Fix: Set working directory for cargo metadata and cargo clean to ensure config discovery (#646)

* tests: Add `cargo_config_discovery` test

* fix: set working directory for cargo  to ensure config discovery

Set `WORKING_DIRECTORY` for all `cargo` invocations to the manifest's directory, matching the existing behavior for `cargo build`. This ensures that Cargo properly discovers configuration files like `.cargo/config.toml` and `toolchain.toml` by walking upward from the manifest directory, rather than from CMake's current working directory.

Updated comments to clarify that Cargo searches for configuration files by walking upward from the current directory.

* test fix: build executable for `cargo_config_discovery_run_cargo_config_discovery`.

* test fix: adjust registry alias / dependency for older toolchain

* test fix: ensure `cargo-clean` waits until `*_run_${exe}` completes.

* test fix: shorten name to `config_discovery` to avoid Windows path limit

Author: DLehenbauer

cmake/Corrosion.cmake

@@ -898,8 +898,10 @@ function(_add_cargo_build out_cargo_build_out_dir)
         # to determine the correct target directory, depending on if the hostbuild target property is
         # set or not.
         # BYPRODUCTS  "${cargo_build_dir}/${build_byproducts}"
-        # The build is conducted in the directory of the Manifest, so that configuration files such as
-        # `.cargo/config.toml` or `toolchain.toml` are applied as expected.
+        
+        # Set WORKING_DIRECTORY to the directory containing the manifest, so that configuration files
+        # such as `.cargo/config.toml` or `toolchain.toml` are applied as expected. Cargo searches for
+        # configuration files by walking upward from the current directory.
         WORKING_DIRECTORY "${workspace_toml_dir}"
         ${cor_uses_terminal}
         COMMAND_EXPAND_LISTS
@@ -930,7 +932,10 @@ function(_add_cargo_build out_cargo_build_out_dir)
         COMMAND
             "${cargo_bin}" clean ${cargo_target_option}
             -p ${package_name} --manifest-path "${path_to_toml}"
-        WORKING_DIRECTORY "${CMAKE_BINARY_DIR}/${build_dir}"
+        # Set WORKING_DIRECTORY to the directory containing the manifest, so that configuration files
+        # such as `.cargo/config.toml` or `toolchain.toml` are applied as expected. Cargo searches for
+        # configuration files by walking upward from the current directory.
+        WORKING_DIRECTORY "${workspace_toml_dir}"
         ${cor_uses_terminal}
     )
 
@@ -2378,4 +2383,3 @@ macro(_corrosion_arg_passthrough_helper arg_name prefix var_name)
 endmacro()
 
 list(POP_BACK CMAKE_MESSAGE_CONTEXT)
-

cmake/CorrosionGenerator.cmake

@@ -21,6 +21,9 @@ function(_cargo_metadata out manifest)
     if(FROZEN)
         set(cargo_frozen "--frozen")
     endif()
+    
+    get_filename_component(workspace_toml_dir "${manifest}" DIRECTORY)
+    
     execute_process(
         COMMAND
             ${CMAKE_COMMAND} -E env
@@ -33,7 +36,10 @@ function(_cargo_metadata out manifest)
                         --no-deps
                         ${cargo_locked}
                         ${cargo_frozen}
-
+        # Set WORKING_DIRECTORY to the directory containing the manifest, so that configuration files
+        # such as `.cargo/config.toml` or `toolchain.toml` are applied as expected. Cargo searches for
+        # configuration files by walking upward from the current directory.
+        WORKING_DIRECTORY "${workspace_toml_dir}"
         OUTPUT_VARIABLE json
         COMMAND_ERROR_IS_FATAL ANY
     )

test/CMakeLists.txt

@@ -163,6 +163,7 @@ function(corrosion_tests_add_test test_name bin_names)
 endfunction()
 
 # Please keep this in alphabetical order.
+add_subdirectory(config_discovery)
 add_subdirectory(cargo_flags)
 add_subdirectory(cpp2rust)
 if(Rust_VERSION VERSION_GREATER_EQUAL "1.64.0")

test/config_discovery/CMakeLists.txt

@@ -0,0 +1,13 @@
+# The `.cargo/config.toml` file registers the `my-registry` index. If Cargo fails to
+# discover the config file, the build will fail with:
+# "registry index was not found in any configuration: `my-registry`"
+corrosion_tests_add_test(config_discovery "config_discovery")
+
+# Run the `cargo-clean` target to verify `.cargo/config.toml` discovery.
+add_test(NAME "config_discovery_run_cargo_clean"
+    COMMAND "${CMAKE_COMMAND}" --build "${CMAKE_CURRENT_BINARY_DIR}/build-config_discovery" --target cargo-clean
+)
+set_tests_properties("config_discovery_run_cargo_clean" PROPERTIES 
+    FIXTURES_REQUIRED "build_fixture_config_discovery"
+    DEPENDS "config_discovery_run_config_discovery"
+)

test/config_discovery/README.md

@@ -0,0 +1,13 @@
+# Cargo Configuration Discovery Test
+
+This test verifies that `cargo` correctly discovers configuration files such as `.cargo/config.toml` and `toolchain.toml` in the source tree.
+
+## What's Being Tested
+
+Cargo discovers configuration files by searching the current working directory and its parent directories. Therefore, Corrosion must set the correct `WORKING_DIRECTORY` for all `cargo` invocations.
+
+## How the Test Works
+
+The test uses a `.cargo/config.toml` that defines a custom registry alias `my-registry`. A dependency in `Cargo.toml` references this alias via `registry = "my-registry"`.
+
+If `cargo` does not find `.cargo/config.toml`, the `registry = "my-registry"` entry will cause an error during manifest parsing.

test/config_discovery/config_discovery/.cargo/config.toml

@@ -0,0 +1,4 @@
+# Defines registry alias `my-registry` pointing to crates.io.
+# If not discovered cargo errors: "registry `my-registry` not found"
+[registries.my-registry]
+index = "https://github.com/rust-lang/crates.io-index"

test/config_discovery/config_discovery/CMakeLists.txt

@@ -0,0 +1,5 @@
+cmake_minimum_required(VERSION 3.15)
+project(test_project VERSION 0.1.0)
+include(../../test_header.cmake)
+
+corrosion_import_crate(MANIFEST_PATH Cargo.toml)

test/config_discovery/config_discovery/Cargo.lock

@@ -0,0 +1,9 @@
+[package]
+name = "config_discovery"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+# Uses registry alias `my-registry`. If `.cargo/config.toml` is not discovered, the test will
+# fail wit the error: "registry `my-registry` not found"
+bitflags = { version = "1.3", registry = "my-registry" }

test/config_discovery/config_discovery/Cargo.toml

@@ -0,0 +1,12 @@
+use bitflags::bitflags;
+
+bitflags! {
+    struct TestFlags: u32 {
+        const VALUE = 0b00000001;
+    }
+}
+
+fn main() {
+    let flags = TestFlags::VALUE;
+    println!("Flag value: {}", flags.bits());
+}