Merge pull request #3 from aehlig/cargo-example

Add example on how to use cargo

26 files changed, 940 insertions, 47 deletions

diff --git a/README.md b/README.md
index 0e6d1f9..5ab1a0d 100644
--- a/README.md
+++ b/README.md
@@ -117,6 +117,9 @@ There are two files pinning dependencies
    calls [etc/generate-repos.sh](./etc/generate-repos.sh) in our `nix-shell`,
    which also brings in tools required for this step.
 
+Specific considerations
+ - [cargo](./src/rust/cargo/README.md)
+
 ### Logical repositories
 
 This project uses several logical repositories.
diff --git a/etc/defaults/rust/TARGETS b/etc/defaults/rust/TARGETS
index fbd1a69..fe4de0a 100644
--- a/etc/defaults/rust/TARGETS
+++ b/etc/defaults/rust/TARGETS
@@ -1,43 +1,3 @@
 { "defaults":
-  { "type": "configure"
-  , "target": "defaults (unconfigured)"
-  , "arguments_config": ["TOOLCHAIN_CONFIG"]
-  , "config":
-    { "type": "let*"
-    , "bindings":
-      [ [ "toolchain"
-        , { "type": "lookup"
-          , "map":
-            { "type": "var"
-            , "name": "TOOLCHAIN_CONFIG"
-            , "default": {"type": "empty_map"}
-            }
-          , "key": "RUST"
-          , "default": {"type": "empty_map"}
-          }
-        ]
-      , [ "RUSTC"
-        , { "type": "lookup"
-          , "map": {"type": "var", "name": "toolchain"}
-          , "key": "RUSTC"
-          , "default": "rustc"
-          }
-        ]
-      , [ "PATH"
-        , { "type": "lookup"
-          , "map": {"type": "var", "name": "toolchain"}
-          , "key": "PATH"
-          , "default": []
-          }
-        ]
-      ]
-    , "body": {"type": "env", "vars": ["RUSTC", "PATH"]}
-    }
-  }
-, "defaults (unconfigured)":
-  { "type": "defaults"
-  , "arguments_config": ["RUSTC", "PATH"]
-  , "RUSTC": [{"type": "var", "name": "RUSTC"}]
-  , "PATH": {"type": "var", "name": "PATH"}
-  }
+  {"type": "defaults", "base": [["@", "orig-rules", "rust", "defaults"]]}
 }
diff --git a/etc/defaults/rust/nix.TARGETS b/etc/defaults/rust/nix.TARGETS
new file mode 100644
index 0000000..fbd1a69
--- /dev/null
+++ b/etc/defaults/rust/nix.TARGETS
@@ -0,0 +1,43 @@
+{ "defaults":
+  { "type": "configure"
+  , "target": "defaults (unconfigured)"
+  , "arguments_config": ["TOOLCHAIN_CONFIG"]
+  , "config":
+    { "type": "let*"
+    , "bindings":
+      [ [ "toolchain"
+        , { "type": "lookup"
+          , "map":
+            { "type": "var"
+            , "name": "TOOLCHAIN_CONFIG"
+            , "default": {"type": "empty_map"}
+            }
+          , "key": "RUST"
+          , "default": {"type": "empty_map"}
+          }
+        ]
+      , [ "RUSTC"
+        , { "type": "lookup"
+          , "map": {"type": "var", "name": "toolchain"}
+          , "key": "RUSTC"
+          , "default": "rustc"
+          }
+        ]
+      , [ "PATH"
+        , { "type": "lookup"
+          , "map": {"type": "var", "name": "toolchain"}
+          , "key": "PATH"
+          , "default": []
+          }
+        ]
+      ]
+    , "body": {"type": "env", "vars": ["RUSTC", "PATH"]}
+    }
+  }
+, "defaults (unconfigured)":
+  { "type": "defaults"
+  , "arguments_config": ["RUSTC", "PATH"]
+  , "RUSTC": [{"type": "var", "name": "RUSTC"}]
+  , "PATH": {"type": "var", "name": "PATH"}
+  }
+}
diff --git a/etc/deps-rust/TARGETS.cfg-if-1.0.0 b/etc/deps-rust/TARGETS.cfg-if-1.0.0
new file mode 100644
index 0000000..2faaaaf
--- /dev/null
+++ b/etc/deps-rust/TARGETS.cfg-if-1.0.0
@@ -0,0 +1,26 @@
+{ "cfg_if":
+  { "type": "export"
+  , "target": "cfg_if-internal"
+  , "flexible_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  }
+, "cfg_if-internal":
+  { "type": ["@", "rules", "rust", "library"]
+  , "name": ["cfg_if"]
+  , "crate_root": ["src/lib.rs"]
+  , "srcs": ["src/lib.rs"]
+  , "edition": ["2018"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps": []
+  , "cargo_features": []
+  , "stage": ["cfg-if-1.0.0"]
+  , "version": ["1", "0", "0"]
+  , "pkg_name": ["cfg-if"]
+  }
+, "compiler_builtins":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["compiler_builtins"]}
+, "core": {"type": ["@", "rules", "cargo", "feature"], "name": ["core"]}
+, "rustc-dep-of-std":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["rustc-dep-of-std"]}
+}
diff --git a/etc/deps-rust/TARGETS.getrandom-0.2.15 b/etc/deps-rust/TARGETS.getrandom-0.2.15
new file mode 100644
index 0000000..c36da18
--- /dev/null
+++ b/etc/deps-rust/TARGETS.getrandom-0.2.15
@@ -0,0 +1,64 @@
+{ "getrandom":
+  { "type": "export"
+  , "target": "getrandom-internal"
+  , "flexible_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  }
+, "getrandom-internal":
+  { "type": ["@", "rules", "rust", "library"]
+  , "name": ["getrandom"]
+  , "crate_root": ["src/lib.rs"]
+  , "srcs":
+    [ "src/linux_android_with_fallback.rs"
+    , "src/fuchsia.rs"
+    , "src/windows.rs"
+    , "src/custom.rs"
+    , "src/vxworks.rs"
+    , "src/util.rs"
+    , "src/espidf.rs"
+    , "src/solid.rs"
+    , "src/use_file.rs"
+    , "src/error_impls.rs"
+    , "src/apple-other.rs"
+    , "src/js.rs"
+    , "src/getentropy.rs"
+    , "src/solaris.rs"
+    , "src/hermit.rs"
+    , "src/linux_android.rs"
+    , "src/error.rs"
+    , "src/lazy.rs"
+    , "src/wasi.rs"
+    , "src/netbsd.rs"
+    , "src/rdrand.rs"
+    , "src/getrandom.rs"
+    , "src/lib.rs"
+    , "src/util_libc.rs"
+    ]
+  , "edition": ["2018"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps": [["@", "cfg-if", "", "cfg_if"], ["@", "libc", "", "libc"]]
+  , "cargo_features": ["std"]
+  , "stage": ["getrandom-0.2.15"]
+  , "version": ["0", "2", "15"]
+  , "pkg_name": ["getrandom"]
+  }
+, "compiler_builtins":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["compiler_builtins"]}
+, "core": {"type": ["@", "rules", "cargo", "feature"], "name": ["core"]}
+, "custom": {"type": ["@", "rules", "cargo", "feature"], "name": ["custom"]}
+, "js": {"type": ["@", "rules", "cargo", "feature"], "name": ["js"]}
+, "js-sys": {"type": ["@", "rules", "cargo", "feature"], "name": ["js-sys"]}
+, "linux_disable_fallback":
+  { "type": ["@", "rules", "cargo", "feature"]
+  , "name": ["linux_disable_fallback"]
+  }
+, "rdrand": {"type": ["@", "rules", "cargo", "feature"], "name": ["rdrand"]}
+, "rustc-dep-of-std":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["rustc-dep-of-std"]}
+, "std": {"type": ["@", "rules", "cargo", "feature"], "name": ["std"]}
+, "test-in-browser":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["test-in-browser"]}
+, "wasm-bindgen":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["wasm-bindgen"]}
+}
diff --git a/etc/deps-rust/TARGETS.libc-0.2.155 b/etc/deps-rust/TARGETS.libc-0.2.155
new file mode 100644
index 0000000..2aa9d20
--- /dev/null
+++ b/etc/deps-rust/TARGETS.libc-0.2.155
@@ -0,0 +1,287 @@
+{ "libc":
+  { "type": "export"
+  , "target": "libc-internal"
+  , "flexible_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  }
+, "libc-internal":
+  { "type": ["@", "rules", "rust", "library"]
+  , "name": ["libc"]
+  , "crate_root": ["src/lib.rs"]
+  , "srcs":
+    [ "build.rs"
+    , "src/fixed_width_ints.rs"
+    , "src/switch.rs"
+    , "src/xous.rs"
+    , "src/sgx.rs"
+    , "src/macros.rs"
+    , "src/wasi.rs"
+    , "src/lib.rs"
+    , "src/psp.rs"
+    , "src/solid/aarch64.rs"
+    , "src/solid/mod.rs"
+    , "src/solid/arm.rs"
+    , "src/fuchsia/aarch64.rs"
+    , "src/fuchsia/riscv64.rs"
+    , "src/fuchsia/no_align.rs"
+    , "src/fuchsia/align.rs"
+    , "src/fuchsia/x86_64.rs"
+    , "src/fuchsia/mod.rs"
+    , "src/unix/no_align.rs"
+    , "src/unix/align.rs"
+    , "src/unix/mod.rs"
+    , "src/unix/haiku/b64.rs"
+    , "src/unix/haiku/x86_64.rs"
+    , "src/unix/haiku/b32.rs"
+    , "src/unix/haiku/mod.rs"
+    , "src/unix/haiku/native.rs"
+    , "src/unix/nto/aarch64.rs"
+    , "src/unix/nto/x86_64.rs"
+    , "src/unix/nto/neutrino.rs"
+    , "src/unix/nto/mod.rs"
+    , "src/unix/newlib/no_align.rs"
+    , "src/unix/newlib/align.rs"
+    , "src/unix/newlib/generic.rs"
+    , "src/unix/newlib/mod.rs"
+    , "src/unix/newlib/aarch64/mod.rs"
+    , "src/unix/newlib/arm/mod.rs"
+    , "src/unix/newlib/vita/mod.rs"
+    , "src/unix/newlib/powerpc/mod.rs"
+    , "src/unix/newlib/horizon/mod.rs"
+    , "src/unix/newlib/espidf/mod.rs"
+    , "src/unix/hurd/b64.rs"
+    , "src/unix/hurd/no_align.rs"
+    , "src/unix/hurd/align.rs"
+    , "src/unix/hurd/b32.rs"
+    , "src/unix/hurd/mod.rs"
+    , "src/unix/linux_like/mod.rs"
+    , "src/unix/linux_like/linux/no_align.rs"
+    , "src/unix/linux_like/linux/align.rs"
+    , "src/unix/linux_like/linux/non_exhaustive.rs"
+    , "src/unix/linux_like/linux/mod.rs"
+    , "src/unix/linux_like/linux/arch/mod.rs"
+    , "src/unix/linux_like/linux/arch/generic/mod.rs"
+    , "src/unix/linux_like/linux/arch/powerpc/mod.rs"
+    , "src/unix/linux_like/linux/arch/mips/mod.rs"
+    , "src/unix/linux_like/linux/arch/sparc/mod.rs"
+    , "src/unix/linux_like/linux/uclibc/no_align.rs"
+    , "src/unix/linux_like/linux/uclibc/align.rs"
+    , "src/unix/linux_like/linux/uclibc/mod.rs"
+    , "src/unix/linux_like/linux/uclibc/x86_64/l4re.rs"
+    , "src/unix/linux_like/linux/uclibc/x86_64/other.rs"
+    , "src/unix/linux_like/linux/uclibc/x86_64/mod.rs"
+    , "src/unix/linux_like/linux/uclibc/arm/no_align.rs"
+    , "src/unix/linux_like/linux/uclibc/arm/align.rs"
+    , "src/unix/linux_like/linux/uclibc/arm/mod.rs"
+    , "src/unix/linux_like/linux/uclibc/mips/mod.rs"
+    , "src/unix/linux_like/linux/uclibc/mips/mips32/no_align.rs"
+    , "src/unix/linux_like/linux/uclibc/mips/mips32/align.rs"
+    , "src/unix/linux_like/linux/uclibc/mips/mips32/mod.rs"
+    , "src/unix/linux_like/linux/uclibc/mips/mips64/no_align.rs"
+    , "src/unix/linux_like/linux/uclibc/mips/mips64/align.rs"
+    , "src/unix/linux_like/linux/uclibc/mips/mips64/mod.rs"
+    , "src/unix/linux_like/linux/musl/lfs64.rs"
+    , "src/unix/linux_like/linux/musl/mod.rs"
+    , "src/unix/linux_like/linux/musl/b64/s390x.rs"
+    , "src/unix/linux_like/linux/musl/b64/powerpc64.rs"
+    , "src/unix/linux_like/linux/musl/b64/mips64.rs"
+    , "src/unix/linux_like/linux/musl/b64/mod.rs"
+    , "src/unix/linux_like/linux/musl/b64/x86_64/align.rs"
+    , "src/unix/linux_like/linux/musl/b64/x86_64/mod.rs"
+    , "src/unix/linux_like/linux/musl/b64/aarch64/align.rs"
+    , "src/unix/linux_like/linux/musl/b64/aarch64/int128.rs"
+    , "src/unix/linux_like/linux/musl/b64/aarch64/mod.rs"
+    , "src/unix/linux_like/linux/musl/b64/loongarch64/align.rs"
+    , "src/unix/linux_like/linux/musl/b64/loongarch64/mod.rs"
+    , "src/unix/linux_like/linux/musl/b64/riscv64/align.rs"
+    , "src/unix/linux_like/linux/musl/b64/riscv64/mod.rs"
+    , "src/unix/linux_like/linux/musl/b32/powerpc.rs"
+    , "src/unix/linux_like/linux/musl/b32/hexagon.rs"
+    , "src/unix/linux_like/linux/musl/b32/mod.rs"
+    , "src/unix/linux_like/linux/musl/b32/arm/align.rs"
+    , "src/unix/linux_like/linux/musl/b32/arm/mod.rs"
+    , "src/unix/linux_like/linux/musl/b32/riscv32/align.rs"
+    , "src/unix/linux_like/linux/musl/b32/riscv32/mod.rs"
+    , "src/unix/linux_like/linux/musl/b32/x86/align.rs"
+    , "src/unix/linux_like/linux/musl/b32/x86/mod.rs"
+    , "src/unix/linux_like/linux/musl/b32/mips/align.rs"
+    , "src/unix/linux_like/linux/musl/b32/mips/mod.rs"
+    , "src/unix/linux_like/linux/gnu/no_align.rs"
+    , "src/unix/linux_like/linux/gnu/align.rs"
+    , "src/unix/linux_like/linux/gnu/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/s390x.rs"
+    , "src/unix/linux_like/linux/gnu/b64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/x86_64/align.rs"
+    , "src/unix/linux_like/linux/gnu/b64/x86_64/x32.rs"
+    , "src/unix/linux_like/linux/gnu/b64/x86_64/not_x32.rs"
+    , "src/unix/linux_like/linux/gnu/b64/x86_64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/aarch64/ilp32.rs"
+    , "src/unix/linux_like/linux/gnu/b64/aarch64/align.rs"
+    , "src/unix/linux_like/linux/gnu/b64/aarch64/lp64.rs"
+    , "src/unix/linux_like/linux/gnu/b64/aarch64/int128.rs"
+    , "src/unix/linux_like/linux/gnu/b64/aarch64/fallback.rs"
+    , "src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/loongarch64/align.rs"
+    , "src/unix/linux_like/linux/gnu/b64/loongarch64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/riscv64/align.rs"
+    , "src/unix/linux_like/linux/gnu/b64/riscv64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/powerpc64/align.rs"
+    , "src/unix/linux_like/linux/gnu/b64/powerpc64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/mips64/align.rs"
+    , "src/unix/linux_like/linux/gnu/b64/mips64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b64/sparc64/align.rs"
+    , "src/unix/linux_like/linux/gnu/b64/sparc64/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/powerpc.rs"
+    , "src/unix/linux_like/linux/gnu/b32/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/csky/align.rs"
+    , "src/unix/linux_like/linux/gnu/b32/csky/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/arm/align.rs"
+    , "src/unix/linux_like/linux/gnu/b32/arm/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/riscv32/align.rs"
+    , "src/unix/linux_like/linux/gnu/b32/riscv32/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/x86/align.rs"
+    , "src/unix/linux_like/linux/gnu/b32/x86/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/mips/align.rs"
+    , "src/unix/linux_like/linux/gnu/b32/mips/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/m68k/align.rs"
+    , "src/unix/linux_like/linux/gnu/b32/m68k/mod.rs"
+    , "src/unix/linux_like/linux/gnu/b32/sparc/align.rs"
+    , "src/unix/linux_like/linux/gnu/b32/sparc/mod.rs"
+    , "src/unix/linux_like/android/mod.rs"
+    , "src/unix/linux_like/android/b64/mod.rs"
+    , "src/unix/linux_like/android/b64/x86_64/align.rs"
+    , "src/unix/linux_like/android/b64/x86_64/mod.rs"
+    , "src/unix/linux_like/android/b64/aarch64/align.rs"
+    , "src/unix/linux_like/android/b64/aarch64/int128.rs"
+    , "src/unix/linux_like/android/b64/aarch64/mod.rs"
+    , "src/unix/linux_like/android/b64/riscv64/align.rs"
+    , "src/unix/linux_like/android/b64/riscv64/mod.rs"
+    , "src/unix/linux_like/android/b32/mod.rs"
+    , "src/unix/linux_like/android/b32/arm.rs"
+    , "src/unix/linux_like/android/b32/x86/align.rs"
+    , "src/unix/linux_like/android/b32/x86/mod.rs"
+    , "src/unix/linux_like/emscripten/no_align.rs"
+    , "src/unix/linux_like/emscripten/align.rs"
+    , "src/unix/linux_like/emscripten/lfs64.rs"
+    , "src/unix/linux_like/emscripten/mod.rs"
+    , "src/unix/aix/powerpc64.rs"
+    , "src/unix/aix/mod.rs"
+    , "src/unix/redox/mod.rs"
+    , "src/unix/solarish/illumos.rs"
+    , "src/unix/solarish/compat.rs"
+    , "src/unix/solarish/x86.rs"
+    , "src/unix/solarish/solaris.rs"
+    , "src/unix/solarish/x86_common.rs"
+    , "src/unix/solarish/x86_64.rs"
+    , "src/unix/solarish/mod.rs"
+    , "src/unix/bsd/mod.rs"
+    , "src/unix/bsd/apple/long_array.rs"
+    , "src/unix/bsd/apple/mod.rs"
+    , "src/unix/bsd/apple/b64/align.rs"
+    , "src/unix/bsd/apple/b64/mod.rs"
+    , "src/unix/bsd/apple/b64/x86_64/align.rs"
+    , "src/unix/bsd/apple/b64/x86_64/mod.rs"
+    , "src/unix/bsd/apple/b64/aarch64/align.rs"
+    , "src/unix/bsd/apple/b64/aarch64/mod.rs"
+    , "src/unix/bsd/apple/b32/align.rs"
+    , "src/unix/bsd/apple/b32/mod.rs"
+    , "src/unix/bsd/netbsdlike/mod.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/mips.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/aarch64.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/x86.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/sparc64.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/riscv64.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/powerpc.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/x86_64.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/mod.rs"
+    , "src/unix/bsd/netbsdlike/netbsd/arm.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/aarch64.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/x86.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/powerpc64.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/sparc64.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/riscv64.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/powerpc.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/x86_64.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/mips64.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/mod.rs"
+    , "src/unix/bsd/netbsdlike/openbsd/arm.rs"
+    , "src/unix/bsd/freebsdlike/mod.rs"
+    , "src/unix/bsd/freebsdlike/dragonfly/errno.rs"
+    , "src/unix/bsd/freebsdlike/dragonfly/mod.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/aarch64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/x86.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/powerpc64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/riscv64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/powerpc.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/mod.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/arm.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/x86_64/align.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/x86_64/mod.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd13/b64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd13/x86_64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd13/mod.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd15/b64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd15/x86_64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd15/mod.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd12/b64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd12/x86_64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd12/mod.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd11/b64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd11/mod.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd14/b64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd14/x86_64.rs"
+    , "src/unix/bsd/freebsdlike/freebsd/freebsd14/mod.rs"
+    , "src/windows/mod.rs"
+    , "src/windows/msvc/mod.rs"
+    , "src/windows/gnu/align.rs"
+    , "src/windows/gnu/mod.rs"
+    , "src/hermit/aarch64.rs"
+    , "src/hermit/x86_64.rs"
+    , "src/hermit/mod.rs"
+    , "src/vxworks/aarch64.rs"
+    , "src/vxworks/x86.rs"
+    , "src/vxworks/powerpc64.rs"
+    , "src/vxworks/powerpc.rs"
+    , "src/vxworks/x86_64.rs"
+    , "src/vxworks/mod.rs"
+    , "src/vxworks/arm.rs"
+    , "src/teeos/mod.rs"
+    ]
+  , "edition": ["2015"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps": []
+  , "cargo_features": []
+  , "stage": ["libc-0.2.155"]
+  , "version": ["0", "2", "155"]
+  , "pkg_name": ["libc"]
+  , "build_script": ["build_script"]
+  }
+, "build_script":
+  { "type": ["@", "rules", "cargo", "build_script"]
+  , "name": ["build_script"]
+  , "crate_root": ["build.rs"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "edition": ["2015"]
+  , "stage": ["libc-0.2.155"]
+  , "deps": []
+  , "cargo_features": []
+  , "version": ["0", "2", "155"]
+  , "pkg_name": ["libc"]
+  }
+, "align": {"type": ["@", "rules", "cargo", "feature"], "name": ["align"]}
+, "const-extern-fn":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["const-extern-fn"]}
+, "default": {"type": ["@", "rules", "cargo", "feature"], "name": ["default"]}
+, "extra_traits":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["extra_traits"]}
+, "rustc-dep-of-std":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["rustc-dep-of-std"]}
+, "rustc-std-workspace-core":
+  { "type": ["@", "rules", "cargo", "feature"]
+  , "name": ["rustc-std-workspace-core"]
+  }
+, "std": {"type": ["@", "rules", "cargo", "feature"], "name": ["std"]}
+, "use_std": {"type": ["@", "rules", "cargo", "feature"], "name": ["use_std"]}
+}
diff --git a/etc/deps-rust/TARGETS.ppv-lite86-0.2.17 b/etc/deps-rust/TARGETS.ppv-lite86-0.2.17
new file mode 100644
index 0000000..c8c3fd7
--- /dev/null
+++ b/etc/deps-rust/TARGETS.ppv-lite86-0.2.17
@@ -0,0 +1,32 @@
+{ "ppv_lite86":
+  { "type": "export"
+  , "target": "ppv_lite86-internal"
+  , "flexible_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  }
+, "ppv_lite86-internal":
+  { "type": ["@", "rules", "rust", "library"]
+  , "name": ["ppv_lite86"]
+  , "crate_root": ["src/lib.rs"]
+  , "srcs":
+    [ "src/soft.rs"
+    , "src/generic.rs"
+    , "src/types.rs"
+    , "src/lib.rs"
+    , "src/x86_64/sse2.rs"
+    , "src/x86_64/mod.rs"
+    ]
+  , "edition": ["2018"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps": []
+  , "cargo_features": ["simd", "std"]
+  , "stage": ["ppv-lite86-0.2.17"]
+  , "version": ["0", "2", "17"]
+  , "pkg_name": ["ppv-lite86"]
+  }
+, "default": {"type": ["@", "rules", "cargo", "feature"], "name": ["default"]}
+, "no_simd": {"type": ["@", "rules", "cargo", "feature"], "name": ["no_simd"]}
+, "simd": {"type": ["@", "rules", "cargo", "feature"], "name": ["simd"]}
+, "std": {"type": ["@", "rules", "cargo", "feature"], "name": ["std"]}
+}
diff --git a/etc/deps-rust/TARGETS.rand-0.8.5 b/etc/deps-rust/TARGETS.rand-0.8.5
new file mode 100644
index 0000000..be9e720
--- /dev/null
+++ b/etc/deps-rust/TARGETS.rand-0.8.5
@@ -0,0 +1,74 @@
+{ "rand":
+  { "type": "export"
+  , "target": "rand-internal"
+  , "flexible_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  }
+, "rand-internal":
+  { "type": ["@", "rules", "rust", "library"]
+  , "name": ["rand"]
+  , "crate_root": ["src/lib.rs"]
+  , "srcs":
+    [ "src/rng.rs"
+    , "src/prelude.rs"
+    , "src/lib.rs"
+    , "src/distributions/distribution.rs"
+    , "src/distributions/uniform.rs"
+    , "src/distributions/weighted.rs"
+    , "src/distributions/other.rs"
+    , "src/distributions/weighted_index.rs"
+    , "src/distributions/bernoulli.rs"
+    , "src/distributions/integer.rs"
+    , "src/distributions/float.rs"
+    , "src/distributions/utils.rs"
+    , "src/distributions/slice.rs"
+    , "src/distributions/mod.rs"
+    , "src/seq/index.rs"
+    , "src/seq/mod.rs"
+    , "src/rngs/small.rs"
+    , "src/rngs/xoshiro128plusplus.rs"
+    , "src/rngs/thread.rs"
+    , "src/rngs/std.rs"
+    , "src/rngs/mock.rs"
+    , "src/rngs/xoshiro256plusplus.rs"
+    , "src/rngs/mod.rs"
+    , "src/rngs/adapter/read.rs"
+    , "src/rngs/adapter/reseeding.rs"
+    , "src/rngs/adapter/mod.rs"
+    ]
+  , "edition": ["2018"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps":
+    [ ["@", "libc", "", "libc"]
+    , ["@", "rand_chacha", "", "rand_chacha"]
+    , ["@", "rand_core", "", "rand_core"]
+    ]
+  , "cargo_features":
+    ["alloc", "default", "getrandom", "libc", "rand_chacha", "std", "std_rng"]
+  , "stage": ["rand-0.8.5"]
+  , "version": ["0", "8", "5"]
+  , "pkg_name": ["rand"]
+  }
+, "alloc": {"type": ["@", "rules", "cargo", "feature"], "name": ["alloc"]}
+, "default": {"type": ["@", "rules", "cargo", "feature"], "name": ["default"]}
+, "getrandom":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["getrandom"]}
+, "libc": {"type": ["@", "rules", "cargo", "feature"], "name": ["libc"]}
+, "log": {"type": ["@", "rules", "cargo", "feature"], "name": ["log"]}
+, "min_const_gen":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["min_const_gen"]}
+, "nightly": {"type": ["@", "rules", "cargo", "feature"], "name": ["nightly"]}
+, "packed_simd":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["packed_simd"]}
+, "rand_chacha":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["rand_chacha"]}
+, "serde": {"type": ["@", "rules", "cargo", "feature"], "name": ["serde"]}
+, "serde1": {"type": ["@", "rules", "cargo", "feature"], "name": ["serde1"]}
+, "simd_support":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["simd_support"]}
+, "small_rng":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["small_rng"]}
+, "std": {"type": ["@", "rules", "cargo", "feature"], "name": ["std"]}
+, "std_rng": {"type": ["@", "rules", "cargo", "feature"], "name": ["std_rng"]}
+}
diff --git a/etc/deps-rust/TARGETS.rand_chacha-0.3.1 b/etc/deps-rust/TARGETS.rand_chacha-0.3.1
new file mode 100644
index 0000000..ff88bbd
--- /dev/null
+++ b/etc/deps-rust/TARGETS.rand_chacha-0.3.1
@@ -0,0 +1,29 @@
+{ "rand_chacha":
+  { "type": "export"
+  , "target": "rand_chacha-internal"
+  , "flexible_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  }
+, "rand_chacha-internal":
+  { "type": ["@", "rules", "rust", "library"]
+  , "name": ["rand_chacha"]
+  , "crate_root": ["src/lib.rs"]
+  , "srcs": ["src/chacha.rs", "src/guts.rs", "src/lib.rs"]
+  , "edition": ["2018"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps":
+    [ ["@", "ppv-lite86", "", "ppv_lite86"]
+    , ["@", "rand_core", "", "rand_core"]
+    ]
+  , "cargo_features": ["std"]
+  , "stage": ["rand_chacha-0.3.1"]
+  , "version": ["0", "3", "1"]
+  , "pkg_name": ["rand_chacha"]
+  }
+, "default": {"type": ["@", "rules", "cargo", "feature"], "name": ["default"]}
+, "serde": {"type": ["@", "rules", "cargo", "feature"], "name": ["serde"]}
+, "serde1": {"type": ["@", "rules", "cargo", "feature"], "name": ["serde1"]}
+, "simd": {"type": ["@", "rules", "cargo", "feature"], "name": ["simd"]}
+, "std": {"type": ["@", "rules", "cargo", "feature"], "name": ["std"]}
+}
diff --git a/etc/deps-rust/TARGETS.rand_core-0.6.4 b/etc/deps-rust/TARGETS.rand_core-0.6.4
new file mode 100644
index 0000000..28896c6
--- /dev/null
+++ b/etc/deps-rust/TARGETS.rand_core-0.6.4
@@ -0,0 +1,34 @@
+{ "rand_core":
+  { "type": "export"
+  , "target": "rand_core-internal"
+  , "flexible_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  }
+, "rand_core-internal":
+  { "type": ["@", "rules", "rust", "library"]
+  , "name": ["rand_core"]
+  , "crate_root": ["src/lib.rs"]
+  , "srcs":
+    [ "src/impls.rs"
+    , "src/block.rs"
+    , "src/os.rs"
+    , "src/le.rs"
+    , "src/error.rs"
+    , "src/lib.rs"
+    ]
+  , "edition": ["2018"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps": [["@", "getrandom", "", "getrandom"]]
+  , "cargo_features": ["alloc", "getrandom", "std"]
+  , "stage": ["rand_core-0.6.4"]
+  , "version": ["0", "6", "4"]
+  , "pkg_name": ["rand_core"]
+  }
+, "alloc": {"type": ["@", "rules", "cargo", "feature"], "name": ["alloc"]}
+, "getrandom":
+  {"type": ["@", "rules", "cargo", "feature"], "name": ["getrandom"]}
+, "serde": {"type": ["@", "rules", "cargo", "feature"], "name": ["serde"]}
+, "serde1": {"type": ["@", "rules", "cargo", "feature"], "name": ["serde1"]}
+, "std": {"type": ["@", "rules", "cargo", "feature"], "name": ["std"]}
+}
diff --git a/etc/generate-repos.sh b/etc/generate-repos.sh
index 8bd1ca6..d8cd187 100755
--- a/etc/generate-repos.sh
+++ b/etc/generate-repos.sh
@@ -8,8 +8,15 @@ readonly ROOT=$(readlink -f $(dirname $0)/..)
 : ${RULES_RUST_REPO:=https://github.com/just-buildsystem/rules-rust}
 : ${RULES_RUST_BRANCH:=master}
 
+# remove files generated by just-import-cargo
+rm -rf etc/deps-rust etc/defaults/rust/TARGETS # common to all cargo imports
+rm -f src/rust/cargo/circle/Cargo.lock src/rust/cargo/circle/TARGETS
+
 just-import-git -C ${ROOT}/etc/repos.template.json \
                 --as rules -b ${RULES_CC_BRANCH} ${RULES_CC_REPO} rules \
     | just-import-git -C - \
                 --as rules-rust -b ${RULES_RUST_BRANCH} ${RULES_RUST_REPO} rules-rust \
+    | just-import-cargo --rules rules-rust/nix --repo-root ${ROOT} -rst \
+                src/rust/cargo/circle \
+    | just-deduplicate-repos \
     | hdump > ${ROOT}/etc/repos.json
diff --git a/etc/repos.json b/etc/repos.json
index 1f68227..3f419a3 100644
--- a/etc/repos.json
+++ b/etc/repos.json
@@ -5,7 +5,8 @@
     }
   , "test":
     { "repository": {"type": "file", "path": "test"}
-    , "bindings": {"rules": "rules/nix-test", "src": ""}
+    , "bindings":
+      {"rules": "rules/nix-test", "src": "", "cargo/circle": "circle_sampling"}
     }
   , "defaults": {"repository": {"type": "file", "path": "etc/defaults"}}
   , "rules/nix":
@@ -14,6 +15,7 @@
     { "repository": "rules-rust"
     , "target_root": "defaults"
     , "rule_root": "rules-rust"
+    , "target_file_name": "nix.TARGETS"
     }
   , "rules/nix-test":
     { "repository": "rules"
@@ -36,9 +38,124 @@
       { "type": "git"
       , "repository": "https://github.com/just-buildsystem/rules-rust"
       , "branch": "master"
-      , "commit": "bf3e05a614f1de5a9a8a0f8e40f1dd9e1f6609da"
+      , "commit": "9a4697a2c948a4bcb4a2232a371b6cb3c178e20b"
       , "subdir": "rules"
       }
     }
+  , "circle_sampling/cfg-if-1.0.0":
+    { "repository":
+      { "type": "archive"
+      , "fetch": "https://crates.io/api/v1/crates/cfg-if/1.0.0/download"
+      , "content": "c77d9a7af0aea15217dfcdd046013598f696acb0"
+      , "subdir": "cfg-if-1.0.0"
+      , "distfile": "cfg-if-1.0.0.tar.gz"
+      }
+    , "bindings": {"rules": "circle_sampling/rust-rules"}
+    , "target_root": "circle_sampling/external-deps"
+    , "target_file_name": "TARGETS.cfg-if-1.0.0"
+    }
+  , "circle_sampling":
+    { "repository": {"type": "file", "path": "src/rust/cargo/circle"}
+    , "bindings":
+      { "rules": "circle_sampling/rust-rules"
+      , "rand": "circle_sampling/rand-0.8.5"
+      }
+    }
+  , "circle_sampling/getrandom-0.2.15":
+    { "repository":
+      { "type": "archive"
+      , "fetch": "https://crates.io/api/v1/crates/getrandom/0.2.15/download"
+      , "content": "8c167a8cdc3f6f149dd3f37ba9c6932a2592052a"
+      , "subdir": "getrandom-0.2.15"
+      , "distfile": "getrandom-0.2.15.tar.gz"
+      }
+    , "bindings":
+      { "rules": "circle_sampling/rust-rules"
+      , "cfg-if": "circle_sampling/cfg-if-1.0.0"
+      , "libc": "circle_sampling/libc-0.2.155"
+      }
+    , "target_root": "circle_sampling/external-deps"
+    , "target_file_name": "TARGETS.getrandom-0.2.15"
+    }
+  , "circle_sampling/libc-0.2.155":
+    { "repository":
+      { "type": "archive"
+      , "fetch": "https://crates.io/api/v1/crates/libc/0.2.155/download"
+      , "content": "67353d815cff7dd0c37e4426c338bf7f2534a5c1"
+      , "subdir": "libc-0.2.155"
+      , "distfile": "libc-0.2.155.tar.gz"
+      }
+    , "bindings": {"rules": "circle_sampling/rust-rules"}
+    , "target_root": "circle_sampling/external-deps"
+    , "target_file_name": "TARGETS.libc-0.2.155"
+    }
+  , "circle_sampling/ppv-lite86-0.2.17":
+    { "repository":
+      { "type": "archive"
+      , "fetch": "https://crates.io/api/v1/crates/ppv-lite86/0.2.17/download"
+      , "content": "b142c0fb86f0c3c585c1579a7d671b78441cad27"
+      , "subdir": "ppv-lite86-0.2.17"
+      , "distfile": "ppv-lite86-0.2.17.tar.gz"
+      }
+    , "bindings": {"rules": "circle_sampling/rust-rules"}
+    , "target_root": "circle_sampling/external-deps"
+    , "target_file_name": "TARGETS.ppv-lite86-0.2.17"
+    }
+  , "circle_sampling/rand-0.8.5":
+    { "repository":
+      { "type": "archive"
+      , "fetch": "https://crates.io/api/v1/crates/rand/0.8.5/download"
+      , "content": "768d8f0c5c7abe7eb847ffc1a0ff6e3e5ccc49d3"
+      , "subdir": "rand-0.8.5"
+      , "distfile": "rand-0.8.5.tar.gz"
+      }
+    , "bindings":
+      { "rules": "circle_sampling/rust-rules"
+      , "libc": "circle_sampling/libc-0.2.155"
+      , "rand_chacha": "circle_sampling/rand_chacha-0.3.1"
+      , "rand_core": "circle_sampling/rand_core-0.6.4"
+      }
+    , "target_root": "circle_sampling/external-deps"
+    , "target_file_name": "TARGETS.rand-0.8.5"
+    }
+  , "circle_sampling/rand_chacha-0.3.1":
+    { "repository":
+      { "type": "archive"
+      , "fetch": "https://crates.io/api/v1/crates/rand_chacha/0.3.1/download"
+      , "content": "67d1b4ac6de64f68ced704ee6133b6e97976eadc"
+      , "subdir": "rand_chacha-0.3.1"
+      , "distfile": "rand_chacha-0.3.1.tar.gz"
+      }
+    , "bindings":
+      { "rules": "circle_sampling/rust-rules"
+      , "ppv-lite86": "circle_sampling/ppv-lite86-0.2.17"
+      , "rand_core": "circle_sampling/rand_core-0.6.4"
+      }
+    , "target_root": "circle_sampling/external-deps"
+    , "target_file_name": "TARGETS.rand_chacha-0.3.1"
+    }
+  , "circle_sampling/rand_core-0.6.4":
+    { "repository":
+      { "type": "archive"
+      , "fetch": "https://crates.io/api/v1/crates/rand_core/0.6.4/download"
+      , "content": "7fb776b46fd89e927d5ea0f5df0c220ce650c7dc"
+      , "subdir": "rand_core-0.6.4"
+      , "distfile": "rand_core-0.6.4.tar.gz"
+      }
+    , "bindings":
+      { "rules": "circle_sampling/rust-rules"
+      , "getrandom": "circle_sampling/getrandom-0.2.15"
+      }
+    , "target_root": "circle_sampling/external-deps"
+    , "target_file_name": "TARGETS.rand_core-0.6.4"
+    }
+  , "circle_sampling/external-deps":
+    {"repository": {"type": "file", "path": "etc/deps-rust"}}
+  , "circle_sampling/rust-rules":
+    { "repository": "rules-rust"
+    , "target_root": "defaults"
+    , "rule_root": "rules-rust"
+    , "bindings": {"orig-rules": "rules-rust/nix"}
+    }
   }
 }
diff --git a/etc/repos.template.json b/etc/repos.template.json
index 929e149..1b898be 100644
--- a/etc/repos.template.json
+++ b/etc/repos.template.json
@@ -5,7 +5,8 @@
     }
   , "test":
     { "repository": {"type": "file", "path": "test"}
-    , "bindings": {"rules": "rules/nix-test", "src": ""}
+    , "bindings":
+      {"rules": "rules/nix-test", "src": "", "cargo/circle": "circle_sampling"}
     }
   , "defaults": {"repository": {"type": "file", "path": "etc/defaults"}}
   , "rules/nix":
@@ -14,6 +15,7 @@
     { "repository": "rules-rust"
     , "target_root": "defaults"
     , "rule_root": "rules-rust"
+    , "target_file_name": "nix.TARGETS"
     }
   , "rules/nix-test":
     { "repository": "rules"
diff --git a/nix-dependencies/dependencies.nix b/nix-dependencies/dependencies.nix
index a328ddd..10a1b3e 100644
--- a/nix-dependencies/dependencies.nix
+++ b/nix-dependencies/dependencies.nix
@@ -7,10 +7,12 @@
 , clang
 , fmt
 , rustc
+, busybox
 
   # for tests
 , gnugrep
 , unixtools
+, python3
 }:
 
 stdenv.mkDerivation rec {
@@ -42,10 +44,11 @@ stdenv.mkDerivation rec {
                      GRPC_PLUGIN=${grpc}/bin/grpc_cpp_plugin \
              ) \
           shell=$(jo PATH=$(jo -a ${coreutils}/bin)) \
-          test=$(jo PATH=$(jo -a ${gnugrep}/bin ${unixtools.xxd}/bin)) \
+          test=$(jo PATH=$(jo -a ${gnugrep}/bin ${unixtools.xxd}/bin ${python3}/bin)) \
           PKGCONFIG=$(jo pkg-config=${pkg-config}/bin/pkg-config \
                          PKG_CONFIG_PATH=$(jo -a $PKG_CONFIG_PATH)) \
-          RUST=$(jo PATH=$(jo -a ${rustc}/bin ${clang}/bin ${coreutils}/bin /bin)) \
+          RUST=$(jo PATH=$(jo -a ${rustc}/bin ${clang}/bin ${coreutils}/bin \
+                                 ${busybox}/bin)) \
           ) > config.json
     cat config.json
     jo "just files"=$(jo config=$(jo -a $(jo root=system path=$out/share/config.json))) > rc.json
diff --git a/nix-import-tools/import-tools.nix b/nix-import-tools/import-tools.nix
index cfb7a91..b12023b 100644
--- a/nix-import-tools/import-tools.nix
+++ b/nix-import-tools/import-tools.nix
@@ -26,7 +26,9 @@ stdenv.mkDerivation rec {
 
   unpackPhase = ''
     cp $srcjust/bin/just-import-git.py .
+    cp $srcjust/bin/just-deduplicate-repos.py .
     cp $srcrustrules/bin/hdump.py .
+    cp $srcrustrules/bin/just-import-cargo.py .
   '';
 
   dontBuild = true;
@@ -34,8 +36,11 @@ stdenv.mkDerivation rec {
   installPhase = ''
     mkdir -p $out/bin
     cp just-import-git.py $out/bin/just-import-git
+    cp just-deduplicate-repos.py $out/bin/just-deduplicate-repos
     cp hdump.py $out/bin/hdump
-    chmod 555 $out/bin/just-import-git $out/bin/hdump
+    cp just-import-cargo.py $out/bin/just-import-cargo
+    chmod 555 $out/bin/just-import-git $out/bin/just-deduplicate-repos
+    chmod 555 $out/bin/hdump $out/bin/just-import-cargo
   '';
 
 }
diff --git a/shell.nix b/shell.nix
index 2a1b356..a42d2ae 100644
--- a/shell.nix
+++ b/shell.nix
@@ -16,6 +16,7 @@ in pkgs.mkShell rec {
   buildInputs = with pkgs; [
      niv
      update-deps
+     cargo
   ];
 
   shellHook = ''
diff --git a/src/rust/cargo/README.md b/src/rust/cargo/README.md
new file mode 100644
index 0000000..5ac8e27
--- /dev/null
+++ b/src/rust/cargo/README.md
@@ -0,0 +1,45 @@
+# Importing cargo dependencies
+
+The [rules for rust](https://github.com/just-buildsystem/rules-rust) also
+bring a tool to import dependencies from cargo. Here we give an overview of
+its usage, using the subidrectory `circle` as a dependency.
+
+## Files written by hand
+
+Cargo dependencies are described as dependencies of a crate. So all the
+files you would normally write by hand when writing a crate have to be
+manually added. As we define a binary, those are
+  - `Cargo.toml`, and
+  - `src/main.rs`.
+
+## Using `just-import-cargo`
+
+As other import tools, `just-import-cargo` expects a repository specification
+on standard input and returns one on standard output. It needs to know
+ - the root of the pyhsical repository, and
+ - the location of the crate directory, relative to the root of the physical
+   repository.
+ - the name of the already imported `rules-rust` repository.
+
+While the tool in general can also import `rules-rust` itself, we need to import
+the rules manually first, as we have to provide our own target root for the
+defaults. Future versions of the rules might bring a defaults target suitable
+for our use case, but so far this is not the case.
+
+The name of the imported main repository is the crate name (without version),
+as specified in the `Cargo.toml` file. Some care should be taken that is does
+not conflict with already existing repositories; repositories from the
+`etc/repos.templace.json` can have a binding to that still to be imported
+repository, as usual.
+
+As opposed to other import tools, however, `just-import-cargo` also creates
+files in the pysical repository. Those are the following.
+ - In the crate the file `Cargo.lock` generated by the call to cargo, as
+   well as a target file,
+ - The file `etc/defaults/rust/TARGETS` relative to in the top-level of the
+   physical repository (with a content independent of the respective crate).
+   This file is the reason that our `rules-rust/nix` use `nix.TARGETS` as
+   target-file name.
+ - In the directory `etc/deps-rust` target files for all the imported crates.
+   As their name encode crate name and version, calling `just-import-cargo`
+   for several crates should not cause a conflict here.
diff --git a/src/rust/cargo/circle/Cargo.lock b/src/rust/cargo/circle/Cargo.lock
new file mode 100644
index 0000000..9b1bff2
--- /dev/null
+++ b/src/rust/cargo/circle/Cargo.lock
@@ -0,0 +1,75 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "circle_sampling"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.155"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
diff --git a/src/rust/cargo/circle/Cargo.toml b/src/rust/cargo/circle/Cargo.toml
new file mode 100644
index 0000000..563be5e
--- /dev/null
+++ b/src/rust/cargo/circle/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "circle_sampling"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rand = "0.8.5"
diff --git a/src/rust/cargo/circle/TARGETS b/src/rust/cargo/circle/TARGETS
new file mode 100644
index 0000000..9085e22
--- /dev/null
+++ b/src/rust/cargo/circle/TARGETS
@@ -0,0 +1,15 @@
+{ "circle_sampling":
+  { "type": ["@", "rules", "rust", "binary"]
+  , "name": ["circle_sampling"]
+  , "crate_root": ["src/main.rs"]
+  , "srcs": ["src/main.rs"]
+  , "edition": ["2021"]
+  , "arguments_config":
+    ["ARCH", "HOST_ARCH", "TARGET_ARCH", "ENV", "TOOLCHAIN_CONFIG"]
+  , "deps": [["@", "rand", "", "rand"]]
+  , "cargo_features": []
+  , "stage": ["circle_sampling-0.1.0"]
+  , "version": ["0", "1", "0"]
+  , "pkg_name": ["circle_sampling"]
+  }
+}
diff --git a/src/rust/cargo/circle/src/main.rs b/src/rust/cargo/circle/src/main.rs
new file mode 100644
index 0000000..329542f
--- /dev/null
+++ b/src/rust/cargo/circle/src/main.rs
@@ -0,0 +1,18 @@
+use rand::Rng;
+
+fn main() {
+    let mut x :i16;
+    let mut y :i16;
+    let mut rng = rand::thread_rng();
+
+    loop {
+       x = rng.gen_range(-100..=100);
+       y = rng.gen_range(-100..=100);
+
+       if x*x + y*y < 100*100 {
+           break;
+       }
+    }
+
+    println!("{x} {y}")
+}
diff --git a/test/rust/TARGETS b/test/rust/TARGETS
index 713ff64..d62b2d3 100644
--- a/test/rust/TARGETS
+++ b/test/rust/TARGETS
@@ -3,6 +3,7 @@
   , "tainted": ["test"]
   , "dirs":
     [ [["./", "hello", ""], "hello"]
+    , [["./", "cargo", ""], "cargo"]
     ]
   }
 }
diff --git a/test/rust/cargo/TARGETS b/test/rust/cargo/TARGETS
new file mode 100644
index 0000000..1552a32
--- /dev/null
+++ b/test/rust/cargo/TARGETS
@@ -0,0 +1,8 @@
+{ "":
+  { "type": "install"
+  , "tainted": ["test"]
+  , "dirs":
+    [ [["./", "circle", ""], "circle"]
+    ]
+  }
+}
diff --git a/test/rust/cargo/circle/TARGETS b/test/rust/cargo/circle/TARGETS
new file mode 100644
index 0000000..565bb37
--- /dev/null
+++ b/test/rust/cargo/circle/TARGETS
@@ -0,0 +1,13 @@
+{ "": {"type": "install", "tainted": ["test"], "deps": ["test-sampling"]}
+, "test-sampling":
+  { "type": ["@", "rules", "shell/test", "script"]
+  , "name": ["sampling"]
+  , "test": ["test_circle_sampling.sh"]
+  , "deps": ["sample", "verify.py"]
+  , "keep": ["sampled"]
+  }
+, "sample":
+  { "type": "install"
+  , "files": {"bin/sample": ["@", "cargo/circle", "", "circle_sampling"]}
+  }
+}
diff --git a/test/rust/cargo/circle/test_circle_sampling.sh b/test/rust/cargo/circle/test_circle_sampling.sh
new file mode 100644
index 0000000..c22109a
--- /dev/null
+++ b/test/rust/cargo/circle/test_circle_sampling.sh
@@ -0,0 +1,8 @@
+set -e
+
+for _ in `seq 1 100`
+do
+    ./bin/sample >> sampled
+done
+
+python3 verify.py sampled
diff --git a/test/rust/cargo/circle/verify.py b/test/rust/cargo/circle/verify.py
new file mode 100644
index 0000000..09dccee
--- /dev/null
+++ b/test/rust/cargo/circle/verify.py
@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+
+import math
+import sys
+
+with open(sys.argv[1]) as f:
+    samples = f.read()
+
+for line in samples.splitlines():
+    xs, ys = line.split()
+    x = int(xs)
+    y = int(ys)
+    radius = math.sqrt(x*x + y*y)
+    print ("(%+3d,%+3d) -> %4.1f" % (x,y,radius))
+    if radius > 100.0:
+        sys.exit(1)