Module decimal 

Decimal scalar(s).

cratestack#505 Direction 2 (the associated-type/marker shape, §7(b) of docs/design/decimal-backend-additivity.md): the two backends are no longer mutually exclusive Cargo features that resolve to one shared Decimal alias. Both decimal-rust-decimal and decimal-bigdecimal may now be selected simultaneously in the same build — each backend is exposed under its own unconditional (per-feature) name, RustDecimal / [BigDecimal], so two independent dependents that each choose a different backend no longer force a shared compile_error! on each other. cratestack-macros’ codegen picks which of the two a given schema uses via the decimal = RustDecimal | BigDecimal argument on the three entry macros (see cratestack-macros/src/include/decimal_arg.rs) — a schema-authored choice, not a Cargo feature — so the choice is resolved per invoking crate instead of once, globally, for the whole dependency graph.

The legacy Decimal alias below is kept for hand-written (non-codegen) call sites that only ever select one backend — it still only exists when exactly one feature is active, symmetrically with the “neither” case (see below): naming one ambiguous alias when two backends are both compiled in has no single correct answer, so — exactly like “neither” — it simply isn’t exported, rather than silently picking one (§6a of the design doc explains why a silent pick is the wrong failure mode). Generated code never references this alias; it names RustDecimal / BigDecimal directly.

DecimalValue is the backend-agnostic bound generated code and shared helpers (validators::validate_range_decimal) are written against — a blanket impl, unconditional, that both concrete backends (and nothing else already in this crate’s dependency graph — see its own doc) satisfy.

Selecting NEITHER feature is not an error (cratestack#505, #521)

Older versions of this crate hard-errored when NEITHER decimal feature was selected, which bit a consumer that legitimately used default-features = false to narrow its dependency graph and never touched Decimal at all. RustDecimal/BigDecimal (and the legacy Decimal alias) simply don’t exist when their backing feature isn’t selected — the crate compiles cleanly with a reduced surface instead of hard-failing every backend-agnostic consumer.

Selecting BOTH features is also not an error (cratestack#505)

This is the actual fix this module implements. Previously: Decimal could only ever be one alias, so both features active at once was a hard compile_error! — and because Cargo features are additive and unify globally across a dependency graph, two independent dependents, each individually well-formed and each deliberately choosing a different backend, could force that error into a combined build that neither one alone controlled or could fix. RustDecimal and BigDecimal are distinct names, each gated on its own feature independently (not on “exactly one”) — both may exist in the same compiled cratestack-core at once with no ambiguity, because nothing has to pick between them at this layer. The choice moves to the schema author, via cratestack-macros’ decimal = ... macro argument — see this module’s top doc.

Structs

RustDecimal

Decimal represents a 128 bit representation of a fixed-precision decimal number. The finite set of values of type Decimal are of the form m / 10^e, where m is an integer such that -2⁹⁶ < m < 2⁹⁶, and e is an integer between 0 and 28 inclusive.

Traits

DecimalValue

Backend-agnostic bound for a decimal scalar. Blanket-implemented for any type satisfying these bounds — deliberately structural rather than naming rust_decimal::Decimal / bigdecimal::BigDecimal explicitly, so this trait (and everything written against it, e.g. validators::validate_range_decimal) compiles unconditionally, with no #[cfg] gate of its own and no dependency on either optional backend crate.

Type Aliases

Decimal

Legacy single-backend alias, kept for hand-written call sites outside generated code. Only exists when exactly one backend feature is active — see this module’s doc for why “both” doesn’t pick a default instead of simply not exporting this name.