Davis Rollman

This commit performs a **maintenance cleanup** by **removing redundant shim files** for `exception_tracer` from the `xplat/folly/experimental` and `fbcode/folly/experimental` directories. These files previously acted as mere redirects to the actual implementation, creating unnecessary layers of indirection. By eliminating these shims, the codebase is simplified, ensuring that all references directly point to the canonical `exception_tracer` code. This change improves code clarity and streamlines the **Folly experimental components** by removing outdated and superfluous indirection.

This commit performs a **refactoring** and **maintenance** task by **removing the `function_scheduler` shim** located within the `xplat/folly/experimental` module. As `Folly/experimental` primarily served as a collection of shims, this change updates all internal references to directly point to the canonical implementation of the **`function_scheduler`**. This action eliminates an unnecessary layer of indirection, thereby **streamlining dependencies** and improving the overall clarity and maintainability of the affected **scheduling components**.

This commit **refactors the build definition** for the **`folly` library's `farmhash` component**. It updates the `folly/external/farmhash/BUCK` file to utilize `fb_dirsync_cpp_library` instead of the older `fbcode_target` and `cpp_library` rules. This **build system maintenance** unifies `folly` targets under `fb_dirsync`, which is crucial for enabling constraint-based selection within the build system. The change primarily affects the **build process** for `farmhash` and contributes to a more consistent and flexible build environment for `folly`.

This commit **removes redundant `xplat_impl` definitions** from various parts of the **Folly library**. These declarations became obsolete as Folly now centrally controls its cross-platform (`xplat`) macro implementations through a package value at its root, rendering any additional, scattered `xplat_impl` code unnecessary. This **maintenance and refactoring** effort streamlines the codebase, ensuring consistency in how cross-platform implementations are managed and reducing potential for conflicts. The change primarily affects the internal structure of Folly, resulting in a **cleaner and more maintainable library**.

This commit **removes a legacy build target**, `//xplat/folly:futures`, which previously served as an umbrella for over 100 Folly sub-targets. This **maintenance** effort was possible because all ~540 consumers have been migrated to use more fine-grained dependencies, primarily `//xplat/folly/futures:core`. Eliminating this `legacy_target` **optimizes the build system** by reducing unnecessary build graph bloat and improving incremental build performance for the **Folly library**.

This commit performs a **build system migration** for the **`folly/algorithm/test`** module, specifically updating how its unit tests and benchmarks are defined. It **refactors** the build targets for `binary_heap_test`, `stable_radix_sort_benchmark`, and `stable_radix_sort_test` from legacy `fbcode_target` macros to the more current `fb_dirsync_cpp_unittest` and `fb_dirsync_cpp_benchmark` macros. This **maintenance** task ensures better integration with the internal `fb_dirsync` system, streamlining build processes and improving consistency for these components. The change is purely infrastructural, confined to the `folly/algorithm/test/BUCK` file, and has no impact on the runtime behavior or functionality of the algorithms themselves.

This commit **refactors** the build system configuration within the **`folly/net/test`** module. It specifically migrates the build definitions for `tcpinfo_test` and `tcpinfo_test_util` from the older `fbcode_macros` to the more modern `fb_dirsync_cpp_library` macros. This **maintenance** change updates the `BUCK` file to align with current build system practices. The work primarily affects the internal build process, ensuring consistency and compatibility with the `fb_dirsync` system without altering any runtime functionality or public interfaces of the `folly/net` library.

This commit performs a **build system refactoring** within the **`folly/json/test`** module. It **migrates** the build targets for `json_schema_test` and `json5_test` from using the `fbcode_target` macro with `cpp_unittest` to directly employing the `fb_dirsync_cpp_unittest` macro in `folly/json/test/BUCK`. This **maintenance** change streamlines the build configuration for these specific JSON-related tests, simplifying their integration with the `fb_dirsync` system. The core functionality of the JSON library or its tests remains unchanged; this is purely an internal build system update.

This commit performs a **maintenance update** by **migrating the build configuration** for the `simd_any_of_test` within the **`folly/algorithm/simd/detail/test`** module. Specifically, it converts the test's build target from `non_fbcode_target` to utilize the **`fb_dirsync_cpp_unittest` macros**. This ensures the test is properly integrated and synchronized with the `fb_dirsync` system, updating its dependencies in the `BUCK` file accordingly. The change primarily impacts the **build system** for this specific SIMD algorithm test.

This commit **migrates** the build configuration for two **fbcode-only benchmark targets**, `find_first_of_bench` and `find_fixed_bench`, within the **`folly/algorithm/simd/test`** module. It updates the `BUCK` file to use the newer `fb_dirsync_cpp_benchmark` macros, replacing the older `fbcode_target` and `cpp_benchmark` definitions. This is a **build system maintenance** task that streamlines the benchmark definitions for internal development. The change has no impact on the functionality or performance of the `folly` library itself, only on how its benchmarks are built internally.

This commit performs a **build system migration** within the `folly/random/test` module, specifically updating its `BUCK` file. It converts two `fbcode`-only targets, `engine_bench` and `seed_seq_test`, from older `fbcode_target` and `non_fbcode_target` macros to the more modern `fb_dirsync_cpp_benchmark` and `fb_dirsync_cpp_unittest` macros, respectively. This **maintenance** task ensures consistency and leverages updated build infrastructure for these **test and benchmark targets**. The change streamlines their integration and synchronization within the build system, improving overall build configuration hygiene.

This commit performs a **build system migration** within the **`folly/lang/test`** module, specifically **refactoring** its `BUCK` file. It converts three `fbcode-only` build targets—`badge_test`, `bits_class_benchmark`, and `bits_class_test`—from using older `fbcode_target` macros to the more modern `fb_dirsync` macros. `badge_test` and `bits_class_test` are now defined with `fb_dirsync_cpp_unittest`, while `bits_class_benchmark` uses `fb_dirsync_cpp_binary`. This **maintenance** task updates the build configurations for these specific `folly` components, aligning them with current build system standards to improve consistency and maintainability.

This commit performs a **build system migration** within the **`folly/chrono/test`** module. It **refactors** the `BUCK` file to update the definitions for the `clock_test` and `conv_test` unittest targets. Specifically, these targets are converted from using older `fbcode_target` and `cpp_unittest` macros to the more standardized `fb_dirsync_cpp_unittest` macros. This **maintenance** task streamlines the build configuration for these tests, aligning them with current build system practices and improving the maintainability of their build definitions. The core functionality of the `folly::chrono` library remains unaffected, with the impact limited to how its tests are declared and built.

This commit performs a **build system migration** within the **`folly/observer`** subsystem, specifically updating its build configuration. It converts three internal `fbcode`-only targets—`core_cached_observer`, `hazptr_observer`, and `read_mostly_tl_observer`—from using `fbcode_target` macros to the `fb_dirsync_cpp_library` macros. This **maintenance update** standardizes the build process for these components, aligning them with current `fb_dirsync` practices. The change is confined to the `folly/observer/BUCK` file and primarily impacts the internal build process, with no functional changes to the `folly` library itself.

This commit performs a **maintenance refactoring** within the **Folly build system** to standardize how on-call information is specified. It migrates from the legacy `contacts` and `emails` attributes to the officially supported `oncall` attribute, which is crucial for unifying targets into `fb_dirsync` and resolving `fbcode` compatibility issues. The change updates various build definitions in `folly/BUCK` files and modifies the `folly_xplat_cxx_test` and `folly_xplat_cxx_binary` macros in `folly/defs.bzl` to accept the new `oncall` parameter. This ensures consistent on-call assignments and improves compatibility for Folly's cross-platform C++ tests and binaries.

This commit performs a **build system refactoring** by **migrating** build definitions within the **`folly/settings`** module. Specifically, it updates three internal, fbcode-only C++ library targets: `command_line_parser`, `settings_accessor_proxy`, and `observer`. These targets are converted from using `fbcode_target` to the `fb_dirsync_cpp_library` macro in `folly/settings/BUCK`. This **maintenance** task standardizes their build configuration, ensuring better integration with the `fb_dirsync` system and improving build consistency for these components.

This commit **refactors the build configuration** for the `folly/observer` component's benchmark. It **migrates** the `observer_benchmark` definition in `folly/observer/test/BUCK` to utilize the `fb_dirsync_cpp_benchmark` macro. This is a **maintenance task** that updates the internal build system to align with new `fb_dirsync` standards, ensuring consistency and proper integration of the benchmark within the larger build environment. The core functionality of `folly/observer` remains unaffected, with the change solely impacting how its benchmark is built.

This commit **refactors the build configuration** for the **`folly/coro`** library by migrating its `rust_adaptors` component. Specifically, the `rust_adaptors` library definition in `folly/coro/BUCK` is updated from the deprecated `fbcode_target` macro to the modern `fb_dirsync_cpp_library` macro. This change is part of a broader **build system modernization** effort to **unify build definitions** and eliminate older `fbcode_target` and `non_fbcode_target` macros. The migration improves the consistency and maintainability of the build system for `folly/coro`, streamlining future build configurations.

This commit **refactors** the build configuration for the **`folly/cli`** module, specifically its `BUCK` file. It converts the `args` library definition to directly utilize the `fb_dirsync_cpp_library` macro, removing deprecated build macro loads. This **maintenance** effort aims to unify and standardize build system configurations, eliminating the need for separate `fbcode_target` and `non_fbcode_target` definitions. The primary impact is a cleaner, more consistent build process for `folly/cli` components, aligning them with the `fb_dirsync` standard across the codebase.

This commit **refactors** the **`folly/observer`** module by **rewriting all internal references** to its components. It updates include paths and build dependencies across the codebase to use the **direct `folly/observer/detail` paths** instead of the deprecated `folly/experimental/observer` shim targets. This **maintenance** effort prepares for the complete removal of the experimental shim BUCK files, **simplifying the build system** and improving dependency clarity within the **`folly` library**. The changes span various `folly/observer` headers, `BUCK` files, and `folly/settings` test files, with no functional impact on external users.