociatedEntities(ImportContext& context,
       import_name_id =
           context.import_entity_names().Get(import_ref->entity_name_id).name_id;
     } else {
+      // We don't need `GetWithAttachedType` here because we don't access the
+      // type.
       CARBON_FATAL("Unhandled associated entity kind: {0}",
                    context.import_insts().Get(inst_id).kind());
     }
@@ -1399,6 +1402,10 @@ static auto RetryOrDone(ImportRefResolver& resolver, SemIR::ConstantId const_id)
 // that there is no new work.
 static auto ResolveAsUntyped(ImportContext& context, SemIR::Inst inst)
     -> ResolveResult {
+  // AddImportedConstant produces an unattached constant, so its type must
+  // be unattached as well.
+  inst.SetType(
+      context.local_context().types().GetUnattachedType(inst.type_id()));
   auto result = AddImportedConstant(context.local_context(), inst);
   CARBON_CHECK(result.is_constant(), "{0} is not constant", inst);
   return ResolveResult::Done(result);
@@ -2854,7 +2861,7 @@ static auto TryResolveInstCanonical(ImportRefResolver& resolver,
     return ResolveResult::Done(resolver.local_constant_values().Get(inst_id));
   }
 
-  auto untyped_inst = resolver.import_insts().Get(inst_id);
+  auto untyped_inst = resolver.import_insts().GetWithAttachedType(inst_id);
   CARBON_KIND_SWITCH(untyped_inst) {
     case CARBON_KIND(SemIR::AdaptDecl inst): {
       return TryResolveTypedInst(resolver, inst, inst_id);

toolchain/check/testdata/class/generic/adapt.carbon

@@ -301,7 +301,7 @@ fn ImportedConvertLocal(a: Adapter(C)) -> i32 {
 // CHECK:STDOUT:   %Main.import_ref.709: <witness> = import_ref Main//adapt_specific_type, loc10_1, loaded [concrete = constants.%complete_type.c07]
 // CHECK:STDOUT:   %Main.import_ref.feb = import_ref Main//adapt_specific_type, inst42 [no loc], unloaded
 // CHECK:STDOUT:   %Core.Int: %Int.type = import_ref Core//prelude/types/int, Int, loaded [concrete = constants.%Int.generic]
-// CHECK:STDOUT:   %.22b: %C.elem.66c = field_decl x, element0 [concrete]
+// CHECK:STDOUT:   %.22b: @C.%C.elem (%C.elem.66c) = field_decl x, element0 [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -670,7 +670,7 @@ fn ImportedConvertLocal(a: Adapter(C)) -> i32 {
 // CHECK:STDOUT:   %Main.import_ref.feb = import_ref Main//extend_adapt_specific_type_library, inst42 [no loc], unloaded
 // CHECK:STDOUT:   %Main.import_ref.19d12e.2: type = import_ref Main//extend_adapt_specific_type_library, loc12_21, loaded [concrete = constants.%C.239]
 // CHECK:STDOUT:   %Core.Int: %Int.type = import_ref Core//prelude/types/int, Int, loaded [concrete = constants.%Int.generic]
-// CHECK:STDOUT:   %.22b: %C.elem.66c = field_decl x, element0 [concrete]
+// CHECK:STDOUT:   %.22b: @C.%C.elem (%C.elem.66c) = field_decl x, element0 [concrete]
 // CHECK:STDOUT:   %Core.ImplicitAs: %ImplicitAs.type.cc7 = import_ref Core//prelude/operators/as, ImplicitAs, loaded [concrete = constants.%ImplicitAs.generic]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/class/generic/base_is_generic.carbon

@@ -295,7 +295,7 @@ fn H() {
 // CHECK:STDOUT:   %Main.import_ref.d24 = import_ref Main//extend_generic_base, loc13_27, unloaded
 // CHECK:STDOUT:   %Main.import_ref.77a301.2: type = import_ref Main//extend_generic_base, loc13_26, loaded [concrete = constants.%Base.7a8]
 // CHECK:STDOUT:   %Core.Int: %Int.type = import_ref Core//prelude/types/int, Int, loaded [concrete = constants.%Int.generic]
-// CHECK:STDOUT:   %.e66: %Base.elem.9af = field_decl x, element0 [concrete]
+// CHECK:STDOUT:   %.e66: @Base.%Base.elem (%Base.elem.9af) = field_decl x, element0 [concrete]
 // CHECK:STDOUT:   %.be7: %Param.elem = field_decl y, element0 [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/class/generic/import.carbon

@@ -490,7 +490,7 @@ class Class(U:! type) {
 // CHECK:STDOUT:   %Main.import_ref.e76: @CompleteClass.%CompleteClass.elem (%CompleteClass.elem.28a) = import_ref Main//foo, loc7_8, loaded [concrete = %.364]
 // CHECK:STDOUT:   %Main.import_ref.a52: @CompleteClass.%F.type (%F.type.14f) = import_ref Main//foo, loc8_17, loaded [symbolic = @CompleteClass.%F (constants.%F.874)]
 // CHECK:STDOUT:   %Main.import_ref.5ab3ec.2: type = import_ref Main//foo, loc6_21, loaded [symbolic = @CompleteClass.%T (constants.%T)]
-// CHECK:STDOUT:   %.364: %CompleteClass.elem.28a = field_decl n, element0 [concrete]
+// CHECK:STDOUT:   %.364: @CompleteClass.%CompleteClass.elem (%CompleteClass.elem.28a) = field_decl n, element0 [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {