carbon-language/carbon-lang
1
0
Fork 0
mirror of https://github.com/carbon-language/carbon-lang.git synced 2026-10-05 22:02:55 +01:00
Code Issues Packages Projects Releases 10 Wiki Activity

Move self to the explicit () parameter list (proposal #7016) (#7272)

Browse Source 
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>
This commit is contained in:
Chandler Carruth
2026-06-10 15:30:43 +00:00
committed by GitHub
co-authored by josh11b
parent fb05da761f
commit 7871237c15
296 changed files with 6101 additions and 4899 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/testdata/interop/cpp/class/export/method.carbon
Vendored
+7 -7
View File
@@ -29,7 +29,7 @@ library "[[@TEST_NAME]]";
import Cpp;
class C {
fn M[self: Self]();
fn M(self);
}
inline Cpp '''
@@ -44,7 +44,7 @@ library "[[@TEST_NAME]]";
import Cpp;
class C {
fn M[self: Self]();
fn M(self);
}
inline Cpp '''
@@ -58,7 +58,7 @@ library "[[@TEST_NAME]]";
import Cpp;
class C {
fn M[ref self: Self]();
fn M(ref self);
}
inline Cpp '''
@@ -73,7 +73,7 @@ library "[[@TEST_NAME]]";
import Cpp;
class C {
fn M[ref self: Self]();
fn M(ref self);
}
inline Cpp '''
@@ -81,9 +81,9 @@ void F() {
// CHECK:STDERR: fail_ref_method_rvalue.carbon:[[@LINE+7]]:3: error: 'this' argument to member function 'M' is an rvalue, but function has non-const lvalue ref-qualifier [CppInteropParseError]
// CHECK:STDERR: 17 | Carbon::C().M();
// CHECK:STDERR: | ^
// CHECK:STDERR: fail_ref_method_rvalue.carbon:[[@LINE-8]]:25: note: 'M' declared here [CppInteropParseNote]
// CHECK:STDERR: 5 | fn M[ref self: Self]();
// CHECK:STDERR: | ^
// CHECK:STDERR: fail_ref_method_rvalue.carbon:[[@LINE-8]]:17: note: 'M' declared here [CppInteropParseNote]
// CHECK:STDERR: 5 | fn M(ref self);
// CHECK:STDERR: | ^
// CHECK:STDERR:
Carbon::C().M();
}