Import rust rules and add a minimal example

Note that the PATH for rust targets also has to include
that for the C compiler and hence also coreutils, as the
rust compiler calls out to `cc`.

1 files changed, 43 insertions, 0 deletions

diff --git a/etc/defaults/rust/TARGETS b/etc/defaults/rust/TARGETS
new file mode 100644
index 0000000..fbd1a69
--- /dev/null
+++ b/etc/defaults/rust/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"}
+  }
+}