["cargo", "build_script"]: support "extra_data"

Build scripts often require additional data; therefore, extend
the rule by a field "extra_data" that will be available when running
the build script.

2 files changed, 19 insertions, 3 deletions

diff --git a/README.md b/README.md
index b24091e..6b77398 100644
--- a/README.md
+++ b/README.md
@@ -160,6 +160,7 @@ provided by the "defaults" for the "HOST_ARCH".
 | `"defaults"` | The Rust toolchain to use. |
 | `"deps"` | Any other libraries this binary depends upon. |
 | `"edition"` | The edition of the compiler to use during compilation. If unset, 2015 is used. |
+| `"extra_data"` | Extra files needed while running the build script. |
 | `"name"` | The name of the crate being built. |
 | `"pkg_name"` | The name of the package the crate belongs to. It is exported to the CARGO_PKG_NAME environment variable. |
 | `"srcs"` | The source files of the binary. |
diff --git a/rules/cargo/RULES b/rules/cargo/RULES
index 59ef326..dd48c4d 100644
--- a/rules/cargo/RULES
+++ b/rules/cargo/RULES
@@ -8,7 +8,8 @@
     , "provided by the \"defaults\" for the \"HOST_ARCH\"."
     ]
   , "string_fields": ["name", "edition", "stage", "version", "pkg_name"]
-  , "target_fields": ["crate_root", "srcs", "deps", "cargo_features"]
+  , "target_fields":
+    ["crate_root", "srcs", "deps", "cargo_features", "extra_data"]
   , "field_doc":
     { "name": ["The name of the crate being built."]
     , "cargo_features":
@@ -37,6 +38,7 @@
       , "three elements are used for the major, minor, and patch"
       , "number respectively."
       ]
+    , "extra_data": ["Extra files needed while running the build script."]
     }
   , "config_vars": ["ARCH", "HOST_ARCH", "ENV"]
   , "config_doc":
@@ -68,7 +70,7 @@
     { "call rustc artifact": ["./", "../rust", "call rustc artifact"]
     , "for host": ["./", "../rust", "for host"]
     , "for host as rlib": ["./", "../rust", "for host as rlib"]
-    , "get_runfiles": ["./", "..", "get_runfiles"]
+    , "get_artifacts": ["./", "..", "get_artifacts"]
     }
   , "implicit": {"defaults": [["./", "../rust", "defaults"]]}
   , "expression":
@@ -134,6 +136,13 @@
           , "map": {"type": "var", "name": "artifact result"}
           }
         ]
+      , [ "extra_data"
+        , { "type": "let*"
+          , "bindings":
+            [["field_content", {"type": "FIELD", "name": "extra_data"}]]
+          , "body": {"type": "CALL_EXPRESSION", "name": "get_artifacts"}
+          }
+        ]
       , [ "out_name"
         , { "type": "join"
           , "$1": [{"type": "var", "name": "stage"}, "out"]
@@ -143,7 +152,13 @@
       , [ "out"
         , { "type": "ACTION"
           , "outs": [{"type": "var", "name": "out_name"}]
-          , "inputs": {"type": "var", "name": "exe"}
+          , "inputs":
+            { "type": "map_union"
+            , "$1":
+              [ {"type": "var", "name": "extra_data"}
+              , {"type": "var", "name": "exe"}
+              ]
+            }
           , "cmd":
             [ "sh"
             , "-ce"