Files
carbon-lang/toolchain/lower/testdata/impl/instance_method.carbon
T
Chandler Carruthandjosh11b 7871237c15 Move self to the explicit () parameter list (proposal #7016) (#7272)
Implements proposal #7016: `self` moves from the deduced implicit list
(`fn F[self: Self]()`) to the front of the explicit list. Its type may
be written explicitly (`fn F(self: Self)`) or omitted, in which case it
defaults to `Self` (`fn F(self)`, `fn F(ref self)`); `self` in the
implicit list is rejected.

Throughout checking, `self` is modeled as the first explicit parameter.
Because a method is just a function whose first parameter is `self`, it
can also be called as an ordinary function with the receiver passed
explicitly (`Type.M(obj, ...)`), not only as `obj.M(...)`. A new
`SemIR::CallArgParamPatterns` helper chooses the parameters matched
against the explicit arguments, excluding a leading `self` only when it
is supplied as a method-call receiver; arity checking, conversion, and
generic deduction use it. The resulting SemIR and lowering are
unchanged: `self` is still `call_param0`, and witnesses, thunks, and
vtables are unaffected.

An omitted `self` type is parsed as a `SelfBindingPattern` node with no
type expression; checking synthesizes the `Self` type so it behaves
exactly like `self: Self`. However, the exact spelling used must match
between a forward declaration and a definition, following #3763's rules
around declaration matching.

Generated functions, thunks, and C++ interop import/export build `self`
as the first explicit parameter, and the `self`-type override (e.g.
Derived->Base for a virtual override) applies to the explicit `self`.
Placement is validated by new diagnostics: `SelfInImplicitParamList`,
`SelfNotFirstParam`, and `SelfOutsideParamList`. The benchmark source
generator and the documentation adopt the `(self)` shorthand; the
prelude, the examples, and the test data are migrated in the following
commits.

Assisted-by: Claude Code with Claude Opus 4.7

---------

Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
2026-06-10 15:30:43 +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/convert.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/impl/instance_method.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/impl/instance_method.carbon
class A;
interface GetSelf {
fn Get(ref self) -> Self*;
}
class A {
extend impl as GetSelf {
fn Get(ref self) -> Self* {
return &self;
}
}
}
fn Call(a: A*) -> A* {
return (*a).Get();
}
// CHECK:STDOUT: ; ModuleID = 'instance_method.carbon'
// CHECK:STDOUT: source_filename = "instance_method.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define ptr @"_CGet.A.Main:GetSelf.Main"(ptr %self) #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: ret ptr %self, !dbg !10
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define ptr @_CCall.Main(ptr %a) #0 !dbg !11 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %A.as.GetSelf.impl.Get.call = call ptr @"_CGet.A.Main:GetSelf.Main"(ptr %a), !dbg !14
// CHECK:STDOUT: ret ptr %A.as.GetSelf.impl.Get.call, !dbg !15
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT:
// CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
// CHECK:STDOUT: !llvm.dbg.cu = !{!2}
// CHECK:STDOUT:
// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
// CHECK:STDOUT: !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
// CHECK:STDOUT: !3 = !DIFile(filename: "instance_method.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "Get", linkageName: "_CGet.A.Main:GetSelf.Main", scope: null, file: !3, line: 21, type: !5, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !8)
// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
// CHECK:STDOUT: !6 = !{!7, !7}
// CHECK:STDOUT: !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
// CHECK:STDOUT: !8 = !{!9}
// CHECK:STDOUT: !9 = !DILocalVariable(arg: 1, scope: !4, type: !7)
// CHECK:STDOUT: !10 = !DILocation(line: 22, column: 7, scope: !4)
// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "Call", linkageName: "_CCall.Main", scope: null, file: !3, line: 27, type: !5, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !12)
// CHECK:STDOUT: !12 = !{!13}
// CHECK:STDOUT: !13 = !DILocalVariable(arg: 1, scope: !11, type: !7)
// CHECK:STDOUT: !14 = !DILocation(line: 28, column: 10, scope: !11)
// CHECK:STDOUT: !15 = !DILocation(line: 28, column: 3, scope: !11)