[Pkg-rust-maintainers] Bug#903118: rustc: FTBFS in stretch (no cargo executable found)

[Santiago Vila]

Package: src:rustc
Version: 1.24.1+dfsg1-1~deb9u1
Severity: serious
Tags: ftbfs

Dear maintainer:

I tried to build this package with "dpkg-buildpackage -A"
but it failed:

--------------------------------------------------------------------------------
[...]
 debian/rules build-indep
/bin/sh: 1: rustc: not found
dh build-indep --parallel
   dh_testdir -i -O--parallel
   dh_update_autotools_config -i -O--parallel
   debian/rules override_dh_auto_configure
make[1]: Entering directory '/<<BUILDDIR>>/rustc-1.24.1+dfsg1'
/bin/sh: 1: rustc: not found
m4  -DDEB_BUILD_RUST_TYPE="x86_64-unknown-linux-gnu" \
	-DDEB_HOST_RUST_TYPE="x86_64-unknown-linux-gnu" \
	-DDEB_TARGET_RUST_TYPE="x86_64-unknown-linux-gnu" \
	-DRELEASE_CHANNEL="stable" \
	-DBUILD_DOCS="true" \
	-DMAKE_OPTIMISATIONS="true" \
	-DLLVM_DESTDIR="" \
	-DLLVM_VERSION="4.0" \
	-DRUST_DESTDIR="" \
	"debian/config.toml.in" > "debian/config.toml"
if false || [ 0 != 0 ]; \
  then sed -i -e '/^rustc = /d' -e '/^cargo = /d' "debian/config.toml"; fi
# Work around armhf issue: https://github.com/rust-lang/rust/issues/45854
[ amd64 != armhf -a \
  amd64 != armel ] || sed -i -e '/^debuginfo-only-std = /d' "debian/config.toml"
# fail the build if we have any instances of OLD_LLVM_VERSION in debian, except for debian/changelog
! grep --color=always -i 'll...\?3\.9' --exclude=changelog -R debian
:
if [ -d stage0 ]; then mkdir -p build && ln -sfT ../stage0 build/cache; fi
# work around #842634
if test $(grep "127.0.0.1\s*localhost" /etc/hosts | wc -l) -gt 1; then \
  debian/ensure-patch -N debian/patches/d-host-duplicates.patch; fi
# We patched mdbook so have to rm the checksums
debian/prune-checksums src/vendor/mdbook/.cargo-checksum.json
# Unfortunately upstream uses a duplicate copy of libbacktrace and wants to
# compile it again for rust-installer, see #43449
ln -rsf src/libbacktrace -t src/vendor/backtrace-sys/src/
debian/prune-checksums src/vendor/backtrace-sys/.cargo-checksum.json
# Link against system liblzma, see https://github.com/alexcrichton/xz2-rs/issues/16
echo 'fn main() { println!("cargo:rustc-link-lib=lzma"); }' > src/vendor/lzma-sys/build.rs
debian/prune-checksums src/vendor/lzma-sys/.cargo-checksum.json
# We excluded some embedded libraries in d/copyright
debian/prune-checksums src/vendor/dbghelp-sys/.cargo-checksum.json
# We patched this for sparc64 support
debian/prune-checksums src/vendor/cc/.cargo-checksum.json
# We don't run ./configure because we use debian/config.toml directly
ln -sf debian/config.toml config.toml
make[1]: Leaving directory '/<<BUILDDIR>>/rustc-1.24.1+dfsg1'
   debian/rules override_dh_auto_build-indep
make[1]: Entering directory '/<<BUILDDIR>>/rustc-1.24.1+dfsg1'
/bin/sh: 1: rustc: not found
/usr/bin/make -C src/rt/hoedown src/html_blocks.c
make[2]: Entering directory '/<<BUILDDIR>>/rustc-1.24.1+dfsg1/src/rt/hoedown'
gperf -I -L ANSI-C -N hoedown_find_block_tag -c -C -E -S 1 --ignore-case -m100 html_block_names.gperf > src/html_blocks.c
make[2]: Leaving directory '/<<BUILDDIR>>/rustc-1.24.1+dfsg1/src/rt/hoedown'
sed -i -e 's/^docs = false/docs = true/' debian/config.toml
RUST_BACKTRACE=1 ./x.py doc --config debian/config.toml -v --on-fail env
Traceback (most recent call last):
  File "./x.py", line 20, in <module>
    bootstrap.main()
  File "/<<BUILDDIR>>/rustc-1.24.1+dfsg1/src/bootstrap/bootstrap.py", line 755, in main
    bootstrap()
  File "/<<BUILDDIR>>/rustc-1.24.1+dfsg1/src/bootstrap/bootstrap.py", line 735, in bootstrap
    build.build_bootstrap()
  File "/<<BUILDDIR>>/rustc-1.24.1+dfsg1/src/bootstrap/bootstrap.py", line 615, in build_bootstrap
    self.cargo()))
Exception: no cargo executable found at `/usr/bin/cargo`
debian/rules:216: recipe for target 'override_dh_auto_build-indep' failed
make[1]: *** [override_dh_auto_build-indep] Error 1
make[1]: Leaving directory '/<<BUILDDIR>>/rustc-1.24.1+dfsg1'
debian/rules:143: recipe for target 'build-indep' failed
make: *** [build-indep] Error 2
dpkg-buildpackage: error: debian/rules build-indep gave error exit status 2
--------------------------------------------------------------------------------

I did "dpkg-buildpackage -A" but apparently it also fails with "dpkg-buildpackage -B"
in every other architecture:

https://buildd.debian.org/status/package.php?p=rustc&suite=stretch

Thanks.