Constant NO_STATIC_TYPE 

pub const NO_STATIC_TYPE: u32 = u32::MAX; // 4_294_967_295u32

DebugLocalMeta::type_id when the MIR local has no static type (MirType::Opaque) — a pipeline accumulator, a fused-loop item.

A Type is an index into the compiler’s arena, so every small integer is a valid handle and there is no in-band “none” — 0 would render as whatever type the arena interned first. u32::MAX is outside any arena the debugger will ever pair this with (type_str already omits an out-of-range id), and the metadata’s null descriptor says the same thing in the other field.