Environment Variables

All environment variables that affect miniextendr’s build, configure, test, and lint processes.

🔗Install mode

There is no env var that controls install mode. configure auto-detects from a single signal:

Mode	When	Behavior
Source	`inst/vendor.tar.xz` absent	Cargo resolves via `[patch."git+url"]` to monorepo siblings, or fetches the git URL when no siblings are detected.
Tarball	`inst/vendor.tar.xz` present	Configure unpacks the tarball, writes `[source]` replacement to `vendored-sources`, build runs `--offline`.

NOT_CRAN, PREPARE_CRAN, FORCE_VENDOR, BUILD_CONTEXT are removed. See CRAN Compatibility for the full table and rationale.

🔗Cargo & Rust

Variable	Purpose	Default
`MINIEXTENDR_FEATURES`	Comma-separated cargo features to enable	All features except `nonapi`
`CARGO_PROFILE`	Build profile: `dev` or `release`	`release`
`CARGO_TARGET_DIR`	Artifact directory (must be outside `src/`)	`${abs_top_srcdir}/rust-target`
`CARGO_BUILD_TARGET`	Rust target triple for cross-compilation	Empty (native); auto-detected from autoconf host
`CARGO_HOME`	Cargo registry/cache directory for offline or restricted environments	Empty (cargo’s default, `~/.cargo`)
`RUST_TOOLCHAIN`	Toolchain selector (e.g., `+stable`, `+nightly`)	Empty (system default)
`ENV_RUSTFLAGS`	Rust compiler flags, passed as `RUSTFLAGS` to cargo	Value of `RUSTFLAGS`

All of the above are declared as AC_ARG_VAR in configure.ac and can be set when invoking ./configure:

cd rpkg && MINIEXTENDR_FEATURES="rayon,serde" CARGO_PROFILE=dev bash ./configure

🔗R Installation

Variable	Purpose	Default
`R_HOME`	Path to R installation	Auto-detected via `R RHOME`
`R_LIBS`	R library path for package installation	System default

🔗Lint

Variable	Purpose	Default
`MINIEXTENDR_LINT`	Disable lint: `0`, `false`, `no`, or `off`	Enabled

The lint runs automatically during cargo build/cargo check via build.rs. Disable with:

MINIEXTENDR_LINT=0 cargo check --manifest-path=rpkg/src/rust/Cargo.toml

🔗Runtime

Variable	Purpose	Default
`MINIEXTENDR_BACKTRACE`	Show full Rust backtraces on panic: `1` or `true` (case-insensitive)	Suppressed
`MINIEXTENDR_ENCODING_DEBUG`	Print encoding snapshot at init (any value enables)	Not set

MINIEXTENDR_BACKTRACE is read at panic time, not at package load, so it can be toggled during a session without restarting R. See Error Handling: Panic Hook and Backtraces.

MINIEXTENDR_ENCODING_DEBUG is only useful when embedding R via miniextendr-engine or on platforms where non-API encoding symbols are exported. See Encoding.

🔗minirextendr (Scaffolding)

Variable	Purpose	Default
`MINIEXTENDR_LOCAL_PATH`	Path to local miniextendr monorepo for tests/scaffolding	Auto-detected

🔗Wrapper generation (Internal)

Set by src/Makevars for the Rscript tools/write-wrappers.R step only; never set it yourself:

Variable	Purpose
`MINIEXTENDR_WRAPPER_GEN`	Presence makes `R_init_<pkg>` take its minimal path (routine registration only: no panic hook, locale check, ALTREP classes or mx_abi), because the library is unloaded right after the writers run. A package loaded with it set works in a degraded state.

🔗Cargo-Internal (Set Automatically)

These are set by cargo/build.rs and not meant for manual use:

Variable	Purpose
`CARGO_MANIFEST_DIR`	Directory containing Cargo.toml
`CARGO_CFG_TARGET_OS`	Target OS (windows, macos, linux)
`CARGO_CFG_TARGET_ENV`	Target environment (msvc, gnu, musl)
`CARGO_FEATURE_*`	One per enabled feature (uppercase + underscore)