diff --git a/toolchain/check/convert.cpp b/toolchain/check/convert.cpp
index 9e57ebde42cc..f3bb30b35960 100644
--- a/toolchain/check/convert.cpp
+++ b/toolchain/check/convert.cpp
@@ -12,6 +12,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "toolchain/base/kind_switch.h"
 #include "toolchain/check/context.h"
+#include "toolchain/check/diagnostic_helpers.h"
 #include "toolchain/check/operator.h"
 #include "toolchain/check/pattern_match.h"
 #include "toolchain/diagnostics/format_providers.h"
@@ -722,7 +723,7 @@ static auto CanUseValueOfInitializer(const SemIR::File& sem_ir,
 }
 
 // Returns the non-adapter type that is compatible with the specified type.
-static auto GetCompatibleBaseType(Context& context, SemIR::TypeId type_id)
+static auto GetFoundationType(Context& context, SemIR::TypeId type_id)
     -> SemIR::TypeId {
   // If the type is an adapter, its object representation type is its compatible
   // non-adapter type.
@@ -792,14 +793,71 @@ static auto PerformBuiltinConversion(Context& context, SemIR::LocId loc_id,
       return context.AddInst<SemIR::ValueOfInitializer>(
           loc_id, {.type_id = value_type_id, .init_id = value_id});
     }
+
+    // PerformBuiltinConversion converts each part of a tuple or struct, even
+    // when the types are the same. This is not done for classes since they have
+    // to define their conversions as part of their api.
+    //
+    // If a class adapts a tuple or struct, we convert each of its parts when
+    // there's no other conversion going on (the source and target types are the
+    // same). To do so, we have to insert a conversion of the value up to the
+    // foundation and back down, and a conversion of the initializing object if
+    // there is one.
+    //
+    // Implementation note: We do the conversion through a call to
+    // PerformBuiltinConversion() call rather than a Convert() call to avoid
+    // extraneous `converted` semir instructions on the adapted types, and as a
+    // shortcut to doing the explicit calls to walk the parts of the
+    // tuple/struct which happens inside PerformBuiltinConversion().
+    if (auto foundation_type_id = GetFoundationType(context, value_type_id);
+        foundation_type_id != value_type_id &&
+        (context.types().Is<SemIR::TupleType>(foundation_type_id) ||
+         context.types().Is<SemIR::StructType>(foundation_type_id))) {
+      auto foundation_value_id = context.AddInst<SemIR::AsCompatible>(
+          loc_id, {.type_id = foundation_type_id, .source_id = value_id});
+
+      auto foundation_init_id = target.init_id;
+      if (foundation_init_id != SemIR::InstId::Invalid) {
+        foundation_init_id = target.init_block->AddInst<SemIR::AsCompatible>(
+            loc_id,
+            {.type_id = foundation_type_id, .source_id = target.init_id});
+      }
+
+      {
+        // While the types are the same, the conversion can still fail if it
+        // performs a copy while converting the value to another category, and
+        // the type (or some part of it) is not copyable.
+        DiagnosticAnnotationScope annotate_diagnostics(
+            &context.emitter(), [&](auto& builder) {
+              CARBON_DIAGNOSTIC(InCopy, Note, "in copy of `{0}`", TypeOfInstId);
+              builder.Note(value_id, InCopy, value_id);
+            });
+
+        foundation_value_id =
+            PerformBuiltinConversion(context, loc_id, foundation_value_id,
+                                     {
+                                         .kind = target.kind,
+                                         .type_id = foundation_type_id,
+                                         .init_id = foundation_init_id,
+                                         .init_block = target.init_block,
+                                     });
+        if (foundation_value_id == SemIR::ErrorInst::SingletonInstId) {
+          return SemIR::ErrorInst::SingletonInstId;
+        }
+      }
+
+      return context.AddInst<SemIR::AsCompatible>(
+          loc_id,
+          {.type_id = target.type_id, .source_id = foundation_value_id});
+    }
   }
 
   // T explicitly converts to U if T is compatible with U.
   if (target.kind == ConversionTarget::Kind::ExplicitAs &&
       target.type_id != value_type_id) {
-    auto target_base_id = GetCompatibleBaseType(context, target.type_id);
-    auto value_base_id = GetCompatibleBaseType(context, value_type_id);
-    if (target_base_id == value_base_id) {
+    auto target_foundation_id = GetFoundationType(context, target.type_id);
+    auto value_foundation_id = GetFoundationType(context, value_type_id);
+    if (target_foundation_id == value_foundation_id) {
       // For a struct or tuple literal, perform a category conversion if
       // necessary.
       if (SemIR::GetExprCategory(context.sem_ir(), value_id) ==
diff --git a/toolchain/check/testdata/as/adapter_conversion.carbon b/toolchain/check/testdata/as/adapter_conversion.carbon
index 3bf811ac33f4..7633b8f42ccc 100644
--- a/toolchain/check/testdata/as/adapter_conversion.carbon
+++ b/toolchain/check/testdata/as/adapter_conversion.carbon
@@ -56,55 +56,6 @@ class D { adapt C; }
 
 let d: D = {} as D;
 
-// --- fail_init_class.carbon
-
-library "[[@TEST_NAME]]";
-
-class A {
-  var x: i32;
-  var y: i32;
-}
-
-class B {
-  adapt A;
-}
-
-let b_value: B = ({.x = 1, .y = 2} as A) as B;
-
-// TODO: Here, we treat `{.x = 1, .y = 2} as A` as a value expression, not an
-// initializing expression, so `(...) as B` is a value expression too, requiring
-// a copy to perform initialization. It's not clear whether that is the right
-// behavior.
-
-// CHECK:STDERR: fail_init_class.carbon:[[@LINE+4]]:17: error: cannot copy value of type `B` [CopyOfUncopyableType]
-// CHECK:STDERR: var b_init: B = ({.x = 1, .y = 2} as A) as B;
-// CHECK:STDERR:                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
-// CHECK:STDERR:
-var b_init: B = ({.x = 1, .y = 2} as A) as B;
-
-// --- fail_adapt_init_from_struct.carbon
-
-library "[[@TEST_NAME]]";
-
-class A {
-  var x: i32;
-}
-
-class B {
-  adapt A;
-}
-
-// We do not try to implicitly convert from the first operand of `as` to the
-// adapted type of the second operand.
-
-// CHECK:STDERR: fail_adapt_init_from_struct.carbon:[[@LINE+6]]:12: error: cannot convert from `{.x: Core.IntLiteral}` to `B` with `as` [ExplicitAsConversionFailure]
-// CHECK:STDERR: var b: B = {.x = 1} as B;
-// CHECK:STDERR:            ^~~~~~~~~~~~~
-// CHECK:STDERR: fail_adapt_init_from_struct.carbon:[[@LINE+3]]:12: note: type `{.x: Core.IntLiteral}` does not implement interface `Core.As(B)` [MissingImplInMemberAccessNote]
-// CHECK:STDERR: var b: B = {.x = 1} as B;
-// CHECK:STDERR:            ^~~~~~~~~~~~~
-var b: B = {.x = 1} as B;
-
 // CHECK:STDOUT: --- adapt_class.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
@@ -425,201 +376,3 @@ var b: B = {.x = 1} as B;
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_init_class.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %A: type = class_type @A [template]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [template]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [template]
-// CHECK:STDOUT:   %A.elem: type = unbound_element_type %A, %i32 [template]
-// CHECK:STDOUT:   %struct_type.x.y.1: type = struct_type {.x: %i32, .y: %i32} [template]
-// CHECK:STDOUT:   %complete_type.3: <witness> = complete_type_witness %struct_type.x.y.1 [template]
-// CHECK:STDOUT:   %B: type = class_type @B [template]
-// CHECK:STDOUT:   %int_1.1: Core.IntLiteral = int_value 1 [template]
-// CHECK:STDOUT:   %int_2.1: Core.IntLiteral = int_value 2 [template]
-// CHECK:STDOUT:   %struct_type.x.y.2: type = struct_type {.x: Core.IntLiteral, .y: Core.IntLiteral} [template]
-// CHECK:STDOUT:   %Convert.type.2: type = fn_type @Convert.1, @ImplicitAs(%i32) [template]
-// CHECK:STDOUT:   %Convert.type.10: type = fn_type @Convert.2, @impl.1(%int_32) [template]
-// CHECK:STDOUT:   %Convert.10: %Convert.type.10 = struct_value () [template]
-// CHECK:STDOUT:   %interface.19: <witness> = interface_witness (%Convert.10) [template]
-// CHECK:STDOUT:   %Convert.bound.1: <bound method> = bound_method %int_1.1, %Convert.10 [template]
-// CHECK:STDOUT:   %Convert.specific_fn.1: <specific function> = specific_function %Convert.bound.1, @Convert.2(%int_32) [template]
-// CHECK:STDOUT:   %int_1.2: %i32 = int_value 1 [template]
-// CHECK:STDOUT:   %Convert.bound.2: <bound method> = bound_method %int_2.1, %Convert.10 [template]
-// CHECK:STDOUT:   %Convert.specific_fn.2: <specific function> = specific_function %Convert.bound.2, @Convert.2(%int_32) [template]
-// CHECK:STDOUT:   %int_2.2: %i32 = int_value 2 [template]
-// CHECK:STDOUT:   %A.val: %A = struct_value (%int_1.2, %int_2.2) [template]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
-// CHECK:STDOUT:     .Int = %import_ref.1
-// CHECK:STDOUT:     .ImplicitAs = %import_ref.5
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [template] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .A = %A.decl
-// CHECK:STDOUT:     .B = %B.decl
-// CHECK:STDOUT:     .b_value = @__global_init.%b_value
-// CHECK:STDOUT:     .b_init = %b_init
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %A.decl: type = class_decl @A [template = constants.%A] {} {}
-// CHECK:STDOUT:   %B.decl: type = class_decl @B [template = constants.%B] {} {}
-// CHECK:STDOUT:   %b_init.var: ref %B = var b_init
-// CHECK:STDOUT:   %b_init: ref %B = bind_name b_init, %b_init.var
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @A {
-// CHECK:STDOUT:   %.loc5: %A.elem = field_decl x, element0 [template]
-// CHECK:STDOUT:   %.loc6: %A.elem = field_decl y, element1 [template]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.y.1 [template = constants.%complete_type.3]
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%A
-// CHECK:STDOUT:   .x = %.loc5
-// CHECK:STDOUT:   .y = %.loc6
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @B {
-// CHECK:STDOUT:   %A.ref: type = name_ref A, file.%A.decl [template = constants.%A]
-// CHECK:STDOUT:   adapt_decl %A.ref [template]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.y.1 [template = constants.%complete_type.3]
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%B
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @__global_init() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %int_1.loc13: Core.IntLiteral = int_value 1 [template = constants.%int_1.1]
-// CHECK:STDOUT:   %int_2.loc13: Core.IntLiteral = int_value 2 [template = constants.%int_2.1]
-// CHECK:STDOUT:   %.loc13_34.1: %struct_type.x.y.2 = struct_literal (%int_1.loc13, %int_2.loc13)
-// CHECK:STDOUT:   %A.ref.loc13: type = name_ref A, file.%A.decl [template = constants.%A]
-// CHECK:STDOUT:   %impl.elem0.loc13_34.1: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
-// CHECK:STDOUT:   %Convert.bound.loc13_34.1: <bound method> = bound_method %int_1.loc13, %impl.elem0.loc13_34.1 [template = constants.%Convert.bound.1]
-// CHECK:STDOUT:   %Convert.specific_fn.loc13_34.1: <specific function> = specific_function %Convert.bound.loc13_34.1, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.1]
-// CHECK:STDOUT:   %int.convert_checked.loc13_34.1: init %i32 = call %Convert.specific_fn.loc13_34.1(%int_1.loc13) [template = constants.%int_1.2]
-// CHECK:STDOUT:   %.loc13_34.2: init %i32 = converted %int_1.loc13, %int.convert_checked.loc13_34.1 [template = constants.%int_1.2]
-// CHECK:STDOUT:   %.loc13_34.3: ref %A = temporary_storage
-// CHECK:STDOUT:   %.loc13_34.4: ref %i32 = class_element_access %.loc13_34.3, element0
-// CHECK:STDOUT:   %.loc13_34.5: init %i32 = initialize_from %.loc13_34.2 to %.loc13_34.4 [template = constants.%int_1.2]
-// CHECK:STDOUT:   %impl.elem0.loc13_34.2: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
-// CHECK:STDOUT:   %Convert.bound.loc13_34.2: <bound method> = bound_method %int_2.loc13, %impl.elem0.loc13_34.2 [template = constants.%Convert.bound.2]
-// CHECK:STDOUT:   %Convert.specific_fn.loc13_34.2: <specific function> = specific_function %Convert.bound.loc13_34.2, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.2]
-// CHECK:STDOUT:   %int.convert_checked.loc13_34.2: init %i32 = call %Convert.specific_fn.loc13_34.2(%int_2.loc13) [template = constants.%int_2.2]
-// CHECK:STDOUT:   %.loc13_34.6: init %i32 = converted %int_2.loc13, %int.convert_checked.loc13_34.2 [template = constants.%int_2.2]
-// CHECK:STDOUT:   %.loc13_34.7: ref %i32 = class_element_access %.loc13_34.3, element1
-// CHECK:STDOUT:   %.loc13_34.8: init %i32 = initialize_from %.loc13_34.6 to %.loc13_34.7 [template = constants.%int_2.2]
-// CHECK:STDOUT:   %.loc13_34.9: init %A = class_init (%.loc13_34.5, %.loc13_34.8), %.loc13_34.3 [template = constants.%A.val]
-// CHECK:STDOUT:   %.loc13_34.10: ref %A = temporary %.loc13_34.3, %.loc13_34.9
-// CHECK:STDOUT:   %.loc13_36: ref %A = converted %.loc13_34.1, %.loc13_34.10
-// CHECK:STDOUT:   %B.ref.loc13: type = name_ref B, file.%B.decl [template = constants.%B]
-// CHECK:STDOUT:   %.loc13_42.1: ref %B = as_compatible %.loc13_36
-// CHECK:STDOUT:   %.loc13_42.2: ref %B = converted %.loc13_36, %.loc13_42.1
-// CHECK:STDOUT:   %.loc13_42.3: %B = bind_value %.loc13_42.2
-// CHECK:STDOUT:   %b_value: %B = bind_name b_value, %.loc13_42.3
-// CHECK:STDOUT:   %int_1.loc24: Core.IntLiteral = int_value 1 [template = constants.%int_1.1]
-// CHECK:STDOUT:   %int_2.loc24: Core.IntLiteral = int_value 2 [template = constants.%int_2.1]
-// CHECK:STDOUT:   %.loc24_33.1: %struct_type.x.y.2 = struct_literal (%int_1.loc24, %int_2.loc24)
-// CHECK:STDOUT:   %A.ref.loc24: type = name_ref A, file.%A.decl [template = constants.%A]
-// CHECK:STDOUT:   %impl.elem0.loc24_33.1: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
-// CHECK:STDOUT:   %Convert.bound.loc24_33.1: <bound method> = bound_method %int_1.loc24, %impl.elem0.loc24_33.1 [template = constants.%Convert.bound.1]
-// CHECK:STDOUT:   %Convert.specific_fn.loc24_33.1: <specific function> = specific_function %Convert.bound.loc24_33.1, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.1]
-// CHECK:STDOUT:   %int.convert_checked.loc24_33.1: init %i32 = call %Convert.specific_fn.loc24_33.1(%int_1.loc24) [template = constants.%int_1.2]
-// CHECK:STDOUT:   %.loc24_33.2: init %i32 = converted %int_1.loc24, %int.convert_checked.loc24_33.1 [template = constants.%int_1.2]
-// CHECK:STDOUT:   %.loc24_33.3: ref %A = temporary_storage
-// CHECK:STDOUT:   %.loc24_33.4: ref %i32 = class_element_access %.loc24_33.3, element0
-// CHECK:STDOUT:   %.loc24_33.5: init %i32 = initialize_from %.loc24_33.2 to %.loc24_33.4 [template = constants.%int_1.2]
-// CHECK:STDOUT:   %impl.elem0.loc24_33.2: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
-// CHECK:STDOUT:   %Convert.bound.loc24_33.2: <bound method> = bound_method %int_2.loc24, %impl.elem0.loc24_33.2 [template = constants.%Convert.bound.2]
-// CHECK:STDOUT:   %Convert.specific_fn.loc24_33.2: <specific function> = specific_function %Convert.bound.loc24_33.2, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.2]
-// CHECK:STDOUT:   %int.convert_checked.loc24_33.2: init %i32 = call %Convert.specific_fn.loc24_33.2(%int_2.loc24) [template = constants.%int_2.2]
-// CHECK:STDOUT:   %.loc24_33.6: init %i32 = converted %int_2.loc24, %int.convert_checked.loc24_33.2 [template = constants.%int_2.2]
-// CHECK:STDOUT:   %.loc24_33.7: ref %i32 = class_element_access %.loc24_33.3, element1
-// CHECK:STDOUT:   %.loc24_33.8: init %i32 = initialize_from %.loc24_33.6 to %.loc24_33.7 [template = constants.%int_2.2]
-// CHECK:STDOUT:   %.loc24_33.9: init %A = class_init (%.loc24_33.5, %.loc24_33.8), %.loc24_33.3 [template = constants.%A.val]
-// CHECK:STDOUT:   %.loc24_33.10: ref %A = temporary %.loc24_33.3, %.loc24_33.9
-// CHECK:STDOUT:   %.loc24_35: ref %A = converted %.loc24_33.1, %.loc24_33.10
-// CHECK:STDOUT:   %B.ref.loc24: type = name_ref B, file.%B.decl [template = constants.%B]
-// CHECK:STDOUT:   %.loc24_41.1: ref %B = as_compatible %.loc24_35
-// CHECK:STDOUT:   %.loc24_41.2: ref %B = converted %.loc24_35, %.loc24_41.1
-// CHECK:STDOUT:   %.loc24_41.3: %B = bind_value %.loc24_41.2
-// CHECK:STDOUT:   assign file.%b_init.var, <error>
-// CHECK:STDOUT:   return
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_adapt_init_from_struct.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %A: type = class_type @A [template]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [template]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [template]
-// CHECK:STDOUT:   %A.elem: type = unbound_element_type %A, %i32 [template]
-// CHECK:STDOUT:   %struct_type.x.1: type = struct_type {.x: %i32} [template]
-// CHECK:STDOUT:   %complete_type.3: <witness> = complete_type_witness %struct_type.x.1 [template]
-// CHECK:STDOUT:   %B: type = class_type @B [template]
-// CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [template]
-// CHECK:STDOUT:   %struct_type.x.2: type = struct_type {.x: Core.IntLiteral} [template]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
-// CHECK:STDOUT:     .Int = %import_ref.1
-// CHECK:STDOUT:     .As = %import_ref.5
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [template] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .A = %A.decl
-// CHECK:STDOUT:     .B = %B.decl
-// CHECK:STDOUT:     .b = %b
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %A.decl: type = class_decl @A [template = constants.%A] {} {}
-// CHECK:STDOUT:   %B.decl: type = class_decl @B [template = constants.%B] {} {}
-// CHECK:STDOUT:   %b.var: ref %B = var b
-// CHECK:STDOUT:   %b: ref %B = bind_name b, %b.var
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @A {
-// CHECK:STDOUT:   %.loc5: %A.elem = field_decl x, element0 [template]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.1 [template = constants.%complete_type.3]
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%A
-// CHECK:STDOUT:   .x = %.loc5
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @B {
-// CHECK:STDOUT:   %A.ref: type = name_ref A, file.%A.decl [template = constants.%A]
-// CHECK:STDOUT:   adapt_decl %A.ref [template]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.1 [template = constants.%complete_type.3]
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%B
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @__global_init() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [template = constants.%int_1]
-// CHECK:STDOUT:   %.loc21_19: %struct_type.x.2 = struct_literal (%int_1)
-// CHECK:STDOUT:   %B.ref: type = name_ref B, file.%B.decl [template = constants.%B]
-// CHECK:STDOUT:   %.loc21_21: %B = converted %.loc21_19, <error> [template = <error>]
-// CHECK:STDOUT:   assign file.%b.var, <error>
-// CHECK:STDOUT:   return
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/as/fail_adapter_conversion.carbon b/toolchain/check/testdata/as/fail_adapter_conversion.carbon
new file mode 100644
index 000000000000..8746944d71de
--- /dev/null
+++ b/toolchain/check/testdata/as/fail_adapter_conversion.carbon
@@ -0,0 +1,390 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/as/fail_adapter_conversion.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/as/fail_adapter_conversion.carbon
+
+// --- fail_init_class.carbon
+
+library "[[@TEST_NAME]]";
+
+class A {
+  var x: i32;
+  var y: i32;
+}
+
+class B {
+  adapt A;
+}
+
+let b_value: B = ({.x = 1, .y = 2} as A) as B;
+
+// TODO: Here, we treat `{.x = 1, .y = 2} as A` as a value expression, not an
+// initializing expression, so `(...) as B` is a value expression too, requiring
+// a copy to perform initialization. It's not clear whether that is the right
+// behavior.
+
+// CHECK:STDERR: fail_init_class.carbon:[[@LINE+4]]:17: error: cannot copy value of type `B` [CopyOfUncopyableType]
+// CHECK:STDERR: var b_init: B = ({.x = 1, .y = 2} as A) as B;
+// CHECK:STDERR:                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// CHECK:STDERR:
+var b_init: B = ({.x = 1, .y = 2} as A) as B;
+
+// --- fail_init_tuple.carbon
+
+library "[[@TEST_NAME]]";
+
+class Noncopyable {
+  // TODO: Ensure this remains non-copyable once we have rules for class copyability.
+}
+
+class A {
+  adapt (i32, Noncopyable);
+}
+
+fn F(a: A) {
+  let a_value: A = (a as (i32, Noncopyable)) as A;
+
+  // TODO: Here, we treat `a as (i32, Noncopyable)` as a value expression, not an
+  // initializing expression, so `(...) as A` is a value expression too, requiring
+  // a copy to perform initialization. It's not clear whether that is the right
+  // behavior.
+
+  // CHECK:STDERR: fail_init_tuple.carbon:[[@LINE+7]]:3: error: cannot copy value of type `Noncopyable` [CopyOfUncopyableType]
+  // CHECK:STDERR:   var a_init: A = (a as (i32, Noncopyable)) as A;
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_init_tuple.carbon:[[@LINE+4]]:19: note: in copy of ``A`` [InCopy]
+  // CHECK:STDERR:   var a_init: A = (a as (i32, Noncopyable)) as A;
+  // CHECK:STDERR:                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  var a_init: A = (a as (i32, Noncopyable)) as A;
+}
+
+// --- fail_adapt_init_from_struct.carbon
+
+library "[[@TEST_NAME]]";
+
+class A {
+  var x: i32;
+}
+
+class B {
+  adapt A;
+}
+
+// We do not try to implicitly convert from the first operand of `as` to the
+// adapted type of the second operand.
+
+// CHECK:STDERR: fail_adapt_init_from_struct.carbon:[[@LINE+6]]:12: error: cannot convert from `{.x: Core.IntLiteral}` to `B` with `as` [ExplicitAsConversionFailure]
+// CHECK:STDERR: var b: B = {.x = 1} as B;
+// CHECK:STDERR:            ^~~~~~~~~~~~~
+// CHECK:STDERR: fail_adapt_init_from_struct.carbon:[[@LINE+3]]:12: note: type `{.x: Core.IntLiteral}` does not implement interface `Core.As(B)` [MissingImplInMemberAccessNote]
+// CHECK:STDERR: var b: B = {.x = 1} as B;
+// CHECK:STDERR:            ^~~~~~~~~~~~~
+var b: B = {.x = 1} as B;
+
+// CHECK:STDOUT: --- fail_init_class.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %A: type = class_type @A [template]
+// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [template]
+// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [template]
+// CHECK:STDOUT:   %A.elem: type = unbound_element_type %A, %i32 [template]
+// CHECK:STDOUT:   %struct_type.x.y.1: type = struct_type {.x: %i32, .y: %i32} [template]
+// CHECK:STDOUT:   %complete_type.3: <witness> = complete_type_witness %struct_type.x.y.1 [template]
+// CHECK:STDOUT:   %B: type = class_type @B [template]
+// CHECK:STDOUT:   %int_1.1: Core.IntLiteral = int_value 1 [template]
+// CHECK:STDOUT:   %int_2.1: Core.IntLiteral = int_value 2 [template]
+// CHECK:STDOUT:   %struct_type.x.y.2: type = struct_type {.x: Core.IntLiteral, .y: Core.IntLiteral} [template]
+// CHECK:STDOUT:   %Convert.type.2: type = fn_type @Convert.1, @ImplicitAs(%i32) [template]
+// CHECK:STDOUT:   %Convert.type.10: type = fn_type @Convert.2, @impl.1(%int_32) [template]
+// CHECK:STDOUT:   %Convert.10: %Convert.type.10 = struct_value () [template]
+// CHECK:STDOUT:   %interface.19: <witness> = interface_witness (%Convert.10) [template]
+// CHECK:STDOUT:   %Convert.bound.1: <bound method> = bound_method %int_1.1, %Convert.10 [template]
+// CHECK:STDOUT:   %Convert.specific_fn.1: <specific function> = specific_function %Convert.bound.1, @Convert.2(%int_32) [template]
+// CHECK:STDOUT:   %int_1.2: %i32 = int_value 1 [template]
+// CHECK:STDOUT:   %Convert.bound.2: <bound method> = bound_method %int_2.1, %Convert.10 [template]
+// CHECK:STDOUT:   %Convert.specific_fn.2: <specific function> = specific_function %Convert.bound.2, @Convert.2(%int_32) [template]
+// CHECK:STDOUT:   %int_2.2: %i32 = int_value 2 [template]
+// CHECK:STDOUT:   %A.val: %A = struct_value (%int_1.2, %int_2.2) [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .Int = %import_ref.1
+// CHECK:STDOUT:     .ImplicitAs = %import_ref.5
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .A = %A.decl
+// CHECK:STDOUT:     .B = %B.decl
+// CHECK:STDOUT:     .b_value = @__global_init.%b_value
+// CHECK:STDOUT:     .b_init = %b_init
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %A.decl: type = class_decl @A [template = constants.%A] {} {}
+// CHECK:STDOUT:   %B.decl: type = class_decl @B [template = constants.%B] {} {}
+// CHECK:STDOUT:   %b_init.var: ref %B = var b_init
+// CHECK:STDOUT:   %b_init: ref %B = bind_name b_init, %b_init.var
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @A {
+// CHECK:STDOUT:   %.loc5: %A.elem = field_decl x, element0 [template]
+// CHECK:STDOUT:   %.loc6: %A.elem = field_decl y, element1 [template]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.y.1 [template = constants.%complete_type.3]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%A
+// CHECK:STDOUT:   .x = %.loc5
+// CHECK:STDOUT:   .y = %.loc6
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @B {
+// CHECK:STDOUT:   %A.ref: type = name_ref A, file.%A.decl [template = constants.%A]
+// CHECK:STDOUT:   adapt_decl %A.ref [template]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.y.1 [template = constants.%complete_type.3]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%B
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @__global_init() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %int_1.loc13: Core.IntLiteral = int_value 1 [template = constants.%int_1.1]
+// CHECK:STDOUT:   %int_2.loc13: Core.IntLiteral = int_value 2 [template = constants.%int_2.1]
+// CHECK:STDOUT:   %.loc13_34.1: %struct_type.x.y.2 = struct_literal (%int_1.loc13, %int_2.loc13)
+// CHECK:STDOUT:   %A.ref.loc13: type = name_ref A, file.%A.decl [template = constants.%A]
+// CHECK:STDOUT:   %impl.elem0.loc13_34.1: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
+// CHECK:STDOUT:   %Convert.bound.loc13_34.1: <bound method> = bound_method %int_1.loc13, %impl.elem0.loc13_34.1 [template = constants.%Convert.bound.1]
+// CHECK:STDOUT:   %Convert.specific_fn.loc13_34.1: <specific function> = specific_function %Convert.bound.loc13_34.1, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.1]
+// CHECK:STDOUT:   %int.convert_checked.loc13_34.1: init %i32 = call %Convert.specific_fn.loc13_34.1(%int_1.loc13) [template = constants.%int_1.2]
+// CHECK:STDOUT:   %.loc13_34.2: init %i32 = converted %int_1.loc13, %int.convert_checked.loc13_34.1 [template = constants.%int_1.2]
+// CHECK:STDOUT:   %.loc13_34.3: ref %A = temporary_storage
+// CHECK:STDOUT:   %.loc13_34.4: ref %i32 = class_element_access %.loc13_34.3, element0
+// CHECK:STDOUT:   %.loc13_34.5: init %i32 = initialize_from %.loc13_34.2 to %.loc13_34.4 [template = constants.%int_1.2]
+// CHECK:STDOUT:   %impl.elem0.loc13_34.2: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
+// CHECK:STDOUT:   %Convert.bound.loc13_34.2: <bound method> = bound_method %int_2.loc13, %impl.elem0.loc13_34.2 [template = constants.%Convert.bound.2]
+// CHECK:STDOUT:   %Convert.specific_fn.loc13_34.2: <specific function> = specific_function %Convert.bound.loc13_34.2, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.2]
+// CHECK:STDOUT:   %int.convert_checked.loc13_34.2: init %i32 = call %Convert.specific_fn.loc13_34.2(%int_2.loc13) [template = constants.%int_2.2]
+// CHECK:STDOUT:   %.loc13_34.6: init %i32 = converted %int_2.loc13, %int.convert_checked.loc13_34.2 [template = constants.%int_2.2]
+// CHECK:STDOUT:   %.loc13_34.7: ref %i32 = class_element_access %.loc13_34.3, element1
+// CHECK:STDOUT:   %.loc13_34.8: init %i32 = initialize_from %.loc13_34.6 to %.loc13_34.7 [template = constants.%int_2.2]
+// CHECK:STDOUT:   %.loc13_34.9: init %A = class_init (%.loc13_34.5, %.loc13_34.8), %.loc13_34.3 [template = constants.%A.val]
+// CHECK:STDOUT:   %.loc13_34.10: ref %A = temporary %.loc13_34.3, %.loc13_34.9
+// CHECK:STDOUT:   %.loc13_36: ref %A = converted %.loc13_34.1, %.loc13_34.10
+// CHECK:STDOUT:   %B.ref.loc13: type = name_ref B, file.%B.decl [template = constants.%B]
+// CHECK:STDOUT:   %.loc13_42.1: ref %B = as_compatible %.loc13_36
+// CHECK:STDOUT:   %.loc13_42.2: ref %B = converted %.loc13_36, %.loc13_42.1
+// CHECK:STDOUT:   %.loc13_42.3: %B = bind_value %.loc13_42.2
+// CHECK:STDOUT:   %b_value: %B = bind_name b_value, %.loc13_42.3
+// CHECK:STDOUT:   %int_1.loc24: Core.IntLiteral = int_value 1 [template = constants.%int_1.1]
+// CHECK:STDOUT:   %int_2.loc24: Core.IntLiteral = int_value 2 [template = constants.%int_2.1]
+// CHECK:STDOUT:   %.loc24_33.1: %struct_type.x.y.2 = struct_literal (%int_1.loc24, %int_2.loc24)
+// CHECK:STDOUT:   %A.ref.loc24: type = name_ref A, file.%A.decl [template = constants.%A]
+// CHECK:STDOUT:   %impl.elem0.loc24_33.1: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
+// CHECK:STDOUT:   %Convert.bound.loc24_33.1: <bound method> = bound_method %int_1.loc24, %impl.elem0.loc24_33.1 [template = constants.%Convert.bound.1]
+// CHECK:STDOUT:   %Convert.specific_fn.loc24_33.1: <specific function> = specific_function %Convert.bound.loc24_33.1, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.1]
+// CHECK:STDOUT:   %int.convert_checked.loc24_33.1: init %i32 = call %Convert.specific_fn.loc24_33.1(%int_1.loc24) [template = constants.%int_1.2]
+// CHECK:STDOUT:   %.loc24_33.2: init %i32 = converted %int_1.loc24, %int.convert_checked.loc24_33.1 [template = constants.%int_1.2]
+// CHECK:STDOUT:   %.loc24_33.3: ref %A = temporary_storage
+// CHECK:STDOUT:   %.loc24_33.4: ref %i32 = class_element_access %.loc24_33.3, element0
+// CHECK:STDOUT:   %.loc24_33.5: init %i32 = initialize_from %.loc24_33.2 to %.loc24_33.4 [template = constants.%int_1.2]
+// CHECK:STDOUT:   %impl.elem0.loc24_33.2: %Convert.type.2 = interface_witness_access constants.%interface.19, element0 [template = constants.%Convert.10]
+// CHECK:STDOUT:   %Convert.bound.loc24_33.2: <bound method> = bound_method %int_2.loc24, %impl.elem0.loc24_33.2 [template = constants.%Convert.bound.2]
+// CHECK:STDOUT:   %Convert.specific_fn.loc24_33.2: <specific function> = specific_function %Convert.bound.loc24_33.2, @Convert.2(constants.%int_32) [template = constants.%Convert.specific_fn.2]
+// CHECK:STDOUT:   %int.convert_checked.loc24_33.2: init %i32 = call %Convert.specific_fn.loc24_33.2(%int_2.loc24) [template = constants.%int_2.2]
+// CHECK:STDOUT:   %.loc24_33.6: init %i32 = converted %int_2.loc24, %int.convert_checked.loc24_33.2 [template = constants.%int_2.2]
+// CHECK:STDOUT:   %.loc24_33.7: ref %i32 = class_element_access %.loc24_33.3, element1
+// CHECK:STDOUT:   %.loc24_33.8: init %i32 = initialize_from %.loc24_33.6 to %.loc24_33.7 [template = constants.%int_2.2]
+// CHECK:STDOUT:   %.loc24_33.9: init %A = class_init (%.loc24_33.5, %.loc24_33.8), %.loc24_33.3 [template = constants.%A.val]
+// CHECK:STDOUT:   %.loc24_33.10: ref %A = temporary %.loc24_33.3, %.loc24_33.9
+// CHECK:STDOUT:   %.loc24_35: ref %A = converted %.loc24_33.1, %.loc24_33.10
+// CHECK:STDOUT:   %B.ref.loc24: type = name_ref B, file.%B.decl [template = constants.%B]
+// CHECK:STDOUT:   %.loc24_41.1: ref %B = as_compatible %.loc24_35
+// CHECK:STDOUT:   %.loc24_41.2: ref %B = converted %.loc24_35, %.loc24_41.1
+// CHECK:STDOUT:   %.loc24_41.3: %B = bind_value %.loc24_41.2
+// CHECK:STDOUT:   assign file.%b_init.var, <error>
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_init_tuple.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %Noncopyable: type = class_type @Noncopyable [template]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [template]
+// CHECK:STDOUT:   %complete_type.1: <witness> = complete_type_witness %empty_struct_type [template]
+// CHECK:STDOUT:   %A: type = class_type @A [template]
+// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [template]
+// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [template]
+// CHECK:STDOUT:   %tuple.type.1: type = tuple_type (type, type) [template]
+// CHECK:STDOUT:   %tuple.type.2: type = tuple_type (%i32, %Noncopyable) [template]
+// CHECK:STDOUT:   %complete_type.4: <witness> = complete_type_witness %tuple.type.2 [template]
+// CHECK:STDOUT:   %F.type: type = fn_type @F [template]
+// CHECK:STDOUT:   %F: %F.type = struct_value () [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .Int = %import_ref.1
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .Noncopyable = %Noncopyable.decl
+// CHECK:STDOUT:     .A = %A.decl
+// CHECK:STDOUT:     .F = %F.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %Noncopyable.decl: type = class_decl @Noncopyable [template = constants.%Noncopyable] {} {}
+// CHECK:STDOUT:   %A.decl: type = class_decl @A [template = constants.%A] {} {}
+// CHECK:STDOUT:   %F.decl: %F.type = fn_decl @F [template = constants.%F] {
+// CHECK:STDOUT:     %a.patt: %A = binding_pattern a
+// CHECK:STDOUT:     %a.param_patt: %A = value_param_pattern %a.patt, runtime_param0
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %a.param: %A = value_param runtime_param0
+// CHECK:STDOUT:     %A.ref.loc12: type = name_ref A, file.%A.decl [template = constants.%A]
+// CHECK:STDOUT:     %a: %A = bind_name a, %a.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @Noncopyable {
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [template = constants.%complete_type.1]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%Noncopyable
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @A {
+// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [template = constants.%i32]
+// CHECK:STDOUT:   %Noncopyable.ref: type = name_ref Noncopyable, file.%Noncopyable.decl [template = constants.%Noncopyable]
+// CHECK:STDOUT:   %.loc9_26: %tuple.type.1 = tuple_literal (%i32, %Noncopyable.ref)
+// CHECK:STDOUT:   %.loc9_27: type = converted %.loc9_26, constants.%tuple.type.2 [template = constants.%tuple.type.2]
+// CHECK:STDOUT:   adapt_decl %.loc9_27 [template]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %tuple.type.2 [template = constants.%complete_type.4]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%A
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F(%a.param_patt: %A) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %a.ref.loc13: %A = name_ref a, %a
+// CHECK:STDOUT:   %int_32.loc13: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:   %i32.loc13: type = class_type @Int, @Int(constants.%int_32) [template = constants.%i32]
+// CHECK:STDOUT:   %Noncopyable.ref.loc13: type = name_ref Noncopyable, file.%Noncopyable.decl [template = constants.%Noncopyable]
+// CHECK:STDOUT:   %.loc13_43.1: %tuple.type.1 = tuple_literal (%i32.loc13, %Noncopyable.ref.loc13)
+// CHECK:STDOUT:   %.loc13_43.2: type = converted %.loc13_43.1, constants.%tuple.type.2 [template = constants.%tuple.type.2]
+// CHECK:STDOUT:   %.loc13_23.1: %tuple.type.2 = as_compatible %a.ref.loc13
+// CHECK:STDOUT:   %.loc13_23.2: %tuple.type.2 = converted %a.ref.loc13, %.loc13_23.1
+// CHECK:STDOUT:   %A.ref.loc13: type = name_ref A, file.%A.decl [template = constants.%A]
+// CHECK:STDOUT:   %.loc13_46.1: %A = as_compatible %.loc13_23.2
+// CHECK:STDOUT:   %.loc13_46.2: %A = converted %.loc13_23.2, %.loc13_46.1
+// CHECK:STDOUT:   %a_value: %A = bind_name a_value, %.loc13_46.2
+// CHECK:STDOUT:   %a_init.var: ref %A = var a_init
+// CHECK:STDOUT:   %a_init: ref %A = bind_name a_init, %a_init.var
+// CHECK:STDOUT:   %a.ref.loc27: %A = name_ref a, %a
+// CHECK:STDOUT:   %int_32.loc27: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:   %i32.loc27: type = class_type @Int, @Int(constants.%int_32) [template = constants.%i32]
+// CHECK:STDOUT:   %Noncopyable.ref.loc27: type = name_ref Noncopyable, file.%Noncopyable.decl [template = constants.%Noncopyable]
+// CHECK:STDOUT:   %.loc27_42.1: %tuple.type.1 = tuple_literal (%i32.loc27, %Noncopyable.ref.loc27)
+// CHECK:STDOUT:   %.loc27_42.2: type = converted %.loc27_42.1, constants.%tuple.type.2 [template = constants.%tuple.type.2]
+// CHECK:STDOUT:   %.loc27_22.1: %tuple.type.2 = as_compatible %a.ref.loc27
+// CHECK:STDOUT:   %.loc27_22.2: %tuple.type.2 = converted %a.ref.loc27, %.loc27_22.1
+// CHECK:STDOUT:   %A.ref.loc27: type = name_ref A, file.%A.decl [template = constants.%A]
+// CHECK:STDOUT:   %.loc27_45.1: %A = as_compatible %.loc27_22.2
+// CHECK:STDOUT:   %.loc27_45.2: %A = converted %.loc27_22.2, %.loc27_45.1
+// CHECK:STDOUT:   %.loc27_49.1: %tuple.type.2 = as_compatible %.loc27_45.2
+// CHECK:STDOUT:   %tuple.elem0.loc27_49.1: %i32 = tuple_access %.loc27_49.1, element0
+// CHECK:STDOUT:   %.loc27_49.2: ref %tuple.type.2 = as_compatible %a_init.var
+// CHECK:STDOUT:   %tuple.elem0.loc27_49.2: ref %i32 = tuple_access %.loc27_49.2, element0
+// CHECK:STDOUT:   %.loc27_49.3: init %i32 = initialize_from %tuple.elem0.loc27_49.1 to %tuple.elem0.loc27_49.2
+// CHECK:STDOUT:   %tuple.elem1: %Noncopyable = tuple_access %.loc27_49.1, element1
+// CHECK:STDOUT:   assign %a_init.var, <error>
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_adapt_init_from_struct.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %A: type = class_type @A [template]
+// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [template]
+// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [template]
+// CHECK:STDOUT:   %A.elem: type = unbound_element_type %A, %i32 [template]
+// CHECK:STDOUT:   %struct_type.x.1: type = struct_type {.x: %i32} [template]
+// CHECK:STDOUT:   %complete_type.3: <witness> = complete_type_witness %struct_type.x.1 [template]
+// CHECK:STDOUT:   %B: type = class_type @B [template]
+// CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [template]
+// CHECK:STDOUT:   %struct_type.x.2: type = struct_type {.x: Core.IntLiteral} [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .Int = %import_ref.1
+// CHECK:STDOUT:     .As = %import_ref.5
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .A = %A.decl
+// CHECK:STDOUT:     .B = %B.decl
+// CHECK:STDOUT:     .b = %b
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %A.decl: type = class_decl @A [template = constants.%A] {} {}
+// CHECK:STDOUT:   %B.decl: type = class_decl @B [template = constants.%B] {} {}
+// CHECK:STDOUT:   %b.var: ref %B = var b
+// CHECK:STDOUT:   %b: ref %B = bind_name b, %b.var
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @A {
+// CHECK:STDOUT:   %.loc5: %A.elem = field_decl x, element0 [template]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.1 [template = constants.%complete_type.3]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%A
+// CHECK:STDOUT:   .x = %.loc5
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @B {
+// CHECK:STDOUT:   %A.ref: type = name_ref A, file.%A.decl [template = constants.%A]
+// CHECK:STDOUT:   adapt_decl %A.ref [template]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.x.1 [template = constants.%complete_type.3]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%B
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @__global_init() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [template = constants.%int_1]
+// CHECK:STDOUT:   %.loc21_19: %struct_type.x.2 = struct_literal (%int_1)
+// CHECK:STDOUT:   %B.ref: type = name_ref B, file.%B.decl [template = constants.%B]
+// CHECK:STDOUT:   %.loc21_21: %B = converted %.loc21_19, <error> [template = <error>]
+// CHECK:STDOUT:   assign file.%b.var, <error>
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/class/adapter/adapt_copy.carbon b/toolchain/check/testdata/class/adapter/adapt_copy.carbon
index b3623c2d0383..9b65072df8ed 100644
--- a/toolchain/check/testdata/class/adapter/adapt_copy.carbon
+++ b/toolchain/check/testdata/class/adapter/adapt_copy.carbon
@@ -23,12 +23,12 @@ fn F(c: AdaptCopyable) -> AdaptCopyable {
   return d;
 }
 
-fn InTuple(c: (AdaptCopyable, i32)) -> (AdaptCopyable, i32) {
-  var d: (AdaptCopyable, i32) = c;
+fn InTuple(c: (AdaptCopyable, u32)) -> (AdaptCopyable, u32) {
+  var d: (AdaptCopyable, u32) = c;
   return d;
 }
 
-// --- fail_todo_adapt_copyable_tuple.carbon
+// --- adapt_copyable_tuple.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -36,18 +36,13 @@ class AdaptTuple {
   adapt (i32, i32);
 }
 
-// TODO: Support copying in this case too, by performing the corresponding copy
-// operation for the adapted type.
 fn F(c: AdaptTuple) -> AdaptTuple {
-  // CHECK:STDERR: fail_todo_adapt_copyable_tuple.carbon:[[@LINE+4]]:23: error: cannot copy value of type `AdaptTuple` [CopyOfUncopyableType]
-  // CHECK:STDERR:   var d: AdaptTuple = c;
-  // CHECK:STDERR:                       ^
-  // CHECK:STDERR:
   var d: AdaptTuple = c;
-  // CHECK:STDERR: fail_todo_adapt_copyable_tuple.carbon:[[@LINE+4]]:10: error: cannot copy value of type `AdaptTuple` [CopyOfUncopyableType]
-  // CHECK:STDERR:   return d;
-  // CHECK:STDERR:          ^
-  // CHECK:STDERR:
+  return d;
+}
+
+fn InTuple(c: (AdaptTuple, u32)) -> (AdaptTuple, u32) {
+  var d: (AdaptTuple, u32) = c;
   return d;
 }
 
@@ -89,17 +84,41 @@ class AdaptNoncopyableIndirect {
 }
 
 fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
-  // CHECK:STDERR: fail_adapt_not_copyable_indirect.carbon:[[@LINE+4]]:37: error: cannot copy value of type `AdaptNoncopyableIndirect` [CopyOfUncopyableType]
+  // CHECK:STDERR: fail_adapt_not_copyable_indirect.carbon:[[@LINE+7]]:3: error: cannot copy value of type `Noncopyable` [CopyOfUncopyableType]
+  // CHECK:STDERR:   var b: AdaptNoncopyableIndirect = a;
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_adapt_not_copyable_indirect.carbon:[[@LINE+4]]:37: note: in copy of ``AdaptNoncopyableIndirect`` [InCopy]
   // CHECK:STDERR:   var b: AdaptNoncopyableIndirect = a;
   // CHECK:STDERR:                                     ^
   // CHECK:STDERR:
   var b: AdaptNoncopyableIndirect = a;
-  // CHECK:STDERR: fail_adapt_not_copyable_indirect.carbon:[[@LINE+3]]:10: error: cannot copy value of type `AdaptNoncopyableIndirect` [CopyOfUncopyableType]
+  // CHECK:STDERR: fail_adapt_not_copyable_indirect.carbon:[[@LINE+6]]:3: error: cannot copy value of type `Noncopyable` [CopyOfUncopyableType]
+  // CHECK:STDERR:   return b;
+  // CHECK:STDERR:   ^~~~~~~~~
+  // CHECK:STDERR: fail_adapt_not_copyable_indirect.carbon:[[@LINE+3]]:10: note: in copy of ``AdaptNoncopyableIndirect`` [InCopy]
   // CHECK:STDERR:   return b;
   // CHECK:STDERR:          ^
   return b;
 }
 
+// --- adapt_copyable_struct.carbon
+
+library "[[@TEST_NAME]]";
+
+class AdaptStruct {
+  adapt {.e: i32, .f: i32};
+}
+
+fn I(g: AdaptStruct) -> AdaptStruct {
+  var h: AdaptStruct = g;
+  return h;
+}
+
+fn InTuple(c: (AdaptStruct, u32)) -> (AdaptStruct, u32) {
+  var d: (AdaptStruct, u32) = c;
+  return d;
+}
+
 // CHECK:STDOUT: --- adapt_copyable.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
@@ -110,8 +129,9 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:   %complete_type.2: <witness> = complete_type_witness %i32.builtin [template]
 // CHECK:STDOUT:   %F.type: type = fn_type @F [template]
 // CHECK:STDOUT:   %F: %F.type = struct_value () [template]
+// CHECK:STDOUT:   %u32: type = class_type @UInt, @UInt(%int_32) [template]
 // CHECK:STDOUT:   %tuple.type.1: type = tuple_type (type, type) [template]
-// CHECK:STDOUT:   %tuple.type.2: type = tuple_type (%AdaptCopyable, %i32) [template]
+// CHECK:STDOUT:   %tuple.type.2: type = tuple_type (%AdaptCopyable, %u32) [template]
 // CHECK:STDOUT:   %InTuple.type: type = fn_type @InTuple [template]
 // CHECK:STDOUT:   %InTuple: %InTuple.type = struct_value () [template]
 // CHECK:STDOUT: }
@@ -119,6 +139,7 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
 // CHECK:STDOUT:     .Int = %import_ref.1
+// CHECK:STDOUT:     .UInt = %import_ref.5
 // CHECK:STDOUT:     import Core//prelude
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
@@ -154,15 +175,15 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:   } {
 // CHECK:STDOUT:     %AdaptCopyable.ref.loc15_41: type = name_ref AdaptCopyable, file.%AdaptCopyable.decl [template = constants.%AdaptCopyable]
 // CHECK:STDOUT:     %int_32.loc15_56: Core.IntLiteral = int_value 32 [template = constants.%int_32]
-// CHECK:STDOUT:     %i32.loc15_56: type = class_type @Int, @Int(constants.%int_32) [template = constants.%i32]
-// CHECK:STDOUT:     %.loc15_59.1: %tuple.type.1 = tuple_literal (%AdaptCopyable.ref.loc15_41, %i32.loc15_56)
+// CHECK:STDOUT:     %u32.loc15_56: type = class_type @UInt, @UInt(constants.%int_32) [template = constants.%u32]
+// CHECK:STDOUT:     %.loc15_59.1: %tuple.type.1 = tuple_literal (%AdaptCopyable.ref.loc15_41, %u32.loc15_56)
 // CHECK:STDOUT:     %.loc15_59.2: type = converted %.loc15_59.1, constants.%tuple.type.2 [template = constants.%tuple.type.2]
 // CHECK:STDOUT:     %c.param: %tuple.type.2 = value_param runtime_param0
 // CHECK:STDOUT:     %.loc15_34.1: type = splice_block %.loc15_34.3 [template = constants.%tuple.type.2] {
 // CHECK:STDOUT:       %AdaptCopyable.ref.loc15_16: type = name_ref AdaptCopyable, file.%AdaptCopyable.decl [template = constants.%AdaptCopyable]
 // CHECK:STDOUT:       %int_32.loc15_31: Core.IntLiteral = int_value 32 [template = constants.%int_32]
-// CHECK:STDOUT:       %i32.loc15_31: type = class_type @Int, @Int(constants.%int_32) [template = constants.%i32]
-// CHECK:STDOUT:       %.loc15_34.2: %tuple.type.1 = tuple_literal (%AdaptCopyable.ref.loc15_16, %i32.loc15_31)
+// CHECK:STDOUT:       %u32.loc15_31: type = class_type @UInt, @UInt(constants.%int_32) [template = constants.%u32]
+// CHECK:STDOUT:       %.loc15_34.2: %tuple.type.1 = tuple_literal (%AdaptCopyable.ref.loc15_16, %u32.loc15_31)
 // CHECK:STDOUT:       %.loc15_34.3: type = converted %.loc15_34.2, constants.%tuple.type.2 [template = constants.%tuple.type.2]
 // CHECK:STDOUT:     }
 // CHECK:STDOUT:     %c: %tuple.type.2 = bind_name c, %c.param
@@ -201,9 +222,9 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:   %tuple.elem0.loc16_33.1: %AdaptCopyable = tuple_access %c.ref, element0
 // CHECK:STDOUT:   %tuple.elem0.loc16_33.2: ref %AdaptCopyable = tuple_access %d.var, element0
 // CHECK:STDOUT:   %.loc16_33.1: init %AdaptCopyable = initialize_from %tuple.elem0.loc16_33.1 to %tuple.elem0.loc16_33.2
-// CHECK:STDOUT:   %tuple.elem1.loc16_33.1: %i32 = tuple_access %c.ref, element1
-// CHECK:STDOUT:   %tuple.elem1.loc16_33.2: ref %i32 = tuple_access %d.var, element1
-// CHECK:STDOUT:   %.loc16_33.2: init %i32 = initialize_from %tuple.elem1.loc16_33.1 to %tuple.elem1.loc16_33.2
+// CHECK:STDOUT:   %tuple.elem1.loc16_33.1: %u32 = tuple_access %c.ref, element1
+// CHECK:STDOUT:   %tuple.elem1.loc16_33.2: ref %u32 = tuple_access %d.var, element1
+// CHECK:STDOUT:   %.loc16_33.2: init %u32 = initialize_from %tuple.elem1.loc16_33.1 to %tuple.elem1.loc16_33.2
 // CHECK:STDOUT:   %.loc16_33.3: init %tuple.type.2 = tuple_init (%.loc16_33.1, %.loc16_33.2) to %d.var
 // CHECK:STDOUT:   %.loc16_34: init %tuple.type.2 = converted %c.ref, %.loc16_33.3
 // CHECK:STDOUT:   assign %d.var, %.loc16_34
@@ -212,16 +233,16 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:   %.loc17_10.1: %AdaptCopyable = bind_value %tuple.elem0.loc17_10.1
 // CHECK:STDOUT:   %tuple.elem0.loc17_10.2: ref %AdaptCopyable = tuple_access %return, element0
 // CHECK:STDOUT:   %.loc17_10.2: init %AdaptCopyable = initialize_from %.loc17_10.1 to %tuple.elem0.loc17_10.2
-// CHECK:STDOUT:   %tuple.elem1.loc17_10.1: ref %i32 = tuple_access %d.ref, element1
-// CHECK:STDOUT:   %.loc17_10.3: %i32 = bind_value %tuple.elem1.loc17_10.1
-// CHECK:STDOUT:   %tuple.elem1.loc17_10.2: ref %i32 = tuple_access %return, element1
-// CHECK:STDOUT:   %.loc17_10.4: init %i32 = initialize_from %.loc17_10.3 to %tuple.elem1.loc17_10.2
+// CHECK:STDOUT:   %tuple.elem1.loc17_10.1: ref %u32 = tuple_access %d.ref, element1
+// CHECK:STDOUT:   %.loc17_10.3: %u32 = bind_value %tuple.elem1.loc17_10.1
+// CHECK:STDOUT:   %tuple.elem1.loc17_10.2: ref %u32 = tuple_access %return, element1
+// CHECK:STDOUT:   %.loc17_10.4: init %u32 = initialize_from %.loc17_10.3 to %tuple.elem1.loc17_10.2
 // CHECK:STDOUT:   %.loc17_10.5: init %tuple.type.2 = tuple_init (%.loc17_10.2, %.loc17_10.4) to %return
 // CHECK:STDOUT:   %.loc17_11: init %tuple.type.2 = converted %d.ref, %.loc17_10.5
 // CHECK:STDOUT:   return %.loc17_11 to %return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_adapt_copyable_tuple.carbon
+// CHECK:STDOUT: --- adapt_copyable_tuple.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %AdaptTuple: type = class_type @AdaptTuple [template]
@@ -232,11 +253,16 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:   %complete_type.3: <witness> = complete_type_witness %tuple.type.2 [template]
 // CHECK:STDOUT:   %F.type: type = fn_type @F [template]
 // CHECK:STDOUT:   %F: %F.type = struct_value () [template]
+// CHECK:STDOUT:   %u32: type = class_type @UInt, @UInt(%int_32) [template]
+// CHECK:STDOUT:   %tuple.type.3: type = tuple_type (%AdaptTuple, %u32) [template]
+// CHECK:STDOUT:   %InTuple.type: type = fn_type @InTuple [template]
+// CHECK:STDOUT:   %InTuple: %InTuple.type = struct_value () [template]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
 // CHECK:STDOUT:     .Int = %import_ref.1
+// CHECK:STDOUT:     .UInt = %import_ref.5
 // CHECK:STDOUT:     import Core//prelude
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
@@ -247,6 +273,7 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:     .Core = imports.%Core
 // CHECK:STDOUT:     .AdaptTuple = %AdaptTuple.decl
 // CHECK:STDOUT:     .F = %F.decl
+// CHECK:STDOUT:     .InTuple = %InTuple.decl
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Core.import = import Core
 // CHECK:STDOUT:   %AdaptTuple.decl: type = class_decl @AdaptTuple [template = constants.%AdaptTuple] {} {}
@@ -256,13 +283,36 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:     %return.patt: %AdaptTuple = return_slot_pattern
 // CHECK:STDOUT:     %return.param_patt: %AdaptTuple = out_param_pattern %return.patt, runtime_param1
 // CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %AdaptTuple.ref.loc10_24: type = name_ref AdaptTuple, file.%AdaptTuple.decl [template = constants.%AdaptTuple]
+// CHECK:STDOUT:     %AdaptTuple.ref.loc8_24: type = name_ref AdaptTuple, file.%AdaptTuple.decl [template = constants.%AdaptTuple]
 // CHECK:STDOUT:     %c.param: %AdaptTuple = value_param runtime_param0
-// CHECK:STDOUT:     %AdaptTuple.ref.loc10_9: type = name_ref AdaptTuple, file.%AdaptTuple.decl [template = constants.%AdaptTuple]
+// CHECK:STDOUT:     %AdaptTuple.ref.loc8_9: type = name_ref AdaptTuple, file.%AdaptTuple.decl [template = constants.%AdaptTuple]
 // CHECK:STDOUT:     %c: %AdaptTuple = bind_name c, %c.param
 // CHECK:STDOUT:     %return.param: ref %AdaptTuple = out_param runtime_param1
 // CHECK:STDOUT:     %return: ref %AdaptTuple = return_slot %return.param
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %InTuple.decl: %InTuple.type = fn_decl @InTuple [template = constants.%InTuple] {
+// CHECK:STDOUT:     %c.patt: %tuple.type.3 = binding_pattern c
+// CHECK:STDOUT:     %c.param_patt: %tuple.type.3 = value_param_pattern %c.patt, runtime_param0
+// CHECK:STDOUT:     %return.patt: %tuple.type.3 = return_slot_pattern
+// CHECK:STDOUT:     %return.param_patt: %tuple.type.3 = out_param_pattern %return.patt, runtime_param1
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %AdaptTuple.ref.loc13_38: type = name_ref AdaptTuple, file.%AdaptTuple.decl [template = constants.%AdaptTuple]
+// CHECK:STDOUT:     %int_32.loc13_50: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:     %u32.loc13_50: type = class_type @UInt, @UInt(constants.%int_32) [template = constants.%u32]
+// CHECK:STDOUT:     %.loc13_53.1: %tuple.type.1 = tuple_literal (%AdaptTuple.ref.loc13_38, %u32.loc13_50)
+// CHECK:STDOUT:     %.loc13_53.2: type = converted %.loc13_53.1, constants.%tuple.type.3 [template = constants.%tuple.type.3]
+// CHECK:STDOUT:     %c.param: %tuple.type.3 = value_param runtime_param0
+// CHECK:STDOUT:     %.loc13_31.1: type = splice_block %.loc13_31.3 [template = constants.%tuple.type.3] {
+// CHECK:STDOUT:       %AdaptTuple.ref.loc13_16: type = name_ref AdaptTuple, file.%AdaptTuple.decl [template = constants.%AdaptTuple]
+// CHECK:STDOUT:       %int_32.loc13_28: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:       %u32.loc13_28: type = class_type @UInt, @UInt(constants.%int_32) [template = constants.%u32]
+// CHECK:STDOUT:       %.loc13_31.2: %tuple.type.1 = tuple_literal (%AdaptTuple.ref.loc13_16, %u32.loc13_28)
+// CHECK:STDOUT:       %.loc13_31.3: type = converted %.loc13_31.2, constants.%tuple.type.3 [template = constants.%tuple.type.3]
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:     %c: %tuple.type.3 = bind_name c, %c.param
+// CHECK:STDOUT:     %return.param: ref %tuple.type.3 = out_param runtime_param1
+// CHECK:STDOUT:     %return: ref %tuple.type.3 = return_slot %return.param
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: class @AdaptTuple {
@@ -285,10 +335,82 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:   %d.var: ref %AdaptTuple = var d
 // CHECK:STDOUT:   %d: ref %AdaptTuple = bind_name d, %d.var
 // CHECK:STDOUT:   %c.ref: %AdaptTuple = name_ref c, %c
-// CHECK:STDOUT:   assign %d.var, <error>
+// CHECK:STDOUT:   %.loc9_24.1: %tuple.type.2 = as_compatible %c.ref
+// CHECK:STDOUT:   %tuple.elem0.loc9_24.1: %i32 = tuple_access %.loc9_24.1, element0
+// CHECK:STDOUT:   %.loc9_24.2: ref %tuple.type.2 = as_compatible %d.var
+// CHECK:STDOUT:   %tuple.elem0.loc9_24.2: ref %i32 = tuple_access %.loc9_24.2, element0
+// CHECK:STDOUT:   %.loc9_24.3: init %i32 = initialize_from %tuple.elem0.loc9_24.1 to %tuple.elem0.loc9_24.2
+// CHECK:STDOUT:   %tuple.elem1.loc9_24.1: %i32 = tuple_access %.loc9_24.1, element1
+// CHECK:STDOUT:   %tuple.elem1.loc9_24.2: ref %i32 = tuple_access %.loc9_24.2, element1
+// CHECK:STDOUT:   %.loc9_24.4: init %i32 = initialize_from %tuple.elem1.loc9_24.1 to %tuple.elem1.loc9_24.2
+// CHECK:STDOUT:   %.loc9_24.5: init %tuple.type.2 = tuple_init (%.loc9_24.3, %.loc9_24.4) to %.loc9_24.2
+// CHECK:STDOUT:   %.loc9_24.6: init %AdaptTuple = as_compatible %.loc9_24.5
+// CHECK:STDOUT:   %.loc9_24.7: init %AdaptTuple = converted %c.ref, %.loc9_24.6
+// CHECK:STDOUT:   assign %d.var, %.loc9_24.7
 // CHECK:STDOUT:   %d.ref: ref %AdaptTuple = name_ref d, %d
-// CHECK:STDOUT:   %.loc20: %AdaptTuple = bind_value %d.ref
-// CHECK:STDOUT:   return <error> to %return
+// CHECK:STDOUT:   %.loc10_11.1: ref %tuple.type.2 = as_compatible %d.ref
+// CHECK:STDOUT:   %tuple.elem0.loc10_11.1: ref %i32 = tuple_access %.loc10_11.1, element0
+// CHECK:STDOUT:   %.loc10_11.2: %i32 = bind_value %tuple.elem0.loc10_11.1
+// CHECK:STDOUT:   %.loc10_11.3: ref %tuple.type.2 = as_compatible %return
+// CHECK:STDOUT:   %tuple.elem0.loc10_11.2: ref %i32 = tuple_access %.loc10_11.3, element0
+// CHECK:STDOUT:   %.loc10_11.4: init %i32 = initialize_from %.loc10_11.2 to %tuple.elem0.loc10_11.2
+// CHECK:STDOUT:   %tuple.elem1.loc10_11.1: ref %i32 = tuple_access %.loc10_11.1, element1
+// CHECK:STDOUT:   %.loc10_11.5: %i32 = bind_value %tuple.elem1.loc10_11.1
+// CHECK:STDOUT:   %tuple.elem1.loc10_11.2: ref %i32 = tuple_access %.loc10_11.3, element1
+// CHECK:STDOUT:   %.loc10_11.6: init %i32 = initialize_from %.loc10_11.5 to %tuple.elem1.loc10_11.2
+// CHECK:STDOUT:   %.loc10_11.7: init %tuple.type.2 = tuple_init (%.loc10_11.4, %.loc10_11.6) to %.loc10_11.3
+// CHECK:STDOUT:   %.loc10_11.8: init %AdaptTuple = as_compatible %.loc10_11.7
+// CHECK:STDOUT:   %.loc10_11.9: init %AdaptTuple = converted %d.ref, %.loc10_11.8
+// CHECK:STDOUT:   return %.loc10_11.9 to %return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @InTuple(%c.param_patt: %tuple.type.3) -> %return.param_patt: %tuple.type.3 {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %d.var: ref %tuple.type.3 = var d
+// CHECK:STDOUT:   %d: ref %tuple.type.3 = bind_name d, %d.var
+// CHECK:STDOUT:   %c.ref: %tuple.type.3 = name_ref c, %c
+// CHECK:STDOUT:   %tuple.elem0.loc14_30.1: %AdaptTuple = tuple_access %c.ref, element0
+// CHECK:STDOUT:   %.loc14_30.1: %tuple.type.2 = as_compatible %tuple.elem0.loc14_30.1
+// CHECK:STDOUT:   %tuple.elem0.loc14_30.2: %i32 = tuple_access %.loc14_30.1, element0
+// CHECK:STDOUT:   %tuple.elem0.loc14_30.3: ref %AdaptTuple = tuple_access %d.var, element0
+// CHECK:STDOUT:   %.loc14_30.2: ref %tuple.type.2 = as_compatible %tuple.elem0.loc14_30.3
+// CHECK:STDOUT:   %tuple.elem0.loc14_30.4: ref %i32 = tuple_access %.loc14_30.2, element0
+// CHECK:STDOUT:   %.loc14_30.3: init %i32 = initialize_from %tuple.elem0.loc14_30.2 to %tuple.elem0.loc14_30.4
+// CHECK:STDOUT:   %tuple.elem1.loc14_30.1: %i32 = tuple_access %.loc14_30.1, element1
+// CHECK:STDOUT:   %tuple.elem1.loc14_30.2: ref %i32 = tuple_access %.loc14_30.2, element1
+// CHECK:STDOUT:   %.loc14_30.4: init %i32 = initialize_from %tuple.elem1.loc14_30.1 to %tuple.elem1.loc14_30.2
+// CHECK:STDOUT:   %.loc14_30.5: init %tuple.type.2 = tuple_init (%.loc14_30.3, %.loc14_30.4) to %.loc14_30.2
+// CHECK:STDOUT:   %.loc14_30.6: init %AdaptTuple = as_compatible %.loc14_30.5
+// CHECK:STDOUT:   %.loc14_30.7: init %AdaptTuple = converted %tuple.elem0.loc14_30.1, %.loc14_30.6
+// CHECK:STDOUT:   %tuple.elem1.loc14_30.3: %u32 = tuple_access %c.ref, element1
+// CHECK:STDOUT:   %tuple.elem1.loc14_30.4: ref %u32 = tuple_access %d.var, element1
+// CHECK:STDOUT:   %.loc14_30.8: init %u32 = initialize_from %tuple.elem1.loc14_30.3 to %tuple.elem1.loc14_30.4
+// CHECK:STDOUT:   %.loc14_30.9: init %tuple.type.3 = tuple_init (%.loc14_30.7, %.loc14_30.8) to %d.var
+// CHECK:STDOUT:   %.loc14_31: init %tuple.type.3 = converted %c.ref, %.loc14_30.9
+// CHECK:STDOUT:   assign %d.var, %.loc14_31
+// CHECK:STDOUT:   %d.ref: ref %tuple.type.3 = name_ref d, %d
+// CHECK:STDOUT:   %tuple.elem0.loc15_10.1: ref %AdaptTuple = tuple_access %d.ref, element0
+// CHECK:STDOUT:   %.loc15_10.1: ref %tuple.type.2 = as_compatible %tuple.elem0.loc15_10.1
+// CHECK:STDOUT:   %tuple.elem0.loc15_10.2: ref %i32 = tuple_access %.loc15_10.1, element0
+// CHECK:STDOUT:   %.loc15_10.2: %i32 = bind_value %tuple.elem0.loc15_10.2
+// CHECK:STDOUT:   %tuple.elem0.loc15_10.3: ref %AdaptTuple = tuple_access %return, element0
+// CHECK:STDOUT:   %.loc15_10.3: ref %tuple.type.2 = as_compatible %tuple.elem0.loc15_10.3
+// CHECK:STDOUT:   %tuple.elem0.loc15_10.4: ref %i32 = tuple_access %.loc15_10.3, element0
+// CHECK:STDOUT:   %.loc15_10.4: init %i32 = initialize_from %.loc15_10.2 to %tuple.elem0.loc15_10.4
+// CHECK:STDOUT:   %tuple.elem1.loc15_10.1: ref %i32 = tuple_access %.loc15_10.1, element1
+// CHECK:STDOUT:   %.loc15_10.5: %i32 = bind_value %tuple.elem1.loc15_10.1
+// CHECK:STDOUT:   %tuple.elem1.loc15_10.2: ref %i32 = tuple_access %.loc15_10.3, element1
+// CHECK:STDOUT:   %.loc15_10.6: init %i32 = initialize_from %.loc15_10.5 to %tuple.elem1.loc15_10.2
+// CHECK:STDOUT:   %.loc15_10.7: init %tuple.type.2 = tuple_init (%.loc15_10.4, %.loc15_10.6) to %.loc15_10.3
+// CHECK:STDOUT:   %.loc15_10.8: init %AdaptTuple = as_compatible %.loc15_10.7
+// CHECK:STDOUT:   %.loc15_10.9: init %AdaptTuple = converted %tuple.elem0.loc15_10.1, %.loc15_10.8
+// CHECK:STDOUT:   %tuple.elem1.loc15_10.3: ref %u32 = tuple_access %d.ref, element1
+// CHECK:STDOUT:   %.loc15_10.10: %u32 = bind_value %tuple.elem1.loc15_10.3
+// CHECK:STDOUT:   %tuple.elem1.loc15_10.4: ref %u32 = tuple_access %return, element1
+// CHECK:STDOUT:   %.loc15_10.11: init %u32 = initialize_from %.loc15_10.10 to %tuple.elem1.loc15_10.4
+// CHECK:STDOUT:   %.loc15_10.12: init %tuple.type.3 = tuple_init (%.loc15_10.9, %.loc15_10.11) to %return
+// CHECK:STDOUT:   %.loc15_11: init %tuple.type.3 = converted %d.ref, %.loc15_10.12
+// CHECK:STDOUT:   return %.loc15_11 to %return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_adapt_not_copyable.carbon
@@ -441,9 +563,192 @@ fn H(a: AdaptNoncopyableIndirect) -> AdaptNoncopyableIndirect {
 // CHECK:STDOUT:   %b.var: ref %AdaptNoncopyableIndirect = var b
 // CHECK:STDOUT:   %b: ref %AdaptNoncopyableIndirect = bind_name b, %b.var
 // CHECK:STDOUT:   %a.ref: %AdaptNoncopyableIndirect = name_ref a, %a
+// CHECK:STDOUT:   %.loc20_38.1: %tuple.type.2 = as_compatible %a.ref
+// CHECK:STDOUT:   %tuple.elem0.loc20_38.1: %i32 = tuple_access %.loc20_38.1, element0
+// CHECK:STDOUT:   %.loc20_38.2: ref %tuple.type.2 = as_compatible %b.var
+// CHECK:STDOUT:   %tuple.elem0.loc20_38.2: ref %i32 = tuple_access %.loc20_38.2, element0
+// CHECK:STDOUT:   %.loc20_38.3: init %i32 = initialize_from %tuple.elem0.loc20_38.1 to %tuple.elem0.loc20_38.2
+// CHECK:STDOUT:   %tuple.elem1.loc20: %Noncopyable = tuple_access %.loc20_38.1, element1
 // CHECK:STDOUT:   assign %b.var, <error>
 // CHECK:STDOUT:   %b.ref: ref %AdaptNoncopyableIndirect = name_ref b, %b
-// CHECK:STDOUT:   %.loc21: %AdaptNoncopyableIndirect = bind_value %b.ref
+// CHECK:STDOUT:   %.loc27_11.1: ref %tuple.type.2 = as_compatible %b.ref
+// CHECK:STDOUT:   %tuple.elem0.loc27_11.1: ref %i32 = tuple_access %.loc27_11.1, element0
+// CHECK:STDOUT:   %.loc27_11.2: %i32 = bind_value %tuple.elem0.loc27_11.1
+// CHECK:STDOUT:   %.loc27_11.3: ref %tuple.type.2 = as_compatible %return
+// CHECK:STDOUT:   %tuple.elem0.loc27_11.2: ref %i32 = tuple_access %.loc27_11.3, element0
+// CHECK:STDOUT:   %.loc27_11.4: init %i32 = initialize_from %.loc27_11.2 to %tuple.elem0.loc27_11.2
+// CHECK:STDOUT:   %tuple.elem1.loc27: ref %Noncopyable = tuple_access %.loc27_11.1, element1
+// CHECK:STDOUT:   %.loc27_11.5: %Noncopyable = bind_value %tuple.elem1.loc27
 // CHECK:STDOUT:   return <error> to %return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: --- adapt_copyable_struct.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %AdaptStruct: type = class_type @AdaptStruct [template]
+// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [template]
+// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [template]
+// CHECK:STDOUT:   %struct_type.e.f: type = struct_type {.e: %i32, .f: %i32} [template]
+// CHECK:STDOUT:   %complete_type.3: <witness> = complete_type_witness %struct_type.e.f [template]
+// CHECK:STDOUT:   %I.type: type = fn_type @I [template]
+// CHECK:STDOUT:   %I: %I.type = struct_value () [template]
+// CHECK:STDOUT:   %u32: type = class_type @UInt, @UInt(%int_32) [template]
+// CHECK:STDOUT:   %tuple.type.1: type = tuple_type (type, type) [template]
+// CHECK:STDOUT:   %tuple.type.2: type = tuple_type (%AdaptStruct, %u32) [template]
+// CHECK:STDOUT:   %InTuple.type: type = fn_type @InTuple [template]
+// CHECK:STDOUT:   %InTuple: %InTuple.type = struct_value () [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .Int = %import_ref.1
+// CHECK:STDOUT:     .UInt = %import_ref.5
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .AdaptStruct = %AdaptStruct.decl
+// CHECK:STDOUT:     .I = %I.decl
+// CHECK:STDOUT:     .InTuple = %InTuple.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %AdaptStruct.decl: type = class_decl @AdaptStruct [template = constants.%AdaptStruct] {} {}
+// CHECK:STDOUT:   %I.decl: %I.type = fn_decl @I [template = constants.%I] {
+// CHECK:STDOUT:     %g.patt: %AdaptStruct = binding_pattern g
+// CHECK:STDOUT:     %g.param_patt: %AdaptStruct = value_param_pattern %g.patt, runtime_param0
+// CHECK:STDOUT:     %return.patt: %AdaptStruct = return_slot_pattern
+// CHECK:STDOUT:     %return.param_patt: %AdaptStruct = out_param_pattern %return.patt, runtime_param1
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %AdaptStruct.ref.loc8_25: type = name_ref AdaptStruct, file.%AdaptStruct.decl [template = constants.%AdaptStruct]
+// CHECK:STDOUT:     %g.param: %AdaptStruct = value_param runtime_param0
+// CHECK:STDOUT:     %AdaptStruct.ref.loc8_9: type = name_ref AdaptStruct, file.%AdaptStruct.decl [template = constants.%AdaptStruct]
+// CHECK:STDOUT:     %g: %AdaptStruct = bind_name g, %g.param
+// CHECK:STDOUT:     %return.param: ref %AdaptStruct = out_param runtime_param1
+// CHECK:STDOUT:     %return: ref %AdaptStruct = return_slot %return.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %InTuple.decl: %InTuple.type = fn_decl @InTuple [template = constants.%InTuple] {
+// CHECK:STDOUT:     %c.patt: %tuple.type.2 = binding_pattern c
+// CHECK:STDOUT:     %c.param_patt: %tuple.type.2 = value_param_pattern %c.patt, runtime_param0
+// CHECK:STDOUT:     %return.patt: %tuple.type.2 = return_slot_pattern
+// CHECK:STDOUT:     %return.param_patt: %tuple.type.2 = out_param_pattern %return.patt, runtime_param1
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %AdaptStruct.ref.loc13_39: type = name_ref AdaptStruct, file.%AdaptStruct.decl [template = constants.%AdaptStruct]
+// CHECK:STDOUT:     %int_32.loc13_52: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:     %u32.loc13_52: type = class_type @UInt, @UInt(constants.%int_32) [template = constants.%u32]
+// CHECK:STDOUT:     %.loc13_55.1: %tuple.type.1 = tuple_literal (%AdaptStruct.ref.loc13_39, %u32.loc13_52)
+// CHECK:STDOUT:     %.loc13_55.2: type = converted %.loc13_55.1, constants.%tuple.type.2 [template = constants.%tuple.type.2]
+// CHECK:STDOUT:     %c.param: %tuple.type.2 = value_param runtime_param0
+// CHECK:STDOUT:     %.loc13_32.1: type = splice_block %.loc13_32.3 [template = constants.%tuple.type.2] {
+// CHECK:STDOUT:       %AdaptStruct.ref.loc13_16: type = name_ref AdaptStruct, file.%AdaptStruct.decl [template = constants.%AdaptStruct]
+// CHECK:STDOUT:       %int_32.loc13_29: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:       %u32.loc13_29: type = class_type @UInt, @UInt(constants.%int_32) [template = constants.%u32]
+// CHECK:STDOUT:       %.loc13_32.2: %tuple.type.1 = tuple_literal (%AdaptStruct.ref.loc13_16, %u32.loc13_29)
+// CHECK:STDOUT:       %.loc13_32.3: type = converted %.loc13_32.2, constants.%tuple.type.2 [template = constants.%tuple.type.2]
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:     %c: %tuple.type.2 = bind_name c, %c.param
+// CHECK:STDOUT:     %return.param: ref %tuple.type.2 = out_param runtime_param1
+// CHECK:STDOUT:     %return: ref %tuple.type.2 = return_slot %return.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @AdaptStruct {
+// CHECK:STDOUT:   %int_32.loc5_14: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:   %i32.loc5_14: type = class_type @Int, @Int(constants.%int_32) [template = constants.%i32]
+// CHECK:STDOUT:   %int_32.loc5_23: Core.IntLiteral = int_value 32 [template = constants.%int_32]
+// CHECK:STDOUT:   %i32.loc5_23: type = class_type @Int, @Int(constants.%int_32) [template = constants.%i32]
+// CHECK:STDOUT:   %struct_type.e.f: type = struct_type {.e: %i32, .f: %i32} [template = constants.%struct_type.e.f]
+// CHECK:STDOUT:   adapt_decl %struct_type.e.f [template]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %struct_type.e.f [template = constants.%complete_type.3]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%AdaptStruct
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @I(%g.param_patt: %AdaptStruct) -> %return.param_patt: %AdaptStruct {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %h.var: ref %AdaptStruct = var h
+// CHECK:STDOUT:   %h: ref %AdaptStruct = bind_name h, %h.var
+// CHECK:STDOUT:   %g.ref: %AdaptStruct = name_ref g, %g
+// CHECK:STDOUT:   %.loc9_25.1: %struct_type.e.f = as_compatible %g.ref
+// CHECK:STDOUT:   %.loc9_25.2: %i32 = struct_access %.loc9_25.1, element0
+// CHECK:STDOUT:   %.loc9_25.3: ref %struct_type.e.f = as_compatible %h.var
+// CHECK:STDOUT:   %.loc9_25.4: ref %i32 = struct_access %.loc9_25.3, element0
+// CHECK:STDOUT:   %.loc9_25.5: init %i32 = initialize_from %.loc9_25.2 to %.loc9_25.4
+// CHECK:STDOUT:   %.loc9_25.6: %i32 = struct_access %.loc9_25.1, element1
+// CHECK:STDOUT:   %.loc9_25.7: ref %i32 = struct_access %.loc9_25.3, element1
+// CHECK:STDOUT:   %.loc9_25.8: init %i32 = initialize_from %.loc9_25.6 to %.loc9_25.7
+// CHECK:STDOUT:   %.loc9_25.9: init %struct_type.e.f = struct_init (%.loc9_25.5, %.loc9_25.8) to %.loc9_25.3
+// CHECK:STDOUT:   %.loc9_25.10: init %AdaptStruct = as_compatible %.loc9_25.9
+// CHECK:STDOUT:   %.loc9_25.11: init %AdaptStruct = converted %g.ref, %.loc9_25.10
+// CHECK:STDOUT:   assign %h.var, %.loc9_25.11
+// CHECK:STDOUT:   %h.ref: ref %AdaptStruct = name_ref h, %h
+// CHECK:STDOUT:   %.loc10_11.1: ref %struct_type.e.f = as_compatible %h.ref
+// CHECK:STDOUT:   %.loc10_11.2: ref %i32 = struct_access %.loc10_11.1, element0
+// CHECK:STDOUT:   %.loc10_11.3: %i32 = bind_value %.loc10_11.2
+// CHECK:STDOUT:   %.loc10_11.4: ref %struct_type.e.f = as_compatible %return
+// CHECK:STDOUT:   %.loc10_11.5: ref %i32 = struct_access %.loc10_11.4, element0
+// CHECK:STDOUT:   %.loc10_11.6: init %i32 = initialize_from %.loc10_11.3 to %.loc10_11.5
+// CHECK:STDOUT:   %.loc10_11.7: ref %i32 = struct_access %.loc10_11.1, element1
+// CHECK:STDOUT:   %.loc10_11.8: %i32 = bind_value %.loc10_11.7
+// CHECK:STDOUT:   %.loc10_11.9: ref %i32 = struct_access %.loc10_11.4, element1
+// CHECK:STDOUT:   %.loc10_11.10: init %i32 = initialize_from %.loc10_11.8 to %.loc10_11.9
+// CHECK:STDOUT:   %.loc10_11.11: init %struct_type.e.f = struct_init (%.loc10_11.6, %.loc10_11.10) to %.loc10_11.4
+// CHECK:STDOUT:   %.loc10_11.12: init %AdaptStruct = as_compatible %.loc10_11.11
+// CHECK:STDOUT:   %.loc10_11.13: init %AdaptStruct = converted %h.ref, %.loc10_11.12
+// CHECK:STDOUT:   return %.loc10_11.13 to %return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @InTuple(%c.param_patt: %tuple.type.2) -> %return.param_patt: %tuple.type.2 {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %d.var: ref %tuple.type.2 = var d
+// CHECK:STDOUT:   %d: ref %tuple.type.2 = bind_name d, %d.var
+// CHECK:STDOUT:   %c.ref: %tuple.type.2 = name_ref c, %c
+// CHECK:STDOUT:   %tuple.elem0.loc14_31.1: %AdaptStruct = tuple_access %c.ref, element0
+// CHECK:STDOUT:   %.loc14_31.1: %struct_type.e.f = as_compatible %tuple.elem0.loc14_31.1
+// CHECK:STDOUT:   %.loc14_31.2: %i32 = struct_access %.loc14_31.1, element0
+// CHECK:STDOUT:   %tuple.elem0.loc14_31.2: ref %AdaptStruct = tuple_access %d.var, element0
+// CHECK:STDOUT:   %.loc14_31.3: ref %struct_type.e.f = as_compatible %tuple.elem0.loc14_31.2
+// CHECK:STDOUT:   %.loc14_31.4: ref %i32 = struct_access %.loc14_31.3, element0
+// CHECK:STDOUT:   %.loc14_31.5: init %i32 = initialize_from %.loc14_31.2 to %.loc14_31.4
+// CHECK:STDOUT:   %.loc14_31.6: %i32 = struct_access %.loc14_31.1, element1
+// CHECK:STDOUT:   %.loc14_31.7: ref %i32 = struct_access %.loc14_31.3, element1
+// CHECK:STDOUT:   %.loc14_31.8: init %i32 = initialize_from %.loc14_31.6 to %.loc14_31.7
+// CHECK:STDOUT:   %.loc14_31.9: init %struct_type.e.f = struct_init (%.loc14_31.5, %.loc14_31.8) to %.loc14_31.3
+// CHECK:STDOUT:   %.loc14_31.10: init %AdaptStruct = as_compatible %.loc14_31.9
+// CHECK:STDOUT:   %.loc14_31.11: init %AdaptStruct = converted %tuple.elem0.loc14_31.1, %.loc14_31.10
+// CHECK:STDOUT:   %tuple.elem1.loc14_31.1: %u32 = tuple_access %c.ref, element1
+// CHECK:STDOUT:   %tuple.elem1.loc14_31.2: ref %u32 = tuple_access %d.var, element1
+// CHECK:STDOUT:   %.loc14_31.12: init %u32 = initialize_from %tuple.elem1.loc14_31.1 to %tuple.elem1.loc14_31.2
+// CHECK:STDOUT:   %.loc14_31.13: init %tuple.type.2 = tuple_init (%.loc14_31.11, %.loc14_31.12) to %d.var
+// CHECK:STDOUT:   %.loc14_32: init %tuple.type.2 = converted %c.ref, %.loc14_31.13
+// CHECK:STDOUT:   assign %d.var, %.loc14_32
+// CHECK:STDOUT:   %d.ref: ref %tuple.type.2 = name_ref d, %d
+// CHECK:STDOUT:   %tuple.elem0.loc15_10.1: ref %AdaptStruct = tuple_access %d.ref, element0
+// CHECK:STDOUT:   %.loc15_10.1: ref %struct_type.e.f = as_compatible %tuple.elem0.loc15_10.1
+// CHECK:STDOUT:   %.loc15_10.2: ref %i32 = struct_access %.loc15_10.1, element0
+// CHECK:STDOUT:   %.loc15_10.3: %i32 = bind_value %.loc15_10.2
+// CHECK:STDOUT:   %tuple.elem0.loc15_10.2: ref %AdaptStruct = tuple_access %return, element0
+// CHECK:STDOUT:   %.loc15_10.4: ref %struct_type.e.f = as_compatible %tuple.elem0.loc15_10.2
+// CHECK:STDOUT:   %.loc15_10.5: ref %i32 = struct_access %.loc15_10.4, element0
+// CHECK:STDOUT:   %.loc15_10.6: init %i32 = initialize_from %.loc15_10.3 to %.loc15_10.5
+// CHECK:STDOUT:   %.loc15_10.7: ref %i32 = struct_access %.loc15_10.1, element1
+// CHECK:STDOUT:   %.loc15_10.8: %i32 = bind_value %.loc15_10.7
+// CHECK:STDOUT:   %.loc15_10.9: ref %i32 = struct_access %.loc15_10.4, element1
+// CHECK:STDOUT:   %.loc15_10.10: init %i32 = initialize_from %.loc15_10.8 to %.loc15_10.9
+// CHECK:STDOUT:   %.loc15_10.11: init %struct_type.e.f = struct_init (%.loc15_10.6, %.loc15_10.10) to %.loc15_10.4
+// CHECK:STDOUT:   %.loc15_10.12: init %AdaptStruct = as_compatible %.loc15_10.11
+// CHECK:STDOUT:   %.loc15_10.13: init %AdaptStruct = converted %tuple.elem0.loc15_10.1, %.loc15_10.12
+// CHECK:STDOUT:   %tuple.elem1.loc15_10.1: ref %u32 = tuple_access %d.ref, element1
+// CHECK:STDOUT:   %.loc15_10.14: %u32 = bind_value %tuple.elem1.loc15_10.1
+// CHECK:STDOUT:   %tuple.elem1.loc15_10.2: ref %u32 = tuple_access %return, element1
+// CHECK:STDOUT:   %.loc15_10.15: init %u32 = initialize_from %.loc15_10.14 to %tuple.elem1.loc15_10.2
+// CHECK:STDOUT:   %.loc15_10.16: init %tuple.type.2 = tuple_init (%.loc15_10.13, %.loc15_10.15) to %return
+// CHECK:STDOUT:   %.loc15_11: init %tuple.type.2 = converted %d.ref, %.loc15_10.16
+// CHECK:STDOUT:   return %.loc15_11 to %return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/diagnostics/diagnostic_kind.def b/toolchain/diagnostics/diagnostic_kind.def
index 457768bb6c8b..2b247b0bba5e 100644
--- a/toolchain/diagnostics/diagnostic_kind.def
+++ b/toolchain/diagnostics/diagnostic_kind.def
@@ -332,6 +332,7 @@ CARBON_DIAGNOSTIC_KIND(IncompleteTypeInLetDecl)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInMemberAccess)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInValueConversion)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInVarDecl)
+CARBON_DIAGNOSTIC_KIND(InCopy)
 CARBON_DIAGNOSTIC_KIND(IntTooLargeForType)
 CARBON_DIAGNOSTIC_KIND(IntWidthNotMultipleOf8)
 CARBON_DIAGNOSTIC_KIND(IntWidthNotPositive)
diff --git a/toolchain/sem_ir/file.h b/toolchain/sem_ir/file.h
index 024ff6c74c40..8446737720f9 100644
--- a/toolchain/sem_ir/file.h
+++ b/toolchain/sem_ir/file.h
@@ -314,12 +314,10 @@ enum class ExprCategory : int8_t {
   // object that outlives the current full expression context.
   DurableRef,
   // This instruction represents an ephemeral reference expression, that denotes
-  // an
-  // object that does not outlive the current full expression context.
+  // an object that does not outlive the current full expression context.
   EphemeralRef,
   // This instruction represents an initializing expression, that describes how
-  // to
-  // initialize an object.
+  // to initialize an object.
   Initializing,
   // This instruction represents a syntactic combination of expressions that are
   // permitted to have different expression categories. This is used for tuple