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Turmeric Compiler Flags

As of v0.24.0, every -X feature flag is an accept-and-warn no-op: the language features they used to gate are unconditionally on. Passing -X<name> for any of the 16 names listed below still parses successfully (downstream build.tur files keep compiling unchanged) but emits TUR-W0050 and otherwise does nothing.

The diagnostic and debug flags below (--strict-effects, --keep-contracts, --no-contracts, --dump-*, --emit-abi-trace, --warn-unused-result, --lint-panic, etc.) are real and still control compiler behavior.

Removed Feature Flags

Flag Feature is now standard; see
-Xlinear substructural-types-guide.md
-Xsubstructural substructural-types-guide.md
-Xunique-types uniqueness-types-guide.md
-Xgadt gadts-guide.md
-Xunion-types union-intersection-types-guide.md
-Xintersection-types union-intersection-types-guide.md
-Xeffect-types effects-system-guide.md
-Xcontracts contract-types-guide.md
-Xsessions session-types-guide.md
-Xdynamic-vars dynamic-vars-guide.md
-Xcallcc effects-system-guide.md
-Xsized-types sized-types-guide.md
-Xdata-literals data-literals-guide.md
-Xjson-reader json-guide.md
-Xschema-reader schema-guide.md
-Xsymbols symbols-guide.md

Each prints warning [TUR-W0050]: -X<name> is no longer needed; the feature is on by default and is otherwise ignored. There is no follow-up release planned to reject the flag entirely; the recognizer stays for the entire v0.24.x line. A v1.0+ cleanup may eventually retire the recognizer with its own deprecation window.

Note. The -X<name> prefix is retired for good -- none of the 16 names above will be reused. For genuinely experimental features in v1+ (the kind that are half-built, in-flux, or carry a known cost), the replacement surface is --enable=<name> with a built-in expiry policy. See experimental-flags-guide.md.

Behavior changes worth knowing

Diagnostic Flags

These are real flags, not deprecated.

--strict-effects

Emits warnings on functions whose inferred effect row is non-empty but whose signature carries no explicit #fx{...} annotation or forall [e] quantification. Opt-in.

--keep-contracts

Retains contract checks in release builds (just release). Without this flag, assert!/require!/ensure! calls are elided in release mode (contracts are on by default in debug). Per-contract ^always granularity may be added later.

--no-contracts (C2)

Strips all contracts at elaboration time -- the assert!/require!/ensure!/invariant! macros and { x : T | pred } refinement-type checks -- so predicates are never evaluated. Folds contract-enabled? to false and sets TUR_CONTRACTS_ENABLED 0 in the C preamble. Build a stripped program with just release-stripped <file> (i.e. tur --no-contracts build <file> -O2).

--warn-unused-result (R6a)

Warns when a result-shaped (ptr<void>) value is computed in statement position and discarded. Silence with ignore!, a let binding, or by using the value (e.g. the ? operator). Off by default.

--lint-panic (R6b)

Emits TUR-W0038 at panic call sites (panic/tur_panic, the contract macros, result-unwrap/option-unwrap). *-unwrap also gets a soft-deprecation hint toward *-must. Silence with a ;; #lint-panic-allow comment (top-of-file = whole file; immediately-preceding = single call). Off by default.

--dump-kinds

Prints the kind of every bound type to stdout after the kind-checking pass. Useful for debugging HKT typeclass definitions.

--dump-effects

Prints the inferred effect row for every function after elaboration, e.g.:

run-twice : forall [e]. (fn [(fn [] #{e} int)] #{e} int)

--dump-sizes (SZ8)

Prints the inferred type-level size index for each sized-GADT constructor application, e.g. size: SVCons : (SizedVec 2); an un-inferable index prints (SizedVec ?).

--emit-abi-trace

Prints, for each resolved call site, which C-level ABI path the emitter takes to reach the callee. Codegen-time diagnostic: fires for tur emit-c and tur build (the tur run interpreter still emits C under the hood, so it also prints). Output goes to stderr, one line per call:

abi-trace <line>:<col> <callee> <path>[ <clone-name>]

The <path> is one of four forms:

Path Meaning When
concrete-clone A monomorphized variant is called. The clone's mangled name is appended (e.g. cube__spec__double_double). A polymorphic global is instantiated at a concrete type whose C ABI differs from the carrier (Phases F/G/H).
carrier The generic int64_t carrier ABI is used; the value round-trips through the universal 64-bit handle. Genuinely polymorphic call sites, type-erased containers, and instantiations whose C type matches the carrier (e.g. cube at :int).
dictionary A typeclass method is dispatched through the instance machinery (dict_arg is set on the call). The callee name is the instance impl, e.g. __inst_Eq_eq__Tuple2. Any (.method ...) typeclass dispatch, whether resolved to a direct instance call (Phase H) or a dictionary vtable load.
polymorphic-wrapper The call goes through a tur_poly_fn_t rank-2 wrapper rather than a direct C function. Calling a forall-quantified function parameter inside a rank-2/rank-N body.

Example, against a file that exercises all four (see tests/fixtures/emit-abi-trace/):

$ tur emit-c --emit-abi-trace input.tur >/dev/null
...
abi-trace 26:11 cube carrier
abi-trace 29:11 cube concrete-clone cube__spec__double_double
abi-trace 17:12 f polymorphic-wrapper
abi-trace 36:9 __inst_Eq_eq__Tuple2 dictionary

Notes:

Use this flag to verify that a fully-typed hot path is being monomorphized rather than silently falling back to the carrier ABI -- specialization is best-effort and otherwise silent on fallback.

See Also