Parse C++23 and C++26 syntax: if consteval, contracts, pack indexing, and more

[arraypress]

Parses C++23 and C++26 syntax that currently produces ERROR nodes, and fixes two misparses of = default / = delete.

Added

• if consteval / if !consteval (C++23; overlaps Add support for C++23 feature if consteval #362).
• Contracts: pre(…) and post(r: …) on function declarators (C++26).
• Pack indexing Ts...[0] in types and expressions (C++26). ...[ is a single token, so a pack expansion followed by a subscript is never misread.
• Attributes on structured bindings: auto [a [[maybe_unused]], b] (C++26).
• = delete("reason") (C++26).
• Explicit instantiation of a class template: template class Ring<int, 4>;.
• Attributes before friend (overlaps Friend leading attribute #366).
• The ->* operator, and pointer-to-member field and typedef declarators (int Widget::* field;, typedef int Widget::* P;).

Fixed

• = default / = delete on a function outside a class. void f() = delete; produced a MISSING node, and void g() = delete("x"); parsed as a variable initialised by a delete expression.
• friend auto operator<=>(A const &, A const &) = default; parsed as a declaration whose initialiser was an identifier named default. Its expected tree in declarations.txt now has a function_definition with a default_method_clause, the same as the member form above it.

Tests: the other existing tests pass unchanged. New test/corpus/cpp23-26.txt covers each construct.

Generated with tree-sitter-cli 0.26.13 against the tree-sitter-c version in package.json. That CLI regenerates the current src/parser.c byte for byte. One conflict entry, [_declaration_modifiers, using_declaration], became unnecessary and is removed.

Size: parser.c grows from 25.9 MB to 26.5 MB.

🤖 Generated with Claude Code