scripts/rust_is_available.sh - pub/scm/linux/kernel/git/mkl/linux-can - Git at Google

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 #
 # Tests whether a suitable Rust toolchain is available.

 set -e

 min_tool_version=$(dirname $0)/min-tool-version.sh

 # Convert the version string x.y.z to a canonical up-to-7-digits form.
 #
 # Note that this function uses one more digit (compared to other
 # instances in other version scripts) to give a bit more space to
 # `rustc` since it will reach 1.100.0 in late 2026.
 get_canonical_version()
 {
 	IFS=.
 	set -- $1
 	echo $((100000 * $1 + 100 * $2 + $3))
 }

 # Print a reference to the Quick Start guide in the documentation.
 print_docs_reference()
 {
 	echo >&2 "***"
 	echo >&2 "*** Please see Documentation/rust/quick-start.rst for details"
 	echo >&2 "*** on how to set up the Rust support."
 	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

 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 "$RUSTC" >/dev/null; then
 	echo >&2 "***"
 	echo >&2 "*** Rust compiler '$RUSTC' could not be found."
 	echo >&2 "***"
 	exit 1
 fi

 # Check that the Rust bindings generator exists.
 if ! command -v "$BINDGEN" >/dev/null; then
 	echo >&2 "***"
 	echo >&2 "*** Rust bindings generator '$BINDGEN' could not be found."
 	echo >&2 "***"
 	exit 1
 fi

 # Check that the Rust compiler version is suitable.
 #
 # Non-stable and distributions' versions may have a version suffix, e.g. `-dev`.
 rust_compiler_output=$( \
 	LC_ALL=C "$RUSTC" --version 2>/dev/null
 ) || rust_compiler_code=$?
 if [ -n "$rust_compiler_code" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Running '$RUSTC' to check the Rust compiler version failed with"
 	echo >&2 "*** code $rust_compiler_code. See output and docs below for details:"
 	echo >&2 "***"
 	echo >&2 "$rust_compiler_output"
 	echo >&2 "***"
 	exit 1
 fi
 rust_compiler_version=$( \
 	echo "$rust_compiler_output" \
 		| sed -nE '1s:.*rustc ([0-9]+\.[0-9]+\.[0-9]+).*:\1:p'
 )
 if [ -z "$rust_compiler_version" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Running '$RUSTC' to check the Rust compiler version did not return"
 	echo >&2 "*** an expected output. See output and docs below for details:"
 	echo >&2 "***"
 	echo >&2 "$rust_compiler_output"
 	echo >&2 "***"
 	exit 1
 fi
 rust_compiler_min_version=$($min_tool_version rustc)
 rust_compiler_cversion=$(get_canonical_version $rust_compiler_version)
 rust_compiler_min_cversion=$(get_canonical_version $rust_compiler_min_version)
 if [ "$rust_compiler_cversion" -lt "$rust_compiler_min_cversion" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Rust compiler '$RUSTC' is too old."
 	echo >&2 "***   Your version:    $rust_compiler_version"
 	echo >&2 "***   Minimum version: $rust_compiler_min_version"
 	echo >&2 "***"
 	exit 1
 fi

 # Check that the Rust bindings generator is suitable.
 #
 # Non-stable and distributions' versions may have a version suffix, e.g. `-dev`.
 #
 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0
 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed when
 # the minimum version is upgraded past the latter (0.69.1 and 0.71.1 both fixed
 # the issue).
 rust_bindings_generator_output=$( \
 	LC_ALL=C "$BINDGEN" --version workaround-for-0.69.0 2>/dev/null
 ) || rust_bindings_generator_code=$?
 if [ -n "$rust_bindings_generator_code" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Running '$BINDGEN' to check the Rust bindings generator version failed with"
 	echo >&2 "*** code $rust_bindings_generator_code. See output and docs below for details:"
 	echo >&2 "***"
 	echo >&2 "$rust_bindings_generator_output"
 	echo >&2 "***"
 	exit 1
 fi
 rust_bindings_generator_version=$( \
 	echo "$rust_bindings_generator_output" \
 		| sed -nE '1s:.*bindgen ([0-9]+\.[0-9]+\.[0-9]+).*:\1:p'
 )
 if [ -z "$rust_bindings_generator_version" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Running '$BINDGEN' to check the bindings generator version did not return"
 	echo >&2 "*** an expected output. See output and docs below for details:"
 	echo >&2 "***"
 	echo >&2 "$rust_bindings_generator_output"
 	echo >&2 "***"
 	exit 1
 fi
 rust_bindings_generator_min_version=$($min_tool_version bindgen)
 rust_bindings_generator_cversion=$(get_canonical_version $rust_bindings_generator_version)
 rust_bindings_generator_min_cversion=$(get_canonical_version $rust_bindings_generator_min_version)
 if [ "$rust_bindings_generator_cversion" -lt "$rust_bindings_generator_min_cversion" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Rust bindings generator '$BINDGEN' is too old."
 	echo >&2 "***   Your version:    $rust_bindings_generator_version"
 	echo >&2 "***   Minimum version: $rust_bindings_generator_min_version"
 	echo >&2 "***"
 	exit 1
 fi
 if [ "$rust_bindings_generator_cversion" -eq 6600 ] ||
 	[ "$rust_bindings_generator_cversion" -eq 6601 ]; then
 	# Distributions may have patched the issue (e.g. Debian did).
 	if ! "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_0_66.h >/dev/null; then
 		echo >&2 "***"
 		echo >&2 "*** Rust bindings generator '$BINDGEN' versions 0.66.0 and 0.66.1 may not"
 		echo >&2 "*** work due to a bug (https://github.com/rust-lang/rust-bindgen/pull/2567),"
 		echo >&2 "*** unless patched (like Debian's)."
 		echo >&2 "***   Your version:     $rust_bindings_generator_version"
 		echo >&2 "***"
 		warning=1
 	fi
 fi

 # Check that the `libclang` used by the Rust bindings generator is suitable.
 #
 # In order to do that, first invoke `bindgen` to get the `libclang` version
 # found by `bindgen`. This step may already fail if, for instance, `libclang`
 # is not found, thus inform the user in such a case.
 bindgen_libclang_output=$( \
 	LC_ALL=C "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_libclang.h 2>&1 >/dev/null
 ) || bindgen_libclang_code=$?
 if [ -n "$bindgen_libclang_code" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Running '$BINDGEN' to check the libclang version (used by the Rust"
 	echo >&2 "*** bindings generator) failed with code $bindgen_libclang_code. This may be caused by"
 	echo >&2 "*** a failure to locate libclang. See output and docs below for details:"
 	echo >&2 "***"
 	echo >&2 "$bindgen_libclang_output"
 	echo >&2 "***"
 	exit 1
 fi

 # `bindgen` returned successfully, thus use the output to check that the version
 # of the `libclang` found by the Rust bindings generator is suitable.
 #
 # Unlike other version checks, note that this one does not necessarily appear
 # in the first line of the output, thus no `sed` address is provided.
 bindgen_libclang_version=$( \
 	echo "$bindgen_libclang_output" \
 		| sed -nE 's:.*clang version ([0-9]+\.[0-9]+\.[0-9]+).*:\1:p'
 )
 if [ -z "$bindgen_libclang_version" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Running '$BINDGEN' to check the libclang version (used by the Rust"
 	echo >&2 "*** bindings generator) did not return an expected output. See output"
 	echo >&2 "*** and docs below for details:"
 	echo >&2 "***"
 	echo >&2 "$bindgen_libclang_output"
 	echo >&2 "***"
 	exit 1
 fi
 bindgen_libclang_min_version=$($min_tool_version llvm)
 bindgen_libclang_cversion=$(get_canonical_version $bindgen_libclang_version)
 bindgen_libclang_min_cversion=$(get_canonical_version $bindgen_libclang_min_version)
 if [ "$bindgen_libclang_cversion" -lt "$bindgen_libclang_min_cversion" ]; then
 	echo >&2 "***"
 	echo >&2 "*** libclang (used by the Rust bindings generator '$BINDGEN') is too old."
 	echo >&2 "***   Your version:    $bindgen_libclang_version"
 	echo >&2 "***   Minimum version: $bindgen_libclang_min_version"
 	echo >&2 "***"
 	exit 1
 fi

 if [ "$bindgen_libclang_cversion" -ge 1900100 ] &&
 	[ "$rust_bindings_generator_cversion" -lt 6905 ]; then
 	# Distributions may have patched the issue (e.g. Debian did).
 	if ! "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_libclang_concat.h | grep -q foofoo; then
 		echo >&2 "***"
 		echo >&2 "*** Rust bindings generator '$BINDGEN' < 0.69.5 together with libclang >= 19.1"
 		echo >&2 "*** may not work due to a bug (https://github.com/rust-lang/rust-bindgen/pull/2824),"
 		echo >&2 "*** unless patched (like Debian's)."
 		echo >&2 "***   Your bindgen version:  $rust_bindings_generator_version"
 		echo >&2 "***   Your libclang version: $bindgen_libclang_version"
 		echo >&2 "***"
 		warning=1
 	fi
 fi

 # If the C compiler is Clang, then we can also check whether its version
 # matches the `libclang` version used by the Rust bindings generator.
 #
 # In the future, we might be able to perform a full version check, see
 # https://github.com/rust-lang/rust-bindgen/issues/2138.
 cc_name=$($(dirname $0)/cc-version.sh $CC | cut -f1 -d' ')
 if [ "$cc_name" = Clang ]; then
 	clang_version=$( \
 		LC_ALL=C $CC --version 2>/dev/null \
 			| sed -nE '1s:.*version ([0-9]+\.[0-9]+\.[0-9]+).*:\1:p'
 	)
 	if [ "$clang_version" != "$bindgen_libclang_version" ]; then
 		echo >&2 "***"
 		echo >&2 "*** libclang (used by the Rust bindings generator '$BINDGEN')"
 		echo >&2 "*** version does not match Clang's. This may be a problem."
 		echo >&2 "***   libclang version: $bindgen_libclang_version"
 		echo >&2 "***   Clang version:    $clang_version"
 		echo >&2 "***"
 		warning=1
 	fi
 fi

 # Check that the source code for the `core` standard library exists.
 #
 # `$KRUSTFLAGS` is passed in case the user added `--sysroot`.
 rustc_sysroot=$("$RUSTC" $KRUSTFLAGS --print sysroot)
 rustc_src=${RUST_LIB_SRC:-"$rustc_sysroot/lib/rustlib/src/rust/library"}
 rustc_src_core="$rustc_src/core/src/lib.rs"
 if [ ! -e "$rustc_src_core" ]; then
 	echo >&2 "***"
 	echo >&2 "*** Source code for the 'core' standard library could not be found"
 	echo >&2 "*** at '$rustc_src_core'."
 	echo >&2 "***"
 	exit 1
 fi
	#!/bin/sh
	# SPDX-License-Identifier: GPL-2.0
	#
	# Tests whether a suitable Rust toolchain is available.

	set -e

	min_tool_version=$(dirname $0)/min-tool-version.sh

	# Convert the version string x.y.z to a canonical up-to-7-digits form.
	#
	# Note that this function uses one more digit (compared to other
	# instances in other version scripts) to give a bit more space to
	# `rustc` since it will reach 1.100.0 in late 2026.
	get_canonical_version()
	{
	IFS=.
	set -- $1
	echo $((100000 * $1 + 100 * $2 + $3))
	}

	# Print a reference to the Quick Start guide in the documentation.
	print_docs_reference()
	{
	echo >&2 "***"
	echo >&2 "*** Please see Documentation/rust/quick-start.rst for details"
	echo >&2 "*** on how to set up the Rust support."
	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

	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 "$RUSTC" >/dev/null; then
	echo >&2 "***"
	echo >&2 "*** Rust compiler '$RUSTC' could not be found."
	echo >&2 "***"
	exit 1
	fi

	# Check that the Rust bindings generator exists.
	if ! command -v "$BINDGEN" >/dev/null; then
	echo >&2 "***"
	echo >&2 "*** Rust bindings generator '$BINDGEN' could not be found."
	echo >&2 "***"
	exit 1
	fi

	# Check that the Rust compiler version is suitable.
	#
	# Non-stable and distributions' versions may have a version suffix, e.g. `-dev`.
	rust_compiler_output=$( \
	LC_ALL=C "$RUSTC" --version 2>/dev/null
	) \|\| rust_compiler_code=$?
	if [ -n "$rust_compiler_code" ]; then
	echo >&2 "***"
	echo >&2 "*** Running '$RUSTC' to check the Rust compiler version failed with"
	echo >&2 "*** code $rust_compiler_code. See output and docs below for details:"
	echo >&2 "***"
	echo >&2 "$rust_compiler_output"
	echo >&2 "***"
	exit 1
	fi
	rust_compiler_version=$( \
	echo "$rust_compiler_output" \
	\| sed -nE '1s:.rustc ([0-9]+\.[0-9]+\.[0-9]+).:\1:p'
	)
	if [ -z "$rust_compiler_version" ]; then
	echo >&2 "***"
	echo >&2 "*** Running '$RUSTC' to check the Rust compiler version did not return"
	echo >&2 "*** an expected output. See output and docs below for details:"
	echo >&2 "***"
	echo >&2 "$rust_compiler_output"
	echo >&2 "***"
	exit 1
	fi
	rust_compiler_min_version=$($min_tool_version rustc)
	rust_compiler_cversion=$(get_canonical_version $rust_compiler_version)
	rust_compiler_min_cversion=$(get_canonical_version $rust_compiler_min_version)
	if [ "$rust_compiler_cversion" -lt "$rust_compiler_min_cversion" ]; then
	echo >&2 "***"
	echo >&2 "*** Rust compiler '$RUSTC' is too old."
	echo >&2 "*** Your version: $rust_compiler_version"
	echo >&2 "*** Minimum version: $rust_compiler_min_version"
	echo >&2 "***"
	exit 1
	fi

	# Check that the Rust bindings generator is suitable.
	#
	# Non-stable and distributions' versions may have a version suffix, e.g. `-dev`.
	#
	# The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
	# (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0
	# (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed when
	# the minimum version is upgraded past the latter (0.69.1 and 0.71.1 both fixed
	# the issue).
	rust_bindings_generator_output=$( \
	LC_ALL=C "$BINDGEN" --version workaround-for-0.69.0 2>/dev/null
	) \|\| rust_bindings_generator_code=$?
	if [ -n "$rust_bindings_generator_code" ]; then
	echo >&2 "***"
	echo >&2 "*** Running '$BINDGEN' to check the Rust bindings generator version failed with"
	echo >&2 "*** code $rust_bindings_generator_code. See output and docs below for details:"
	echo >&2 "***"
	echo >&2 "$rust_bindings_generator_output"
	echo >&2 "***"
	exit 1
	fi
	rust_bindings_generator_version=$( \
	echo "$rust_bindings_generator_output" \
	\| sed -nE '1s:.bindgen ([0-9]+\.[0-9]+\.[0-9]+).:\1:p'
	)
	if [ -z "$rust_bindings_generator_version" ]; then
	echo >&2 "***"
	echo >&2 "*** Running '$BINDGEN' to check the bindings generator version did not return"
	echo >&2 "*** an expected output. See output and docs below for details:"
	echo >&2 "***"
	echo >&2 "$rust_bindings_generator_output"
	echo >&2 "***"
	exit 1
	fi
	rust_bindings_generator_min_version=$($min_tool_version bindgen)
	rust_bindings_generator_cversion=$(get_canonical_version $rust_bindings_generator_version)
	rust_bindings_generator_min_cversion=$(get_canonical_version $rust_bindings_generator_min_version)
	if [ "$rust_bindings_generator_cversion" -lt "$rust_bindings_generator_min_cversion" ]; then
	echo >&2 "***"
	echo >&2 "*** Rust bindings generator '$BINDGEN' is too old."
	echo >&2 "*** Your version: $rust_bindings_generator_version"
	echo >&2 "*** Minimum version: $rust_bindings_generator_min_version"
	echo >&2 "***"
	exit 1
	fi
	if [ "$rust_bindings_generator_cversion" -eq 6600 ] \|\|
	[ "$rust_bindings_generator_cversion" -eq 6601 ]; then
	# Distributions may have patched the issue (e.g. Debian did).
	if ! "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_0_66.h >/dev/null; then
	echo >&2 "***"
	echo >&2 "*** Rust bindings generator '$BINDGEN' versions 0.66.0 and 0.66.1 may not"
	echo >&2 "*** work due to a bug (https://github.com/rust-lang/rust-bindgen/pull/2567),"
	echo >&2 "*** unless patched (like Debian's)."
	echo >&2 "*** Your version: $rust_bindings_generator_version"
	echo >&2 "***"
	warning=1
	fi
	fi

	# Check that the `libclang` used by the Rust bindings generator is suitable.
	#
	# In order to do that, first invoke `bindgen` to get the `libclang` version
	# found by `bindgen`. This step may already fail if, for instance, `libclang`
	# is not found, thus inform the user in such a case.
	bindgen_libclang_output=$( \
	LC_ALL=C "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_libclang.h 2>&1 >/dev/null
	) \|\| bindgen_libclang_code=$?
	if [ -n "$bindgen_libclang_code" ]; then
	echo >&2 "***"
	echo >&2 "*** Running '$BINDGEN' to check the libclang version (used by the Rust"
	echo >&2 "*** bindings generator) failed with code $bindgen_libclang_code. This may be caused by"
	echo >&2 "*** a failure to locate libclang. See output and docs below for details:"
	echo >&2 "***"
	echo >&2 "$bindgen_libclang_output"
	echo >&2 "***"
	exit 1
	fi

	# `bindgen` returned successfully, thus use the output to check that the version
	# of the `libclang` found by the Rust bindings generator is suitable.
	#
	# Unlike other version checks, note that this one does not necessarily appear
	# in the first line of the output, thus no `sed` address is provided.
	bindgen_libclang_version=$( \
	echo "$bindgen_libclang_output" \
	\| sed -nE 's:.clang version ([0-9]+\.[0-9]+\.[0-9]+).:\1:p'
	)
	if [ -z "$bindgen_libclang_version" ]; then
	echo >&2 "***"
	echo >&2 "*** Running '$BINDGEN' to check the libclang version (used by the Rust"
	echo >&2 "*** bindings generator) did not return an expected output. See output"
	echo >&2 "*** and docs below for details:"
	echo >&2 "***"
	echo >&2 "$bindgen_libclang_output"
	echo >&2 "***"
	exit 1
	fi
	bindgen_libclang_min_version=$($min_tool_version llvm)
	bindgen_libclang_cversion=$(get_canonical_version $bindgen_libclang_version)
	bindgen_libclang_min_cversion=$(get_canonical_version $bindgen_libclang_min_version)
	if [ "$bindgen_libclang_cversion" -lt "$bindgen_libclang_min_cversion" ]; then
	echo >&2 "***"
	echo >&2 "*** libclang (used by the Rust bindings generator '$BINDGEN') is too old."
	echo >&2 "*** Your version: $bindgen_libclang_version"
	echo >&2 "*** Minimum version: $bindgen_libclang_min_version"
	echo >&2 "***"
	exit 1
	fi

	if [ "$bindgen_libclang_cversion" -ge 1900100 ] &&
	[ "$rust_bindings_generator_cversion" -lt 6905 ]; then
	# Distributions may have patched the issue (e.g. Debian did).
	if ! "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_libclang_concat.h \| grep -q foofoo; then
	echo >&2 "***"
	echo >&2 "*** Rust bindings generator '$BINDGEN' < 0.69.5 together with libclang >= 19.1"
	echo >&2 "*** may not work due to a bug (https://github.com/rust-lang/rust-bindgen/pull/2824),"
	echo >&2 "*** unless patched (like Debian's)."
	echo >&2 "*** Your bindgen version: $rust_bindings_generator_version"
	echo >&2 "*** Your libclang version: $bindgen_libclang_version"
	echo >&2 "***"
	warning=1
	fi
	fi

	# If the C compiler is Clang, then we can also check whether its version
	# matches the `libclang` version used by the Rust bindings generator.
	#
	# In the future, we might be able to perform a full version check, see
	# https://github.com/rust-lang/rust-bindgen/issues/2138.
	cc_name=$($(dirname $0)/cc-version.sh $CC \| cut -f1 -d' ')
	if [ "$cc_name" = Clang ]; then
	clang_version=$( \
	LC_ALL=C $CC --version 2>/dev/null \
	\| sed -nE '1s:.version ([0-9]+\.[0-9]+\.[0-9]+).:\1:p'
	)
	if [ "$clang_version" != "$bindgen_libclang_version" ]; then
	echo >&2 "***"
	echo >&2 "*** libclang (used by the Rust bindings generator '$BINDGEN')"
	echo >&2 "*** version does not match Clang's. This may be a problem."
	echo >&2 "*** libclang version: $bindgen_libclang_version"
	echo >&2 "*** Clang version: $clang_version"
	echo >&2 "***"
	warning=1
	fi
	fi

	# Check that the source code for the `core` standard library exists.
	#
	# `$KRUSTFLAGS` is passed in case the user added `--sysroot`.
	rustc_sysroot=$("$RUSTC" $KRUSTFLAGS --print sysroot)
	rustc_src=${RUST_LIB_SRC:-"$rustc_sysroot/lib/rustlib/src/rust/library"}
	rustc_src_core="$rustc_src/core/src/lib.rs"
	if [ ! -e "$rustc_src_core" ]; then
	echo >&2 "***"
	echo >&2 "*** Source code for the 'core' standard library could not be found"
	echo >&2 "*** at '$rustc_src_core'."
	echo >&2 "***"
	exit 1
	fi