On Fri, Jun 16, 2023 at 9:17 AM Miguel Ojeda <ojeda@xxxxxxxxxx> wrote: > > Sometimes [1] users may attempt to setup the Rust support by > checking what Kbuild does and they end up finding out about > `scripts/rust_is_available.sh`. Inevitably, they run the script > directly, but unless they setup the required variables, > the result of the script is not meaningful. > > We could add some defaults to the variables, but that could be > confusing for those that may override the defaults (compared > to their kernel builds), and `$CC` would not be a simple default > in any case. > > Therefore, instead, explicitly check whether the expected variables > are set (`$RUSTC`, `$BINDGEN` and `$CC`). If not, print an explanation > about the fact that the script is meant to be called from Kbuild, > since that is the most likely cause for the variables not being set. > > Link: https://lore.kernel.org/oe-kbuild-all/Y6r4mXz5NS0+HVXo@xxxxxxx/ [1] > Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx> > --- > scripts/rust_is_available.sh | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/scripts/rust_is_available.sh b/scripts/rust_is_available.sh > index 1bdff4472cbe..7e0368babe64 100755 > --- a/scripts/rust_is_available.sh > +++ b/scripts/rust_is_available.sh > @@ -28,11 +28,40 @@ print_docs_reference() > echo >&2 "***" > } > > +# Print an explanation about the fact that the script is meant to be called from Kbuild. > +print_kbuild_explanation() > +{ > + echo >&2 "***" > + echo >&2 "*** This script is intended to be called from Kbuild." > + echo >&2 "*** Please use the 'rustavailable' target to call it instead." > + echo >&2 "*** Otherwise, the results may not be meaningful." > + exit 1 > +} > + > # If the script fails for any reason, or if there was any warning, then > # print a reference to the documentation on exit. > warning=0 > trap 'if [ $? -ne 0 ] || [ $warning -ne 0 ]; then print_docs_reference; fi' EXIT > > +# Check that the expected environment variables are set. > +if [ -z "${RUSTC+x}" ]; then > + echo >&2 "***" > + echo >&2 "*** Environment variable 'RUSTC' is not set." > + print_kbuild_explanation > +fi So, you want to check whether RUSTC is set or unset. (that is, you allow a case where RUSTC is set, but empty. It will eventually fail with a different error message anyway.) $ ./scripts/rust_is_available.sh *** *** Environment variable 'RUSTC' is not set. *** *** This script is intended to be called from Kbuild. *** Please use the 'rustavailable' target to call it instead. *** Otherwise, the results may not be meaningful. *** *** Please see Documentation/rust/quick-start.rst for details *** on how to set up the Rust support. *** $ RUSTC= BINDGEN= CC= ./scripts/rust_is_available.sh *** *** Rust compiler '' could not be found. *** *** *** Please see Documentation/rust/quick-start.rst for details *** on how to set up the Rust support. *** I would rather check whether RUSTC is empty or not with simpler code. if [ -z "${RUSTC}" ]; then ... fi > + > +if [ -z "${BINDGEN+x}" ]; then > + echo >&2 "***" > + echo >&2 "*** Environment variable 'BINDGEN' is not set." > + print_kbuild_explanation > +fi > + > +if [ -z "${CC+x}" ]; then > + echo >&2 "***" > + echo >&2 "*** Environment variable 'CC' is not set." > + print_kbuild_explanation > +fi > + > # Check that the Rust compiler exists. > if ! command -v "$RUSTC" >/dev/null; then > echo >&2 "***" > -- > 2.41.0 > -- Best Regards Masahiro Yamada
