Add support for converting between integer types

core/prelude/types/int.carbon

@@ -32,6 +32,11 @@ impl forall [N:! IntLiteral()] Int(N) as As(IntLiteral()) {
   fn Convert[self: Self]() -> IntLiteral() = "int.convert_checked";
 }
 
+// TODO: Allow as an implicit conversion if N > M.
+impl forall [M:! IntLiteral(), N:! IntLiteral()] Int(M) as As(Int(N)) {
+  fn Convert[self: Self]() -> Int(N) = "int.convert";
+}
+
 // Comparisons.
 
 impl forall [N:! IntLiteral()] Int(N) as Eq {

core/prelude/types/uint.carbon

@@ -5,6 +5,7 @@
 package Core library "prelude/types/uint";
 
 import library "prelude/types/int_literal";
+import library "prelude/types/int";
 import library "prelude/operators";
 
 private fn MakeUInt(size: IntLiteral()) -> type = "int.make_type_unsigned";
@@ -32,6 +33,21 @@ impl forall [N:! IntLiteral()] UInt(N) as As(IntLiteral()) {
   fn Convert[self: Self]() -> IntLiteral() = "int.convert_checked";
 }
 
+// TODO: Allow as an implicit conversion if N > M.
+impl forall [M:! IntLiteral(), N:! IntLiteral()] UInt(M) as As(UInt(N)) {
+  fn Convert[self: Self]() -> UInt(N) = "int.convert";
+}
+
+// TODO: Allow as an implicit conversion if N > M.
+impl forall [M:! IntLiteral(), N:! IntLiteral()] UInt(M) as As(Int(N)) {
+  fn Convert[self: Self]() -> Int(N) = "int.convert";
+}
+
+// Never implicit.
+impl forall [M:! IntLiteral(), N:! IntLiteral()] Int(M) as As(UInt(N)) {
+  fn Convert[self: Self]() -> UInt(N) = "int.convert";
+}
+
 // Comparisons.
 
 impl forall [N:! IntLiteral()] UInt(N) as Eq {

toolchain/check/eval.cpp

@@ -721,6 +721,26 @@ static auto ValidateFloatType(Context& context, SemIRLoc loc,
   return ValidateFloatBitWidth(context, loc, result.bit_width_id);
 }
 
+// Performs a conversion between integer types, truncating if the value doesn't
+// fit in the destination type.
+static auto PerformIntConvert(Context& context, SemIR::InstId arg_id,
+                              SemIR::TypeId dest_type_id) -> SemIR::ConstantId {
+  auto arg_val =
+      context.ints().Get(context.insts().GetAs<SemIR::IntValue>(arg_id).int_id);
+  auto [dest_is_signed, bit_width_id] =
+      context.sem_ir().types().GetIntTypeInfo(dest_type_id);
+  if (bit_width_id.is_valid()) {
+    // TODO: If the value fits in the destination type, reuse the existing
+    // int_id rather than recomputing it. This is probably the most common case.
+    bool src_is_signed = context.sem_ir().types().IsSignedInt(
+        context.insts().Get(arg_id).type_id());
+    unsigned width = context.ints().Get(bit_width_id).getZExtValue();
+    arg_val =
+        src_is_signed ? arg_val.sextOrTrunc(width) : arg_val.zextOrTrunc(width);
+  }
+  return MakeIntResult(context, dest_type_id, dest_is_signed, arg_val);
+}
+
 // Performs a conversion between integer types, diagnosing if the value doesn't
 // fit in the destination type.
 static auto PerformCheckedIntConvert(Context& context, SemIRLoc loc,
@@ -1284,6 +1304,12 @@ static auto MakeConstantForBuiltinCall(Context& context, SemIRLoc loc,
     }
 
     // Integer conversions.
+    case SemIR::BuiltinFunctionKind::IntConvert: {
+      if (phase == Phase::Symbolic) {
+        return MakeConstantResult(context, call, phase);
+      }
+      return PerformIntConvert(context, arg_ids[0], call.type_id);
+    }
     case SemIR::BuiltinFunctionKind::IntConvertChecked: {
       if (phase == Phase::Symbolic) {
         return MakeConstantResult(context, call, phase);

toolchain/check/testdata/builtins/int/convert.carbon

@@ -0,0 +1,226 @@
+// 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
+//
+// EXTRA-ARGS: --no-dump-sem-ir
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/builtins/int/convert.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/builtins/int/convert.carbon
+
+// --- int_ops.carbon
+
+library "[[@TEST_NAME]]";
+
+// Size preserving
+fn Int32ToInt32(a: i32) -> i32 = "int.convert";
+fn Int32ToUint32(a: i32) -> u32 = "int.convert";
+fn Uint32ToInt32(a: u32) -> i32 = "int.convert";
+fn Uint32ToUint32(a: u32) -> u32 = "int.convert";
+fn IntLiteralToIntLiteral(a: Core.IntLiteral()) -> Core.IntLiteral() = "int.convert";
+
+// Narrowing
+fn Int32ToInt16(a: i32) -> i16 = "int.convert";
+fn Int32ToUint16(a: i32) -> u16 = "int.convert";
+fn Uint32ToInt16(a: u32) -> i16 = "int.convert";
+fn Uint32ToUint16(a: u32) -> u16 = "int.convert";
+fn IntLiteralToInt16(a: Core.IntLiteral()) -> i16 = "int.convert";
+fn IntLiteralToUint16(a: Core.IntLiteral()) -> u16 = "int.convert";
+
+// Widening
+fn Int32ToInt64(a: i32) -> i64 = "int.convert";
+fn Int32ToUint64(a: i32) -> u64 = "int.convert";
+fn Uint32ToInt64(a: u32) -> i64 = "int.convert";
+fn Uint32ToUint64(a: u32) -> u64 = "int.convert";
+fn Int32ToIntLiteral(a: i32) -> Core.IntLiteral() = "int.convert";
+fn Uint32ToIntLiteral(a: u32) -> Core.IntLiteral() = "int.convert";
+
+class Expect[T:! type](N:! T) {}
+fn Test[T:! type](N:! T) -> Expect(N) { return {}; }
+
+// --- fail_self_test.carbon
+
+library "[[@TEST_NAME]]";
+import library "int_ops";
+
+fn F() {
+  // Ensure our testing machinery works.
+  // CHECK:STDERR: fail_self_test.carbon:[[@LINE+7]]:3: error: cannot convert from `Expect(0)` to `Expect(1)` with `as` [ExplicitAsConversionFailure]
+  // CHECK:STDERR:   Test(Int32ToInt32(0)) as Expect(1 as i32);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR: fail_self_test.carbon:[[@LINE+4]]:3: note: type `Expect(0)` does not implement interface `Core.As(Expect(1))` [MissingImplInMemberAccessNote]
+  // CHECK:STDERR:   Test(Int32ToInt32(0)) as Expect(1 as i32);
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  Test(Int32ToInt32(0)) as Expect(1 as i32);
+}
+
+// --- identity.carbon
+
+library "[[@TEST_NAME]]";
+import library "int_ops";
+
+fn F() {
+  Test(Int32ToInt32(-0x8000_0000)) as Expect(-0x8000_0000 as i32);
+  Test(Int32ToInt32(-1)) as Expect(-1 as i32);
+  Test(Int32ToInt32(0)) as Expect(0 as i32);
+  Test(Int32ToInt32(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as i32);
+
+  Test(Uint32ToUint32(0)) as Expect(0 as u32);
+  Test(Uint32ToUint32(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as u32);
+  Test(Uint32ToUint32(0x8000_0000)) as Expect(0x8000_0000 as u32);
+  Test(Uint32ToUint32(0xFFFF_FFFF)) as Expect(0xFFFF_FFFF as u32);
+
+  Test(IntLiteralToIntLiteral(0x1_0000_0000_0000_0000)) as
+      Expect(0x1_0000_0000_0000_0000);
+  Test(IntLiteralToIntLiteral(-1)) as Expect(-1);
+}
+
+// --- same_size.carbon
+
+library "[[@TEST_NAME]]";
+import library "int_ops";
+
+fn F() {
+  Test(Int32ToUint32(-0x8000_0000)) as Expect(0x8000_0000 as u32);
+  Test(Int32ToUint32(-1)) as Expect(0xFFFF_FFFF as u32);
+  Test(Int32ToUint32(0)) as Expect(0 as u32);
+  Test(Int32ToUint32(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as u32);
+
+  Test(Uint32ToInt32(0)) as Expect(0 as i32);
+  Test(Uint32ToInt32(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as i32);
+  Test(Uint32ToInt32(0x8000_0000)) as Expect(-0x8000_0000 as i32);
+  Test(Uint32ToInt32(0xFFFF_FFFF)) as Expect(-1 as i32);
+}
+
+// --- truncate.carbon
+
+library "[[@TEST_NAME]]";
+import library "int_ops";
+
+fn F() {
+  Test(Int32ToInt16(-0x8000_0000)) as Expect(0 as i16);
+  Test(Int32ToInt16(-0x7FFF_EDCC)) as Expect(0x1234 as i16);
+  Test(Int32ToInt16(-0x7FFF_1234)) as Expect(-0x1234 as i16);
+  Test(Int32ToInt16(-0x8000)) as Expect(-0x8000 as i16);
+  Test(Int32ToInt16(-1)) as Expect(-1 as i16);
+  Test(Int32ToInt16(0)) as Expect(0 as i16);
+  Test(Int32ToInt16(0x7FFF)) as Expect(0x7FFF as i16);
+  Test(Int32ToInt16(0xFFFF)) as Expect(-1 as i16);
+  Test(Int32ToInt16(0x7FFF_1234)) as Expect(0x1234 as i16);
+  Test(Int32ToInt16(0x7FFF_EDCC)) as Expect(-0x1234 as i16);
+  Test(Int32ToInt16(0x7FFF_FFFF)) as Expect(-1 as i16);
+
+  Test(Int32ToUint16(-0x8000_0000)) as Expect(0 as u16);
+  Test(Int32ToUint16(-0x7FFF_EDCC)) as Expect(0x1234 as u16);
+  Test(Int32ToUint16(-0x7FFF_1234)) as Expect(0xEDCC as u16);
+  Test(Int32ToUint16(-0x8000)) as Expect(0x8000 as u16);
+  Test(Int32ToUint16(-1)) as Expect(0xFFFF as u16);
+  Test(Int32ToUint16(0)) as Expect(0 as u16);
+  Test(Int32ToUint16(0x7FFF)) as Expect(0x7FFF as u16);
+  Test(Int32ToUint16(0xFFFF)) as Expect(0xFFFF as u16);
+  Test(Int32ToUint16(0x7FFF_1234)) as Expect(0x1234 as u16);
+  Test(Int32ToUint16(0x7FFF_EDCC)) as Expect(0xEDCC as u16);
+  Test(Int32ToUint16(0x7FFF_FFFF)) as Expect(0xFFFF as u16);
+
+  Test(Uint32ToInt16(0x8000_0000)) as Expect(0 as i16);
+  Test(Uint32ToInt16(0xFFFF_1234)) as Expect(0x1234 as i16);
+  Test(Uint32ToInt16(0xFFFF_EDCC)) as Expect(-0x1234 as i16);
+  Test(Uint32ToInt16(0xFFFF_8000)) as Expect(-0x8000 as i16);
+  Test(Uint32ToInt16(0xFFFF_FFFF)) as Expect(-1 as i16);
+  Test(Uint32ToInt16(0)) as Expect(0 as i16);
+  Test(Uint32ToInt16(0x7FFF)) as Expect(0x7FFF as i16);
+  Test(Uint32ToInt16(0xFFFF)) as Expect(-1 as i16);
+  Test(Uint32ToInt16(0x7FFF_1234)) as Expect(0x1234 as i16);
+  Test(Uint32ToInt16(0x7FFF_EDCC)) as Expect(-0x1234 as i16);
+  Test(Uint32ToInt16(0x7FFF_FFFF)) as Expect(-1 as i16);
+
+  Test(Uint32ToUint16(0x8000_0000)) as Expect(0 as u16);
+  Test(Uint32ToUint16(0xFFFF_1234)) as Expect(0x1234 as u16);
+  Test(Uint32ToUint16(0xFFFF_EDCC)) as Expect(0xEDCC as u16);
+  Test(Uint32ToUint16(0xFFFF_8000)) as Expect(0x8000 as u16);
+  Test(Uint32ToUint16(0xFFFF_FFFF)) as Expect(0xFFFF as u16);
+  Test(Uint32ToUint16(0)) as Expect(0 as u16);
+  Test(Uint32ToUint16(0x7FFF)) as Expect(0x7FFF as u16);
+  Test(Uint32ToUint16(0xFFFF)) as Expect(0xFFFF as u16);
+  Test(Uint32ToUint16(0x7FFF_1234)) as Expect(0x1234 as u16);
+  Test(Uint32ToUint16(0x7FFF_EDCC)) as Expect(0xEDCC as u16);
+  Test(Uint32ToUint16(0x7FFF_FFFF)) as Expect(0xFFFF as u16);
+
+  Test(IntLiteralToInt16(0)) as Expect(0 as i16);
+  Test(IntLiteralToInt16(0x7FFF)) as Expect(0x7FFF as i16);
+  Test(IntLiteralToInt16(0x8000)) as Expect(-0x8000 as i16);
+  Test(IntLiteralToInt16(0xFFFF)) as Expect(-1 as i16);
+  Test(IntLiteralToInt16(0x1_2345)) as Expect(0x2345 as i16);
+  Test(IntLiteralToInt16(-1)) as Expect(-1 as i16);
+
+  Test(IntLiteralToUint16(0)) as Expect(0 as u16);
+  Test(IntLiteralToUint16(0x7FFF)) as Expect(0x7FFF as u16);
+  Test(IntLiteralToUint16(0x8000)) as Expect(0x8000 as u16);
+  Test(IntLiteralToUint16(0xFFFF)) as Expect(0xFFFF as u16);
+  Test(IntLiteralToUint16(0x1_2345)) as Expect(0x2345 as u16);
+  Test(IntLiteralToUint16(-1)) as Expect(0xFFFF as u16);
+}
+
+// --- zero_extend.carbon
+
+library "[[@TEST_NAME]]";
+import library "int_ops";
+
+fn F() {
+  Test(Uint32ToInt64(0)) as Expect(0 as i64);
+  Test(Uint32ToInt64(0x1234_5678)) as Expect(0x1234_5678 as i64);
+  Test(Uint32ToInt64(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as i64);
+  Test(Uint32ToInt64(0x8000_0000)) as Expect(0x8000_0000 as i64);
+  Test(Uint32ToInt64(0xFFFF_FFFF)) as Expect(0xFFFF_FFFF as i64);
+
+  Test(Uint32ToUint64(0)) as Expect(0 as u64);
+  Test(Uint32ToUint64(0x1234_5678)) as Expect(0x1234_5678 as u64);
+  Test(Uint32ToUint64(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as u64);
+  Test(Uint32ToUint64(0x8000_0000)) as Expect(0x8000_0000 as u64);
+  Test(Uint32ToUint64(0xFFFF_FFFF)) as Expect(0xFFFF_FFFF as u64);
+
+  Test(Uint32ToIntLiteral(0x1234_5678)) as Expect(0x1234_5678);
+  Test(Uint32ToIntLiteral(0x8765_4321)) as Expect(0x8765_4321);
+  Test(Uint32ToIntLiteral(0xFFFF_FFFF)) as Expect(0xFFFF_FFFF);
+}
+
+// --- sign_extend.carbon
+
+library "[[@TEST_NAME]]";
+import library "int_ops";
+
+fn F() {
+  Test(Int32ToInt64(0)) as Expect(0 as i64);
+  Test(Int32ToInt64(0x1234_5678)) as Expect(0x1234_5678 as i64);
+  Test(Int32ToInt64(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as i64);
+  Test(Int32ToInt64(-1)) as Expect(-1 as i64);
+
+  Test(Int32ToUint64(0)) as Expect(0 as u64);
+  Test(Int32ToUint64(0x1234_5678)) as Expect(0x1234_5678 as u64);
+  Test(Int32ToUint64(0x7FFF_FFFF)) as Expect(0x7FFF_FFFF as u64);
+  Test(Int32ToUint64(-1)) as Expect(0xFFFF_FFFF_FFFF_FFFF as u64);
+  Test(Int32ToUint64(-0x8000_0000)) as Expect(0xFFFF_FFFF_8000_0000 as u64);
+
+  Test(Int32ToIntLiteral(0x1234_5678)) as Expect(0x1234_5678);
+  Test(Int32ToIntLiteral(-0x1234_5678)) as Expect(-0x1234_5678);
+  Test(Int32ToIntLiteral(-1)) as Expect(-1);
+}
+
+// --- fail_not_constant.carbon
+
+library "[[@TEST_NAME]]";
+import library "int_ops";
+
+let not_constant: Core.IntLiteral() = 0;
+
+// CHECK:STDERR: fail_not_constant.carbon:[[@LINE+7]]:33: error: non-constant call to compile-time-only function [NonConstantCallToCompTimeOnlyFunction]
+// CHECK:STDERR: let convert_not_constant: i16 = IntLiteralToInt16(not_constant);
+// CHECK:STDERR:                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// CHECK:STDERR: fail_not_constant.carbon:[[@LINE-7]]:1: in import [InImport]
+// CHECK:STDERR: int_ops.carbon:16:1: note: compile-time-only function declared here [CompTimeOnlyFunctionHere]
+// CHECK:STDERR: fn IntLiteralToInt16(a: Core.IntLiteral()) -> i16 = "int.convert";
+// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+let convert_not_constant: i16 = IntLiteralToInt16(not_constant);

toolchain/check/testdata/class/import.carbon

@@ -319,5 +319,5 @@ fn Run() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F[%self.param_patt: %ForwardDeclared.7b34f2.1]() [from "a.carbon"];
 // CHECK:STDOUT:
-// CHECK:STDOUT: fn @G[addr <unexpected>.inst1019: %ptr.6cf]() [from "a.carbon"];
+// CHECK:STDOUT: fn @G[addr <unexpected>.inst1063: %ptr.6cf]() [from "a.carbon"];
 // CHECK:STDOUT:

toolchain/check/testdata/operators/overloaded/fail_error_recovery.carbon

@@ -37,8 +37,8 @@ fn G(n: i32) {
 // CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [template]
 // CHECK:STDOUT:   %G.type: type = fn_type @G [template]
 // CHECK:STDOUT:   %G: %G.type = struct_value () [template]
-// CHECK:STDOUT:   %impl_witness.a03: <witness> = impl_witness (imports.%import_ref.c16), @impl.13(%int_32) [template]
-// CHECK:STDOUT:   %Op.type.16e: type = fn_type @Op.2, @impl.13(%int_32) [template]
+// CHECK:STDOUT:   %impl_witness.a03: <witness> = impl_witness (imports.%import_ref.c16), @impl.14(%int_32) [template]
+// CHECK:STDOUT:   %Op.type.16e: type = fn_type @Op.2, @impl.14(%int_32) [template]
 // CHECK:STDOUT:   %Op.ceb: %Op.type.16e = struct_value () [template]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/struct/import.carbon

@@ -276,7 +276,7 @@ var c_bad: C({.a = 3, .b = 4}) = F();
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %import_ref.8f2: <witness> = import_ref Implicit//default, loc8_34, loaded [template = constants.%complete_type.357]
-// CHECK:STDOUT:   %import_ref.5c7 = import_ref Implicit//default, inst1017 [no loc], unloaded
+// CHECK:STDOUT:   %import_ref.5c7 = import_ref Implicit//default, inst1061 [no loc], unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -396,7 +396,7 @@ var c_bad: C({.a = 3, .b = 4}) = F();
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %import_ref.8f2: <witness> = import_ref Implicit//default, loc8_34, loaded [template = constants.%complete_type.357]
-// CHECK:STDOUT:   %import_ref.5c7 = import_ref Implicit//default, inst1017 [no loc], unloaded
+// CHECK:STDOUT:   %import_ref.5c7 = import_ref Implicit//default, inst1061 [no loc], unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -486,7 +486,7 @@ var c_bad: C({.a = 3, .b = 4}) = F();
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %import_ref.8f2: <witness> = import_ref Implicit//default, loc8_34, loaded [template = constants.%complete_type.357]
-// CHECK:STDOUT:   %import_ref.5c7 = import_ref Implicit//default, inst1017 [no loc], unloaded
+// CHECK:STDOUT:   %import_ref.5c7 = import_ref Implicit//default, inst1061 [no loc], unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {

toolchain/check/testdata/tuple/import.carbon

@@ -293,7 +293,7 @@ var c_bad: C((3, 4)) = F();
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %import_ref.8f2: <witness> = import_ref Implicit//default, loc7_26, loaded [template = constants.%complete_type.357]
-// CHECK:STDOUT:   %import_ref.2e0 = import_ref Implicit//default, inst1052 [no loc], unloaded
+// CHECK:STDOUT:   %import_ref.2e0 = import_ref Implicit//default, inst1096 [no loc], unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -421,7 +421,7 @@ var c_bad: C((3, 4)) = F();
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %import_ref.8f2: <witness> = import_ref Implicit//default, loc7_26, loaded [template = constants.%complete_type.357]
-// CHECK:STDOUT:   %import_ref.2e0 = import_ref Implicit//default, inst1052 [no loc], unloaded
+// CHECK:STDOUT:   %import_ref.2e0 = import_ref Implicit//default, inst1096 [no loc], unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -511,7 +511,7 @@ var c_bad: C((3, 4)) = F();
 // CHECK:STDOUT:     import Core//prelude/...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %import_ref.8f2: <witness> = import_ref Implicit//default, loc7_26, loaded [template = constants.%complete_type.357]
-// CHECK:STDOUT:   %import_ref.2e0 = import_ref Implicit//default, inst1052 [no loc], unloaded
+// CHECK:STDOUT:   %import_ref.2e0 = import_ref Implicit//default, inst1096 [no loc], unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {