Allocator passing

Decided

D-0010, settled by the language’s author: part of spec §18. Older text cites it as 18.10.

Explicit parameter with a default argument. It is the user’s and the library’s concern, not the language’s (§14)

Superseded by D-0091 (r81, 2026-10-27, by the user): ordinary code no longer names an allocator; the compiler places memory (§14.6), and ties make every placement safe (§6.7). The explicit parameter stays only until that is implemented (T-0107), and the Allocator trait stays for std.