build/rust/tests/test_rust_metadata/BUILD.gn

# Copyright 2023 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/config/rust.gni")
import("//build/rust/rust_executable.gni")
import("//build/rust/rust_static_library.gni")
import("//build/rust/rust_unit_test.gni")

# This target depends on two variants of the same crate: one directly, and one
# transitively. With correct metadata handling, this will work.
rust_static_library("test_rust_metadata_lib") {
  crate_name = "lib"
  crate_root = "lib.rs"
  sources = [ "lib.rs" ]
  deps = [
    ":foo_dependency",
    ":transitive_dep_2",
  ]

  # Depending on the other variant directly will fail, as expected. rustc
  # gives
  #
  #   error[E0464]: multiple candidates for `rlib` dependency `transitive_dep`
  #   found
  #
  # deps += [":transitive_dep_1"]

  # We also test this in a C++ binary, so we want a #[no_mangle] fn. This is
  # considered unsafe.
  allow_unsafe = true
}

if (can_build_rust_unit_tests) {
  # Tests that the different variants return the expected strings.
  rust_unit_test("test_rust_metadata_unittests") {
    crate_root = "tests.rs"
    sources = [ "tests.rs" ]
    deps = [ ":test_rust_metadata_lib" ]
  }
}

rust_executable("test_rust_metadata_exe") {
  crate_root = "main.rs"
  sources = [ "main.rs" ]
  deps = [ ":test_rust_metadata_lib" ]
}

# Check that the metadata handling works when linking into a C++ binary too.
executable("test_rust_metadata_cc_exe") {
  sources = [ "main.cc" ]
  deps = [ ":test_rust_metadata_lib" ]
}

# A source file whose behavior depends on cfg options.
rust_static_library("transitive_dep_1") {
  crate_name = "transitive_dep"
  crate_root = "transitive_dep.rs"
  sources = [ "transitive_dep.rs" ]

  rustc_metadata = "foo"
}

# Build the same source again, but with a feature enabled. The metadata should
# disambiguate the symbols when linking.
rust_static_library("transitive_dep_2") {
  crate_name = "transitive_dep"
  crate_root = "transitive_dep.rs"
  sources = [ "transitive_dep.rs" ]

  rustc_metadata = "bar"
  features = [ "bar_feature" ]
}

# Include one version transitively, since otherwise the names in Rust will
# conflict.
rust_static_library("foo_dependency") {
  crate_root = "foo_dependency.rs"
  sources = [ "foo_dependency.rs" ]
  deps = [ ":transitive_dep_1" ]
}