Support expanding locations in rustc_env and build_script_env

cargo/cargo_build_script.bzl

@@ -4,6 +4,19 @@ load("@io_bazel_rules_rust//rust:private/rustc.bzl", "BuildInfo", "DepInfo", "ge
 load("@io_bazel_rules_rust//rust:private/utils.bzl", "find_toolchain")
 load("@io_bazel_rules_rust//rust:rust.bzl", "rust_binary")
 
+def _expand_location(ctx, env, data):
+    if env.startswith("$(execpath ") or env.startswith("$(location "):
+        # build script runner will replace with execroot
+        return "${pwd}/" + ctx.expand_location(env, data)
+    else:
+        return env
+
+def _expand_locations(ctx):
+    "Expand $(execroot ...) references in user-provided env vars."
+    env = ctx.attr.build_script_env
+    data = getattr(ctx.attr, "data", [])
+    return dict([(k, _expand_location(ctx, v, data)) for (k, v) in env.items()])
+
 def _build_script_impl(ctx):
     """The implementation for the `_build_script_run` rule.
 
@@ -88,14 +101,14 @@ def _build_script_impl(ctx):
     for f in ctx.attr.crate_features:
         env["CARGO_FEATURE_" + f.upper().replace("-", "_")] = "1"
 
-    env.update(ctx.attr.build_script_env)
+    env.update(_expand_locations(ctx))
 
     tools = depset(
         direct = [
             script,
             ctx.executable._cargo_build_script_runner,
             toolchain.rustc,
-        ],
+        ] + ctx.files.data,
         transitive = toolchain_tools,
     )
 
@@ -164,6 +177,10 @@ _build_script_run = rule(
         "build_script_env": attr.string_dict(
             doc = "Environment variables for build scripts.",
         ),
+        "data": attr.label_list(
+            doc = "Data or tools required by the build script.",
+            allow_files = True,
+        ),
         "_cc_toolchain": attr.label(
             default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
         ),
@@ -188,6 +205,7 @@ def cargo_build_script(
         version = None,
         deps = [],
         build_script_env = {},
+        data = [],
         **kwargs):
     """Compile and execute a rust build script to generate build attributes
 
@@ -220,10 +238,16 @@ def cargo_build_script(
     cargo_build_script(
         name = "build_script",
         srcs = ["build.rs"],
-        # Data are shipped during execution.
-        data = ["src/lib.rs"],
-        # Environment variables passed during build.rs execution
-        build_script_env = {"CARGO_PKG_VERSION": "0.1.2"},
+        # Optional environment variables passed during build.rs compilation
+        rustc_env = {
+           "CARGO_PKG_VERSION": "0.1.2",
+        },
+        # Optional environment variables passed during build.rs execution.
+        build_script_env = {
+            "SOME_TOOL_OR_FILE": "$(execroot @tool//:binary)"
+        }
+        # Optional data/tool dependencies
+        data = ["@tool//:binary"],
     )
 
     rust_library(
@@ -245,13 +269,15 @@ def cargo_build_script(
         version (str, optional): The semantic version (semver) of the crate.
         deps (list, optional): The dependencies of the crate defined by `crate_name`.
         build_script_env (dict, optional): Environment variables for build scripts.
+        data (list, optional): Files or tools needed by the build script.
         **kwargs: Forwards to the underlying `rust_binary` rule.
     """
     rust_binary(
         name = name + "_script_",
         crate_features = crate_features,
         version = version,
         deps = deps,
+        data = data,
         **kwargs
     )
     _build_script_run(
@@ -261,5 +287,5 @@ def cargo_build_script(
         crate_features = crate_features,
         version = version,
         build_script_env = build_script_env,
-        deps = deps,
+        data = data,
     )

cargo/cargo_build_script_runner/bin.rs

@@ -48,7 +48,7 @@ fn main() -> Result<(), String> {
 
             let mut command = Command::new(exec_root.join(&progname));
             command
-                .current_dir(manifest_dir.clone())
+                .current_dir(&manifest_dir)
                 .envs(target_env_vars)
                 .env("OUT_DIR", out_dir_abs)
                 .env("CARGO_MANIFEST_DIR", manifest_dir)
@@ -92,6 +92,15 @@ fn main() -> Result<(), String> {
                 }
             }
 
+            // replace env vars with a ${pwd} prefix with the exec_root
+            for (key, value) in env::vars() {
+                let exec_root_str = exec_root.to_str().expect("exec_root not in utf8");
+                if value.starts_with("${pwd}") {
+                    env::set_var(key, value.replacen("${pwd}", exec_root_str, 1));
+                }
+            }
+
+
             let output = BuildScriptOutput::from_command(&mut command).map_err(|exit_code| {
                 format!(
                     "Build script process failed{}",

docs/cargo_build_script.md

@@ -6,7 +6,7 @@
 ## cargo_build_script
 
 <pre>
-cargo_build_script(<a href="#cargo_build_script-name">name</a>, <a href="#cargo_build_script-crate_name">crate_name</a>, <a href="#cargo_build_script-crate_features">crate_features</a>, <a href="#cargo_build_script-version">version</a>, <a href="#cargo_build_script-deps">deps</a>, <a href="#cargo_build_script-build_script_env">build_script_env</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
+cargo_build_script(<a href="#cargo_build_script-name">name</a>, <a href="#cargo_build_script-crate_name">crate_name</a>, <a href="#cargo_build_script-crate_features">crate_features</a>, <a href="#cargo_build_script-version">version</a>, <a href="#cargo_build_script-deps">deps</a>, <a href="#cargo_build_script-build_script_env">build_script_env</a>, <a href="#cargo_build_script-data">data</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
 </pre>
 
 Compile and execute a rust build script to generate build attributes
@@ -40,10 +40,16 @@ load("@io_bazel_rules_rust//cargo:cargo_build_script.bzl", "cargo_build_script")
 cargo_build_script(
     name = "build_script",
     srcs = ["build.rs"],
-    # Data are shipped during execution.
-    data = ["src/lib.rs"],
-    # Environment variables passed during build.rs execution
-    build_script_env = {"CARGO_PKG_VERSION": "0.1.2"},
+    # Optional environment variables passed during build.rs compilation
+    rustc_env = {
+       "CARGO_PKG_VERSION": "0.1.2",
+    },
+    # Optional environment variables passed during build.rs execution.
+    build_script_env = {
+        "SOME_TOOL_OR_FILE": "$(execroot @tool//:binary)"
+    }
+    # Optional data/tool dependencies
+    data = ["@tool//:binary"],
 )
 
 rust_library(
@@ -69,6 +75,7 @@ The `hello_lib` target will be build with the flags and the environment variable
 | <a id="cargo_build_script-version"></a>version |  The semantic version (semver) of the crate.   |  <code>None</code> |
 | <a id="cargo_build_script-deps"></a>deps |  The dependencies of the crate defined by <code>crate_name</code>.   |  <code>[]</code> |
 | <a id="cargo_build_script-build_script_env"></a>build_script_env |  Environment variables for build scripts.   |  <code>{}</code> |
+| <a id="cargo_build_script-data"></a>data |  Files or tools needed by the build script.   |  <code>[]</code> |
 | <a id="cargo_build_script-kwargs"></a>kwargs |  Forwards to the underlying <code>rust_binary</code> rule.   |  none |
 
 

docs/flatten.md

@@ -122,7 +122,7 @@ Run the benchmark test using: `bazel run //fibonacci:fibonacci_bench`.
 | <a id="rust_benchmark-edition"></a>edition |  The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.   | String | optional | "" |
 | <a id="rust_benchmark-out_dir_tar"></a>out_dir_tar |  __Deprecated__, do not use, see [#cargo_build_script] instead.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
 | <a id="rust_benchmark-proc_macro_deps"></a>proc_macro_deps |  List of <code>rust_library</code> targets with kind <code>proc-macro</code> used to help build this library target.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
-| <a id="rust_benchmark-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
+| <a id="rust_benchmark-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.<br><br>rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
 | <a id="rust_benchmark-rustc_flags"></a>rustc_flags |  List of compiler flags passed to <code>rustc</code>.   | List of strings | optional | [] |
 | <a id="rust_benchmark-srcs"></a>srcs |  List of Rust <code>.rs</code> source files used to build the library.<br><br>If <code>srcs</code> contains more than one file, then there must be a file either named <code>lib.rs</code>. Otherwise, <code>crate_root</code> must be set to the source file that is the root of the crate to be passed to rustc to build this crate.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
 | <a id="rust_benchmark-version"></a>version |  A version to inject in the cargo environment variable.   | String | optional | "0.0.0" |
@@ -239,7 +239,7 @@ Hello world
 | <a id="rust_binary-out_binary"></a>out_binary |  -   | Boolean | optional | False |
 | <a id="rust_binary-out_dir_tar"></a>out_dir_tar |  __Deprecated__, do not use, see [#cargo_build_script] instead.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
 | <a id="rust_binary-proc_macro_deps"></a>proc_macro_deps |  List of <code>rust_library</code> targets with kind <code>proc-macro</code> used to help build this library target.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
-| <a id="rust_binary-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
+| <a id="rust_binary-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.<br><br>rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
 | <a id="rust_binary-rustc_flags"></a>rustc_flags |  List of compiler flags passed to <code>rustc</code>.   | List of strings | optional | [] |
 | <a id="rust_binary-srcs"></a>srcs |  List of Rust <code>.rs</code> source files used to build the library.<br><br>If <code>srcs</code> contains more than one file, then there must be a file either named <code>lib.rs</code>. Otherwise, <code>crate_root</code> must be set to the source file that is the root of the crate to be passed to rustc to build this crate.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
 | <a id="rust_binary-version"></a>version |  A version to inject in the cargo environment variable.   | String | optional | "0.0.0" |
@@ -535,7 +535,7 @@ INFO: Elapsed time: 1.245s, Critical Path: 1.01s
 | <a id="rust_library-edition"></a>edition |  The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.   | String | optional | "" |
 | <a id="rust_library-out_dir_tar"></a>out_dir_tar |  __Deprecated__, do not use, see [#cargo_build_script] instead.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
 | <a id="rust_library-proc_macro_deps"></a>proc_macro_deps |  List of <code>rust_library</code> targets with kind <code>proc-macro</code> used to help build this library target.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
-| <a id="rust_library-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
+| <a id="rust_library-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.<br><br>rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
 | <a id="rust_library-rustc_flags"></a>rustc_flags |  List of compiler flags passed to <code>rustc</code>.   | List of strings | optional | [] |
 | <a id="rust_library-srcs"></a>srcs |  List of Rust <code>.rs</code> source files used to build the library.<br><br>If <code>srcs</code> contains more than one file, then there must be a file either named <code>lib.rs</code>. Otherwise, <code>crate_root</code> must be set to the source file that is the root of the crate to be passed to rustc to build this crate.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
 | <a id="rust_library-version"></a>version |  A version to inject in the cargo environment variable.   | String | optional | "0.0.0" |
@@ -792,7 +792,7 @@ Run the test with `bazel build //hello_lib:hello_lib_test`.
 | <a id="rust_test-edition"></a>edition |  The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.   | String | optional | "" |
 | <a id="rust_test-out_dir_tar"></a>out_dir_tar |  __Deprecated__, do not use, see [#cargo_build_script] instead.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
 | <a id="rust_test-proc_macro_deps"></a>proc_macro_deps |  List of <code>rust_library</code> targets with kind <code>proc-macro</code> used to help build this library target.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
-| <a id="rust_test-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
+| <a id="rust_test-rustc_env"></a>rustc_env |  Dictionary of additional <code>"key": "value"</code> environment variables to set for rustc.<br><br>rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
 | <a id="rust_test-rustc_flags"></a>rustc_flags |  List of compiler flags passed to <code>rustc</code>.   | List of strings | optional | [] |
 | <a id="rust_test-srcs"></a>srcs |  List of Rust <code>.rs</code> source files used to build the library.<br><br>If <code>srcs</code> contains more than one file, then there must be a file either named <code>lib.rs</code>. Otherwise, <code>crate_root</code> must be set to the source file that is the root of the crate to be passed to rustc to build this crate.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
 | <a id="rust_test-version"></a>version |  A version to inject in the cargo environment variable.   | String | optional | "0.0.0" |
@@ -963,15 +963,15 @@ The tools required for the `rust_wasm_bindgen` rule.
 | Name  | Description | Type | Mandatory | Default |
 | :------------- | :------------- | :------------- | :------------- | :------------- |
 | <a id="rust_wasm_bindgen_toolchain-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/docs/build-ref.html#name">Name</a> | required |  |
-| <a id="rust_wasm_bindgen_toolchain-bindgen"></a>bindgen |  The label of a <code>bindgen</code> executable.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
+| <a id="rust_wasm_bindgen_toolchain-bindgen"></a>bindgen |  The label of a <code>wasm-bindgen</code> executable.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
 
 
 <a id="#cargo_build_script"></a>
 
 ## cargo_build_script
 
 <pre>
-cargo_build_script(<a href="#cargo_build_script-name">name</a>, <a href="#cargo_build_script-crate_name">crate_name</a>, <a href="#cargo_build_script-crate_features">crate_features</a>, <a href="#cargo_build_script-version">version</a>, <a href="#cargo_build_script-deps">deps</a>, <a href="#cargo_build_script-build_script_env">build_script_env</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
+cargo_build_script(<a href="#cargo_build_script-name">name</a>, <a href="#cargo_build_script-crate_name">crate_name</a>, <a href="#cargo_build_script-crate_features">crate_features</a>, <a href="#cargo_build_script-version">version</a>, <a href="#cargo_build_script-deps">deps</a>, <a href="#cargo_build_script-build_script_env">build_script_env</a>, <a href="#cargo_build_script-data">data</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
 </pre>
 
 Compile and execute a rust build script to generate build attributes
@@ -1005,10 +1005,16 @@ load("@io_bazel_rules_rust//cargo:cargo_build_script.bzl", "cargo_build_script")
 cargo_build_script(
     name = "build_script",
     srcs = ["build.rs"],
-    # Data are shipped during execution.
-    data = ["src/lib.rs"],
-    # Environment variables passed during build.rs execution
-    build_script_env = {"CARGO_PKG_VERSION": "0.1.2"},
+    # Optional environment variables passed during build.rs compilation
+    rustc_env = {
+       "CARGO_PKG_VERSION": "0.1.2",
+    },
+    # Optional environment variables passed during build.rs execution.
+    build_script_env = {
+        "SOME_TOOL_OR_FILE": "$(execroot @tool//:binary)"
+    }
+    # Optional data/tool dependencies
+    data = ["@tool//:binary"],
 )
 
 rust_library(
@@ -1034,6 +1040,7 @@ The `hello_lib` target will be build with the flags and the environment variable
 | <a id="cargo_build_script-version"></a>version |  The semantic version (semver) of the crate.   |  <code>None</code> |
 | <a id="cargo_build_script-deps"></a>deps |  The dependencies of the crate defined by <code>crate_name</code>.   |  <code>[]</code> |
 | <a id="cargo_build_script-build_script_env"></a>build_script_env |  Environment variables for build scripts.   |  <code>{}</code> |
+| <a id="cargo_build_script-data"></a>data |  Files or tools needed by the build script.   |  <code>[]</code> |
 | <a id="cargo_build_script-kwargs"></a>kwargs |  Forwards to the underlying <code>rust_binary</code> rule.   |  none |