Files
carbon-lang/toolchain/check/testdata/match_first/basic.carbon
T
Dana Jansens 168420f805 Allow impl redecl in match_first after a definition (#7491)
Previously the last decl had to be the definition. Now we allow a
declaration after a definition, so that the user can write a match_first
block last, and put (re-)declarations of impls in it, after the
definitions have already been written elsewhere.

We track the location of the decl that was associated with a match_first
block so that we can correctly point to it in diagnostics when an impl
is written twice in match_first blocks. Since impls may not be
redeclared across an import boundary, we will never have a `SemIR::Impl`
with a match_first from a different file in a redeclaration, so we don't
need to import the location of a previous decl that was in a match_first
for diagnostics. As such we just store a LocId on the `SemIR::Impl`
struct.
2026-07-15 14:12:37 +00:00

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// 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/none.carbon
// ^ARGS: -v compile %s
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/match_first/basic.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/match_first/basic.carbon
// --- empty.carbon
library "[[@TEST_NAME]]";
match_first {}
// --- todo_fail_class_inside.carbon
library "[[@TEST_NAME]]";
match_first {
// TODO: Only impls are allowed inside match_first.
class C;
}
// --- todo_fail_interface_inside.carbon
library "[[@TEST_NAME]]";
match_first {
// TODO: Only impls are allowed inside match_first.
interface Z;
}
// --- todo_fail_constraint_inside.carbon
library "[[@TEST_NAME]]";
match_first {
// TODO: Only impls are allowed inside match_first.
constraint N;
}
// --- todo_fail_function_inside.carbon
library "[[@TEST_NAME]]";
match_first {
// TODO: Only impls are allowed inside match_first.
fn F();
}
// --- fail_final_inside.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
// CHECK:STDERR: fail_final_inside.carbon:[[@LINE+7]]:3: error: `final impl` in `match_first` block [FinalImplInMatchFirst]
// CHECK:STDERR: final impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_final_inside.carbon:[[@LINE-4]]:1: note: the `match_first` block can be modified as `final` instead [FinalImplInMatchFirstNote]
// CHECK:STDERR: match_first {
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
final impl () as Z {}
}
// --- fail_final_redecl.carbon
library "[[@TEST_NAME]]";
interface Z {}
// CHECK:STDERR: fail_final_redecl.carbon:[[@LINE+4]]:1: error: impl declared but not defined [ImplMissingDefinition]
// CHECK:STDERR: final impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
final impl () as Z;
match_first {
// This is not seen as a redecl of the `final impl`. It's not valid to write
// an `impl` in `match_first` that overlaps a `final impl`, but we already
// have a diagnostic.
impl () as Z {}
}
// --- fail_final_redecl_defined_once.carbon
library "[[@TEST_NAME]]";
interface Z {}
final impl () as Z {}
match_first {
// This is not seen as a redecl of the `final impl`. It's not valid to write
// an `impl` in `match_first` that overlaps a `final impl`, but we already
// have a diagnostic.
// CHECK:STDERR: fail_final_redecl_defined_once.carbon:[[@LINE+4]]:3: error: impl declared but not defined [ImplMissingDefinition]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z;
}
// --- fail_final_redecl_defined_twice.carbon
library "[[@TEST_NAME]]";
interface Z {}
final impl () as Z {}
match_first {
// This is not seen as a redecl of the `final impl`. It's not valid to write
// an `impl` in `match_first` that overlaps a `final impl`, but we already
// have a diagnostic.
// CHECK:STDERR: fail_final_redecl_defined_twice.carbon:[[@LINE+7]]:3: error: `impl` will never be used [ImplFinalOverlapsNonFinal]
// CHECK:STDERR: impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR: fail_final_redecl_defined_twice.carbon:[[@LINE-8]]:1: note: `final impl` declared here would always be used instead [ImplFinalOverlapsNonFinalNote]
// CHECK:STDERR: final impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z {}
}
// --- fail_final_final_redecl.carbon
library "[[@TEST_NAME]]";
interface Z {}
final impl () as Z;
match_first {
// This _is_ seen as a redecl of the `final impl`. It's not valid to write
// an `impl` in `match_first` that overlaps a `final impl`, but we already
// have a diagnostic.
// CHECK:STDERR: fail_final_final_redecl.carbon:[[@LINE+7]]:3: error: `final impl` in `match_first` block [FinalImplInMatchFirst]
// CHECK:STDERR: final impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_final_final_redecl.carbon:[[@LINE-7]]:1: note: the `match_first` block can be modified as `final` instead [FinalImplInMatchFirstNote]
// CHECK:STDERR: match_first {
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
final impl () as Z {}
}
// --- decl.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
impl () as Z;
}
//@dump-sem-ir-begin
impl () as Z {}
//@dump-sem-ir-end
// --- definition.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
//@dump-sem-ir-begin
impl () as Z {}
//@dump-sem-ir-end
}
// --- redecl_defined.carbon
library "[[@TEST_NAME]]";
interface Z {}
impl () as Z;
match_first {
//@dump-sem-ir-begin
impl () as Z {}
//@dump-sem-ir-end
}
// --- redecl.carbon
library "[[@TEST_NAME]]";
interface Z {}
impl () as Z;
match_first {
impl () as Z;
}
impl () as Z {}
// --- redecl_after_defined.carbon
library "[[@TEST_NAME]]";
interface Z {}
impl () as Z {}
match_first {
impl () as Z;
}
// --- fail_redecl_with_definition_after_defined.carbon
library "[[@TEST_NAME]]";
interface Z {}
impl () as Z {}
match_first {
// CHECK:STDERR: fail_redecl_with_definition_after_defined.carbon:[[@LINE+7]]:3: error: redefinition of `impl () as Z` [ImplRedefinition]
// CHECK:STDERR: impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR: fail_redecl_with_definition_after_defined.carbon:[[@LINE-5]]:1: note: previous definition was here [ImplPreviousDefinition]
// CHECK:STDERR: impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z {}
}
// --- inside_class.carbon
library "[[@TEST_NAME]]";
interface Z {}
class C {
match_first {
impl Self as Z {}
}
}
// --- inside_function.carbon
library "[[@TEST_NAME]]";
interface Z {}
fn F() {
match_first {
impl () as Z {}
}
}
// --- fail_inside_interface.carbon
library "[[@TEST_NAME]]";
interface Z {}
interface Y {
// CHECK:STDERR: fail_inside_interface.carbon:[[@LINE+7]]:3: error: found `match_first` in invalid scope; expected namespace or class [MatchFirstInWrongScope]
// CHECK:STDERR: match_first {
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_inside_interface.carbon:[[@LINE-4]]:1: note: in enclosing scope here [MatchFirstInWrongScopeNote]
// CHECK:STDERR: interface Y {
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
match_first {
impl Self as Z {}
}
}
// --- fail_inside_constraint.carbon
library "[[@TEST_NAME]]";
interface Z {}
constraint N {
// CHECK:STDERR: fail_inside_constraint.carbon:[[@LINE+7]]:3: error: found `match_first` in invalid scope; expected namespace or class [MatchFirstInWrongScope]
// CHECK:STDERR: match_first {
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_inside_constraint.carbon:[[@LINE-4]]:1: note: in enclosing scope here [MatchFirstInWrongScopeNote]
// CHECK:STDERR: constraint N {
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR:
match_first {
impl Self as Z {}
}
}
// --- fail_inside_match_first.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
// CHECK:STDERR: fail_inside_match_first.carbon:[[@LINE+5]]:3: error: found `match_first` in invalid scope; expected namespace or class [MatchFirstInWrongScope]
// CHECK:STDERR: match_first {
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_inside_match_first.carbon: note: in enclosing scope here [MatchFirstInWrongScopeNote]
// CHECK:STDERR:
match_first {
impl () as Z {}
}
}
// --- fail_redecl_in_same_block.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
impl () as Z;
// CHECK:STDERR: fail_redecl_in_same_block.carbon:[[@LINE+7]]:3: error: impl declared in `match_first` more than once [ImplInTwoMatchFirst]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_redecl_in_same_block.carbon:[[@LINE-4]]:3: note: previous declaration here [ImplInTwoMatchFirstNote]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z;
}
impl () as Z {}
// --- fail_defined_in_same_block.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
impl () as Z;
// CHECK:STDERR: fail_defined_in_same_block.carbon:[[@LINE+7]]:3: error: impl declared in `match_first` more than once [ImplInTwoMatchFirst]
// CHECK:STDERR: impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR: fail_defined_in_same_block.carbon:[[@LINE-4]]:3: note: previous declaration here [ImplInTwoMatchFirstNote]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z {}
}
// --- fail_redecl_after_defined_in_same_block.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
impl () as Z {}
// CHECK:STDERR: fail_redecl_after_defined_in_same_block.carbon:[[@LINE+7]]:3: error: impl declared in `match_first` more than once [ImplInTwoMatchFirst]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_redecl_after_defined_in_same_block.carbon:[[@LINE-4]]:3: note: previous declaration here [ImplInTwoMatchFirstNote]
// CHECK:STDERR: impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z;
}
// --- fail_two_redecl_in_same_block.carbon
library "[[@TEST_NAME]]";
interface Z {}
impl () as Z {}
match_first {
impl () as Z;
// TODO: This "previous declaration" location is wrong. The redecl came after.
// CHECK:STDERR: fail_two_redecl_in_same_block.carbon:[[@LINE+7]]:3: error: impl declared in `match_first` more than once [ImplInTwoMatchFirst]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_two_redecl_in_same_block.carbon:[[@LINE-5]]:3: note: previous declaration here [ImplInTwoMatchFirstNote]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z;
}
// --- fail_redecl_in_different_block.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
impl () as Z;
}
match_first {
// CHECK:STDERR: fail_redecl_in_different_block.carbon:[[@LINE+7]]:3: error: impl declared in `match_first` more than once [ImplInTwoMatchFirst]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_redecl_in_different_block.carbon:[[@LINE-6]]:3: note: previous declaration here [ImplInTwoMatchFirstNote]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z;
}
impl () as Z {}
// --- fail_redecl_defined_in_different_block_firset.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
impl () as Z {}
}
match_first {
// CHECK:STDERR: fail_redecl_defined_in_different_block_firset.carbon:[[@LINE+7]]:3: error: impl declared in `match_first` more than once [ImplInTwoMatchFirst]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR: fail_redecl_defined_in_different_block_firset.carbon:[[@LINE-6]]:3: note: previous declaration here [ImplInTwoMatchFirstNote]
// CHECK:STDERR: impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z;
}
// --- fail_redecl_defined_in_different_block_second.carbon
library "[[@TEST_NAME]]";
interface Z {}
match_first {
impl () as Z;
}
match_first {
// CHECK:STDERR: fail_redecl_defined_in_different_block_second.carbon:[[@LINE+7]]:3: error: impl declared in `match_first` more than once [ImplInTwoMatchFirst]
// CHECK:STDERR: impl () as Z {}
// CHECK:STDERR: ^~~~~~~~~~~~~~
// CHECK:STDERR: fail_redecl_defined_in_different_block_second.carbon:[[@LINE-6]]:3: note: previous declaration here [ImplInTwoMatchFirstNote]
// CHECK:STDERR: impl () as Z;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
impl () as Z {}
}
// --- final_block_redecl.carbon
library "[[@TEST_NAME]]";
interface Z {}
impl () as Z;
final match_first {
impl () as Z;
}
//@dump-sem-ir-begin
impl () as Z {}
//@dump-sem-ir-end
// --- final_block_decl.carbon
library "[[@TEST_NAME]]";
interface Z {}
final match_first {
impl () as Z;
}
//@dump-sem-ir-begin
impl () as Z {}
//@dump-sem-ir-end
// --- final_block_defined.carbon
library "[[@TEST_NAME]]";
interface Z {}
impl () as Z;
final match_first {
//@dump-sem-ir-begin
impl () as Z {}
//@dump-sem-ir-end
}
// CHECK:STDOUT: --- decl.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Z.type: type = facet_type <@Z> [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %empty_tuple: %empty_tuple.type = tuple_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: impl_decl @empty_tuple.type.as.Z.impl [concrete] {} {
// CHECK:STDOUT: %.loc9_7.1: %empty_tuple.type = tuple_literal () [concrete = constants.%empty_tuple]
// CHECK:STDOUT: %.loc9_7.2: type = converted %.loc9_7.1, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
// CHECK:STDOUT: %Z.ref.loc9: type = name_ref Z, file.%Z.decl [concrete = constants.%Z.type]
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: impl @empty_tuple.type.as.Z.impl: %.loc6_9.2 as %Z.ref.loc6 {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: extend %Z.ref.loc6
// CHECK:STDOUT: match_first = position 0
// CHECK:STDOUT: witness = %Z.impl_witness
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- definition.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Z.type: type = facet_type <@Z> [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %empty_tuple: %empty_tuple.type = tuple_value () [concrete]
// CHECK:STDOUT: %Z.impl_witness: <witness> = impl_witness @empty_tuple.type.as.Z.impl.%Z.impl_witness_table [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: impl_decl @empty_tuple.type.as.Z.impl [concrete] {} {
// CHECK:STDOUT: %.loc7_9.1: %empty_tuple.type = tuple_literal () [concrete = constants.%empty_tuple]
// CHECK:STDOUT: %.loc7_9.2: type = converted %.loc7_9.1, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
// CHECK:STDOUT: %Z.ref: type = name_ref Z, file.%Z.decl [concrete = constants.%Z.type]
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: impl @empty_tuple.type.as.Z.impl: %.loc7_9.2 as %Z.ref {
// CHECK:STDOUT: %Z.impl_witness_table = impl_witness_table (), @empty_tuple.type.as.Z.impl [concrete]
// CHECK:STDOUT: %Z.impl_witness: <witness> = impl_witness %Z.impl_witness_table [concrete = constants.%Z.impl_witness]
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: extend %Z.ref
// CHECK:STDOUT: match_first = position 0
// CHECK:STDOUT: witness = %Z.impl_witness
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- redecl_defined.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Z.type: type = facet_type <@Z> [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %empty_tuple: %empty_tuple.type = tuple_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: impl_decl @empty_tuple.type.as.Z.impl [concrete] {} {
// CHECK:STDOUT: %.loc8_9.1: %empty_tuple.type = tuple_literal () [concrete = constants.%empty_tuple]
// CHECK:STDOUT: %.loc8_9.2: type = converted %.loc8_9.1, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
// CHECK:STDOUT: %Z.ref.loc8: type = name_ref Z, file.%Z.decl [concrete = constants.%Z.type]
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: impl @empty_tuple.type.as.Z.impl: %.loc5_7.2 as %Z.ref.loc5 {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: extend %Z.ref.loc5
// CHECK:STDOUT: match_first = position 0
// CHECK:STDOUT: witness = %Z.impl_witness
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- final_block_redecl.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Z.type: type = facet_type <@Z> [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %empty_tuple: %empty_tuple.type = tuple_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: impl_decl @empty_tuple.type.as.Z.impl [concrete] {} {
// CHECK:STDOUT: %.loc10_7.1: %empty_tuple.type = tuple_literal () [concrete = constants.%empty_tuple]
// CHECK:STDOUT: %.loc10_7.2: type = converted %.loc10_7.1, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
// CHECK:STDOUT: %Z.ref.loc10: type = name_ref Z, file.%Z.decl [concrete = constants.%Z.type]
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: impl @empty_tuple.type.as.Z.impl: %.loc5_7.2 as %Z.ref.loc5 {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: extend %Z.ref.loc5
// CHECK:STDOUT: match_first = position 0, final
// CHECK:STDOUT: witness = %Z.impl_witness
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- final_block_decl.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Z.type: type = facet_type <@Z> [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %empty_tuple: %empty_tuple.type = tuple_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: impl_decl @empty_tuple.type.as.Z.impl [concrete] {} {
// CHECK:STDOUT: %.loc9_7.1: %empty_tuple.type = tuple_literal () [concrete = constants.%empty_tuple]
// CHECK:STDOUT: %.loc9_7.2: type = converted %.loc9_7.1, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
// CHECK:STDOUT: %Z.ref.loc9: type = name_ref Z, file.%Z.decl [concrete = constants.%Z.type]
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: impl @empty_tuple.type.as.Z.impl: %.loc6_9.2 as %Z.ref.loc6 {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: extend %Z.ref.loc6
// CHECK:STDOUT: match_first = position 0, final
// CHECK:STDOUT: witness = %Z.impl_witness
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- final_block_defined.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Z.type: type = facet_type <@Z> [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %empty_tuple: %empty_tuple.type = tuple_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: impl_decl @empty_tuple.type.as.Z.impl [concrete] {} {
// CHECK:STDOUT: %.loc8_9.1: %empty_tuple.type = tuple_literal () [concrete = constants.%empty_tuple]
// CHECK:STDOUT: %.loc8_9.2: type = converted %.loc8_9.1, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
// CHECK:STDOUT: %Z.ref.loc8: type = name_ref Z, file.%Z.decl [concrete = constants.%Z.type]
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: impl @empty_tuple.type.as.Z.impl: %.loc5_7.2 as %Z.ref.loc5 {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: extend %Z.ref.loc5
// CHECK:STDOUT: match_first = position 0, final
// CHECK:STDOUT: witness = %Z.impl_witness
// CHECK:STDOUT: }
// CHECK:STDOUT: