Add reference support to C++ interop. (#6082)

For now this works as follows:

* `T&&` is mapped to a by-value `param: T` parameter.
* `T&` is mapped to an `addr param: T*` parameter.

In either case, we will generate a thunk, which will internally pass the
parameter as a pointer.

toolchain/check/cpp_import.cpp

@@ -1393,22 +1393,32 @@ static auto MakeParamPatternsBlockId(Context& context, SemIR::LocId loc_id,
     // be cv-qualified.
     clang::QualType param_type = param->getType();
 
+    // We map `T&` parameters to `addr param: T*`, and `T&&` parameters to
+    // `param: T`.
+    // TODO: Revisit this and decide what we really want to do here.
+    bool is_ref_param = param_type->isLValueReferenceType();
+    param_type = param_type.getNonReferenceType();
+
     // Mark the start of a region of insts, needed for the type expression
     // created later with the call of `EndSubpatternAsExpr()`.
     BeginSubpattern(context);
-    auto [type_inst_id, type_id] = MapType(context, loc_id, param_type);
+    auto [orig_type_inst_id, type_id] = MapType(context, loc_id, param_type);
     // Type expression of the binding pattern - a single-entry/single-exit
     // region that allows control flow in the type expression e.g. fn F(x: if C
     // then i32 else i64).
     SemIR::ExprRegionId type_expr_region_id =
-        EndSubpatternAsExpr(context, type_inst_id);
+        EndSubpatternAsExpr(context, orig_type_inst_id);
 
     if (!type_id.has_value()) {
       context.TODO(loc_id, llvm::formatv("Unsupported: parameter type: {0}",
-                                         param_type.getAsString()));
+                                         param->getType().getAsString()));
       return SemIR::InstBlockId::None;
     }
 
+    if (is_ref_param) {
+      type_id = GetPointerType(context, orig_type_inst_id);
+    }
+
     llvm::StringRef param_name = param->getName();
     SemIR::NameId name_id =
         param_name.empty()
@@ -1421,19 +1431,29 @@ static auto MakeParamPatternsBlockId(Context& context, SemIR::LocId loc_id,
     bool is_template = false;
     // TODO: Fix this once generics are supported.
     bool is_generic = false;
-    SemIR::InstId binding_pattern_id =
+    SemIR::InstId pattern_id =
         // TODO: Fill in a location once available.
         AddBindingPattern(context, SemIR::LocId::None, name_id, type_id,
                           type_expr_region_id, is_generic, is_template)
             .pattern_id;
-    SemIR::InstId var_pattern_id = AddPatternInst(
+    pattern_id = AddPatternInst(
         context,
         // TODO: Fill in a location once available.
         SemIR::LocIdAndInst::NoLoc(SemIR::ValueParamPattern(
-            {.type_id = context.insts().Get(binding_pattern_id).type_id(),
-             .subpattern_id = binding_pattern_id,
+            {.type_id = context.insts().Get(pattern_id).type_id(),
+             .subpattern_id = pattern_id,
              .index = SemIR::CallParamIndex::None})));
-    params.push_back(var_pattern_id);
+    if (is_ref_param) {
+      pattern_id = AddPatternInst(
+          context,
+          // TODO: Fill in a location once available.
+          SemIR::LocIdAndInst::NoLoc(SemIR::AddrPattern(
+              {.type_id = GetPatternType(
+                   context,
+                   context.types().GetTypeIdForTypeInstId(orig_type_inst_id)),
+               .inner_id = pattern_id})));
+    }
+    params.push_back(pattern_id);
   }
   return context.inst_blocks().Add(params);
 }

toolchain/check/cpp_thunk.cpp

@@ -89,6 +89,17 @@ auto IsCppThunkRequired(Context& context, const SemIR::Function& function)
   // we don't generate a thunk if any relevant type is erroneous.
   bool thunk_required = false;
 
+  // We require a thunk if any parameter is of reference type, even if the
+  // corresponding SemIR function has an acceptable parameter type.
+  // TODO: We should be able to avoid thunks for reference parameters.
+  const auto* decl = cast<clang::FunctionDecl>(
+      context.sem_ir().clang_decls().Get(function.clang_decl_id).decl);
+  for (auto* param : decl->parameters()) {
+    if (param->getType()->isReferenceType()) {
+      thunk_required = true;
+    }
+  }
+
   SemIR::TypeId return_type_id =
       function.GetDeclaredReturnType(context.sem_ir());
   if (return_type_id.has_value()) {
@@ -217,7 +228,8 @@ static auto GetThunkParameterType(clang::ASTContext& ast_context,
   if (IsSimpleAbiType(ast_context, callee_type)) {
     return callee_type;
   }
-  return GetNonnullType(ast_context, ast_context.getPointerType(callee_type));
+  return GetNonnullType(ast_context, ast_context.getPointerType(
+                                         callee_type.getNonReferenceType()));
 }
 
 // Creates the thunk parameter types given the callee function.
@@ -358,13 +370,24 @@ static auto BuildThunkParamRef(clang::Sema& sema,
       thunk_param, thunk_param->getType().getNonReferenceType(),
       clang::VK_LValue, clang_loc);
   if (!type.isNull() && thunk_param->getType() != type) {
-    // TODO: Consider inserting a cast to an rvalue. Note that we currently
-    // pass pointers to non-temporary objects as the argument when calling a
-    // thunk, so we'll need to either change that or generate different thunks
-    // depending on whether we're moving from each parameter.
     clang::ExprResult deref_result =
         sema.BuildUnaryOp(nullptr, clang_loc, clang::UO_Deref, call_arg);
     CARBON_CHECK(deref_result.isUsable());
+
+    // Cast to an rvalue when initializing an rvalue reference. The validity of
+    // the initialization of the reference should be validated by the caller of
+    // the thunk.
+    //
+    // TODO: Consider inserting a cast to an rvalue in more cases. Note that we
+    // currently pass pointers to non-temporary objects as the argument when
+    // calling a thunk, so we'll need to either change that or generate
+    // different thunks depending on whether we're moving from each parameter.
+    if (type->isRValueReferenceType()) {
+      deref_result = clang::ImplicitCastExpr::Create(
+          sema.getASTContext(), deref_result.get()->getType(), clang::CK_NoOp,
+          deref_result.get(), nullptr, clang::ExprValueKind::VK_XValue,
+          clang::FPOptionsOverride());
+    }
     call_arg = deref_result.get();
   }
   return call_arg;

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

@@ -423,104 +423,6 @@ fn F() {
   //@dump-sem-ir-end
 }
 
-// ============================================================================
-// short reference param
-// ============================================================================
-
-// --- short_ref_param.h
-
-auto foo(short& a) -> void;
-
-// --- fail_todo_import_short_ref_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "short_ref_param.h";
-
-fn F() {
-  var a: i16 = 1;
-  //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_short_ref_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: short &` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR: fail_todo_import_short_ref_param.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR:
-  Cpp.foo(a);
-  //@dump-sem-ir-end
-}
-
-// ============================================================================
-// const short reference param
-// ============================================================================
-
-// --- const_short_ref_param.h
-
-auto foo(const short& a) -> void;
-
-// --- fail_todo_import_const_short_ref_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "const_short_ref_param.h";
-
-fn F() {
-  var a: i16 = 1;
-  //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_const_short_ref_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const short &` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR: fail_todo_import_const_short_ref_param.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR:
-  Cpp.foo(a);
-  //@dump-sem-ir-end
-}
-
-// ============================================================================
-// short pointer param
-// ============================================================================
-
-// --- short_pointer_param.h
-
-auto foo(short* _Nonnull a) -> void;
-
-// --- import_short_pointer_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "short_pointer_param.h";
-
-fn F() {
-  var a: i16 = 1;
-  //@dump-sem-ir-begin
-  Cpp.foo(&a);
-  //@dump-sem-ir-end
-}
-
-// ============================================================================
-// const short pointer param
-// ============================================================================
-
-// --- const_short_pointer_param.h
-
-auto foo(const short* _Nonnull a) -> void;
-
-// --- import_const_short_pointer_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "const_short_pointer_param.h";
-
-fn F() {
-  var a: i16 = 1;
-  //@dump-sem-ir-begin
-  Cpp.foo(&a);
-  //@dump-sem-ir-end
-}
-
 // ============================================================================
 // _Float16 param
 // ============================================================================
@@ -1931,136 +1833,6 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_short_ref_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %int_16: Core.IntLiteral = int_value 16 [concrete]
-// CHECK:STDOUT:   %i16: type = class_type @Int, @Int(%int_16) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i16 = name_ref a, %a
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_const_short_ref_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %int_16: Core.IntLiteral = int_value 16 [concrete]
-// CHECK:STDOUT:   %i16: type = class_type @Int, @Int(%int_16) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i16 = name_ref a, %a
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- import_short_pointer_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %int_16: Core.IntLiteral = int_value 16 [concrete]
-// CHECK:STDOUT:   %i16: type = class_type @Int, @Int(%int_16) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT:   %ptr.251: type = ptr_type %i16 [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i16 = name_ref a, %a
-// CHECK:STDOUT:   %addr.loc9: %ptr.251 = addr_of %a.ref
-// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%addr.loc9)
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- import_const_short_pointer_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %int_16: Core.IntLiteral = int_value 16 [concrete]
-// CHECK:STDOUT:   %i16: type = class_type @Int, @Int(%int_16) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT:   %ptr.251: type = ptr_type %i16 [concrete]
-// CHECK:STDOUT:   %const: type = const_type %i16 [concrete]
-// CHECK:STDOUT:   %ptr.758: type = ptr_type %const [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i16 = name_ref a, %a
-// 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 imports.%foo.decl(%.loc9_11.2)
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
 // CHECK:STDOUT: --- import_float16_param.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {

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

@@ -327,104 +327,6 @@ fn F() {
   //@dump-sem-ir-end
 }
 
-// ============================================================================
-// int reference param
-// ============================================================================
-
-// --- int_ref_param.h
-
-auto foo(int& a) -> int;
-
-// --- fail_todo_import_int_ref_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "int_ref_param.h";
-
-fn F() {
-  var a: i32 = 1;
-  //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_int_ref_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: int &` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR: fail_todo_import_int_ref_param.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR:
-  Cpp.foo(a);
-  //@dump-sem-ir-end
-}
-
-// ============================================================================
-// const int reference param
-// ============================================================================
-
-// --- const_int_ref_param.h
-
-auto foo(const int& a) -> int;
-
-// --- fail_todo_import_const_int_ref_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "const_int_ref_param.h";
-
-fn F() {
-  var a : i32 = 1;
-  //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_const_int_ref_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const int &` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR: fail_todo_import_const_int_ref_param.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
-  // CHECK:STDERR:   Cpp.foo(a);
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR:
-  Cpp.foo(a);
-  //@dump-sem-ir-end
-}
-
-// ============================================================================
-// int pointer param
-// ============================================================================
-
-// --- int_pointer_param.h
-
-auto foo(int* _Nonnull a) -> void;
-
-// --- import_int_pointer_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "int_pointer_param.h";
-
-fn F() {
-  var a: i32 = 1;
-  //@dump-sem-ir-begin
-  Cpp.foo(&a);
-  //@dump-sem-ir-end
-}
-
-// ============================================================================
-// const int pointer param
-// ============================================================================
-
-// --- const_int_pointer_param.h
-
-auto foo(const int* _Nonnull a) -> int;
-
-// --- import_const_int_pointer_param.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "const_int_pointer_param.h";
-
-fn F() {
-  var a : i32 = 1;
-  //@dump-sem-ir-begin
-  Cpp.foo(&a);
-  //@dump-sem-ir-end
-}
-
 // ============================================================================
 // int return
 // ============================================================================
@@ -1243,135 +1145,6 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_int_ref_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i32 = name_ref a, %a
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_const_int_ref_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i32 = name_ref a, %a
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- import_int_pointer_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT:   %ptr.235: type = ptr_type %i32 [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i32 = name_ref a, %a
-// CHECK:STDOUT:   %addr.loc9: %ptr.235 = addr_of %a.ref
-// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%addr.loc9)
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- import_const_int_pointer_param.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %.c5d: type = cpp_overload_set_type @ImplicitAs.Convert [concrete]
-// CHECK:STDOUT:   %empty_struct: %.c5d = struct_value () [concrete]
-// CHECK:STDOUT:   %ptr.235: type = ptr_type %i32 [concrete]
-// CHECK:STDOUT:   %const: type = const_type %i32 [concrete]
-// CHECK:STDOUT:   %ptr.36b: type = ptr_type %const [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %.a21
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.a21: %.c5d = cpp_overload_set_value @ImplicitAs.Convert [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %a.ref: ref %i32 = name_ref a, %a
-// 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 imports.%foo.decl(%.loc9_11.2)
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int_return.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {

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

@@ -0,0 +1,755 @@
+// 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/convert.carbon
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/interop/cpp/function/reference.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/function/reference.carbon
+
+// ============================================================================
+// Lvalue reference as a parameter type
+// ============================================================================
+
+// --- lvalue_ref.h
+
+struct S {};
+struct T {};
+
+auto TakesLValue(S&) -> void;
+
+// --- call_lvalue_ref.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "lvalue_ref.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  var s: Cpp.S = {};
+  Cpp.TakesLValue(s);
+  //@dump-sem-ir-end
+}
+
+// --- fail_lvalue_ref.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "lvalue_ref.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  var v: Cpp.S;
+  let s: Cpp.S = v;
+  // CHECK:STDERR: fail_lvalue_ref.carbon:[[@LINE+7]]:3: error: no matching function for call to `TakesLValue` [CppOverloadingNoViableFunctionFound]
+  // CHECK:STDERR:   Cpp.TakesLValue(s);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_lvalue_ref.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
+  // CHECK:STDERR:   Cpp.TakesLValue(s);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Cpp.TakesLValue(s);
+
+  var t: Cpp.T;
+  // CHECK:STDERR: fail_lvalue_ref.carbon:[[@LINE+7]]:3: error: no matching function for call to `TakesLValue` [CppOverloadingNoViableFunctionFound]
+  // CHECK:STDERR:   Cpp.TakesLValue(t);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_lvalue_ref.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
+  // CHECK:STDERR:   Cpp.TakesLValue(t);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Cpp.TakesLValue(t);
+
+  var u: Cpp.S;
+  // CHECK:STDERR: fail_lvalue_ref.carbon:[[@LINE+7]]:3: error: no matching function for call to `TakesLValue` [CppOverloadingNoViableFunctionFound]
+  // CHECK:STDERR:   Cpp.TakesLValue(u as const Cpp.S);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_lvalue_ref.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
+  // CHECK:STDERR:   Cpp.TakesLValue(u as const Cpp.S);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Cpp.TakesLValue(u as const Cpp.S);
+  //@dump-sem-ir-end
+}
+
+// ============================================================================
+// Rvalue reference as a parameter type
+// ============================================================================
+
+// --- rvalue_ref.h
+
+struct S {};
+struct T {};
+
+auto TakesRValue(S&&) -> void;
+
+// --- call_rvalue_ref.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "rvalue_ref.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  Cpp.TakesRValue({} as Cpp.S);
+  //@dump-sem-ir-end
+}
+
+// --- todo_fail_value_arg_for_rvalue_ref.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "rvalue_ref.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  // TODO: We should probably reject binding an rvalue reference to a value
+  // expression. If we don't reject, we should instead force a copy to be made,
+  // at least if the type has a pointer value representation, so that moving
+  // from the reference doesn't alter tne original value.
+  let s: Cpp.S = {};
+  Cpp.TakesRValue(s);
+  //@dump-sem-ir-end
+}
+
+// --- fail_rvalue_ref.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "rvalue_ref.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  var s: Cpp.S;
+  // CHECK:STDERR: fail_rvalue_ref.carbon:[[@LINE+7]]:3: error: no matching function for call to `TakesRValue` [CppOverloadingNoViableFunctionFound]
+  // CHECK:STDERR:   Cpp.TakesRValue(s);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_rvalue_ref.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
+  // CHECK:STDERR:   Cpp.TakesRValue(s);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Cpp.TakesRValue(s);
+
+  var t: Cpp.T;
+  // CHECK:STDERR: fail_rvalue_ref.carbon:[[@LINE+7]]:3: error: no matching function for call to `TakesRValue` [CppOverloadingNoViableFunctionFound]
+  // CHECK:STDERR:   Cpp.TakesRValue(t);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_rvalue_ref.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
+  // CHECK:STDERR:   Cpp.TakesRValue(t);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Cpp.TakesRValue(t);
+
+  // CHECK:STDERR: fail_rvalue_ref.carbon:[[@LINE+7]]:3: error: no matching function for call to `TakesRValue` [CppOverloadingNoViableFunctionFound]
+  // CHECK:STDERR:   Cpp.TakesRValue(({} as Cpp.S) as const Cpp.S);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_rvalue_ref.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
+  // CHECK:STDERR:   Cpp.TakesRValue(({} as Cpp.S) as const Cpp.S);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Cpp.TakesRValue(({} as Cpp.S) as const Cpp.S);
+  //@dump-sem-ir-end
+}
+
+// ============================================================================
+// Const reference as a parameter type
+// ============================================================================
+
+// --- const_lvalue_ref.h
+
+struct S {};
+struct T {};
+
+auto TakesConstLValue(const S&) -> void;
+
+// --- call_const_lvalue_ref.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "const_lvalue_ref.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  var s: Cpp.S = {};
+  Cpp.TakesConstLValue(s as const Cpp.S);
+
+  Cpp.TakesConstLValue(s);
+  //@dump-sem-ir-end
+}
+
+// --- fail_const_lvalue_ref.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "const_lvalue_ref.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  // TODO: Should this work? We could create a temporary. Overload resolution
+  // accepts this but the Carbon-side call fails.
+  // TODO: The diagnostic here is wrong; we're internally using `addr` but this
+  // is not `addr self`.
+  let s: Cpp.S = {};
+  // CHECK:STDERR: fail_const_lvalue_ref.carbon:[[@LINE+5]]:24: error: `addr self` method cannot be invoked on a value [AddrSelfIsNonRef]
+  // CHECK:STDERR:   Cpp.TakesConstLValue(s);
+  // CHECK:STDERR:                        ^
+  // CHECK:STDERR: fail_const_lvalue_ref.carbon: note: initializing function parameter [InCallToFunctionParam]
+  // CHECK:STDERR:
+  Cpp.TakesConstLValue(s);
+
+  var t: Cpp.T;
+  // CHECK:STDERR: fail_const_lvalue_ref.carbon:[[@LINE+7]]:3: error: no matching function for call to `TakesConstLValue` [CppOverloadingNoViableFunctionFound]
+  // CHECK:STDERR:   Cpp.TakesConstLValue(t);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_const_lvalue_ref.carbon:[[@LINE+4]]:3: note: in call to Cpp function here [InCallToCppFunction]
+  // CHECK:STDERR:   Cpp.TakesConstLValue(t);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Cpp.TakesConstLValue(t);
+  //@dump-sem-ir-end
+}
+
+// CHECK:STDOUT: --- call_lvalue_ref.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
+// CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
+// CHECK:STDOUT:   %.547: type = cpp_overload_set_type @TakesLValue [concrete]
+// CHECK:STDOUT:   %empty_struct: %.547 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
+// CHECK:STDOUT:   %TakesLValue__carbon_thunk.type: type = fn_type @TakesLValue__carbon_thunk [concrete]
+// CHECK:STDOUT:   %TakesLValue__carbon_thunk: %TakesLValue__carbon_thunk.type = struct_value () [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.d46: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%S) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.062: %T.as.Destroy.impl.Op.type.d46 = struct_value () [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     .TakesLValue = %.a7f
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %.a7f: %.547 = cpp_overload_set_value @TakesLValue [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %TakesLValue__carbon_thunk.decl: %TakesLValue__carbon_thunk.type = fn_decl @TakesLValue__carbon_thunk [concrete = constants.%TakesLValue__carbon_thunk] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %s.patt: %pattern_type.7da = binding_pattern s [concrete]
+// CHECK:STDOUT:     %s.var_patt: %pattern_type.7da = var_pattern %s.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %s.var: ref %S = var %s.var_patt
+// CHECK:STDOUT:   %.loc8_19.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc8_19.2: init %S = class_init (), %s.var [concrete = constants.%S.val]
+// CHECK:STDOUT:   %.loc8_3: init %S = converted %.loc8_19.1, %.loc8_19.2 [concrete = constants.%S.val]
+// CHECK:STDOUT:   assign %s.var, %.loc8_3
+// CHECK:STDOUT:   %.loc8_13: type = splice_block %S.ref [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %s: ref %S = bind_name s, %s.var
+// CHECK:STDOUT:   %Cpp.ref.loc9: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesLValue.ref: %.547 = name_ref TakesLValue, imports.%.a7f [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %s.ref: ref %S = name_ref s, %s
+// CHECK:STDOUT:   %addr.loc9: %ptr.5c7 = addr_of %s.ref
+// CHECK:STDOUT:   %TakesLValue__carbon_thunk.call: init %empty_tuple.type = call imports.%TakesLValue__carbon_thunk.decl(%addr.loc9)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound: <bound method> = bound_method %s.var, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method: <bound method> = bound_method %s.var, %T.as.Destroy.impl.Op.specific_fn
+// CHECK:STDOUT:   %addr.loc8: %ptr.5c7 = addr_of %s.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call: init %empty_tuple.type = call %bound_method(%addr.loc8)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_lvalue_ref.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
+// CHECK:STDOUT:   %.547: type = cpp_overload_set_type @Destroy.Op [concrete]
+// CHECK:STDOUT:   %empty_struct: %.547 = struct_value () [concrete]
+// CHECK:STDOUT:   %T.e15: type = class_type @T [concrete]
+// CHECK:STDOUT:   %pattern_type.e6b: type = pattern_type %T.e15 [concrete]
+// CHECK:STDOUT:   %const: type = const_type %S [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.d46: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%S) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.062: %T.as.Destroy.impl.Op.type.d46 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.559: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%T.e15) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.b53: %T.as.Destroy.impl.Op.type.559 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.b04: type = ptr_type %T.e15 [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     .TakesLValue = %.a7f
+// CHECK:STDOUT:     .T = %T.decl
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %.a7f: %.547 = cpp_overload_set_value @Destroy.Op [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %T.decl: type = class_decl @T [concrete = constants.%T.e15] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %v.patt: %pattern_type.7da = binding_pattern v [concrete]
+// CHECK:STDOUT:     %v.var_patt: %pattern_type.7da = var_pattern %v.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %v.var: ref %S = var %v.var_patt
+// CHECK:STDOUT:   %.loc8: type = splice_block %S.ref.loc8 [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref.loc8: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %v: ref %S = bind_name v, %v.var
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %s.patt: %pattern_type.7da = binding_pattern s [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %v.ref: ref %S = name_ref v, %v
+// CHECK:STDOUT:   %.loc9_13: type = splice_block %S.ref.loc9 [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc9: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref.loc9: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc9_18: %S = bind_value %v.ref
+// CHECK:STDOUT:   %s: %S = bind_name s, %.loc9_18
+// CHECK:STDOUT:   %Cpp.ref.loc17: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesLValue.ref.loc17: %.547 = name_ref TakesLValue, imports.%.a7f [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %s.ref: %S = name_ref s, %s
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %t.patt: %pattern_type.e6b = binding_pattern t [concrete]
+// CHECK:STDOUT:     %t.var_patt: %pattern_type.e6b = var_pattern %t.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %t.var: ref %T.e15 = var %t.var_patt
+// CHECK:STDOUT:   %.loc19: type = splice_block %T.ref [concrete = constants.%T.e15] {
+// CHECK:STDOUT:     %Cpp.ref.loc19: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %T.ref: type = name_ref T, imports.%T.decl [concrete = constants.%T.e15]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %t: ref %T.e15 = bind_name t, %t.var
+// CHECK:STDOUT:   %Cpp.ref.loc27: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesLValue.ref.loc27: %.547 = name_ref TakesLValue, imports.%.a7f [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %t.ref: ref %T.e15 = name_ref t, %t
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %u.patt: %pattern_type.7da = binding_pattern u [concrete]
+// CHECK:STDOUT:     %u.var_patt: %pattern_type.7da = var_pattern %u.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %u.var: ref %S = var %u.var_patt
+// CHECK:STDOUT:   %.loc29: type = splice_block %S.ref.loc29 [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc29: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref.loc29: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %u: ref %S = bind_name u, %u.var
+// CHECK:STDOUT:   %Cpp.ref.loc37_3: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesLValue.ref.loc37: %.547 = name_ref TakesLValue, imports.%.a7f [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %u.ref: ref %S = name_ref u, %u
+// CHECK:STDOUT:   %Cpp.ref.loc37_30: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %S.ref.loc37: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   %const: type = const_type %S.ref.loc37 [concrete = constants.%const]
+// CHECK:STDOUT:   %.loc37_21.1: ref %const = as_compatible %u.ref
+// CHECK:STDOUT:   %.loc37_21.2: ref %const = converted %u.ref, %.loc37_21.1
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc29: <bound method> = bound_method %u.var, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc29: <bound method> = bound_method %u.var, %T.as.Destroy.impl.Op.specific_fn.1
+// CHECK:STDOUT:   %addr.loc29: %ptr.5c7 = addr_of %u.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc29: init %empty_tuple.type = call %bound_method.loc29(%addr.loc29)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc19: <bound method> = bound_method %t.var, constants.%T.as.Destroy.impl.Op.b53
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc19: <bound method> = bound_method %t.var, %T.as.Destroy.impl.Op.specific_fn.2
+// CHECK:STDOUT:   %addr.loc19: %ptr.b04 = addr_of %t.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc19: init %empty_tuple.type = call %bound_method.loc19(%addr.loc19)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc8: <bound method> = bound_method %v.var, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc8: <bound method> = bound_method %v.var, %T.as.Destroy.impl.Op.specific_fn.3
+// CHECK:STDOUT:   %addr.loc8: %ptr.5c7 = addr_of %v.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc8: init %empty_tuple.type = call %bound_method.loc8(%addr.loc8)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- call_rvalue_ref.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %.1b9: type = cpp_overload_set_type @TakesRValue [concrete]
+// CHECK:STDOUT:   %empty_struct: %.1b9 = struct_value () [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk.type: type = fn_type @TakesRValue__carbon_thunk [concrete]
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk: %TakesRValue__carbon_thunk.type = struct_value () [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.d46: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%S) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.062: %T.as.Destroy.impl.Op.type.d46 = struct_value () [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .TakesRValue = %.1f6
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %.1f6: %.1b9 = cpp_overload_set_value @TakesRValue [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk.decl: %TakesRValue__carbon_thunk.type = fn_decl @TakesRValue__carbon_thunk [concrete = constants.%TakesRValue__carbon_thunk] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %Cpp.ref.loc8_3: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesRValue.ref: %.1b9 = name_ref TakesRValue, imports.%.1f6 [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %.loc8_20.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %Cpp.ref.loc8_25: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %S.ref: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   %.loc8_20.2: ref %S = temporary_storage
+// CHECK:STDOUT:   %.loc8_20.3: init %S = class_init (), %.loc8_20.2 [concrete = constants.%S.val]
+// CHECK:STDOUT:   %.loc8_20.4: ref %S = temporary %.loc8_20.2, %.loc8_20.3
+// CHECK:STDOUT:   %.loc8_22.1: ref %S = converted %.loc8_20.1, %.loc8_20.4
+// CHECK:STDOUT:   %.loc8_22.2: %S = bind_value %.loc8_22.1
+// CHECK:STDOUT:   %.loc8_22.3: ref %S = value_as_ref %.loc8_22.2
+// CHECK:STDOUT:   %addr.loc8_30: %ptr.5c7 = addr_of %.loc8_22.3
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk.call: init %empty_tuple.type = call imports.%TakesRValue__carbon_thunk.decl(%addr.loc8_30)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound: <bound method> = bound_method %.loc8_20.4, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method: <bound method> = bound_method %.loc8_20.4, %T.as.Destroy.impl.Op.specific_fn
+// CHECK:STDOUT:   %addr.loc8_20: %ptr.5c7 = addr_of %.loc8_20.4
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call: init %empty_tuple.type = call %bound_method(%addr.loc8_20)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- todo_fail_value_arg_for_rvalue_ref.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
+// CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
+// CHECK:STDOUT:   %.1b9: type = cpp_overload_set_type @TakesRValue [concrete]
+// CHECK:STDOUT:   %empty_struct: %.1b9 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk.type: type = fn_type @TakesRValue__carbon_thunk [concrete]
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk: %TakesRValue__carbon_thunk.type = struct_value () [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.d46: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%S) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.062: %T.as.Destroy.impl.Op.type.d46 = struct_value () [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     .TakesRValue = %.1f6
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %.1f6: %.1b9 = cpp_overload_set_value @TakesRValue [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk.decl: %TakesRValue__carbon_thunk.type = fn_decl @TakesRValue__carbon_thunk [concrete = constants.%TakesRValue__carbon_thunk] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %s.patt: %pattern_type.7da = binding_pattern s [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc12_19.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc12_13: type = splice_block %S.ref [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc12: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc12_19.2: ref %S = temporary_storage
+// CHECK:STDOUT:   %.loc12_19.3: init %S = class_init (), %.loc12_19.2 [concrete = constants.%S.val]
+// CHECK:STDOUT:   %.loc12_19.4: ref %S = temporary %.loc12_19.2, %.loc12_19.3
+// CHECK:STDOUT:   %.loc12_19.5: ref %S = converted %.loc12_19.1, %.loc12_19.4
+// CHECK:STDOUT:   %.loc12_19.6: %S = bind_value %.loc12_19.5
+// CHECK:STDOUT:   %s: %S = bind_name s, %.loc12_19.6
+// CHECK:STDOUT:   %Cpp.ref.loc13: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesRValue.ref: %.1b9 = name_ref TakesRValue, imports.%.1f6 [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %s.ref: %S = name_ref s, %s
+// CHECK:STDOUT:   %.loc13: ref %S = value_as_ref %s.ref
+// CHECK:STDOUT:   %addr.loc13: %ptr.5c7 = addr_of %.loc13
+// CHECK:STDOUT:   %TakesRValue__carbon_thunk.call: init %empty_tuple.type = call imports.%TakesRValue__carbon_thunk.decl(%addr.loc13)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound: <bound method> = bound_method %.loc12_19.4, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method: <bound method> = bound_method %.loc12_19.4, %T.as.Destroy.impl.Op.specific_fn
+// CHECK:STDOUT:   %addr.loc12: %ptr.5c7 = addr_of %.loc12_19.4
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call: init %empty_tuple.type = call %bound_method(%addr.loc12)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_rvalue_ref.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
+// CHECK:STDOUT:   %.1b9: type = cpp_overload_set_type @Destroy.Op [concrete]
+// CHECK:STDOUT:   %empty_struct: %.1b9 = struct_value () [concrete]
+// CHECK:STDOUT:   %T.e15: type = class_type @T [concrete]
+// CHECK:STDOUT:   %pattern_type.e6b: type = pattern_type %T.e15 [concrete]
+// CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
+// CHECK:STDOUT:   %const: type = const_type %S [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.d46: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%S) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.062: %T.as.Destroy.impl.Op.type.d46 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.559: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%T.e15) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.b53: %T.as.Destroy.impl.Op.type.559 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.b04: type = ptr_type %T.e15 [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     .TakesRValue = %.1f6
+// CHECK:STDOUT:     .T = %T.decl
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %.1f6: %.1b9 = cpp_overload_set_value @Destroy.Op [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %T.decl: type = class_decl @T [concrete = constants.%T.e15] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %s.patt: %pattern_type.7da = binding_pattern s [concrete]
+// CHECK:STDOUT:     %s.var_patt: %pattern_type.7da = var_pattern %s.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %s.var: ref %S = var %s.var_patt
+// CHECK:STDOUT:   %.loc8: type = splice_block %S.ref.loc8 [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref.loc8: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %s: ref %S = bind_name s, %s.var
+// CHECK:STDOUT:   %Cpp.ref.loc16: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesRValue.ref.loc16: %.1b9 = name_ref TakesRValue, imports.%.1f6 [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %s.ref: ref %S = name_ref s, %s
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %t.patt: %pattern_type.e6b = binding_pattern t [concrete]
+// CHECK:STDOUT:     %t.var_patt: %pattern_type.e6b = var_pattern %t.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %t.var: ref %T.e15 = var %t.var_patt
+// CHECK:STDOUT:   %.loc18: type = splice_block %T.ref [concrete = constants.%T.e15] {
+// CHECK:STDOUT:     %Cpp.ref.loc18: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %T.ref: type = name_ref T, imports.%T.decl [concrete = constants.%T.e15]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %t: ref %T.e15 = bind_name t, %t.var
+// CHECK:STDOUT:   %Cpp.ref.loc26: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesRValue.ref.loc26: %.1b9 = name_ref TakesRValue, imports.%.1f6 [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %t.ref: ref %T.e15 = name_ref t, %t
+// CHECK:STDOUT:   %Cpp.ref.loc35_3: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesRValue.ref.loc35: %.1b9 = name_ref TakesRValue, imports.%.1f6 [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %.loc35_21.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %Cpp.ref.loc35_26: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %S.ref.loc35_29: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   %.loc35_21.2: ref %S = temporary_storage
+// CHECK:STDOUT:   %.loc35_21.3: init %S = class_init (), %.loc35_21.2 [concrete = constants.%S.val]
+// CHECK:STDOUT:   %.loc35_21.4: ref %S = temporary %.loc35_21.2, %.loc35_21.3
+// CHECK:STDOUT:   %.loc35_23: ref %S = converted %.loc35_21.1, %.loc35_21.4
+// CHECK:STDOUT:   %Cpp.ref.loc35_42: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %S.ref.loc35_45: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   %const: type = const_type %S.ref.loc35_45 [concrete = constants.%const]
+// CHECK:STDOUT:   %.loc35_33.1: ref %const = as_compatible %.loc35_23
+// CHECK:STDOUT:   %.loc35_33.2: ref %const = converted %.loc35_23, %.loc35_33.1
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc35: <bound method> = bound_method %.loc35_21.4, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc35: <bound method> = bound_method %.loc35_21.4, %T.as.Destroy.impl.Op.specific_fn.1
+// CHECK:STDOUT:   %addr.loc35: %ptr.5c7 = addr_of %.loc35_21.4
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc35: init %empty_tuple.type = call %bound_method.loc35(%addr.loc35)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc18: <bound method> = bound_method %t.var, constants.%T.as.Destroy.impl.Op.b53
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc18: <bound method> = bound_method %t.var, %T.as.Destroy.impl.Op.specific_fn.2
+// CHECK:STDOUT:   %addr.loc18: %ptr.b04 = addr_of %t.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc18: init %empty_tuple.type = call %bound_method.loc18(%addr.loc18)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc8: <bound method> = bound_method %s.var, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc8: <bound method> = bound_method %s.var, %T.as.Destroy.impl.Op.specific_fn.3
+// CHECK:STDOUT:   %addr.loc8: %ptr.5c7 = addr_of %s.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc8: init %empty_tuple.type = call %bound_method.loc8(%addr.loc8)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- call_const_lvalue_ref.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
+// CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
+// CHECK:STDOUT:   %.4e1: type = cpp_overload_set_type @TakesConstLValue [concrete]
+// CHECK:STDOUT:   %empty_struct: %.4e1 = struct_value () [concrete]
+// CHECK:STDOUT:   %const: type = const_type %S [concrete]
+// CHECK:STDOUT:   %ptr.ff5: type = ptr_type %const [concrete]
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.type: type = fn_type @TakesConstLValue__carbon_thunk [concrete]
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk: %TakesConstLValue__carbon_thunk.type = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.d46: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%S) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.062: %T.as.Destroy.impl.Op.type.d46 = struct_value () [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     .TakesConstLValue = %.9bc
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %.9bc: %.4e1 = cpp_overload_set_value @TakesConstLValue [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.decl: %TakesConstLValue__carbon_thunk.type = fn_decl @TakesConstLValue__carbon_thunk [concrete = constants.%TakesConstLValue__carbon_thunk] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %s.patt: %pattern_type.7da = binding_pattern s [concrete]
+// CHECK:STDOUT:     %s.var_patt: %pattern_type.7da = var_pattern %s.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %s.var: ref %S = var %s.var_patt
+// CHECK:STDOUT:   %.loc8_19.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc8_19.2: init %S = class_init (), %s.var [concrete = constants.%S.val]
+// CHECK:STDOUT:   %.loc8_3: init %S = converted %.loc8_19.1, %.loc8_19.2 [concrete = constants.%S.val]
+// CHECK:STDOUT:   assign %s.var, %.loc8_3
+// CHECK:STDOUT:   %.loc8_13: type = splice_block %S.ref.loc8 [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref.loc8: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %s: ref %S = bind_name s, %s.var
+// CHECK:STDOUT:   %Cpp.ref.loc9_3: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesConstLValue.ref.loc9: %.4e1 = name_ref TakesConstLValue, imports.%.9bc [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %s.ref.loc9: ref %S = name_ref s, %s
+// CHECK:STDOUT:   %Cpp.ref.loc9_35: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %S.ref.loc9: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   %const: type = const_type %S.ref.loc9 [concrete = constants.%const]
+// CHECK:STDOUT:   %.loc9_26.1: ref %const = as_compatible %s.ref.loc9
+// CHECK:STDOUT:   %.loc9_26.2: ref %const = converted %s.ref.loc9, %.loc9_26.1
+// CHECK:STDOUT:   %addr.loc9: %ptr.ff5 = addr_of %.loc9_26.2
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.call.loc9: init %empty_tuple.type = call imports.%TakesConstLValue__carbon_thunk.decl(%addr.loc9)
+// CHECK:STDOUT:   %Cpp.ref.loc11: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesConstLValue.ref.loc11: %.4e1 = name_ref TakesConstLValue, imports.%.9bc [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %s.ref.loc11: ref %S = name_ref s, %s
+// CHECK:STDOUT:   %addr.loc11: %ptr.5c7 = addr_of %s.ref.loc11
+// CHECK:STDOUT:   %.loc11_24.1: %ptr.ff5 = as_compatible %addr.loc11
+// CHECK:STDOUT:   %.loc11_24.2: %ptr.ff5 = converted %addr.loc11, %.loc11_24.1
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.call.loc11: init %empty_tuple.type = call imports.%TakesConstLValue__carbon_thunk.decl(%.loc11_24.2)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound: <bound method> = bound_method %s.var, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method: <bound method> = bound_method %s.var, %T.as.Destroy.impl.Op.specific_fn
+// CHECK:STDOUT:   %addr.loc8: %ptr.5c7 = addr_of %s.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call: init %empty_tuple.type = call %bound_method(%addr.loc8)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_const_lvalue_ref.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
+// CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
+// CHECK:STDOUT:   %.4e1: type = cpp_overload_set_type @TakesConstLValue [concrete]
+// CHECK:STDOUT:   %empty_struct: %.4e1 = struct_value () [concrete]
+// CHECK:STDOUT:   %const: type = const_type %S [concrete]
+// CHECK:STDOUT:   %ptr.ff5: type = ptr_type %const [concrete]
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.type: type = fn_type @TakesConstLValue__carbon_thunk [concrete]
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk: %TakesConstLValue__carbon_thunk.type = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
+// CHECK:STDOUT:   %T.e15: type = class_type @T [concrete]
+// CHECK:STDOUT:   %pattern_type.e6b: type = pattern_type %T.e15 [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.559: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%T.e15) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.b53: %T.as.Destroy.impl.Op.type.559 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.b04: type = ptr_type %T.e15 [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.d46: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%S) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.062: %T.as.Destroy.impl.Op.type.d46 = struct_value () [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     .TakesConstLValue = %.9bc
+// CHECK:STDOUT:     .T = %T.decl
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %.9bc: %.4e1 = cpp_overload_set_value @TakesConstLValue [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.decl: %TakesConstLValue__carbon_thunk.type = fn_decl @TakesConstLValue__carbon_thunk [concrete = constants.%TakesConstLValue__carbon_thunk] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %T.decl: type = class_decl @T [concrete = constants.%T.e15] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %s.patt: %pattern_type.7da = binding_pattern s [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc12_19.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc12_13: type = splice_block %S.ref [concrete = constants.%S] {
+// CHECK:STDOUT:     %Cpp.ref.loc12: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %S.ref: type = name_ref S, imports.%S.decl [concrete = constants.%S]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc12_19.2: ref %S = temporary_storage
+// CHECK:STDOUT:   %.loc12_19.3: init %S = class_init (), %.loc12_19.2 [concrete = constants.%S.val]
+// CHECK:STDOUT:   %.loc12_19.4: ref %S = temporary %.loc12_19.2, %.loc12_19.3
+// CHECK:STDOUT:   %.loc12_19.5: ref %S = converted %.loc12_19.1, %.loc12_19.4
+// CHECK:STDOUT:   %.loc12_19.6: %S = bind_value %.loc12_19.5
+// CHECK:STDOUT:   %s: %S = bind_name s, %.loc12_19.6
+// CHECK:STDOUT:   %Cpp.ref.loc18: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesConstLValue.ref.loc18: %.4e1 = name_ref TakesConstLValue, imports.%.9bc [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %s.ref: %S = name_ref s, %s
+// CHECK:STDOUT:   %.loc18_24.1: ref %S = temporary_storage
+// CHECK:STDOUT:   %addr.loc18: %ptr.5c7 = addr_of %.loc18_24.1
+// CHECK:STDOUT:   %.loc18_24.2: %ptr.ff5 = as_compatible %addr.loc18
+// CHECK:STDOUT:   %.loc18_24.3: %ptr.ff5 = converted %addr.loc18, %.loc18_24.2
+// CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.call: init %empty_tuple.type = call imports.%TakesConstLValue__carbon_thunk.decl(%.loc18_24.3)
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %t.patt: %pattern_type.e6b = binding_pattern t [concrete]
+// CHECK:STDOUT:     %t.var_patt: %pattern_type.e6b = var_pattern %t.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %t.var: ref %T.e15 = var %t.var_patt
+// CHECK:STDOUT:   %.loc20: type = splice_block %T.ref [concrete = constants.%T.e15] {
+// CHECK:STDOUT:     %Cpp.ref.loc20: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %T.ref: type = name_ref T, imports.%T.decl [concrete = constants.%T.e15]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %t: ref %T.e15 = bind_name t, %t.var
+// CHECK:STDOUT:   %Cpp.ref.loc28: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %TakesConstLValue.ref.loc28: %.4e1 = name_ref TakesConstLValue, imports.%.9bc [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %t.ref: ref %T.e15 = name_ref t, %t
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc20: <bound method> = bound_method %t.var, constants.%T.as.Destroy.impl.Op.b53
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc20: <bound method> = bound_method %t.var, %T.as.Destroy.impl.Op.specific_fn.1
+// CHECK:STDOUT:   %addr.loc20: %ptr.b04 = addr_of %t.var
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc20: init %empty_tuple.type = call %bound_method.loc20(%addr.loc20)
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound.loc12: <bound method> = bound_method %.loc12_19.4, constants.%T.as.Destroy.impl.Op.062
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method.loc12: <bound method> = bound_method %.loc12_19.4, %T.as.Destroy.impl.Op.specific_fn.2
+// CHECK:STDOUT:   %addr.loc12: %ptr.5c7 = addr_of %.loc12_19.4
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call.loc12: init %empty_tuple.type = call %bound_method.loc12(%addr.loc12)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:

toolchain/lower/testdata/interop/cpp/reference.carbon

@@ -0,0 +1,179 @@
+// 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/lower/testdata/interop/cpp/reference.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/interop/cpp/reference.carbon
+
+// --- reference_params.h
+
+class C {};
+
+void TakeCRef(C&);
+void TakeCRRef(C&&);
+void TakeConstCRef(const C&);
+
+void TakeIntRef(int&);
+void TakeIntRRef(int&&);
+void TakeConstIntRef(const int&);
+
+// --- pass_references.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "reference_params.h";
+
+fn PassRefs() {
+  var c: Cpp.C;
+  Cpp.TakeCRef(c);
+  Cpp.TakeCRRef({} as Cpp.C);
+  Cpp.TakeConstCRef(c);
+
+  var n: i32;
+  Cpp.TakeIntRef(n);
+  Cpp.TakeIntRRef(42 as i32);
+  Cpp.TakeConstIntRef(n);
+}
+
+// CHECK:STDOUT: ; ModuleID = 'pass_references.carbon'
+// CHECK:STDOUT: source_filename = "pass_references.carbon"
+// CHECK:STDOUT: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+// CHECK:STDOUT: target triple = "x86_64-unknown-linux-gnu"
+// CHECK:STDOUT:
+// CHECK:STDOUT: @C.val.loc9_18.3 = internal constant {} zeroinitializer
+// CHECK:STDOUT:
+// CHECK:STDOUT: define void @_CPassRefs.Main() !dbg !7 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %c.var = alloca {}, align 8, !dbg !10
+// CHECK:STDOUT:   %.loc9_18.2.temp = alloca {}, align 8, !dbg !11
+// CHECK:STDOUT:   %n.var = alloca i32, align 4, !dbg !12
+// CHECK:STDOUT:   %.loc14_22.3.temp = alloca i32, align 4, !dbg !13
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %c.var), !dbg !10
+// CHECK:STDOUT:   call void @_Z8TakeCRefR1C.carbon_thunk(ptr %c.var), !dbg !14
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc9_18.2.temp), !dbg !11
+// CHECK:STDOUT:   call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc9_18.2.temp, ptr align 1 @C.val.loc9_18.3, i64 0, i1 false), !dbg !11
+// CHECK:STDOUT:   call void @_Z9TakeCRRefO1C.carbon_thunk(ptr %.loc9_18.2.temp), !dbg !15
+// CHECK:STDOUT:   call void @_Z13TakeConstCRefRK1C.carbon_thunk(ptr %c.var), !dbg !16
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %n.var), !dbg !12
+// CHECK:STDOUT:   call void @_Z10TakeIntRefRi.carbon_thunk(ptr %n.var), !dbg !17
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc14_22.3.temp), !dbg !13
+// CHECK:STDOUT:   store i32 42, ptr %.loc14_22.3.temp, align 4, !dbg !13
+// CHECK:STDOUT:   call void @_Z11TakeIntRRefOi.carbon_thunk(ptr %.loc14_22.3.temp), !dbg !18
+// CHECK:STDOUT:   call void @_Z15TakeConstIntRefRKi.carbon_thunk(ptr %n.var), !dbg !19
+// CHECK:STDOUT:   ret void, !dbg !20
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_Z8TakeCRefR1C(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_Z9TakeCRRefO1C(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_Z13TakeConstCRefRK1C(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_Z10TakeIntRefRi(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_Z11TakeIntRRefOi(i32)
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_Z15TakeConstIntRefRKi(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #0
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress
+// CHECK:STDOUT: define dso_local void @_Z8TakeCRefR1C.carbon_thunk(ptr %0) #2 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %0, ptr %.addr, align 8
+// CHECK:STDOUT:   %1 = load ptr, ptr %.addr, align 8
+// CHECK:STDOUT:   call void @_Z8TakeCRefR1C(ptr nonnull align 1 dereferenceable(1) %1)
+// CHECK:STDOUT:   ret void
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress
+// CHECK:STDOUT: define dso_local void @_Z9TakeCRRefO1C.carbon_thunk(ptr %0) #2 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %0, ptr %.addr, align 8
+// CHECK:STDOUT:   %1 = load ptr, ptr %.addr, align 8
+// CHECK:STDOUT:   call void @_Z9TakeCRRefO1C(ptr nonnull align 1 dereferenceable(1) %1)
+// CHECK:STDOUT:   ret void
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress
+// CHECK:STDOUT: define dso_local void @_Z13TakeConstCRefRK1C.carbon_thunk(ptr %0) #2 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %0, ptr %.addr, align 8
+// CHECK:STDOUT:   %1 = load ptr, ptr %.addr, align 8
+// CHECK:STDOUT:   call void @_Z13TakeConstCRefRK1C(ptr nonnull align 1 dereferenceable(1) %1)
+// CHECK:STDOUT:   ret void
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress
+// CHECK:STDOUT: define dso_local void @_Z10TakeIntRefRi.carbon_thunk(ptr %0) #2 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %0, ptr %.addr, align 8
+// CHECK:STDOUT:   %1 = load ptr, ptr %.addr, align 8
+// CHECK:STDOUT:   call void @_Z10TakeIntRefRi(ptr nonnull align 4 dereferenceable(4) %1)
+// CHECK:STDOUT:   ret void
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress
+// CHECK:STDOUT: define dso_local void @_Z11TakeIntRRefOi.carbon_thunk(ptr %0) #2 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %0, ptr %.addr, align 8
+// CHECK:STDOUT:   %1 = load ptr, ptr %.addr, align 8
+// CHECK:STDOUT:   call void @_Z11TakeIntRRefOi(ptr nonnull align 4 dereferenceable(4) %1)
+// CHECK:STDOUT:   ret void
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress
+// CHECK:STDOUT: define dso_local void @_Z15TakeConstIntRefRKi.carbon_thunk(ptr %0) #2 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %0, ptr %.addr, align 8
+// CHECK:STDOUT:   %1 = load ptr, ptr %.addr, align 8
+// CHECK:STDOUT:   call void @_Z15TakeConstIntRefRKi(ptr nonnull align 4 dereferenceable(4) %1)
+// CHECK:STDOUT:   ret void
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; uselistorder directives
+// CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 3, 2, 1, 0 }
+// CHECK:STDOUT:
+// CHECK:STDOUT: attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="0" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT:
+// CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
+// CHECK:STDOUT: !llvm.dbg.cu = !{!5}
+// CHECK:STDOUT:
+// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
+// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
+// CHECK:STDOUT: !2 = !{i32 1, !"wchar_size", i32 4}
+// CHECK:STDOUT: !3 = !{i32 8, !"PIC Level", i32 0}
+// CHECK:STDOUT: !4 = !{i32 7, !"PIE Level", i32 2}
+// CHECK:STDOUT: !5 = distinct !DICompileUnit(language: DW_LANG_C, file: !6, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+// CHECK:STDOUT: !6 = !DIFile(filename: "pass_references.carbon", directory: "")
+// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "PassRefs", linkageName: "_CPassRefs.Main", scope: null, file: !6, line: 6, type: !8, spFlags: DISPFlagDefinition, unit: !5)
+// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
+// CHECK:STDOUT: !9 = !{}
+// CHECK:STDOUT: !10 = !DILocation(line: 7, column: 3, scope: !7)
+// CHECK:STDOUT: !11 = !DILocation(line: 9, column: 17, scope: !7)
+// CHECK:STDOUT: !12 = !DILocation(line: 12, column: 3, scope: !7)
+// CHECK:STDOUT: !13 = !DILocation(line: 14, column: 19, scope: !7)
+// CHECK:STDOUT: !14 = !DILocation(line: 8, column: 3, scope: !7)
+// CHECK:STDOUT: !15 = !DILocation(line: 9, column: 3, scope: !7)
+// CHECK:STDOUT: !16 = !DILocation(line: 10, column: 3, scope: !7)
+// CHECK:STDOUT: !17 = !DILocation(line: 13, column: 3, scope: !7)
+// CHECK:STDOUT: !18 = !DILocation(line: 14, column: 3, scope: !7)
+// CHECK:STDOUT: !19 = !DILocation(line: 15, column: 3, scope: !7)
+// CHECK:STDOUT: !20 = !DILocation(line: 6, column: 1, scope: !7)