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https://github.com/carbon-language/carbon-lang.git
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Chandler Carruthandjosh11b
7871237c15
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>
80 lines
3.1 KiB
C++
80 lines
3.1 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/parse/context.h"
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#include "toolchain/parse/handle.h"
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namespace Carbon::Parse {
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auto HandlePattern(Context& context) -> void {
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auto state = context.PopState();
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switch (context.PositionKind()) {
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case Lex::TokenKind::OpenParen:
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context.PushStateForPattern(StateKind::PatternListAsTuple,
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state.in_var_pattern, state.in_unused_pattern,
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state.ambient_precedence);
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break;
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case Lex::TokenKind::Var:
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context.PushStateForPattern(StateKind::VariablePattern,
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state.in_var_pattern, state.in_unused_pattern,
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state.ambient_precedence);
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break;
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case Lex::TokenKind::Unused:
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context.PushStateForPattern(StateKind::UnusedPattern,
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state.in_var_pattern, state.in_unused_pattern,
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state.ambient_precedence);
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break;
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case Lex::TokenKind::Template:
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case Lex::TokenKind::Ref:
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// `self` is always a binding, even when its type is omitted (and so is not
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// followed by a `:`).
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case Lex::TokenKind::SelfValueIdentifier:
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context.PushStateForPattern(StateKind::BindingPattern,
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state.in_var_pattern, state.in_unused_pattern,
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state.ambient_precedence);
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break;
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default:
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if (context.PositionKind().is_word() &&
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context.PositionKind(Lookahead::NextToken)
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.is_binding_pattern_operator()) {
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context.PushStateForPattern(
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StateKind::BindingPattern, state.in_var_pattern,
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state.in_unused_pattern, state.ambient_precedence);
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break;
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}
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context.PushState(StateKind::ExprPattern);
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context.PushStateForExpr(state.ambient_precedence);
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break;
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}
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}
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auto HandleExprPattern(Context& context) -> void {
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auto state = context.PopState();
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// If we parsed an expression followed by a binding operator, we most likely
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// have a malformed attempt to introduce a binding pattern that we interpreted
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// as an expression pattern, so diagnose that here rather than diagnosing a
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// missing `;` at an outer level.
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if (context.PositionKind().is_binding_pattern_operator()) {
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if (!state.has_error) {
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CARBON_DIAGNOSTIC(ExpectedBindingName, Error,
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"unexpected expression before {0} in binding pattern",
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Lex::TokenKind);
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// TODO: Underline the parsed expression.
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context.emitter().Emit(*context.position(), ExpectedBindingName,
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context.PositionKind());
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state.has_error = true;
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}
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context.Consume();
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// It'd be nice to skip the type expression here too, but we can't determine
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// the end of it.
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}
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if (state.has_error) {
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context.ReturnErrorOnState();
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}
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}
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} // namespace Carbon::Parse
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