Support conversion from T* to const T*. (#5971)

Also support conversion from Derived* to const Base*.

---------

Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>

toolchain/check/convert.cpp

@@ -673,13 +673,20 @@ static auto ConvertDerivedToBase(Context& context, SemIR::LocId loc_id,
   // Materialize a temporary if necessary.
   value_id = ConvertToValueOrRefExpr(context, value_id);
 
+  // Preserve type qualifiers.
+  auto quals = context.types()
+                   .GetUnqualifiedTypeAndQualifiers(
+                       context.insts().Get(value_id).type_id())
+                   .second;
+
   // Add a series of `.base` accesses.
   for (auto [base_id, base_type_id] : path) {
     auto base_decl = context.insts().GetAs<SemIR::BaseDecl>(base_id);
-    value_id = AddInst<SemIR::ClassElementAccess>(context, loc_id,
-                                                  {.type_id = base_type_id,
-                                                   .base_id = value_id,
-                                                   .index = base_decl.index});
+    value_id = AddInst<SemIR::ClassElementAccess>(
+        context, loc_id,
+        {.type_id = GetQualifiedType(context, base_type_id, quals),
+         .base_id = value_id,
+         .index = base_decl.index});
   }
   return value_id;
 }
@@ -689,13 +696,13 @@ static auto ConvertDerivedPointerToBasePointer(
     Context& context, SemIR::LocId loc_id, SemIR::PointerType src_ptr_type,
     SemIR::TypeId dest_ptr_type_id, SemIR::InstId ptr_id,
     const InheritancePath& path) -> SemIR::InstId {
+  auto pointee_type_id =
+      context.types().GetTypeIdForTypeInstId(src_ptr_type.pointee_id);
+
   // Form `*p`.
   ptr_id = ConvertToValueExpr(context, ptr_id);
   auto ref_id = AddInst<SemIR::Deref>(
-      context, loc_id,
-      {.type_id =
-           context.types().GetTypeIdForTypeInstId(src_ptr_type.pointee_id),
-       .pointer_id = ptr_id});
+      context, loc_id, {.type_id = pointee_type_id, .pointer_id = ptr_id});
 
   // Convert as a reference expression.
   ref_id = ConvertDerivedToBase(context, loc_id, ref_id, path);
@@ -950,6 +957,12 @@ static auto PerformBuiltinConversion(
     }
   }
 
+  // No other conversions apply when the source and destination types are the
+  // same.
+  if (value_type_id == target.type_id) {
+    return value_id;
+  }
+
   // A tuple (T1, T2, ..., Tn) converts to array(T, n) if each Ti converts to T.
   if (auto target_array_type = target_type_inst.TryAs<SemIR::ArrayType>()) {
     if (auto src_tuple_type =
@@ -983,21 +996,50 @@ static auto PerformBuiltinConversion(
     }
   }
 
-  // A pointer T* converts to U* if T is a class derived from U.
+  // A pointer T* converts to [const] U* if T is the same as U, or is a class
+  // derived from U.
   if (auto target_pointer_type = target_type_inst.TryAs<SemIR::PointerType>()) {
     if (auto src_pointer_type =
             sem_ir.types().TryGetAs<SemIR::PointerType>(value_type_id)) {
-      if (auto path =
-              ComputeInheritancePath(context, loc_id,
-                                     context.types().GetTypeIdForTypeInstId(
-                                         src_pointer_type->pointee_id),
-                                     context.types().GetTypeIdForTypeInstId(
-                                         target_pointer_type->pointee_id));
-          path && !path->empty()) {
-        return ConvertDerivedPointerToBasePointer(
-            context, loc_id, *src_pointer_type, target.type_id, value_id,
-            *path);
+      auto [unqual_target_pointee_type_id, target_quals] =
+          sem_ir.types().GetUnqualifiedTypeAndQualifiers(
+              context.types().GetTypeIdForTypeInstId(
+                  target_pointer_type->pointee_id));
+      auto [unqual_src_pointee_type_id, src_quals] =
+          sem_ir.types().GetUnqualifiedTypeAndQualifiers(
+              context.types().GetTypeIdForTypeInstId(
+                  src_pointer_type->pointee_id));
+
+      // If the qualifiers are incompatible, we can't perform a conversion.
+      if ((src_quals & ~target_quals) != SemIR::TypeQualifiers::None) {
+        // TODO: Consider producing a custom diagnostic here for a cast that
+        // discards constness. We should allow this with `unsafe as`.
+        return value_id;
       }
+
+      if (unqual_target_pointee_type_id != unqual_src_pointee_type_id) {
+        // If there's an inheritance path from target to source, this is a
+        // derived to base conversion.
+        if (auto path = ComputeInheritancePath(context, loc_id,
+                                               unqual_src_pointee_type_id,
+                                               unqual_target_pointee_type_id);
+            path && !path->empty()) {
+          value_id = ConvertDerivedPointerToBasePointer(
+              context, loc_id, *src_pointer_type, target.type_id, value_id,
+              *path);
+        } else {
+          // No conversion was possible.
+          return value_id;
+        }
+      }
+
+      // Perform a compatible conversion to add any new qualifiers.
+      if (src_quals != target_quals) {
+        return AddInst<SemIR::AsCompatible>(
+            context, loc_id,
+            {.type_id = target.type_id, .source_id = value_id});
+      }
+      return value_id;
     }
   }
 

toolchain/check/testdata/class/derived_to_base.carbon

@@ -3,8 +3,6 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // INCLUDE-FILE: toolchain/testing/testdata/min_prelude/int.carbon
-// TODO: Add ranges and switch to "--dump-sem-ir-ranges=only".
-// EXTRA-ARGS: --dump-sem-ir-ranges=if-present
 //
 // AUTOUPDATE
 // TIP: To test this file alone, run:
@@ -12,6 +10,10 @@
 // TIP: To dump output, run:
 // TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/class/derived_to_base.carbon
 
+// --- basic.carbon
+
+library "[[@TEST_NAME]]";
+
 base class A {
   var a: i32;
 }
@@ -26,6 +28,7 @@ class C {
   var c: i32;
 }
 
+//@dump-sem-ir-begin
 fn ConvertCToB(p: C*) -> B* { return p; }
 fn ConvertBToA(p: B*) -> A* { return p; }
 fn ConvertCToA(p: C*) -> A* { return p; }
@@ -41,46 +44,95 @@ fn ConvertRef(c: C*) -> A* {
 fn ConvertInit() {
   let a: A = {.base = {.base = {.a = 1}, .b = 2}, .c = 3} as C;
 }
+//@dump-sem-ir-end
+
+// --- qualified.carbon
+
+library "[[@TEST_NAME]]";
+
+base class A {
+}
+
+class B {
+  extend base: A;
+}
+
+fn TakeConstAPtr(p: const A*);
+
+fn PassNonConstBPtr(p: B*) {
+  //@dump-sem-ir-begin
+  TakeConstAPtr(p);
+  //@dump-sem-ir-end
+}
+
+fn PassConstBPtr(p: const B*) {
+  //@dump-sem-ir-begin
+  TakeConstAPtr(p);
+  //@dump-sem-ir-end
+}
+
+// --- fail_todo_qualified_non_ptr.carbon
+
+library "[[@TEST_NAME]]";
+
+base class A {
+}
+
+class B {
+  extend base: A;
+}
 
-// CHECK:STDOUT: --- derived_to_base.carbon
+fn TakeConstA(p: const A);
+
+fn PassNonConstB(p: B) {
+  //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_qualified_non_ptr.carbon:[[@LINE+10]]:14: error: cannot implicitly convert expression of type `B` to `const A` [ConversionFailure]
+  // CHECK:STDERR:   TakeConstA(p);
+  // CHECK:STDERR:              ^
+  // CHECK:STDERR: fail_todo_qualified_non_ptr.carbon:[[@LINE+7]]:14: note: type `B` does not implement interface `Core.ImplicitAs(const A)` [MissingImplInMemberAccessNote]
+  // CHECK:STDERR:   TakeConstA(p);
+  // CHECK:STDERR:              ^
+  // CHECK:STDERR: fail_todo_qualified_non_ptr.carbon:[[@LINE-10]]:15: note: initializing function parameter [InCallToFunctionParam]
+  // CHECK:STDERR: fn TakeConstA(p: const A);
+  // CHECK:STDERR:               ^~~~~~~~~~
+  // CHECK:STDERR:
+  TakeConstA(p);
+  //@dump-sem-ir-end
+}
+
+fn PassConstB(p: const B) {
+  //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_qualified_non_ptr.carbon:[[@LINE+10]]:14: error: cannot implicitly convert expression of type `const B` to `const A` [ConversionFailure]
+  // CHECK:STDERR:   TakeConstA(p);
+  // CHECK:STDERR:              ^
+  // CHECK:STDERR: fail_todo_qualified_non_ptr.carbon:[[@LINE+7]]:14: note: type `const B` does not implement interface `Core.ImplicitAs(const A)` [MissingImplInMemberAccessNote]
+  // CHECK:STDERR:   TakeConstA(p);
+  // CHECK:STDERR:              ^
+  // CHECK:STDERR: fail_todo_qualified_non_ptr.carbon:[[@LINE-26]]:15: note: initializing function parameter [InCallToFunctionParam]
+  // CHECK:STDERR: fn TakeConstA(p: const A);
+  // CHECK:STDERR:               ^~~~~~~~~~
+  // CHECK:STDERR:
+  TakeConstA(p);
+  //@dump-sem-ir-end
+}
+
+// CHECK:STDOUT: --- basic.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %A: type = class_type @A [concrete]
 // CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %Int.type: type = generic_class_type @Int [concrete]
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %Int.generic: %Int.type = struct_value () [concrete]
 // CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %A.elem: type = unbound_element_type %A, %i32 [concrete]
-// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
-// CHECK:STDOUT:   %pattern_type.f6d: type = pattern_type auto [concrete]
-// CHECK:STDOUT:   %Destroy.impl_witness.b44: <witness> = impl_witness @A.%Destroy.impl_witness_table [concrete]
 // CHECK:STDOUT:   %ptr.6db: type = ptr_type %A [concrete]
 // CHECK:STDOUT:   %pattern_type.5f8: type = pattern_type %ptr.6db [concrete]
-// CHECK:STDOUT:   %A.as.Destroy.impl.Op.type: type = fn_type @A.as.Destroy.impl.Op [concrete]
-// CHECK:STDOUT:   %A.as.Destroy.impl.Op: %A.as.Destroy.impl.Op.type = struct_value () [concrete]
-// CHECK:STDOUT:   %struct_type.a.ba9: type = struct_type {.a: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.fd7: <witness> = complete_type_witness %struct_type.a.ba9 [concrete]
 // CHECK:STDOUT:   %B: type = class_type @B [concrete]
-// CHECK:STDOUT:   %B.elem.e38: type = unbound_element_type %B, %A [concrete]
-// CHECK:STDOUT:   %B.elem.5c3: type = unbound_element_type %B, %i32 [concrete]
-// CHECK:STDOUT:   %Destroy.impl_witness.40d: <witness> = impl_witness @B.%Destroy.impl_witness_table [concrete]
 // CHECK:STDOUT:   %ptr.e79: type = ptr_type %B [concrete]
 // CHECK:STDOUT:   %pattern_type.960: type = pattern_type %ptr.e79 [concrete]
-// CHECK:STDOUT:   %B.as.Destroy.impl.Op.type: type = fn_type @B.as.Destroy.impl.Op [concrete]
-// CHECK:STDOUT:   %B.as.Destroy.impl.Op: %B.as.Destroy.impl.Op.type = struct_value () [concrete]
-// CHECK:STDOUT:   %struct_type.base.b.b44: type = struct_type {.base: %A, .b: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.725: <witness> = complete_type_witness %struct_type.base.b.b44 [concrete]
 // CHECK:STDOUT:   %C: type = class_type @C [concrete]
-// CHECK:STDOUT:   %C.elem.f0c: type = unbound_element_type %C, %B [concrete]
-// CHECK:STDOUT:   %C.elem.646: type = unbound_element_type %C, %i32 [concrete]
-// CHECK:STDOUT:   %Destroy.impl_witness.edd: <witness> = impl_witness @C.%Destroy.impl_witness_table [concrete]
 // CHECK:STDOUT:   %ptr.019: type = ptr_type %C [concrete]
 // CHECK:STDOUT:   %pattern_type.44a: type = pattern_type %ptr.019 [concrete]
 // CHECK:STDOUT:   %C.as.Destroy.impl.Op.type: type = fn_type @C.as.Destroy.impl.Op [concrete]
 // CHECK:STDOUT:   %C.as.Destroy.impl.Op: %C.as.Destroy.impl.Op.type = struct_value () [concrete]
-// CHECK:STDOUT:   %struct_type.base.c.8e2: type = struct_type {.base: %B, .c: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.58a: <witness> = complete_type_witness %struct_type.base.c.8e2 [concrete]
 // CHECK:STDOUT:   %ConvertCToB.type: type = fn_type @ConvertCToB [concrete]
 // CHECK:STDOUT:   %ConvertCToB: %ConvertCToB.type = struct_value () [concrete]
 // CHECK:STDOUT:   %ConvertBToA.type: type = fn_type @ConvertBToA [concrete]
@@ -101,8 +153,6 @@ fn ConvertInit() {
 // CHECK:STDOUT:   %struct_type.base.b.bf0: type = struct_type {.base: %struct_type.a.a6c, .b: Core.IntLiteral} [concrete]
 // CHECK:STDOUT:   %int_3.1ba: Core.IntLiteral = int_value 3 [concrete]
 // CHECK:STDOUT:   %struct_type.base.c.136: type = struct_type {.base: %struct_type.base.b.bf0, .c: Core.IntLiteral} [concrete]
-// CHECK:STDOUT:   %ImplicitAs.type.cc7: type = generic_interface_type @ImplicitAs [concrete]
-// CHECK:STDOUT:   %ImplicitAs.generic: %ImplicitAs.type.cc7 = struct_value () [concrete]
 // CHECK:STDOUT:   %ImplicitAs.type.205: type = facet_type <@ImplicitAs, @ImplicitAs(%i32)> [concrete]
 // CHECK:STDOUT:   %ImplicitAs.Convert.type.1b6: type = fn_type @ImplicitAs.Convert, @ImplicitAs(%i32) [concrete]
 // CHECK:STDOUT:   %To: Core.IntLiteral = bind_symbolic_name To, 0 [symbolic]
@@ -129,37 +179,11 @@ fn ConvertInit() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
-// CHECK:STDOUT:     .Int = %Core.Int
-// CHECK:STDOUT:     .Destroy = %Core.Destroy
-// CHECK:STDOUT:     .ImplicitAs = %Core.ImplicitAs
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.Int: %Int.type = import_ref Core//prelude/parts/int, Int, loaded [concrete = constants.%Int.generic]
-// CHECK:STDOUT:   %Core.Destroy: type = import_ref Core//prelude/parts/destroy, Destroy, loaded [concrete = constants.%Destroy.type]
-// CHECK:STDOUT:   %Core.ImplicitAs: %ImplicitAs.type.cc7 = import_ref Core//prelude/parts/as, ImplicitAs, loaded [concrete = constants.%ImplicitAs.generic]
 // CHECK:STDOUT:   %Core.import_ref.a5b: @Core.IntLiteral.as.ImplicitAs.impl.%Core.IntLiteral.as.ImplicitAs.impl.Convert.type (%Core.IntLiteral.as.ImplicitAs.impl.Convert.type.0f9) = import_ref Core//prelude/parts/int, loc16_39, loaded [symbolic = @Core.IntLiteral.as.ImplicitAs.impl.%Core.IntLiteral.as.ImplicitAs.impl.Convert (constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.f06)]
 // CHECK:STDOUT:   %ImplicitAs.impl_witness_table.a2f = impl_witness_table (%Core.import_ref.a5b), @Core.IntLiteral.as.ImplicitAs.impl [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .A = %A.decl
-// CHECK:STDOUT:     .B = %B.decl
-// CHECK:STDOUT:     .C = %C.decl
-// CHECK:STDOUT:     .ConvertCToB = %ConvertCToB.decl
-// CHECK:STDOUT:     .ConvertBToA = %ConvertBToA.decl
-// CHECK:STDOUT:     .ConvertCToA = %ConvertCToA.decl
-// CHECK:STDOUT:     .ConvertValue = %ConvertValue.decl
-// CHECK:STDOUT:     .ConvertRef = %ConvertRef.decl
-// CHECK:STDOUT:     .ConvertInit = %ConvertInit.decl
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %A.decl: type = class_decl @A [concrete = constants.%A] {} {}
-// CHECK:STDOUT:   %B.decl: type = class_decl @B [concrete = constants.%B] {} {}
-// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
 // CHECK:STDOUT:   %ConvertCToB.decl: %ConvertCToB.type = fn_decl @ConvertCToB [concrete = constants.%ConvertCToB] {
 // CHECK:STDOUT:     %p.patt: %pattern_type.44a = binding_pattern p [concrete]
 // CHECK:STDOUT:     %p.param_patt: %pattern_type.44a = value_param_pattern %p.patt, call_param0 [concrete]
@@ -167,11 +191,11 @@ fn ConvertInit() {
 // CHECK:STDOUT:     %return.param_patt: %pattern_type.960 = out_param_pattern %return.patt, call_param1 [concrete]
 // CHECK:STDOUT:   } {
 // CHECK:STDOUT:     %B.ref: type = name_ref B, file.%B.decl [concrete = constants.%B]
-// CHECK:STDOUT:     %ptr.loc29_27: type = ptr_type %B.ref [concrete = constants.%ptr.e79]
+// CHECK:STDOUT:     %ptr.loc19_27: type = ptr_type %B.ref [concrete = constants.%ptr.e79]
 // CHECK:STDOUT:     %p.param: %ptr.019 = value_param call_param0
-// CHECK:STDOUT:     %.loc29_20: type = splice_block %ptr.loc29_20 [concrete = constants.%ptr.019] {
+// CHECK:STDOUT:     %.loc19_20: type = splice_block %ptr.loc19_20 [concrete = constants.%ptr.019] {
 // CHECK:STDOUT:       %C.ref: type = name_ref C, file.%C.decl [concrete = constants.%C]
-// CHECK:STDOUT:       %ptr.loc29_20: type = ptr_type %C.ref [concrete = constants.%ptr.019]
+// CHECK:STDOUT:       %ptr.loc19_20: type = ptr_type %C.ref [concrete = constants.%ptr.019]
 // CHECK:STDOUT:     }
 // CHECK:STDOUT:     %p: %ptr.019 = bind_name p, %p.param
 // CHECK:STDOUT:     %return.param: ref %ptr.e79 = out_param call_param1
@@ -184,11 +208,11 @@ fn ConvertInit() {
 // CHECK:STDOUT:     %return.param_patt: %pattern_type.5f8 = out_param_pattern %return.patt, call_param1 [concrete]
 // CHECK:STDOUT:   } {
 // CHECK:STDOUT:     %A.ref: type = name_ref A, file.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:     %ptr.loc30_27: type = ptr_type %A.ref [concrete = constants.%ptr.6db]
+// CHECK:STDOUT:     %ptr.loc20_27: type = ptr_type %A.ref [concrete = constants.%ptr.6db]
 // CHECK:STDOUT:     %p.param: %ptr.e79 = value_param call_param0
-// CHECK:STDOUT:     %.loc30_20: type = splice_block %ptr.loc30_20 [concrete = constants.%ptr.e79] {
+// CHECK:STDOUT:     %.loc20_20: type = splice_block %ptr.loc20_20 [concrete = constants.%ptr.e79] {
 // CHECK:STDOUT:       %B.ref: type = name_ref B, file.%B.decl [concrete = constants.%B]
-// CHECK:STDOUT:       %ptr.loc30_20: type = ptr_type %B.ref [concrete = constants.%ptr.e79]
+// CHECK:STDOUT:       %ptr.loc20_20: type = ptr_type %B.ref [concrete = constants.%ptr.e79]
 // CHECK:STDOUT:     }
 // CHECK:STDOUT:     %p: %ptr.e79 = bind_name p, %p.param
 // CHECK:STDOUT:     %return.param: ref %ptr.6db = out_param call_param1
@@ -201,11 +225,11 @@ fn ConvertInit() {
 // CHECK:STDOUT:     %return.param_patt: %pattern_type.5f8 = out_param_pattern %return.patt, call_param1 [concrete]
 // CHECK:STDOUT:   } {
 // CHECK:STDOUT:     %A.ref: type = name_ref A, file.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:     %ptr.loc31_27: type = ptr_type %A.ref [concrete = constants.%ptr.6db]
+// CHECK:STDOUT:     %ptr.loc21_27: type = ptr_type %A.ref [concrete = constants.%ptr.6db]
 // CHECK:STDOUT:     %p.param: %ptr.019 = value_param call_param0
-// CHECK:STDOUT:     %.loc31_20: type = splice_block %ptr.loc31_20 [concrete = constants.%ptr.019] {
+// CHECK:STDOUT:     %.loc21_20: type = splice_block %ptr.loc21_20 [concrete = constants.%ptr.019] {
 // CHECK:STDOUT:       %C.ref: type = name_ref C, file.%C.decl [concrete = constants.%C]
-// CHECK:STDOUT:       %ptr.loc31_20: type = ptr_type %C.ref [concrete = constants.%ptr.019]
+// CHECK:STDOUT:       %ptr.loc21_20: type = ptr_type %C.ref [concrete = constants.%ptr.019]
 // CHECK:STDOUT:     }
 // CHECK:STDOUT:     %p: %ptr.019 = bind_name p, %p.param
 // CHECK:STDOUT:     %return.param: ref %ptr.6db = out_param call_param1
@@ -225,12 +249,12 @@ fn ConvertInit() {
 // CHECK:STDOUT:     %return.patt: %pattern_type.5f8 = return_slot_pattern [concrete]
 // CHECK:STDOUT:     %return.param_patt: %pattern_type.5f8 = out_param_pattern %return.patt, call_param1 [concrete]
 // CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %A.ref.loc37: type = name_ref A, file.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:     %ptr.loc37_26: type = ptr_type %A.ref.loc37 [concrete = constants.%ptr.6db]
+// CHECK:STDOUT:     %A.ref.loc27: type = name_ref A, file.%A.decl [concrete = constants.%A]
+// CHECK:STDOUT:     %ptr.loc27_26: type = ptr_type %A.ref.loc27 [concrete = constants.%ptr.6db]
 // CHECK:STDOUT:     %c.param: %ptr.019 = value_param call_param0
-// CHECK:STDOUT:     %.loc37: type = splice_block %ptr.loc37_19 [concrete = constants.%ptr.019] {
+// CHECK:STDOUT:     %.loc27: type = splice_block %ptr.loc27_19 [concrete = constants.%ptr.019] {
 // CHECK:STDOUT:       %C.ref: type = name_ref C, file.%C.decl [concrete = constants.%C]
-// CHECK:STDOUT:       %ptr.loc37_19: type = ptr_type %C.ref [concrete = constants.%ptr.019]
+// CHECK:STDOUT:       %ptr.loc27_19: type = ptr_type %C.ref [concrete = constants.%ptr.019]
 // CHECK:STDOUT:     }
 // CHECK:STDOUT:     %c: %ptr.019 = bind_name c, %c.param
 // CHECK:STDOUT:     %return.param: ref %ptr.6db = out_param call_param1
@@ -239,147 +263,35 @@ fn ConvertInit() {
 // CHECK:STDOUT:   %ConvertInit.decl: %ConvertInit.type = fn_decl @ConvertInit [concrete = constants.%ConvertInit] {} {}
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: impl @A.as.Destroy.impl: @A.%Self.ref as constants.%Destroy.type {
-// CHECK:STDOUT:   %A.as.Destroy.impl.Op.decl: %A.as.Destroy.impl.Op.type = fn_decl @A.as.Destroy.impl.Op [concrete = constants.%A.as.Destroy.impl.Op] {
-// CHECK:STDOUT:     %self.patt: %pattern_type.5f8 = binding_pattern self [concrete]
-// CHECK:STDOUT:     %self.param_patt: %pattern_type.5f8 = value_param_pattern %self.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %.loc15: %pattern_type.f6d = addr_pattern %self.param_patt [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %self.param: %ptr.6db = value_param call_param0
-// CHECK:STDOUT:     %Self.ref: type = name_ref Self, constants.%A [concrete = constants.%A]
-// CHECK:STDOUT:     %self: %ptr.6db = bind_name self, %self.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Op = %A.as.Destroy.impl.Op.decl
-// CHECK:STDOUT:   witness = @A.%Destroy.impl_witness
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: impl @B.as.Destroy.impl: @B.%Self.ref as constants.%Destroy.type {
-// CHECK:STDOUT:   %B.as.Destroy.impl.Op.decl: %B.as.Destroy.impl.Op.type = fn_decl @B.as.Destroy.impl.Op [concrete = constants.%B.as.Destroy.impl.Op] {
-// CHECK:STDOUT:     %self.patt: %pattern_type.960 = binding_pattern self [concrete]
-// CHECK:STDOUT:     %self.param_patt: %pattern_type.960 = value_param_pattern %self.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %.loc19: %pattern_type.f6d = addr_pattern %self.param_patt [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %self.param: %ptr.e79 = value_param call_param0
-// CHECK:STDOUT:     %Self.ref: type = name_ref Self, constants.%B [concrete = constants.%B]
-// CHECK:STDOUT:     %self: %ptr.e79 = bind_name self, %self.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Op = %B.as.Destroy.impl.Op.decl
-// CHECK:STDOUT:   witness = @B.%Destroy.impl_witness
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: impl @C.as.Destroy.impl: @C.%Self.ref as constants.%Destroy.type {
-// CHECK:STDOUT:   %C.as.Destroy.impl.Op.decl: %C.as.Destroy.impl.Op.type = fn_decl @C.as.Destroy.impl.Op [concrete = constants.%C.as.Destroy.impl.Op] {
-// CHECK:STDOUT:     %self.patt: %pattern_type.44a = binding_pattern self [concrete]
-// CHECK:STDOUT:     %self.param_patt: %pattern_type.44a = value_param_pattern %self.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %.loc24: %pattern_type.f6d = addr_pattern %self.param_patt [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %self.param: %ptr.019 = value_param call_param0
-// CHECK:STDOUT:     %Self.ref: type = name_ref Self, constants.%C [concrete = constants.%C]
-// CHECK:STDOUT:     %self: %ptr.019 = bind_name self, %self.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Op = %C.as.Destroy.impl.Op.decl
-// CHECK:STDOUT:   witness = @C.%Destroy.impl_witness
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @A {
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.loc16: %A.elem = field_decl a, element0 [concrete]
-// CHECK:STDOUT:   %Self.ref: type = name_ref Self, constants.%A [concrete = constants.%A]
-// CHECK:STDOUT:   impl_decl @A.as.Destroy.impl [concrete] {} {}
-// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (@A.as.Destroy.impl.%A.as.Destroy.impl.Op.decl), @A.as.Destroy.impl [concrete]
-// CHECK:STDOUT:   %Destroy.impl_witness: <witness> = impl_witness %Destroy.impl_witness_table [concrete = constants.%Destroy.impl_witness.b44]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness constants.%struct_type.a.ba9 [concrete = constants.%complete_type.fd7]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%A
-// CHECK:STDOUT:   .a = %.loc16
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @B {
-// CHECK:STDOUT:   %A.ref: type = name_ref A, file.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:   %.loc20: %B.elem.e38 = base_decl %A.ref, element0 [concrete]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.loc21: %B.elem.5c3 = field_decl b, element1 [concrete]
-// CHECK:STDOUT:   %Self.ref: type = name_ref Self, constants.%B [concrete = constants.%B]
-// CHECK:STDOUT:   impl_decl @B.as.Destroy.impl [concrete] {} {}
-// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (@B.as.Destroy.impl.%B.as.Destroy.impl.Op.decl), @B.as.Destroy.impl [concrete]
-// CHECK:STDOUT:   %Destroy.impl_witness: <witness> = impl_witness %Destroy.impl_witness_table [concrete = constants.%Destroy.impl_witness.40d]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness constants.%struct_type.base.b.b44 [concrete = constants.%complete_type.725]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%B
-// CHECK:STDOUT:   .A = <poisoned>
-// CHECK:STDOUT:   .base = %.loc20
-// CHECK:STDOUT:   .b = %.loc21
-// CHECK:STDOUT:   extend %A.ref
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @C {
-// CHECK:STDOUT:   %B.ref: type = name_ref B, file.%B.decl [concrete = constants.%B]
-// CHECK:STDOUT:   %.loc25: %C.elem.f0c = base_decl %B.ref, element0 [concrete]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.loc26: %C.elem.646 = field_decl c, element1 [concrete]
-// CHECK:STDOUT:   %Self.ref: type = name_ref Self, constants.%C [concrete = constants.%C]
-// CHECK:STDOUT:   impl_decl @C.as.Destroy.impl [concrete] {} {}
-// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (@C.as.Destroy.impl.%C.as.Destroy.impl.Op.decl), @C.as.Destroy.impl [concrete]
-// CHECK:STDOUT:   %Destroy.impl_witness: <witness> = impl_witness %Destroy.impl_witness_table [concrete = constants.%Destroy.impl_witness.edd]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness constants.%struct_type.base.c.8e2 [concrete = constants.%complete_type.58a]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%C
-// CHECK:STDOUT:   .B = <poisoned>
-// CHECK:STDOUT:   .base = %.loc25
-// CHECK:STDOUT:   .c = %.loc26
-// CHECK:STDOUT:   extend %B.ref
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @A.as.Destroy.impl.Op(%self.param: %ptr.6db) = "no_op";
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @B.as.Destroy.impl.Op(%self.param: %ptr.e79) = "no_op";
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @C.as.Destroy.impl.Op(%self.param: %ptr.019) = "no_op";
-// CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertCToB(%p.param: %ptr.019) -> %ptr.e79 {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %p.ref: %ptr.019 = name_ref p, %p
-// CHECK:STDOUT:   %.loc29_39.1: ref %C = deref %p.ref
-// CHECK:STDOUT:   %.loc29_39.2: ref %B = class_element_access %.loc29_39.1, element0
-// CHECK:STDOUT:   %addr: %ptr.e79 = addr_of %.loc29_39.2
-// CHECK:STDOUT:   %.loc29_39.3: %ptr.e79 = converted %p.ref, %addr
-// CHECK:STDOUT:   return %.loc29_39.3
+// CHECK:STDOUT:   %.loc19_39.1: ref %C = deref %p.ref
+// CHECK:STDOUT:   %.loc19_39.2: ref %B = class_element_access %.loc19_39.1, element0
+// CHECK:STDOUT:   %addr: %ptr.e79 = addr_of %.loc19_39.2
+// CHECK:STDOUT:   %.loc19_39.3: %ptr.e79 = converted %p.ref, %addr
+// CHECK:STDOUT:   return %.loc19_39.3
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertBToA(%p.param: %ptr.e79) -> %ptr.6db {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %p.ref: %ptr.e79 = name_ref p, %p
-// CHECK:STDOUT:   %.loc30_39.1: ref %B = deref %p.ref
-// CHECK:STDOUT:   %.loc30_39.2: ref %A = class_element_access %.loc30_39.1, element0
-// CHECK:STDOUT:   %addr: %ptr.6db = addr_of %.loc30_39.2
-// CHECK:STDOUT:   %.loc30_39.3: %ptr.6db = converted %p.ref, %addr
-// CHECK:STDOUT:   return %.loc30_39.3
+// CHECK:STDOUT:   %.loc20_39.1: ref %B = deref %p.ref
+// CHECK:STDOUT:   %.loc20_39.2: ref %A = class_element_access %.loc20_39.1, element0
+// CHECK:STDOUT:   %addr: %ptr.6db = addr_of %.loc20_39.2
+// CHECK:STDOUT:   %.loc20_39.3: %ptr.6db = converted %p.ref, %addr
+// CHECK:STDOUT:   return %.loc20_39.3
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertCToA(%p.param: %ptr.019) -> %ptr.6db {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %p.ref: %ptr.019 = name_ref p, %p
-// CHECK:STDOUT:   %.loc31_39.1: ref %C = deref %p.ref
-// CHECK:STDOUT:   %.loc31_39.2: ref %B = class_element_access %.loc31_39.1, element0
-// CHECK:STDOUT:   %.loc31_39.3: ref %A = class_element_access %.loc31_39.2, element0
-// CHECK:STDOUT:   %addr: %ptr.6db = addr_of %.loc31_39.3
-// CHECK:STDOUT:   %.loc31_39.4: %ptr.6db = converted %p.ref, %addr
-// CHECK:STDOUT:   return %.loc31_39.4
+// CHECK:STDOUT:   %.loc21_39.1: ref %C = deref %p.ref
+// CHECK:STDOUT:   %.loc21_39.2: ref %B = class_element_access %.loc21_39.1, element0
+// CHECK:STDOUT:   %.loc21_39.3: ref %A = class_element_access %.loc21_39.2, element0
+// CHECK:STDOUT:   %addr: %ptr.6db = addr_of %.loc21_39.3
+// CHECK:STDOUT:   %.loc21_39.4: %ptr.6db = converted %p.ref, %addr
+// CHECK:STDOUT:   return %.loc21_39.4
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertValue(%c.param: %C) {
@@ -389,23 +301,23 @@ fn ConvertInit() {
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %c.ref: %C = name_ref c, %c
 // CHECK:STDOUT:   %A.ref: type = name_ref A, file.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:   %.loc34_14.1: ref %B = class_element_access %c.ref, element0
-// CHECK:STDOUT:   %.loc34_14.2: ref %A = class_element_access %.loc34_14.1, element0
-// CHECK:STDOUT:   %.loc34_14.3: ref %A = converted %c.ref, %.loc34_14.2
-// CHECK:STDOUT:   %.loc34_14.4: %A = bind_value %.loc34_14.3
-// CHECK:STDOUT:   %a: %A = bind_name a, %.loc34_14.4
+// CHECK:STDOUT:   %.loc24_14.1: ref %B = class_element_access %c.ref, element0
+// CHECK:STDOUT:   %.loc24_14.2: ref %A = class_element_access %.loc24_14.1, element0
+// CHECK:STDOUT:   %.loc24_14.3: ref %A = converted %c.ref, %.loc24_14.2
+// CHECK:STDOUT:   %.loc24_14.4: %A = bind_value %.loc24_14.3
+// CHECK:STDOUT:   %a: %A = bind_name a, %.loc24_14.4
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertRef(%c.param: %ptr.019) -> %ptr.6db {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %c.ref: %ptr.019 = name_ref c, %c
-// CHECK:STDOUT:   %.loc38_12: ref %C = deref %c.ref
-// CHECK:STDOUT:   %A.ref.loc38: type = name_ref A, file.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:   %.loc38_15.1: ref %B = class_element_access %.loc38_12, element0
-// CHECK:STDOUT:   %.loc38_15.2: ref %A = class_element_access %.loc38_15.1, element0
-// CHECK:STDOUT:   %.loc38_15.3: ref %A = converted %.loc38_12, %.loc38_15.2
-// CHECK:STDOUT:   %addr: %ptr.6db = addr_of %.loc38_15.3
+// CHECK:STDOUT:   %.loc28_12: ref %C = deref %c.ref
+// CHECK:STDOUT:   %A.ref.loc28: type = name_ref A, file.%A.decl [concrete = constants.%A]
+// CHECK:STDOUT:   %.loc28_15.1: ref %B = class_element_access %.loc28_12, element0
+// CHECK:STDOUT:   %.loc28_15.2: ref %A = class_element_access %.loc28_15.1, element0
+// CHECK:STDOUT:   %.loc28_15.3: ref %A = converted %.loc28_12, %.loc28_15.2
+// CHECK:STDOUT:   %addr: %ptr.6db = addr_of %.loc28_15.3
 // CHECK:STDOUT:   return %addr
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -415,55 +327,131 @@ fn ConvertInit() {
 // CHECK:STDOUT:     %a.patt: %pattern_type.c10 = binding_pattern a [concrete]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1.5b8]
-// CHECK:STDOUT:   %.loc42_39.1: %struct_type.a.a6c = struct_literal (%int_1)
+// CHECK:STDOUT:   %.loc32_39.1: %struct_type.a.a6c = struct_literal (%int_1)
 // CHECK:STDOUT:   %int_2: Core.IntLiteral = int_value 2 [concrete = constants.%int_2.ecc]
-// CHECK:STDOUT:   %.loc42_48.1: %struct_type.base.b.bf0 = struct_literal (%.loc42_39.1, %int_2)
+// CHECK:STDOUT:   %.loc32_48.1: %struct_type.base.b.bf0 = struct_literal (%.loc32_39.1, %int_2)
 // CHECK:STDOUT:   %int_3: Core.IntLiteral = int_value 3 [concrete = constants.%int_3.1ba]
-// CHECK:STDOUT:   %.loc42_57.1: %struct_type.base.c.136 = struct_literal (%.loc42_48.1, %int_3)
+// CHECK:STDOUT:   %.loc32_57.1: %struct_type.base.c.136 = struct_literal (%.loc32_48.1, %int_3)
 // CHECK:STDOUT:   %C.ref: type = name_ref C, file.%C.decl [concrete = constants.%C]
-// CHECK:STDOUT:   %impl.elem0.loc42_39: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.956]
-// CHECK:STDOUT:   %bound_method.loc42_39.1: <bound method> = bound_method %int_1, %impl.elem0.loc42_39 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.bound.ab5]
-// CHECK:STDOUT:   %specific_fn.loc42_39: <specific function> = specific_function %impl.elem0.loc42_39, @Core.IntLiteral.as.ImplicitAs.impl.Convert(constants.%int_32) [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.specific_fn]
-// CHECK:STDOUT:   %bound_method.loc42_39.2: <bound method> = bound_method %int_1, %specific_fn.loc42_39 [concrete = constants.%bound_method.9a1]
-// CHECK:STDOUT:   %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc42_39: init %i32 = call %bound_method.loc42_39.2(%int_1) [concrete = constants.%int_1.5d2]
-// CHECK:STDOUT:   %.loc42_39.2: init %i32 = converted %int_1, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc42_39 [concrete = constants.%int_1.5d2]
-// CHECK:STDOUT:   %.loc42_57.2: ref %C = temporary_storage
-// CHECK:STDOUT:   %.loc42_57.3: ref %B = class_element_access %.loc42_57.2, element0
-// CHECK:STDOUT:   %.loc42_48.2: ref %A = class_element_access %.loc42_57.3, element0
-// CHECK:STDOUT:   %.loc42_39.3: ref %i32 = class_element_access %.loc42_48.2, element0
-// CHECK:STDOUT:   %.loc42_39.4: init %i32 = initialize_from %.loc42_39.2 to %.loc42_39.3 [concrete = constants.%int_1.5d2]
-// CHECK:STDOUT:   %.loc42_39.5: init %A = class_init (%.loc42_39.4), %.loc42_48.2 [concrete = constants.%A.val]
-// CHECK:STDOUT:   %.loc42_48.3: init %A = converted %.loc42_39.1, %.loc42_39.5 [concrete = constants.%A.val]
-// CHECK:STDOUT:   %impl.elem0.loc42_48: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.956]
-// CHECK:STDOUT:   %bound_method.loc42_48.1: <bound method> = bound_method %int_2, %impl.elem0.loc42_48 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.bound.ef9]
-// CHECK:STDOUT:   %specific_fn.loc42_48: <specific function> = specific_function %impl.elem0.loc42_48, @Core.IntLiteral.as.ImplicitAs.impl.Convert(constants.%int_32) [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.specific_fn]
-// CHECK:STDOUT:   %bound_method.loc42_48.2: <bound method> = bound_method %int_2, %specific_fn.loc42_48 [concrete = constants.%bound_method.b92]
-// CHECK:STDOUT:   %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc42_48: init %i32 = call %bound_method.loc42_48.2(%int_2) [concrete = constants.%int_2.ef8]
-// CHECK:STDOUT:   %.loc42_48.4: init %i32 = converted %int_2, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc42_48 [concrete = constants.%int_2.ef8]
-// CHECK:STDOUT:   %.loc42_48.5: ref %i32 = class_element_access %.loc42_57.3, element1
-// CHECK:STDOUT:   %.loc42_48.6: init %i32 = initialize_from %.loc42_48.4 to %.loc42_48.5 [concrete = constants.%int_2.ef8]
-// CHECK:STDOUT:   %.loc42_48.7: init %B = class_init (%.loc42_48.3, %.loc42_48.6), %.loc42_57.3 [concrete = constants.%B.val]
-// CHECK:STDOUT:   %.loc42_57.4: init %B = converted %.loc42_48.1, %.loc42_48.7 [concrete = constants.%B.val]
-// CHECK:STDOUT:   %impl.elem0.loc42_57: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.956]
-// CHECK:STDOUT:   %bound_method.loc42_57.1: <bound method> = bound_method %int_3, %impl.elem0.loc42_57 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.bound.b30]
-// CHECK:STDOUT:   %specific_fn.loc42_57: <specific function> = specific_function %impl.elem0.loc42_57, @Core.IntLiteral.as.ImplicitAs.impl.Convert(constants.%int_32) [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.specific_fn]
-// CHECK:STDOUT:   %bound_method.loc42_57.2: <bound method> = bound_method %int_3, %specific_fn.loc42_57 [concrete = constants.%bound_method.047]
-// CHECK:STDOUT:   %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc42_57: init %i32 = call %bound_method.loc42_57.2(%int_3) [concrete = constants.%int_3.822]
-// CHECK:STDOUT:   %.loc42_57.5: init %i32 = converted %int_3, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc42_57 [concrete = constants.%int_3.822]
-// CHECK:STDOUT:   %.loc42_57.6: ref %i32 = class_element_access %.loc42_57.2, element1
-// CHECK:STDOUT:   %.loc42_57.7: init %i32 = initialize_from %.loc42_57.5 to %.loc42_57.6 [concrete = constants.%int_3.822]
-// CHECK:STDOUT:   %.loc42_57.8: init %C = class_init (%.loc42_57.4, %.loc42_57.7), %.loc42_57.2 [concrete = constants.%C.val]
-// CHECK:STDOUT:   %.loc42_57.9: ref %C = temporary %.loc42_57.2, %.loc42_57.8
-// CHECK:STDOUT:   %.loc42_59.1: ref %C = converted %.loc42_57.1, %.loc42_57.9
+// CHECK:STDOUT:   %impl.elem0.loc32_39: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.956]
+// CHECK:STDOUT:   %bound_method.loc32_39.1: <bound method> = bound_method %int_1, %impl.elem0.loc32_39 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.bound.ab5]
+// CHECK:STDOUT:   %specific_fn.loc32_39: <specific function> = specific_function %impl.elem0.loc32_39, @Core.IntLiteral.as.ImplicitAs.impl.Convert(constants.%int_32) [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc32_39.2: <bound method> = bound_method %int_1, %specific_fn.loc32_39 [concrete = constants.%bound_method.9a1]
+// CHECK:STDOUT:   %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc32_39: init %i32 = call %bound_method.loc32_39.2(%int_1) [concrete = constants.%int_1.5d2]
+// CHECK:STDOUT:   %.loc32_39.2: init %i32 = converted %int_1, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc32_39 [concrete = constants.%int_1.5d2]
+// CHECK:STDOUT:   %.loc32_57.2: ref %C = temporary_storage
+// CHECK:STDOUT:   %.loc32_57.3: ref %B = class_element_access %.loc32_57.2, element0
+// CHECK:STDOUT:   %.loc32_48.2: ref %A = class_element_access %.loc32_57.3, element0
+// CHECK:STDOUT:   %.loc32_39.3: ref %i32 = class_element_access %.loc32_48.2, element0
+// CHECK:STDOUT:   %.loc32_39.4: init %i32 = initialize_from %.loc32_39.2 to %.loc32_39.3 [concrete = constants.%int_1.5d2]
+// CHECK:STDOUT:   %.loc32_39.5: init %A = class_init (%.loc32_39.4), %.loc32_48.2 [concrete = constants.%A.val]
+// CHECK:STDOUT:   %.loc32_48.3: init %A = converted %.loc32_39.1, %.loc32_39.5 [concrete = constants.%A.val]
+// CHECK:STDOUT:   %impl.elem0.loc32_48: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.956]
+// CHECK:STDOUT:   %bound_method.loc32_48.1: <bound method> = bound_method %int_2, %impl.elem0.loc32_48 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.bound.ef9]
+// CHECK:STDOUT:   %specific_fn.loc32_48: <specific function> = specific_function %impl.elem0.loc32_48, @Core.IntLiteral.as.ImplicitAs.impl.Convert(constants.%int_32) [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc32_48.2: <bound method> = bound_method %int_2, %specific_fn.loc32_48 [concrete = constants.%bound_method.b92]
+// CHECK:STDOUT:   %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc32_48: init %i32 = call %bound_method.loc32_48.2(%int_2) [concrete = constants.%int_2.ef8]
+// CHECK:STDOUT:   %.loc32_48.4: init %i32 = converted %int_2, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc32_48 [concrete = constants.%int_2.ef8]
+// CHECK:STDOUT:   %.loc32_48.5: ref %i32 = class_element_access %.loc32_57.3, element1
+// CHECK:STDOUT:   %.loc32_48.6: init %i32 = initialize_from %.loc32_48.4 to %.loc32_48.5 [concrete = constants.%int_2.ef8]
+// CHECK:STDOUT:   %.loc32_48.7: init %B = class_init (%.loc32_48.3, %.loc32_48.6), %.loc32_57.3 [concrete = constants.%B.val]
+// CHECK:STDOUT:   %.loc32_57.4: init %B = converted %.loc32_48.1, %.loc32_48.7 [concrete = constants.%B.val]
+// CHECK:STDOUT:   %impl.elem0.loc32_57: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.956]
+// CHECK:STDOUT:   %bound_method.loc32_57.1: <bound method> = bound_method %int_3, %impl.elem0.loc32_57 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.bound.b30]
+// CHECK:STDOUT:   %specific_fn.loc32_57: <specific function> = specific_function %impl.elem0.loc32_57, @Core.IntLiteral.as.ImplicitAs.impl.Convert(constants.%int_32) [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc32_57.2: <bound method> = bound_method %int_3, %specific_fn.loc32_57 [concrete = constants.%bound_method.047]
+// CHECK:STDOUT:   %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc32_57: init %i32 = call %bound_method.loc32_57.2(%int_3) [concrete = constants.%int_3.822]
+// CHECK:STDOUT:   %.loc32_57.5: init %i32 = converted %int_3, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc32_57 [concrete = constants.%int_3.822]
+// CHECK:STDOUT:   %.loc32_57.6: ref %i32 = class_element_access %.loc32_57.2, element1
+// CHECK:STDOUT:   %.loc32_57.7: init %i32 = initialize_from %.loc32_57.5 to %.loc32_57.6 [concrete = constants.%int_3.822]
+// CHECK:STDOUT:   %.loc32_57.8: init %C = class_init (%.loc32_57.4, %.loc32_57.7), %.loc32_57.2 [concrete = constants.%C.val]
+// CHECK:STDOUT:   %.loc32_57.9: ref %C = temporary %.loc32_57.2, %.loc32_57.8
+// CHECK:STDOUT:   %.loc32_59.1: ref %C = converted %.loc32_57.1, %.loc32_57.9
 // CHECK:STDOUT:   %A.ref: type = name_ref A, file.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:   %.loc42_59.2: ref %B = class_element_access %.loc42_59.1, element0
-// CHECK:STDOUT:   %.loc42_59.3: ref %A = class_element_access %.loc42_59.2, element0
-// CHECK:STDOUT:   %.loc42_59.4: ref %A = converted %.loc42_59.1, %.loc42_59.3
-// CHECK:STDOUT:   %.loc42_59.5: %A = bind_value %.loc42_59.4
-// CHECK:STDOUT:   %a: %A = bind_name a, %.loc42_59.5
-// CHECK:STDOUT:   %C.as.Destroy.impl.Op.bound: <bound method> = bound_method %.loc42_57.2, constants.%C.as.Destroy.impl.Op
-// CHECK:STDOUT:   %addr: %ptr.019 = addr_of %.loc42_57.2
+// CHECK:STDOUT:   %.loc32_59.2: ref %B = class_element_access %.loc32_59.1, element0
+// CHECK:STDOUT:   %.loc32_59.3: ref %A = class_element_access %.loc32_59.2, element0
+// CHECK:STDOUT:   %.loc32_59.4: ref %A = converted %.loc32_59.1, %.loc32_59.3
+// CHECK:STDOUT:   %.loc32_59.5: %A = bind_value %.loc32_59.4
+// CHECK:STDOUT:   %a: %A = bind_name a, %.loc32_59.5
+// CHECK:STDOUT:   %C.as.Destroy.impl.Op.bound: <bound method> = bound_method %.loc32_57.2, constants.%C.as.Destroy.impl.Op
+// CHECK:STDOUT:   %addr: %ptr.019 = addr_of %.loc32_57.2
 // CHECK:STDOUT:   %C.as.Destroy.impl.Op.call: init %empty_tuple.type = call %C.as.Destroy.impl.Op.bound(%addr)
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: --- qualified.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %A: type = class_type @A [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %B: type = class_type @B [concrete]
+// CHECK:STDOUT:   %ptr.e79: type = ptr_type %B [concrete]
+// CHECK:STDOUT:   %const.d98: type = const_type %A [concrete]
+// CHECK:STDOUT:   %ptr.985: type = ptr_type %const.d98 [concrete]
+// CHECK:STDOUT:   %TakeConstAPtr.type: type = fn_type @TakeConstAPtr [concrete]
+// CHECK:STDOUT:   %TakeConstAPtr: %TakeConstAPtr.type = struct_value () [concrete]
+// CHECK:STDOUT:   %const.44f: type = const_type %B [concrete]
+// CHECK:STDOUT:   %ptr.eb4: type = ptr_type %const.44f [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @PassNonConstBPtr(%p.param: %ptr.e79) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConstAPtr.ref: %TakeConstAPtr.type = name_ref TakeConstAPtr, file.%TakeConstAPtr.decl [concrete = constants.%TakeConstAPtr]
+// CHECK:STDOUT:   %p.ref: %ptr.e79 = name_ref p, %p
+// CHECK:STDOUT:   %.loc15_17.1: ref %B = deref %p.ref
+// CHECK:STDOUT:   %.loc15_17.2: ref %A = class_element_access %.loc15_17.1, element0
+// CHECK:STDOUT:   %addr: %ptr.985 = addr_of %.loc15_17.2
+// CHECK:STDOUT:   %.loc15_17.3: %ptr.985 = as_compatible %addr
+// CHECK:STDOUT:   %.loc15_17.4: %ptr.985 = converted %p.ref, %.loc15_17.3
+// CHECK:STDOUT:   %TakeConstAPtr.call: init %empty_tuple.type = call %TakeConstAPtr.ref(%.loc15_17.4)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @PassConstBPtr(%p.param: %ptr.eb4) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConstAPtr.ref: %TakeConstAPtr.type = name_ref TakeConstAPtr, file.%TakeConstAPtr.decl [concrete = constants.%TakeConstAPtr]
+// CHECK:STDOUT:   %p.ref: %ptr.eb4 = name_ref p, %p
+// CHECK:STDOUT:   %.loc21_17.1: ref %const.44f = deref %p.ref
+// CHECK:STDOUT:   %.loc21_17.2: ref %const.d98 = class_element_access %.loc21_17.1, element0
+// CHECK:STDOUT:   %addr: %ptr.985 = addr_of %.loc21_17.2
+// CHECK:STDOUT:   %.loc21_17.3: %ptr.985 = converted %p.ref, %addr
+// CHECK:STDOUT:   %TakeConstAPtr.call: init %empty_tuple.type = call %TakeConstAPtr.ref(%.loc21_17.3)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_todo_qualified_non_ptr.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %A: type = class_type @A [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %B: type = class_type @B [concrete]
+// CHECK:STDOUT:   %const.d98: type = const_type %A [concrete]
+// CHECK:STDOUT:   %TakeConstA.type: type = fn_type @TakeConstA [concrete]
+// CHECK:STDOUT:   %TakeConstA: %TakeConstA.type = struct_value () [concrete]
+// CHECK:STDOUT:   %const.44f: type = const_type %B [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @PassNonConstB(%p.param: %B) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConstA.ref: %TakeConstA.type = name_ref TakeConstA, file.%TakeConstA.decl [concrete = constants.%TakeConstA]
+// CHECK:STDOUT:   %p.ref: %B = name_ref p, %p
+// CHECK:STDOUT:   %.loc25: %const.d98 = converted %p.ref, <error> [concrete = <error>]
+// CHECK:STDOUT:   %TakeConstA.call: init %empty_tuple.type = call %TakeConstA.ref(<error>)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @PassConstB(%p.param: %const.44f) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConstA.ref: %TakeConstA.type = name_ref TakeConstA, file.%TakeConstA.decl [concrete = constants.%TakeConstA]
+// CHECK:STDOUT:   %p.ref: %const.44f = name_ref p, %p
+// CHECK:STDOUT:   %.loc41: %const.d98 = converted %p.ref, <error> [concrete = <error>]
+// CHECK:STDOUT:   %TakeConstA.call: init %empty_tuple.type = call %TakeConstA.ref(<error>)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:

toolchain/check/testdata/const/import.carbon

@@ -35,22 +35,22 @@ var a_ptr: const C* = a_ptr_ref;
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %C: type = class_type @C [concrete]
 // CHECK:STDOUT:   %const: type = const_type %C [concrete]
-// CHECK:STDOUT:   %ptr.801: type = ptr_type %const [concrete]
-// CHECK:STDOUT:   %pattern_type.c0d: type = pattern_type %ptr.801 [concrete]
+// CHECK:STDOUT:   %ptr: type = ptr_type %const [concrete]
+// CHECK:STDOUT:   %pattern_type.c0d: type = pattern_type %ptr [concrete]
 // CHECK:STDOUT:   %pattern_type.6af: type = pattern_type %const [concrete]
-// CHECK:STDOUT:   %addr: %ptr.801 = addr_of imports.%a_ref.var [concrete]
+// CHECK:STDOUT:   %addr: %ptr = addr_of imports.%a_ref.var [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Main.C: type = import_ref Main//implicit, C, loaded [concrete = constants.%C]
 // CHECK:STDOUT:   %Main.a_ref: ref %const = import_ref Main//implicit, a_ref, loaded [concrete = %a_ref.var]
-// CHECK:STDOUT:   %Main.a_ptr_ref: ref %ptr.801 = import_ref Main//implicit, a_ptr_ref, loaded [concrete = %a_ptr_ref.var]
+// CHECK:STDOUT:   %Main.a_ptr_ref: ref %ptr = import_ref Main//implicit, a_ptr_ref, loaded [concrete = %a_ptr_ref.var]
 // CHECK:STDOUT:   %a_ref.patt: %pattern_type.6af = binding_pattern a_ref [concrete]
 // CHECK:STDOUT:   %a_ref.var_patt: %pattern_type.6af = var_pattern %a_ref.patt [concrete]
 // CHECK:STDOUT:   %a_ref.var: ref %const = var %a_ref.var_patt [concrete]
 // CHECK:STDOUT:   %a_ptr_ref.patt: %pattern_type.c0d = binding_pattern a_ptr_ref [concrete]
 // CHECK:STDOUT:   %a_ptr_ref.var_patt: %pattern_type.c0d = var_pattern %a_ptr_ref.patt [concrete]
-// CHECK:STDOUT:   %a_ptr_ref.var: ref %ptr.801 = var %a_ptr_ref.var_patt [concrete]
+// CHECK:STDOUT:   %a_ptr_ref.var: ref %ptr = var %a_ptr_ref.var_patt [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -58,33 +58,33 @@ var a_ptr: const C* = a_ptr_ref;
 // CHECK:STDOUT:     %a.patt: %pattern_type.c0d = binding_pattern a [concrete]
 // CHECK:STDOUT:     %a.var_patt: %pattern_type.c0d = var_pattern %a.patt [concrete]
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %a.var: ref %ptr.801 = var %a.var_patt [concrete]
-// CHECK:STDOUT:   %.loc6: type = splice_block %ptr.loc6 [concrete = constants.%ptr.801] {
+// CHECK:STDOUT:   %a.var: ref %ptr = var %a.var_patt [concrete]
+// CHECK:STDOUT:   %.loc6: type = splice_block %ptr.loc6 [concrete = constants.%ptr] {
 // CHECK:STDOUT:     %C.ref.loc6: type = name_ref C, imports.%Main.C [concrete = constants.%C]
 // CHECK:STDOUT:     %const.loc6: type = const_type %C.ref.loc6 [concrete = constants.%const]
-// CHECK:STDOUT:     %ptr.loc6: type = ptr_type %const.loc6 [concrete = constants.%ptr.801]
+// CHECK:STDOUT:     %ptr.loc6: type = ptr_type %const.loc6 [concrete = constants.%ptr]
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %a: ref %ptr.801 = bind_name a, %a.var [concrete = %a.var]
+// CHECK:STDOUT:   %a: ref %ptr = bind_name a, %a.var [concrete = %a.var]
 // CHECK:STDOUT:   name_binding_decl {
 // CHECK:STDOUT:     %a_ptr.patt: %pattern_type.c0d = binding_pattern a_ptr [concrete]
 // CHECK:STDOUT:     %a_ptr.var_patt: %pattern_type.c0d = var_pattern %a_ptr.patt [concrete]
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %a_ptr.var: ref %ptr.801 = var %a_ptr.var_patt [concrete]
-// CHECK:STDOUT:   %.loc7: type = splice_block %ptr.loc7 [concrete = constants.%ptr.801] {
+// CHECK:STDOUT:   %a_ptr.var: ref %ptr = var %a_ptr.var_patt [concrete]
+// CHECK:STDOUT:   %.loc7: type = splice_block %ptr.loc7 [concrete = constants.%ptr] {
 // CHECK:STDOUT:     %C.ref.loc7: type = name_ref C, imports.%Main.C [concrete = constants.%C]
 // CHECK:STDOUT:     %const.loc7: type = const_type %C.ref.loc7 [concrete = constants.%const]
-// CHECK:STDOUT:     %ptr.loc7: type = ptr_type %const.loc7 [concrete = constants.%ptr.801]
+// CHECK:STDOUT:     %ptr.loc7: type = ptr_type %const.loc7 [concrete = constants.%ptr]
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %a_ptr: ref %ptr.801 = bind_name a_ptr, %a_ptr.var [concrete = %a_ptr.var]
+// CHECK:STDOUT:   %a_ptr: ref %ptr = bind_name a_ptr, %a_ptr.var [concrete = %a_ptr.var]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @__global_init() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %a_ref.ref: ref %const = name_ref a_ref, imports.%Main.a_ref [concrete = imports.%a_ref.var]
-// CHECK:STDOUT:   %addr: %ptr.801 = addr_of %a_ref.ref [concrete = constants.%addr]
+// CHECK:STDOUT:   %addr: %ptr = addr_of %a_ref.ref [concrete = constants.%addr]
 // CHECK:STDOUT:   assign file.%a.var, %addr
-// CHECK:STDOUT:   %a_ptr_ref.ref: ref %ptr.801 = name_ref a_ptr_ref, imports.%Main.a_ptr_ref [concrete = imports.%a_ptr_ref.var]
-// CHECK:STDOUT:   %.loc7: %ptr.801 = bind_value %a_ptr_ref.ref
+// CHECK:STDOUT:   %a_ptr_ref.ref: ref %ptr = name_ref a_ptr_ref, imports.%Main.a_ptr_ref [concrete = imports.%a_ptr_ref.var]
+// CHECK:STDOUT:   %.loc7: %ptr = bind_value %a_ptr_ref.ref
 // CHECK:STDOUT:   assign file.%a_ptr.var, %.loc7
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }

toolchain/check/testdata/interop/cpp/function/arithmetic_types_bridged.carbon

@@ -337,7 +337,7 @@ fn F() {
 
 auto foo(const short* _Nonnull a) -> void;
 
-// --- fail_todo_import_const_short_pointer_param.carbon
+// --- import_const_short_pointer_param.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -346,14 +346,6 @@ import Cpp library "const_short_pointer_param.h";
 fn F() {
   var a: i16 = 1;
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_const_short_pointer_param.carbon:[[@LINE+8]]:11: error: cannot implicitly convert expression of type `i16*` to `const i16*` [ConversionFailure]
-  // CHECK:STDERR:   Cpp.foo(&a);
-  // CHECK:STDERR:           ^~
-  // CHECK:STDERR: fail_todo_import_const_short_pointer_param.carbon:[[@LINE+5]]:11: note: type `i16*` does not implement interface `Core.ImplicitAs(const i16*)` [MissingImplInMemberAccessNote]
-  // CHECK:STDERR:   Cpp.foo(&a);
-  // CHECK:STDERR:           ^~
-  // CHECK:STDERR: fail_todo_import_const_short_pointer_param.carbon: note: initializing function parameter [InCallToFunctionParam]
-  // CHECK:STDERR:
   Cpp.foo(&a);
   //@dump-sem-ir-end
 }
@@ -1355,7 +1347,7 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_const_short_pointer_param.carbon
+// CHECK:STDOUT: --- import_const_short_pointer_param.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
@@ -1386,9 +1378,10 @@ fn F() {
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %a.ref: ref %i16 = name_ref a, %a
-// CHECK:STDOUT:   %addr.loc17: %ptr.251 = addr_of %a.ref
-// CHECK:STDOUT:   %.loc17: %ptr.758 = converted %addr.loc17, <error> [concrete = <error>]
-// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
+// CHECK:STDOUT:   %addr.loc9: %ptr.251 = addr_of %a.ref
+// CHECK:STDOUT:   %.loc9_11.1: %ptr.758 = as_compatible %addr.loc9
+// CHECK:STDOUT:   %.loc9_11.2: %ptr.758 = converted %addr.loc9, %.loc9_11.1
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc9_11.2)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/arithmetic_types_direct.carbon

@@ -364,7 +364,7 @@ fn F() {
 
 auto foo(const int* _Nonnull a) -> int;
 
-// --- fail_todo_import_const_int_pointer_param.carbon
+// --- import_const_int_pointer_param.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -373,14 +373,6 @@ import Cpp library "const_int_pointer_param.h";
 fn F() {
   var a : i32 = 1;
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_const_int_pointer_param.carbon:[[@LINE+8]]:11: error: cannot implicitly convert expression of type `i32*` to `const i32*` [ConversionFailure]
-  // CHECK:STDERR:   Cpp.foo(&a);
-  // CHECK:STDERR:           ^~
-  // CHECK:STDERR: fail_todo_import_const_int_pointer_param.carbon:[[@LINE+5]]:11: note: type `i32*` does not implement interface `Core.ImplicitAs(const i32*)` [MissingImplInMemberAccessNote]
-  // CHECK:STDERR:   Cpp.foo(&a);
-  // CHECK:STDERR:           ^~
-  // CHECK:STDERR: fail_todo_import_const_int_pointer_param.carbon: note: initializing function parameter [InCallToFunctionParam]
-  // CHECK:STDERR:
   Cpp.foo(&a);
   //@dump-sem-ir-end
 }
@@ -1138,7 +1130,7 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_const_int_pointer_param.carbon
+// CHECK:STDOUT: --- import_const_int_pointer_param.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
@@ -1168,9 +1160,10 @@ fn F() {
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %a.ref: ref %i32 = name_ref a, %a
-// CHECK:STDOUT:   %addr.loc17: %ptr.235 = addr_of %a.ref
-// CHECK:STDOUT:   %.loc17: %ptr.36b = converted %addr.loc17, <error> [concrete = <error>]
-// CHECK:STDOUT:   %foo.call: init %i32 = call %foo.ref(<error>)
+// CHECK:STDOUT:   %addr.loc9: %ptr.235 = addr_of %a.ref
+// CHECK:STDOUT:   %.loc9_11.1: %ptr.36b = as_compatible %addr.loc9
+// CHECK:STDOUT:   %.loc9_11.2: %ptr.36b = converted %addr.loc9, %.loc9_11.1
+// CHECK:STDOUT:   %foo.call: init %i32 = call %foo.ref(%.loc9_11.2)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/pointer/convert_qualifiers.carbon

@@ -0,0 +1,214 @@
+// 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
+//
+// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/int.carbon
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/pointer/convert_qualifiers.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/pointer/convert_qualifiers.carbon
+
+// --- same_or_added_qualifiers.carbon
+
+library "[[@TEST_NAME]]";
+
+class X {}
+
+fn TakeConst(p: const X*);
+fn TakeNonConst(p: X*);
+
+fn NonConst(p: X*) {
+  //@dump-sem-ir-begin
+  TakeNonConst(p);
+  TakeConst(p);
+  //@dump-sem-ir-end
+}
+fn Const(p: const X*) {
+  //@dump-sem-ir-begin
+  TakeConst(p);
+  //@dump-sem-ir-end
+}
+
+// Same thing, but the pointee type happens to be a pointer.
+fn TakeConstConst(p: const (const X*)*);
+fn NonConstConst(p: const X**) {
+  //@dump-sem-ir-begin
+  TakeConstConst(p);
+  //@dump-sem-ir-end
+}
+
+// --- fail_removed_qualifiers.carbon
+
+library "[[@TEST_NAME]]";
+
+class X {}
+
+fn TakeNonConst(p: X*);
+
+// CHECK:STDERR: fail_removed_qualifiers.carbon:[[@LINE+10]]:38: error: cannot implicitly convert expression of type `const X*` to `X*` [ConversionFailure]
+// CHECK:STDERR: fn Const(p: const X*) { TakeNonConst(p); }
+// CHECK:STDERR:                                      ^
+// CHECK:STDERR: fail_removed_qualifiers.carbon:[[@LINE+7]]:38: note: type `const X*` does not implement interface `Core.ImplicitAs(X*)` [MissingImplInMemberAccessNote]
+// CHECK:STDERR: fn Const(p: const X*) { TakeNonConst(p); }
+// CHECK:STDERR:                                      ^
+// CHECK:STDERR: fail_removed_qualifiers.carbon:[[@LINE-8]]:17: note: initializing function parameter [InCallToFunctionParam]
+// CHECK:STDERR: fn TakeNonConst(p: X*);
+// CHECK:STDERR:                 ^~~~~
+// CHECK:STDERR:
+fn Const(p: const X*) { TakeNonConst(p); }
+
+// --- fail_todo_nested_qualifiers.carbon
+
+library "[[@TEST_NAME]]";
+
+class X {}
+
+fn TakeConstConst(p: const (const X*)*);
+
+// TODO: We should allow these conversions.
+
+fn NonConstNonConst(p: X**) {
+  //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_nested_qualifiers.carbon:[[@LINE+10]]:18: error: cannot implicitly convert expression of type `X**` to `const (const X*)*` [ConversionFailure]
+  // CHECK:STDERR:   TakeConstConst(p);
+  // CHECK:STDERR:                  ^
+  // CHECK:STDERR: fail_todo_nested_qualifiers.carbon:[[@LINE+7]]:18: note: type `X**` does not implement interface `Core.ImplicitAs(const (const X*)*)` [MissingImplInMemberAccessNote]
+  // CHECK:STDERR:   TakeConstConst(p);
+  // CHECK:STDERR:                  ^
+  // CHECK:STDERR: fail_todo_nested_qualifiers.carbon:[[@LINE-12]]:19: note: initializing function parameter [InCallToFunctionParam]
+  // CHECK:STDERR: fn TakeConstConst(p: const (const X*)*);
+  // CHECK:STDERR:                   ^~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  TakeConstConst(p);
+  //@dump-sem-ir-end
+}
+
+fn ConstNonConst(p: const (X*)*) {
+  //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_nested_qualifiers.carbon:[[@LINE+10]]:18: error: cannot implicitly convert expression of type `const (X*)*` to `const (const X*)*` [ConversionFailure]
+  // CHECK:STDERR:   TakeConstConst(p);
+  // CHECK:STDERR:                  ^
+  // CHECK:STDERR: fail_todo_nested_qualifiers.carbon:[[@LINE+7]]:18: note: type `const (X*)*` does not implement interface `Core.ImplicitAs(const (const X*)*)` [MissingImplInMemberAccessNote]
+  // CHECK:STDERR:   TakeConstConst(p);
+  // CHECK:STDERR:                  ^
+  // CHECK:STDERR: fail_todo_nested_qualifiers.carbon:[[@LINE-28]]:19: note: initializing function parameter [InCallToFunctionParam]
+  // CHECK:STDERR: fn TakeConstConst(p: const (const X*)*);
+  // CHECK:STDERR:                   ^~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  TakeConstConst(p);
+  //@dump-sem-ir-end
+}
+
+// --- fail_nested_added_qualifiers.carbon
+
+library "[[@TEST_NAME]]";
+
+class X {}
+
+fn TakeNonConstConst(p: (const X*)*);
+
+// CHECK:STDERR: fail_nested_added_qualifiers.carbon:[[@LINE+10]]:49: error: cannot implicitly convert expression of type `X**` to `const X**` [ConversionFailure]
+// CHECK:STDERR: fn NonConstNonConst(p: X**) { TakeNonConstConst(p); }
+// CHECK:STDERR:                                                 ^
+// CHECK:STDERR: fail_nested_added_qualifiers.carbon:[[@LINE+7]]:49: note: type `X**` does not implement interface `Core.ImplicitAs(const X**)` [MissingImplInMemberAccessNote]
+// CHECK:STDERR: fn NonConstNonConst(p: X**) { TakeNonConstConst(p); }
+// CHECK:STDERR:                                                 ^
+// CHECK:STDERR: fail_nested_added_qualifiers.carbon:[[@LINE-8]]:22: note: initializing function parameter [InCallToFunctionParam]
+// CHECK:STDERR: fn TakeNonConstConst(p: (const X*)*);
+// CHECK:STDERR:                      ^~~~~~~~~~~~~~
+// CHECK:STDERR:
+fn NonConstNonConst(p: X**) { TakeNonConstConst(p); }
+
+// CHECK:STDOUT: --- same_or_added_qualifiers.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %X: type = class_type @X [concrete]
+// CHECK:STDOUT:   %ptr.d17: type = ptr_type %X [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %const.dde: type = const_type %X [concrete]
+// CHECK:STDOUT:   %ptr.cbd: type = ptr_type %const.dde [concrete]
+// CHECK:STDOUT:   %TakeConst.type: type = fn_type @TakeConst [concrete]
+// CHECK:STDOUT:   %TakeConst: %TakeConst.type = struct_value () [concrete]
+// CHECK:STDOUT:   %TakeNonConst.type: type = fn_type @TakeNonConst [concrete]
+// CHECK:STDOUT:   %TakeNonConst: %TakeNonConst.type = struct_value () [concrete]
+// CHECK:STDOUT:   %const.5df: type = const_type %ptr.cbd [concrete]
+// CHECK:STDOUT:   %ptr.20a: type = ptr_type %const.5df [concrete]
+// CHECK:STDOUT:   %TakeConstConst.type: type = fn_type @TakeConstConst [concrete]
+// CHECK:STDOUT:   %TakeConstConst: %TakeConstConst.type = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.dd0: type = ptr_type %ptr.cbd [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @NonConst(%p.param: %ptr.d17) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeNonConst.ref: %TakeNonConst.type = name_ref TakeNonConst, file.%TakeNonConst.decl [concrete = constants.%TakeNonConst]
+// CHECK:STDOUT:   %p.ref.loc11: %ptr.d17 = name_ref p, %p
+// CHECK:STDOUT:   %TakeNonConst.call: init %empty_tuple.type = call %TakeNonConst.ref(%p.ref.loc11)
+// CHECK:STDOUT:   %TakeConst.ref: %TakeConst.type = name_ref TakeConst, file.%TakeConst.decl [concrete = constants.%TakeConst]
+// CHECK:STDOUT:   %p.ref.loc12: %ptr.d17 = name_ref p, %p
+// CHECK:STDOUT:   %.loc12_13.1: %ptr.cbd = as_compatible %p.ref.loc12
+// CHECK:STDOUT:   %.loc12_13.2: %ptr.cbd = converted %p.ref.loc12, %.loc12_13.1
+// CHECK:STDOUT:   %TakeConst.call: init %empty_tuple.type = call %TakeConst.ref(%.loc12_13.2)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @Const(%p.param: %ptr.cbd) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConst.ref: %TakeConst.type = name_ref TakeConst, file.%TakeConst.decl [concrete = constants.%TakeConst]
+// CHECK:STDOUT:   %p.ref: %ptr.cbd = name_ref p, %p
+// CHECK:STDOUT:   %TakeConst.call: init %empty_tuple.type = call %TakeConst.ref(%p.ref)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @NonConstConst(%p.param: %ptr.dd0) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConstConst.ref: %TakeConstConst.type = name_ref TakeConstConst, file.%TakeConstConst.decl [concrete = constants.%TakeConstConst]
+// CHECK:STDOUT:   %p.ref: %ptr.dd0 = name_ref p, %p
+// CHECK:STDOUT:   %.loc25_18.1: %ptr.20a = as_compatible %p.ref
+// CHECK:STDOUT:   %.loc25_18.2: %ptr.20a = converted %p.ref, %.loc25_18.1
+// CHECK:STDOUT:   %TakeConstConst.call: init %empty_tuple.type = call %TakeConstConst.ref(%.loc25_18.2)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_todo_nested_qualifiers.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %X: type = class_type @X [concrete]
+// CHECK:STDOUT:   %ptr.d17: type = ptr_type %X [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %const.dde: type = const_type %X [concrete]
+// CHECK:STDOUT:   %ptr.cbd: type = ptr_type %const.dde [concrete]
+// CHECK:STDOUT:   %const.5df: type = const_type %ptr.cbd [concrete]
+// CHECK:STDOUT:   %ptr.20a: type = ptr_type %const.5df [concrete]
+// CHECK:STDOUT:   %TakeConstConst.type: type = fn_type @TakeConstConst [concrete]
+// CHECK:STDOUT:   %TakeConstConst: %TakeConstConst.type = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.b1b: type = ptr_type %ptr.d17 [concrete]
+// CHECK:STDOUT:   %const.2bc: type = const_type %ptr.d17 [concrete]
+// CHECK:STDOUT:   %ptr.297: type = ptr_type %const.2bc [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @NonConstNonConst(%p.param: %ptr.b1b) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConstConst.ref: %TakeConstConst.type = name_ref TakeConstConst, file.%TakeConstConst.decl [concrete = constants.%TakeConstConst]
+// CHECK:STDOUT:   %p.ref: %ptr.b1b = name_ref p, %p
+// CHECK:STDOUT:   %.loc22: %ptr.20a = converted %p.ref, <error> [concrete = <error>]
+// CHECK:STDOUT:   %TakeConstConst.call: init %empty_tuple.type = call %TakeConstConst.ref(<error>)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @ConstNonConst(%p.param: %ptr.297) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %TakeConstConst.ref: %TakeConstConst.type = name_ref TakeConstConst, file.%TakeConstConst.decl [concrete = constants.%TakeConstConst]
+// CHECK:STDOUT:   %p.ref: %ptr.297 = name_ref p, %p
+// CHECK:STDOUT:   %.loc38: %ptr.20a = converted %p.ref, <error> [concrete = <error>]
+// CHECK:STDOUT:   %TakeConstConst.call: init %empty_tuple.type = call %TakeConstConst.ref(<error>)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:

toolchain/check/type.cpp

@@ -136,6 +136,16 @@ auto GetConstType(Context& context, SemIR::TypeInstId inner_type_id)
   return GetTypeImpl<SemIR::ConstType>(context, inner_type_id);
 }
 
+auto GetQualifiedType(Context& context, SemIR::TypeId type_id,
+                      SemIR::TypeQualifiers quals) -> SemIR::TypeId {
+  if ((quals & SemIR::TypeQualifiers::Const) != SemIR::TypeQualifiers::None) {
+    type_id = GetConstType(context, context.types().GetInstId(type_id));
+    quals &= ~SemIR::TypeQualifiers::Const;
+  }
+  CARBON_CHECK(quals == SemIR::TypeQualifiers::None);
+  return type_id;
+}
+
 auto GetSingletonType(Context& context, SemIR::TypeInstId singleton_id)
     -> SemIR::TypeId {
   CARBON_CHECK(SemIR::IsSingletonInstId(singleton_id));

toolchain/check/type.h

@@ -39,6 +39,10 @@ auto GetSingletonType(Context& context, SemIR::TypeInstId singleton_id)
 auto GetConstType(Context& context, SemIR::TypeInstId inner_type_id)
     -> SemIR::TypeId;
 
+// Gets a qualified version of a type.
+auto GetQualifiedType(Context& context, SemIR::TypeId type_id,
+                      SemIR::TypeQualifiers quals) -> SemIR::TypeId;
+
 // Gets a class type.
 auto GetClassType(Context& context, SemIR::ClassId class_id,
                   SemIR::SpecificId specific_id) -> SemIR::TypeId;

toolchain/sem_ir/type.cpp

@@ -93,12 +93,14 @@ auto TypeStore::GetTransitiveAdaptedType(TypeId type_id) const -> TypeId {
   return type_id;
 }
 
-auto TypeStore::GetUnqualifiedType(TypeId type_id) const -> TypeId {
+auto TypeStore::GetUnqualifiedTypeAndQualifiers(TypeId type_id) const
+    -> std::pair<TypeId, TypeQualifiers> {
   if (auto const_type = TryGetAs<ConstType>(type_id)) {
-    return file_->types().GetTypeIdForTypeInstId(const_type->inner_id);
+    return {file_->types().GetTypeIdForTypeInstId(const_type->inner_id),
+            TypeQualifiers::Const};
   }
   // TODO: Look through PartialType when this is reachable/testable
-  return type_id;
+  return {type_id, TypeQualifiers::None};
 }
 
 auto TypeStore::TryGetIntTypeInfo(TypeId int_type_id) const

toolchain/sem_ir/type.h

@@ -5,6 +5,7 @@
 #ifndef CARBON_TOOLCHAIN_SEM_IR_TYPE_H_
 #define CARBON_TOOLCHAIN_SEM_IR_TYPE_H_
 
+#include "llvm/ADT/BitmaskEnum.h"
 #include "llvm/ADT/STLExtras.h"
 #include "toolchain/base/shared_value_stores.h"
 #include "toolchain/sem_ir/constant.h"
@@ -14,6 +15,17 @@
 
 namespace Carbon::SemIR {
 
+LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
+
+// A bitmask of type qualifiers.
+enum class TypeQualifiers {
+  None = 0,
+  Const = 1 << 0,
+  // TODO: Partial
+
+  LLVM_MARK_AS_BITMASK_ENUM(Const)
+};
+
 // Provides a ValueStore wrapper with an API specific to types.
 class TypeStore : public Yaml::Printable<TypeStore> {
  public:
@@ -160,8 +172,15 @@ class TypeStore : public Yaml::Printable<TypeStore> {
     return complete_type_info_.Contains(type_id);
   }
 
-  // Removes any top-level `const` qualifiers from a type.
-  auto GetUnqualifiedType(TypeId type_id) const -> TypeId;
+  // Removes any top-level qualifiers from a type.
+  auto GetUnqualifiedType(TypeId type_id) const -> TypeId {
+    return GetUnqualifiedTypeAndQualifiers(type_id).first;
+  }
+
+  // Removes any top-level qualifiers from a type and returns the unqualified
+  // type and qualifiers.
+  auto GetUnqualifiedTypeAndQualifiers(TypeId type_id) const
+      -> std::pair<TypeId, TypeQualifiers>;
 
   // Determines whether the given type is a signed integer type. This includes
   // the case where the type is `Core.IntLiteral` or a class type whose object