Merge pull request #165 from aherrmann/dyndeps

feat: Support linking against shared libraries

.bazelrc

@@ -15,8 +15,8 @@ import %workspace%/.bazelrc.remote
 # To update these lines, execute
 # `bazel run @rules_bazel_integration_test//tools:update_deleted_packages`
 # docs: https://bazel.build/reference/command-line-reference#flag--deleted_packages
-build --deleted_packages=e2e/workspace,e2e/workspace/c-sources,e2e/workspace/configure-mode,e2e/workspace/configure-target,e2e/workspace/configure-threaded,e2e/workspace/data-dependencies,e2e/workspace/embed-file,e2e/workspace/include-dependencies,e2e/workspace/include-dependencies/zig-include,e2e/workspace/include-dependencies/zig-include-define,e2e/workspace/include-dependencies/zig-include-isystem,e2e/workspace/include-dependencies/zig-std-include,e2e/workspace/link-dependencies,e2e/workspace/link-dependencies/static-library,e2e/workspace/linker-script,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-shared-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace,zig/tests/integration_tests/workspace/custom_interpreter
-query --deleted_packages=e2e/workspace,e2e/workspace/c-sources,e2e/workspace/configure-mode,e2e/workspace/configure-target,e2e/workspace/configure-threaded,e2e/workspace/data-dependencies,e2e/workspace/embed-file,e2e/workspace/include-dependencies,e2e/workspace/include-dependencies/zig-include,e2e/workspace/include-dependencies/zig-include-define,e2e/workspace/include-dependencies/zig-include-isystem,e2e/workspace/include-dependencies/zig-std-include,e2e/workspace/link-dependencies,e2e/workspace/link-dependencies/static-library,e2e/workspace/linker-script,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-shared-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace,zig/tests/integration_tests/workspace/custom_interpreter
+build --deleted_packages=e2e/workspace,e2e/workspace/c-sources,e2e/workspace/configure-mode,e2e/workspace/configure-target,e2e/workspace/configure-threaded,e2e/workspace/data-dependencies,e2e/workspace/embed-file,e2e/workspace/include-dependencies,e2e/workspace/include-dependencies/zig-include,e2e/workspace/include-dependencies/zig-include-define,e2e/workspace/include-dependencies/zig-include-isystem,e2e/workspace/include-dependencies/zig-std-include,e2e/workspace/link-dependencies,e2e/workspace/link-dependencies/shared-library,e2e/workspace/link-dependencies/static-library,e2e/workspace/linker-script,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-shared-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace,zig/tests/integration_tests/workspace/custom_interpreter
+query --deleted_packages=e2e/workspace,e2e/workspace/c-sources,e2e/workspace/configure-mode,e2e/workspace/configure-target,e2e/workspace/configure-threaded,e2e/workspace/data-dependencies,e2e/workspace/embed-file,e2e/workspace/include-dependencies,e2e/workspace/include-dependencies/zig-include,e2e/workspace/include-dependencies/zig-include-define,e2e/workspace/include-dependencies/zig-include-isystem,e2e/workspace/include-dependencies/zig-std-include,e2e/workspace/link-dependencies,e2e/workspace/link-dependencies/shared-library,e2e/workspace/link-dependencies/static-library,e2e/workspace/linker-script,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-shared-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace,zig/tests/integration_tests/workspace/custom_interpreter
 
 # Load any settings specific to the current user.
 # .bazelrc.user should appear in .gitignore so that settings are not shared with team members

e2e/workspace/link-dependencies/shared-library/BUILD.bazel

@@ -0,0 +1,71 @@
+load("@bazel_skylib//rules:build_test.bzl", "build_test")
+load("@bazel_skylib//rules:diff_test.bzl", "diff_test")
+load("@rules_zig//zig:defs.bzl", "zig_binary", "zig_library", "zig_test")
+
+cc_binary(
+    name = "add",
+    srcs = ["add.c"],
+    linkopts = select({
+        "@platforms//os:linux": ["-Wl,-soname,libadd.so"],
+        "@platforms//os:macos": ["-Wl,-install_name,@rpath/libadd.dylib"],
+        "//conditions:default": [],
+    }),
+    linkshared = True,
+)
+
+cc_library(
+    name = "add_shared",
+    srcs = [":add"],
+)
+
+zig_binary(
+    name = "binary",
+    cdeps = [
+        ":add_shared",
+        "@rules_zig//zig/lib:libc",
+    ],
+    main = "main.zig",
+)
+
+zig_library(
+    name = "library",
+    cdeps = [
+        ":add_shared",
+        "@rules_zig//zig/lib:libc",
+    ],
+    main = "main.zig",
+)
+
+zig_test(
+    name = "test",
+    size = "small",
+    cdeps = [
+        ":add_shared",
+        "@rules_zig//zig/lib:libc",
+    ],
+    main = "main.zig",
+)
+
+build_test(
+    name = "build",
+    size = "small",
+    targets = [
+        ":binary",
+        ":library",
+        ":test",
+    ],
+)
+
+genrule(
+    name = "output",
+    outs = ["output.actual"],
+    cmd = "$(execpath :binary) > $(OUTS)",
+    tools = [":binary"],
+)
+
+diff_test(
+    name = "output_test",
+    size = "small",
+    file1 = ":output.expected",
+    file2 = ":output.actual",
+)

e2e/workspace/link-dependencies/shared-library/add.c

@@ -0,0 +1,3 @@
+char add(char a, char b) {
+    return a + b;
+}

e2e/workspace/link-dependencies/shared-library/main.zig

@@ -0,0 +1,12 @@
+const std = @import("std");
+
+extern fn add(u8, u8) u8;
+
+pub fn main() !void {
+    const three = add(1, 2);
+    try std.io.getStdOut().writer().print("{d}\n", .{three});
+}
+
+test "One plus two equals three" {
+    try std.testing.expectEqual(@as(u8, 3), add(1, 2));
+}

e2e/workspace/link-dependencies/shared-library/output.expected

@@ -0,0 +1 @@
+3

zig/private/common/BUILD.bazel

@@ -37,6 +37,7 @@ bzl_library(
     name = "cdeps",
     srcs = ["cdeps.bzl"],
     visibility = ["//zig:__subpackages__"],
+    deps = ["@bazel_skylib//lib:paths"],
 )
 
 bzl_library(

zig/private/common/cdeps.bzl

@@ -1,16 +1,21 @@
 """Handle C library dependencies."""
 
-def zig_cdeps(*, cdeps, direct_inputs, transitive_inputs, args):
+load("@bazel_skylib//lib:paths.bzl", "paths")
+
+def zig_cdeps(*, cdeps, output_dir, os, direct_inputs, transitive_inputs, args, data):
     """Handle C library dependencies.
 
     Sets the appropriate command-line flags for the Zig compiler to expose
     provided headers and link against the provided libraries.
 
     Args:
       cdeps: List of Target, Must provide `CcInfo`.
+      output_dir: String, The directory in which the binary or library is created. Used for RUNPATH calcuation.
+      os: String, The OS component of the target triple.
       direct_inputs: List of File; mutable, Append the needed inputs to this list.
       transitive_inputs: List of depset of File; mutable, Append the needed inputs to this list.
       args: Args; mutable, Append the Zig command-line flags to this object.
+      data: List of File; mutable, Append the needed runtime dependencies.
     """
     cc_info = cc_common.merge_cc_infos(direct_cc_infos = [cdep[CcInfo] for cdep in cdeps])
     _compilation_context(
@@ -20,8 +25,11 @@ def zig_cdeps(*, cdeps, direct_inputs, transitive_inputs, args):
     )
     _linking_context(
         linking_context = cc_info.linking_context,
+        output_dir = output_dir,
+        os = os,
         inputs = direct_inputs,
         args = args,
+        data = data,
     )
 
 def _compilation_context(*, compilation_context, inputs, args):
@@ -38,20 +46,27 @@ def _compilation_context(*, compilation_context, inputs, args):
         args.add_all(compilation_context.external_includes, before_each = "-isystem")
     args.add_all(compilation_context.framework_includes, format_each = "-F%s")
 
-def _linking_context(*, linking_context, inputs, args):
+def _linking_context(*, linking_context, output_dir, os, inputs, args, data):
+    dynamic_libraries = []
     for link in linking_context.linker_inputs.to_list():
         args.add_all(link.user_link_flags)
         inputs.extend(link.additional_inputs)
         for lib in link.libraries:
             file = None
+            dynamic = False
             if lib.static_library != None:
                 file = lib.static_library
             elif lib.pic_static_library != None:
                 file = lib.pic_static_library
             elif lib.interface_library != None:
                 file = lib.interface_library
+                dynamic = True
             elif lib.dynamic_library != None:
                 file = lib.dynamic_library
+                dynamic = True
+
+            if dynamic and lib.dynamic_library:
+                dynamic_libraries.append(lib.dynamic_library)
 
             # TODO[AH] Handle the remaining fields of LibraryToLink as needed:
             #   alwayslink
@@ -65,3 +80,53 @@ def _linking_context(*, linking_context, inputs, args):
             if file:
                 inputs.append(file)
                 args.add(file)
+
+    data.extend(dynamic_libraries)
+    args.add_all(dynamic_libraries, map_each = _make_to_rpath(output_dir, os), allow_closure = True, before_each = "-rpath")
+
+def _make_to_rpath(output_dir, os):
+    origin = "$ORIGIN"
+
+    # Based on `zig targets | jq .os`
+    if os in ["freebsd", "ios", "macos", "netbsd", "openbsd", "tvos", "watchos"]:
+        origin = "@loader_path"
+
+    def to_rpath(lib):
+        result = paths.join(origin, _relativize(lib.dirname, output_dir))
+        return result
+
+    return to_rpath
+
+def _relativize(path, start):
+    """Generates a path to `path` relative to `start`.
+
+    Strips any common prefix, generates up-directory references corresponding
+    to the depth of the remainder of `start`, and appends the remainder of
+    `path`.
+
+    Note, Bazel Skylib's `paths.relativize` does not generate up-directory
+    references.
+
+    Args:
+      path: String, The target path.
+      start: String, The starting point.
+
+    Returns:
+      String, A relative path.
+    """
+    path_segments = path.split("/")
+    start_segments = start.split("/")
+
+    common = 0
+    for path_segment, start_segment in zip(path_segments, start_segments):
+        if path_segment != start_segment:
+            break
+
+        common += 1
+
+    up_count = len(start_segments) - common
+
+    result_segments = [".."] * up_count + path_segments[common:]
+    result = paths.join(*result_segments)
+
+    return result

zig/private/common/zig_build.bzl

@@ -1,5 +1,6 @@
 """Common implementation of the zig_binary|library|test rules."""
 
+load("@bazel_skylib//lib:paths.bzl", "paths")
 load("//zig/private/common:cdeps.bzl", "zig_cdeps")
 load("//zig/private/common:csrcs.bzl", "zig_csrcs")
 load("//zig/private/common:data.bzl", "zig_collect_data", "zig_create_runfiles")
@@ -177,9 +178,12 @@ def zig_build_impl(ctx, *, kind):
 
     zig_cdeps(
         cdeps = ctx.attr.cdeps,
+        output_dir = paths.join(ctx.bin_dir.path, ctx.label.package),
+        os = zigtargetinfo.triple.os,
         direct_inputs = direct_inputs,
         transitive_inputs = transitive_inputs,
         args = args,
+        data = direct_data,
     )
 
     zig_linker_script(
@@ -251,7 +255,7 @@ def zig_build_impl(ctx, *, kind):
         files = files,
         runfiles = zig_create_runfiles(
             ctx_runfiles = ctx.runfiles,
-            direct_data = [],
+            direct_data = direct_data,
             transitive_data = transitive_data,
             transitive_runfiles = transitive_runfiles,
         ),