Update rust_bindgen_library to only link into the direct consumer

bindgen/private/bindgen.bzl

@@ -20,6 +20,7 @@ load(
 )
 load("@rules_cc//cc:defs.bzl", "CcInfo")
 load("//rust:defs.bzl", "rust_library")
+load("//rust:rust_common.bzl", "BuildInfo")
 
 # buildifier: disable=bzl-visibility
 load("//rust/private:rustc.bzl", "get_linker_and_args")
@@ -64,27 +65,94 @@ def rust_bindgen_library(
     if "tags" in kwargs:
         kwargs.pop("tags")
 
+    sub_tags = tags + ([] if "manual" in tags else ["manual"])
+
     deps = kwargs.get("deps") or []
     if "deps" in kwargs:
         kwargs.pop("deps")
 
+    bindgen_kwargs = {}
+    if "leak_symbols" in kwargs:
+        bindgen_kwargs.update({"leak_symbols": kwargs.pop("leak_symbols")})
+
     rust_bindgen(
         name = name + "__bindgen",
         header = header,
         cc_lib = cc_lib,
         bindgen_flags = bindgen_flags or [],
         clang_flags = clang_flags or [],
-        tags = ["manual"],
+        tags = sub_tags,
+        **bindgen_kwargs
     )
 
+    for custom_tag in ["__bindgen", "no-clippy", "no-rustfmt"]:
+        tags = tags + ([] if custom_tag in tags else [custom_tag])
+
     rust_library(
         name = name,
         srcs = [name + "__bindgen.rs"],
-        tags = tags + ["__bindgen", "noclippy"],
-        deps = deps + [cc_lib],
+        deps = deps + [name + "__bindgen"],
+        tags = tags,
         **kwargs
     )
 
+def _generate_cc_link_build_info(ctx, cc_lib):
+    """Produce the eqivilant cargo_build_script providers for use in linking the library.
+
+    Args:
+        ctx (ctx): The rule's context object
+        cc_lib (Target): The `rust_bindgen.cc_lib` target.
+
+    Returns:
+        The `BuildInfo` provider.
+    """
+    compile_data = []
+    linker_flags = []
+    linker_search_paths = []
+
+    for linker_input in cc_lib[CcInfo].linking_context.linker_inputs.to_list():
+        for lib in linker_input.libraries:
+            if lib.static_library:
+                linker_flags.append("-lstatic={}".format(lib.static_library.owner.name))
+                linker_search_paths.append(lib.static_library.dirname)
+                compile_data.append(lib.static_library)
+            elif lib.pic_static_library:
+                linker_flags.append("-lstatic={}".format(lib.pic_static_library.owner.name))
+                linker_search_paths.append(lib.pic_static_library.dirname)
+                compile_data.append(lib.pic_static_library)
+
+        linker_flags.extend(linker_input.user_link_flags)
+
+    if not compile_data:
+        fail("No static libraries found in {}".format(
+            cc_lib.label,
+        ))
+
+    link_flags = ctx.actions.declare_file("{}.link_flags".format(ctx.label.name))
+    ctx.actions.write(
+        output = link_flags,
+        content = "\n".join(linker_flags),
+    )
+
+    link_search_paths = ctx.actions.declare_file("{}.link_search_paths".format(ctx.label.name))
+    ctx.actions.write(
+        output = link_search_paths,
+        content = "\n".join([
+            "-Lnative=${{pwd}}/{}".format(path)
+            for path in depset(linker_search_paths).to_list()
+        ]),
+    )
+
+    return BuildInfo(
+        compile_data = depset(compile_data),
+        dep_env = None,
+        flags = None,
+        link_flags = link_flags,
+        link_search_paths = link_search_paths,
+        out_dir = None,
+        rustc_env = None,
+    )
+
 def _rust_bindgen_impl(ctx):
     # nb. We can't grab the cc_library`s direct headers, so a header must be provided.
     cc_lib = ctx.attr.cc_lib
@@ -200,6 +268,21 @@ def _rust_bindgen_impl(ctx):
         tools = tools,
     )
 
+    if ctx.attr.leak_symbols:
+        # buildifier: disable=print
+        print("WARN: rust_bindgen.leak_symbols is set to True for {} - please file an issue at https://github.com/bazelbuild/rules_rust/issues explaining why this was necessary, as this support will be removed soon.".format(ctx.label))
+        providers = [cc_common.merge_cc_infos(
+            direct_cc_infos = [cc_lib[CcInfo]],
+        )]
+    else:
+        providers = [_generate_cc_link_build_info(ctx, cc_lib)]
+
+    return providers + [
+        OutputGroupInfo(
+            bindgen_bindings = depset([output]),
+        ),
+    ]
+
 rust_bindgen = rule(
     doc = "Generates a rust source file from a cc_library and a header.",
     implementation = _rust_bindgen_impl,
@@ -220,6 +303,13 @@ rust_bindgen = rule(
             allow_single_file = True,
             mandatory = True,
         ),
+        "leak_symbols": attr.bool(
+            doc = (
+                "If True, `cc_lib` will be exposed and linked into all downstream consumers of the target vs. the " +
+                "`rust_library` directly consuming it."
+            ),
+            default = False,
+        ),
         "_cc_toolchain": attr.label(
             default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
         ),

cargo/private/cargo_build_script.bzl

@@ -301,6 +301,7 @@ def _cargo_build_script_impl(ctx):
             flags = flags_out,
             link_flags = link_flags,
             link_search_paths = link_search_paths,
+            compile_data = depset([]),
         ),
         OutputGroupInfo(
             streams = depset([streams.stdout, streams.stderr]),
@@ -449,6 +450,7 @@ def _cargo_dep_env_implementation(ctx):
             link_search_paths = empty_file,
             out_dir = out_dir,
             rustc_env = empty_file,
+            compile_data = depset([]),
         ))
     return [
         DefaultInfo(files = depset(ctx.files.src)),
@@ -465,8 +467,9 @@ def _cargo_dep_env_implementation(ctx):
             flags = empty_file,
             link_flags = empty_file,
             link_search_paths = empty_file,
-            out_dir = empty_dir,
+            out_dir = None,
             rustc_env = empty_file,
+            compile_data = depset([]),
         ),
         # Information here is used directly by dependencies, and it is an error to have more than
         # one dependency which sets this. This is the main way to specify information from build

docs/flatten.md

@@ -359,7 +359,7 @@ is available under the key `dsym_folder` in `OutputGroupInfo`.
 ## rust_bindgen
 
 <pre>
-rust_bindgen(<a href="#rust_bindgen-name">name</a>, <a href="#rust_bindgen-bindgen_flags">bindgen_flags</a>, <a href="#rust_bindgen-cc_lib">cc_lib</a>, <a href="#rust_bindgen-clang_flags">clang_flags</a>, <a href="#rust_bindgen-header">header</a>)
+rust_bindgen(<a href="#rust_bindgen-name">name</a>, <a href="#rust_bindgen-bindgen_flags">bindgen_flags</a>, <a href="#rust_bindgen-cc_lib">cc_lib</a>, <a href="#rust_bindgen-clang_flags">clang_flags</a>, <a href="#rust_bindgen-header">header</a>, <a href="#rust_bindgen-leak_symbols">leak_symbols</a>)
 </pre>
 
 Generates a rust source file from a cc_library and a header.
@@ -374,6 +374,7 @@ Generates a rust source file from a cc_library and a header.
 | <a id="rust_bindgen-cc_lib"></a>cc_lib |  The cc_library that contains the <code>.h</code> file. This is used to find the transitive includes.   | <a href="https://bazel.build/concepts/labels">Label</a> | required |  |
 | <a id="rust_bindgen-clang_flags"></a>clang_flags |  Flags to pass directly to the clang executable.   | List of strings | optional | <code>[]</code> |
 | <a id="rust_bindgen-header"></a>header |  The <code>.h</code> file to generate bindings for.   | <a href="https://bazel.build/concepts/labels">Label</a> | required |  |
+| <a id="rust_bindgen-leak_symbols"></a>leak_symbols |  If True, <code>cc_lib</code> will be exposed and linked into all downstream consumers of the target vs. the <code>rust_library</code> directly consuming it.   | Boolean | optional | <code>False</code> |
 
 
 <a id="rust_bindgen_toolchain"></a>

docs/rust_bindgen.md

@@ -53,7 +53,7 @@ toolchains following the instructions for [rust_bindgen_toolchain](#rust_bindgen
 ## rust_bindgen
 
 <pre>
-rust_bindgen(<a href="#rust_bindgen-name">name</a>, <a href="#rust_bindgen-bindgen_flags">bindgen_flags</a>, <a href="#rust_bindgen-cc_lib">cc_lib</a>, <a href="#rust_bindgen-clang_flags">clang_flags</a>, <a href="#rust_bindgen-header">header</a>)
+rust_bindgen(<a href="#rust_bindgen-name">name</a>, <a href="#rust_bindgen-bindgen_flags">bindgen_flags</a>, <a href="#rust_bindgen-cc_lib">cc_lib</a>, <a href="#rust_bindgen-clang_flags">clang_flags</a>, <a href="#rust_bindgen-header">header</a>, <a href="#rust_bindgen-leak_symbols">leak_symbols</a>)
 </pre>
 
 Generates a rust source file from a cc_library and a header.
@@ -68,6 +68,7 @@ Generates a rust source file from a cc_library and a header.
 | <a id="rust_bindgen-cc_lib"></a>cc_lib |  The cc_library that contains the <code>.h</code> file. This is used to find the transitive includes.   | <a href="https://bazel.build/concepts/labels">Label</a> | required |  |
 | <a id="rust_bindgen-clang_flags"></a>clang_flags |  Flags to pass directly to the clang executable.   | List of strings | optional | <code>[]</code> |
 | <a id="rust_bindgen-header"></a>header |  The <code>.h</code> file to generate bindings for.   | <a href="https://bazel.build/concepts/labels">Label</a> | required |  |
+| <a id="rust_bindgen-leak_symbols"></a>leak_symbols |  If True, <code>cc_lib</code> will be exposed and linked into all downstream consumers of the target vs. the <code>rust_library</code> directly consuming it.   | Boolean | optional | <code>False</code> |
 
 
 <a id="rust_bindgen_toolchain"></a>

examples/bindgen/BUILD.bazel

@@ -1,19 +1,15 @@
-load("@rules_cc//cc:defs.bzl", "cc_library")
 load("@rules_rust//bindgen:defs.bzl", "rust_bindgen_library")
 load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_test")
 
-cc_library(
-    name = "simple",
-    srcs = ["simple.h"],
-)
-
 rust_bindgen_library(
     name = "simple_bindgen",
     bindgen_flags = [
+        "--allowlist-function=simple_.*",
         "--allowlist-var=SIMPLE_.*",
     ],
-    cc_lib = ":simple",
-    header = "simple.h",
+    cc_lib = "//bindgen/simple",
+    header = "//bindgen/simple:simple.h",
+    leak_symbols = False,
 )
 
 rust_binary(
@@ -26,3 +22,25 @@ rust_test(
     name = "simple_test",
     crate = ":simple_example",
 )
+
+rust_bindgen_library(
+    name = "simple_leaked_bindgen",
+    bindgen_flags = [
+        "--allowlist-function=simple_.*",
+        "--allowlist-var=SIMPLE_.*",
+    ],
+    cc_lib = "//bindgen/simple",
+    header = "//bindgen/simple:simple.h",
+    leak_symbols = True,
+)
+
+rust_binary(
+    name = "simple_leaked_example",
+    srcs = ["main_leaked.rs"],
+    deps = [":simple_leaked_bindgen"],
+)
+
+rust_test(
+    name = "simple_leaked_test",
+    crate = ":simple_leaked_example",
+)

examples/bindgen/main.rs

@@ -1,11 +1,22 @@
+//! rust_bindgen_library example consumer
+
+fn simple_function() -> i64 {
+    unsafe { simple_bindgen::simple_function() }
+}
+
 fn main() {
-    println!("The value is {}!", simple_bindgen::SIMPLE_VALUE);
+    println!(
+        "The values are {} and {}!",
+        simple_bindgen::SIMPLE_VALUE,
+        simple_function()
+    );
 }
 
 #[cfg(test)]
 mod test {
     #[test]
     fn do_the_test() {
         assert_eq!(42, simple_bindgen::SIMPLE_VALUE);
+        assert_eq!(1337, super::simple_function());
     }
 }

examples/bindgen/main_leaked.rs

@@ -0,0 +1,22 @@
+//! rust_bindgen_library example consumer
+
+fn simple_function() -> i64 {
+    unsafe { simple_leaked_bindgen::simple_function() }
+}
+
+fn main() {
+    println!(
+        "The values are {} and {}!",
+        simple_leaked_bindgen::SIMPLE_VALUE,
+        simple_function()
+    );
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn do_the_test() {
+        assert_eq!(42, simple_leaked_bindgen::SIMPLE_VALUE);
+        assert_eq!(1337, super::simple_function());
+    }
+}

examples/bindgen/simple/BUILD.bazel

@@ -0,0 +1,15 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+exports_files(
+    [
+        "simple.h",
+    ],
+    visibility = ["//bindgen:__pkg__"],
+)
+
+cc_library(
+    name = "simple",
+    srcs = ["simple.cc"],
+    hdrs = ["simple.h"],
+    visibility = ["//bindgen:__pkg__"],
+)

examples/bindgen/simple/simple.cc

@@ -0,0 +1,3 @@
+#include "simple.h"
+
+EXTERN_C const int64_t simple_function() { return 1337; }

examples/bindgen/simple/simple.h

@@ -0,0 +1,16 @@
+#ifndef __SIMPLE_H_INCLUDE__
+#define __SIMPLE_H_INCLUDE__
+
+#ifdef __cplusplus
+#define EXTERN_C extern "C"
+#else
+#define EXTERN_C
+#endif
+
+#include <stdint.h>
+
+EXTERN_C const int64_t SIMPLE_VALUE = 42;
+
+EXTERN_C const int64_t simple_function();
+
+#endif

rust/private/providers.bzl

@@ -72,12 +72,13 @@ CrateGroupInfo = provider(
 BuildInfo = provider(
     doc = "A provider containing `rustc` build settings for a given Crate.",
     fields = {
-        "dep_env": "File: extra build script environment varibles to be set to direct dependencies.",
-        "flags": "File: file containing additional flags to pass to rustc",
-        "link_flags": "File: file containing flags to pass to the linker",
-        "link_search_paths": "File: file containing search paths to pass to the linker",
-        "out_dir": "File: directory containing the result of a build script",
-        "rustc_env": "File: file containing additional environment variables to set for rustc.",
+        "compile_data": "Depset[File]: Compile data provided by the build script that was not copied into `out_dir`.",
+        "dep_env": "Optinal[File]: extra build script environment varibles to be set to direct dependencies.",
+        "flags": "Optional[File]: file containing additional flags to pass to rustc",
+        "link_flags": "Optional[File]: file containing flags to pass to the linker",
+        "link_search_paths": "Optional[File]: file containing search paths to pass to the linker",
+        "out_dir": "Optional[File]: directory containing the result of a build script",
+        "rustc_env": "Optional[File]: file containing additional environment variables to set for rustc.",
     },
 )