Define BAZEL_CURRENT_REPOSITORY for runfiles library dependents

When a cc_* target directly depends on a target that advertises
`RunfilesLibraryInfo`, `BAZEL_CURRENT_REPOSITORY` is added as a local
define with value the canonical name of the repository containing the
target.

src/main/starlark/builtins_bzl/common/cc/cc_binary.bzl

@@ -690,7 +690,7 @@ def cc_binary_impl(ctx, additional_linkopts):
         cc_toolchain = cc_toolchain,
         user_compile_flags = cc_helper.get_copts(ctx, common, feature_configuration, additional_make_variable_substitutions),
         defines = common.defines,
-        local_defines = common.local_defines,
+        local_defines = common.local_defines + cc_helper.get_local_defines_for_runfiles_libraries(ctx),
         loose_includes = common.loose_include_dirs,
         system_includes = common.system_include_dirs,
         private_hdrs = common.private_hdrs,

src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl

@@ -916,6 +916,15 @@ def _is_stamping_enabled_for_aspect(ctx):
         stamp = ctx.rule.attr.stamp
     return stamp
 
+_DEPS_ATTRS = ["deps", "implementation_deps"]
+
+def _get_local_defines_for_runfiles_libraries(ctx):
+    for attr in _DEPS_ATTRS:
+        for dep in getattr(ctx.attr, attr, []):
+            if RunfilesLibraryInfo in dep:
+                return ["BAZEL_CURRENT_REPOSITORY=\"{}\"".format(ctx.label.workspace_name)]
+    return []
+
 cc_helper = struct(
     merge_cc_debug_contexts = _merge_cc_debug_contexts,
     is_code_coverage_enabled = _is_code_coverage_enabled,
@@ -960,4 +969,5 @@ cc_helper = struct(
     build_linking_context_from_libraries = _build_linking_context_from_libraries,
     is_stamping_enabled = _is_stamping_enabled,
     is_stamping_enabled_for_aspect = _is_stamping_enabled_for_aspect,
+    get_local_defines_for_runfiles_libraries = _get_local_defines_for_runfiles_libraries,
 )

src/main/starlark/builtins_bzl/common/cc/cc_library.bzl

@@ -58,7 +58,7 @@ def _cc_library_impl(ctx):
         feature_configuration = feature_configuration,
         user_compile_flags = cc_helper.get_copts(ctx, common, feature_configuration, additional_make_variable_substitutions),
         defines = common.defines,
-        local_defines = common.local_defines,
+        local_defines = common.local_defines + cc_helper.get_local_defines_for_runfiles_libraries(ctx),
         loose_includes = common.loose_include_dirs,
         system_includes = common.system_include_dirs,
         copts_filter = common.copts_filter,

src/test/shell/bazel/cc_integration_test.sh

@@ -1506,4 +1506,67 @@ EOF
   expect_log "\"PWD\": \"/proc/self/cwd\""
 }
 
+function test_bazel_current_repository_define() {
+  add_to_bazelrc "build --experimental_cc_implementation_deps"
+
+  mkdir -p pkg
+  cat > pkg/BUILD.bazel <<'EOF'
+cc_library(
+  name = "library",
+  srcs = ["define.cpp"],
+  deps = ["@bazel_tools//tools/cpp/runfiles"],
+)
+cc_library(
+  name = "library_implementation_deps",
+  srcs = ["define.cpp"],
+  implementation_deps = ["@bazel_tools//tools/cpp/runfiles"],
+)
+cc_library(
+  name = "library_fail",
+  srcs = ["define.cpp"],
+)
+
+cc_binary(
+  name = "binary",
+  srcs = ["define.cpp"],
+  deps = ["@bazel_tools//tools/cpp/runfiles"],
+)
+cc_binary(
+  name = "binary_fail",
+  srcs = ["define.cpp"],
+  deps = [":library"],
+)
+
+cc_test(
+  name = "test",
+  srcs = ["define.cpp"],
+  deps = ["@bazel_tools//tools/cpp/runfiles"],
+)
+cc_test(
+  name = "test_fail",
+  srcs = ["define.cpp"],
+  deps = [":library"],
+)
+EOF
+
+  cat > pkg/define.cpp <<'EOF'
+#include <iostream>
+int main() {
+  std::cout << BAZEL_CURRENT_REPOSITORY << std::endl;
+}
+EOF
+
+  bazel build //pkg:library &>"$TEST_log" || fail "Build should succeed"
+  bazel build //pkg:library_implementation_deps &>"$TEST_log" || fail "Build should succeed"
+  bazel build //pkg:binary &>"$TEST_log" || fail "Build should succeed"
+  bazel build //pkg:test &>"$TEST_log" || fail "Build should succeed"
+
+  bazel build //pkg:library_fail &>"$TEST_log" && fail "Build should fail"
+  expect_log "'BAZEL_CURRENT_REPOSITORY'"
+  bazel build //pkg:binary_fail &>"$TEST_log" && fail "Build should fail"
+  expect_log "'BAZEL_CURRENT_REPOSITORY'"
+  bazel build //pkg:test_fail &>"$TEST_log" && fail "Build should fail"
+  expect_log "'BAZEL_CURRENT_REPOSITORY'"
+}
+
 run_suite "cc_integration_test"

tools/cpp/BUILD

@@ -34,7 +34,9 @@ filegroup(
 
 filegroup(
     name = "bzl_srcs",
-    srcs = glob(["*.bzl"]),
+    srcs = glob(["*.bzl"]) + [
+        "//tools/cpp/runfiles:bzl_srcs",
+    ],
     visibility = ["//tools:__pkg__"],
 )
 

tools/cpp/BUILD.tools

@@ -137,7 +137,9 @@ filegroup(
 
 filegroup(
     name = "bzl_srcs",
-    srcs = glob(["*.bzl"]),
+    srcs = glob(["*.bzl"]) + [
+        "//tools/cpp/runfiles:bzl_srcs",
+    ],
     visibility = ["//tools:__pkg__"],
 )
 

tools/cpp/runfiles/BUILD

@@ -16,11 +16,18 @@ filegroup(
     name = "embedded_tools",
     srcs = [
         "BUILD.tools",
+        "cc_runfiles_library.bzl",
         ":srcs_for_embedded_tools",
     ],
     visibility = ["//tools/cpp:__pkg__"],
 )
 
+filegroup(
+    name = "bzl_srcs",
+    srcs = glob(["*.bzl"]),
+    visibility = ["//tools/cpp:__pkg__"],
+)
+
 # Rewrite the include path for runfiles.h in runfiles_src.cc, and create
 # "generated_runfiles.{h,cc}". These files are renamed to "runfiles.{h,cc}" as
 # part of creating the embedded tools of Bazel.

tools/cpp/runfiles/BUILD.tools

@@ -1,8 +1,19 @@
-# This package will host the C++ runfiles library when it's finally released.
+load(":cc_runfiles_library.bzl", "cc_runfiles_library")
 
-cc_library(
+cc_runfiles_library(
     name = "runfiles",
+    exports = ":runfiles_impl",
+    visibility = ["//visibility:public"],
+)
+
+cc_library(
+    name = "runfiles_impl",
     srcs = ["runfiles.cc"],
     hdrs = ["runfiles.h"],
-    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "bzl_srcs",
+    srcs = glob(["*.bzl"]),
+    visibility = ["//tools/cpp:__pkg__"],
 )

tools/cpp/runfiles/cc_runfiles_library.bzl

@@ -0,0 +1,13 @@
+def _cc_runfiles_library_impl(ctx):
+    return [
+        ctx.attr.exports[DefaultInfo],
+        ctx.attr.exports[CcInfo],
+        RunfilesLibraryInfo(),
+    ]
+
+cc_runfiles_library = rule(
+    implementation = _cc_runfiles_library_impl,
+    attrs = {
+        "exports": attr.label(),
+    },
+)