Richard Howell

This commit introduces a **new capability** by adding a native `startswith` method to the `ResolvedStringWithMacros` type within the **Buck2 build API's Starlark interpreter**. This enhancement allows **rule authors** to directly check string prefixes on macro-resolved strings in `.bzl` files, eliminating the need for explicit `str()` conversions. The change improves the ergonomics and efficiency of string manipulation for Starlark rules. Comprehensive new tests, including Starlark rule definitions in `defs.bzl`, verify the functionality of `startswith` and its interaction with equality checks.

This commit **refactors** the **Apple build rules** to make the `swift_version` attribute non-optional, ensuring it always defaults to `SwiftVersion[0]` (Swift 5) if not explicitly specified. This **maintenance** change impacts `apple_binary`, `apple_library`, and `apple_test` definitions, simplifying downstream **Swift compilation logic** by removing the need for conditional checks on `swift_version` in functions like `get_swift_cxx_flags` and `_get_shared_flags`. By guaranteeing the attribute's presence, the system becomes more robust, and `SwiftCompilationModes` and `SwiftVersion` are also converted from lists to tuples for internal consistency.

This commit **refactors** the internal mechanism for **GraphQL code generation** within the build system, specifically impacting **Apple targets**. It renames the internal helper function `_graphql_codegen_sets` to `graphql_codegen_sets` in `prelude/apple/graphql.bzl`. This **refactoring** makes the function directly accessible and updates its usage within `graphql_providers`, streamlining the process of **merging GraphQL output into binary targets**.

This commit introduces a **new capability** to the **GraphQL codegen system** for **Apple platforms** by adding a `GraphQLCodegenInput` provider. This provider, along with helper functions like `_graphql_info_provider` and `_graphql_codegen_sets` in `prelude/apple/graphql.bzl`, enables the recursive propagation of GraphQL codegen output using `ArtifactTSet`. The primary purpose of this **feature** is to ensure the correct generation of binary-level GraphQL outputs, improving the robustness of the build process for GraphQL-dependent targets. This enhancement directly impacts how GraphQL artifacts are managed and consumed during the build.

This commit **enhances the comparison logic** for `ResolvedStringWithMacros` objects within the **Starlark interpreter** by modifying the `equals` method in `resolved_macro.rs`. This **usability improvement** allows `ResolvedStringWithMacros` instances to be correctly compared against plain Starlark strings when their resolved value contains no macros. Previously, such comparisons always returned false, preventing common and intuitive Starlark patterns like `"-some-flag" in ctx.attrs.compiler_flags`. This change enables **more robust and readable Starlark rule implementations** by making string comparisons behave as expected, particularly within the `buck2_build_api` module.

This commit introduces a **new capability** by **extending** the `GraphQLInfo` provider within the **Apple GraphQL build system** (`prelude/apple/graphql.bzl`). It adds several new fields to the provider, encompassing configuration details like colocation enforcement, header path prefix, and subconfig/test target status. This enhancement is critical for enabling the construction of recursive JSON input, which is essential for facilitating advanced **codegen** processes.

This commit introduces a **new capability** for propagating GraphQL codegen information within the build system. A new `GraphQLInfo` provider is defined in `prelude/apple/graphql.bzl`, along with a utility function `graphql_providers` to collect this information from dependencies. The `apple_library_impl` function in `prelude/apple/apple_library.bzl` is updated to integrate and automatically pass this `GraphQLInfo` from dependent targets. This enhancement to the **Apple build system** ensures that `apple_library` targets can seamlessly collect and utilize GraphQL-related build details from their transitive dependencies, streamlining GraphQL integration.

This commit **enables Swift compatibility** for the **ReactInternal** target on **iOS**, a significant **maintenance** and **compatibility fix**. It achieves this by **refactoring** module definitions, correctly specifying `exported_deps`, and addressing several associated fixes like adding missing dependencies and adjusting header files for module compatibility. Specifically, changes include modifying conditional compilation in `RCTDefines.h`, adding Clang diagnostic pragmas to manage deprecation warnings in various `RCTRootView`, `RCTSurface`, `RCTProfile`, and `RCTScrollView` headers, and updating nullability annotations in `RCTDevMenuConfigurationDecorator.h`. This work improves **interoperability** and unblocks the use of Swift within core React Native components, paving the way for more modern iOS development practices.

This commit introduces a **bug fix** to the **Apple build system logic** by ensuring that `-framework` linker flags and associated search paths are only applied when a **Darwin linker** is in use. Previously, these flags were unconditionally added to `cxx_library` targets, which could lead to build failures or warnings on non-Darwin platforms. By adding a specific check within `prelude/apple/apple_frameworks.bzl`, this change prevents incorrect linker arguments from being passed to incompatible linkers. This significantly improves **cross-platform build compatibility** for C++ libraries by correctly scoping framework-specific linking behavior.

This commit **optimizes modulemap generation** for **Apple builds** by conditionally enabling the use of relative paths in modulemaps when supported by the toolchain. This **refactoring** introduces a **new capability** in `prelude/apple/swift/swift_toolchain.bzl` to detect toolchain support via `supports_modulemaps_with_hmaps` and provides corresponding include path flags. It updates the core `create_modulemap` function in `prelude/apple/modulemap.bzl` and adjusts **Swift compilation** logic in `prelude/apple/swift/swift_compilation.bzl` to leverage this feature. The primary impact is the **elimination of symlink trees** for modulemaps, which can improve build performance and reduce build graph complexity.

This commit **refactors** the **Swift PCM compilation logic** by removing the explicit construction of modulemap-related command arguments within the `compile_underlying_pcm` function in `prelude/apple/swift/swift_pcm_compilation.bzl`. These arguments are now correctly derived and applied through existing framework search path flags, leveraging information from `uncompiled_pcm_info`. This change **simplifies** the build process by eliminating redundant preprocessor setup, leading to a cleaner and more maintainable **Swift build system**.

This commit **re-enables** the `exported_deps` attribute for the **`apple_test` rule** by adding `exported_deps_arg` to its definition within `prelude/apple/apple_rules_decls.bzl`. This **feature enhancement** allows **Apple test targets** to explicitly declare and manage their exported dependencies. By supporting `exported_deps`, the change improves the **correctness and flexibility** of dependency resolution for Apple test builds, ensuring that necessary transitive dependencies are properly linked and available.

This commit introduces a **new capability** by adding `has_exported_headers` and `is_modular` boolean fields to the **`SwiftDependencyInfo` provider**. These fields, defined in `prelude/apple/swift/swift_types.bzl`, are populated during the creation of `SwiftDependencyInfo` objects via `create_swift_dependency_info` in `prelude/apple/swift/swift_compilation.bzl`. The addition of this **dependency information** is crucial for future **modular validation**, allowing an attribute validator to determine if a Swift target is modular and exports headers. This enhancement will prevent the inclusion of incompatible `exported_deps` by ensuring proper dependency compatibility checks.

This commit **refactors the modulemap generation process** within the **prelude/apple** module to enhance flexibility and reduce reliance on specific build system structures. The `create_modulemap` function in `modulemap.bzl` and the `make_modulemap.py` script are updated to accept explicit `(include_path, disk_path)` pairs for headers. This **refactoring** eliminates the previous inference of paths based on symlink trees, which simplifies the underlying logic. The change enables the adoption of relative modulemap paths, thereby improving the robustness and maintainability of the build system by removing the dependency on symlink tree roots.

This commit introduces a **new capability** to the **Apple Swift build rules** by adding a `supports_modulemaps_with_hmaps` attribute to the `swift_toolchain` rule definition. This attribute allows users to explicitly declare whether a given Swift toolchain supports modulemaps with header maps, a feature that requires more recent Swift toolchain versions. The configuration is propagated from the `swift_toolchain_impl` to the `SwiftToolchainInfo` provider, making this capability information available throughout the build system. This enhancement provides finer-grained control over Swift compilation, enabling the build system to adapt its behavior and ensure compatibility when dealing with advanced modulemap features across diverse Swift toolchain environments.

This commit performs a **refactoring** of the **Apple build rules** by **removing the redundant `preprocessor_info_for_modulemap` function** from `prelude/apple/modulemap.bzl`. The `create_modulemap` function is now updated to directly return a `CPreprocessor` object, eliminating an unnecessary abstraction layer. This change simplifies the internal API for **modulemap generation** and streamlines the integration of CPreprocessor information. Modules such as `apple_bundle_resources`, `apple_library`, and `swift_compilation` have been updated to consume the new direct `CPreprocessor` return type. The update improves code clarity and efficiency within the **Apple build system** by removing an intermediate wrapper.

This commit **refactors** the internal representation of **Clang importer arguments** within the **Swift PCM compilation system** to enhance clarity and simplify integration. It renames the `SwiftPCMUncompiledInfo` provider fields `propagated_preprocessor_args_cmd` to `clang_importer_args` and `exported_preprocessor` to `exported_clang_importer_args`. This **refactoring** clarifies the distinction between flags required for compiling a Swift module versus those propagated to its reverse dependencies, impacting the `prelude/apple/swift` and `prelude/apple` modules. The change streamlines argument construction and flag propagation for **Swift modules** and **prebuilt Apple frameworks**, making the build system's handling of C/Objective-C dependencies more explicit.

This commit **refactors** the `SwiftPCMUncompiledInfo` provider within the **Swift PCM compilation system** to enhance clarity and simplify the integration of **Clang importer arguments**. It renames `propagated_preprocessor_args_cmd` to `clang_importer_args` and `exported_preprocessor` to `exported_clang_importer_args`, distinguishing between flags needed for a module's own compilation and those propagated to its dependents. This **maintenance refactoring** improves the semantic understanding of how Clang flags are managed for Swift modules, affecting files like `swift_compilation.bzl` and `swift_pcm_compilation_types.bzl`. The change streamlines the handling of these critical build flags, making the system more robust and easier to maintain.

This commit **refactors the Swift compilation pipeline** by introducing a dedicated `modulemap_artifact` field to the `SwiftPCMUncompiledInfo` provider. This **enhancement** ensures the direct and explicit propagation of the modulemap artifact, which is essential for its subsequent use in `SwiftCompiledModuleInfo` and paves the way for removing the `exported_preprocessor` field. Specifically, functions within `prelude/apple/swift/swift_pcm_compilation.bzl` are updated to leverage this new direct field, streamlining the handling of preprocessor information. This change improves the clarity and maintainability of the **Swift module compilation logic** by simplifying data structures and dependencies.

This commit performs **style maintenance** on the `SwiftPCMUncompiledInfo` provider within the `prelude/apple/swift/swift_pcm_compilation_types.bzl` file. It **reformats the fields** of this provider to remove inconsistent formatting and **removes an unsorted linter directive**. This work improves the **readability and consistency** of the **Swift PCM compilation types** definition, ensuring better adherence to code style standards for the **Apple Swift build system**.