fix: set C/C++ language standards per target (#1217)

This PR refactors the creation of C, C++, ObjC, and ObjC++ targets. For
each C-like target in a Swift package, we now create a separate
`xxx_library` target based upon the type of the source file (e.g. C,
C++, ObjC, ObjC++, and assembly). These child libraries are added to a
parent library that represents the Swift package target.

The goal of this work was to support language standard flags in the
Bazel targets generated by `rules_swift_package_manager`. If a C
language standard is specified in the Swift package, it is applied to
the C and ObjC targets. If a C++ language standard is specified, it is
applied to the C++ and the ObjC++ targets.

> [!NOTE]
> The configuration for `rules_xcodeproj` in the Firebase example had to
be updated to use the sandbox. Without this change, we were seeing
duplicate definition errors. If you see these errors in your build, you
may need to do the same.

Closes #1079 .

Author: cgrindel

examples/firebase_example/.bazelrc

@@ -20,3 +20,16 @@ build --cxxopt='-std=gnu++14'
 # Firebase SPM support requires `-ObjC` linker option.
 # https://github.com/firebase/firebase-ios-sdk/blob/master/SwiftPackageManager.md#requirements
 build --linkopt='-ObjC'
+
+# Use the sandbox for rules_xcodeproj-specific builds.  rules_xcodeproj removes
+# the sandboxed spawn strategy (--spawn_strategy=remote,worker,local) by
+# default to speed up builds. However, to support setting C/C++ language
+# standard flags per target
+# (https://github.com/cgrindel/rules_swift_package_manager/issues/1079), we
+# need to generate multiple {cc,objc}_library targets based upon the type of
+# source files (e.g. C, C++, ObjC, ObjC++). When builds occur outside of the
+# sandbox, we can experience "error: duplicate interface definition for class
+# 'XXX'" errors. Until we can address the underlying error, clients that use
+# rules_swift_package_manager with rules_xcodeproj may need to use sandbox
+# builds.
+common:rules_xcodeproj --spawn_strategy=remote,worker,sandboxed,local

examples/google_maps_example/MODULE.bazel.lock

@@ -6,6 +6,3 @@ import %workspace%/../../ci.bazelrc
 
 # Try to import a local.rc file; typically, written by CI
 try-import %workspace%/../../local.bazelrc
-
-# Required by geos
-build --cxxopt='-std=c++11'

examples/interesting_deps/.bazelrc

@@ -11,27 +11,26 @@ class MyAppTests: XCTestCase {
         XCTAssertNotNil(actual)
     }
 
-    
     func test_CoolStuff_bundleName() {
         let bundle = Bundle.bundle(named: "package-with-resources_CoolUI")
         XCTAssertNotNil(bundle)
     }
-    
+
     func test_AppLovinSDKResources() throws {
         let url = ALResourceManager.resourceBundleURL
         XCTAssertNotNil(url)
     }
-    
+
     func test_IterableDataModel() throws {
         // Log Iterable messages to an array
         class LogDelegate: IterableLogDelegate {
             var messages: [String] = []
-            
-            func log(level: LogLevel, message: String) {
+
+            func log(level _: LogLevel, message: String) {
                 messages.append(message)
             }
         }
-        
+
         let logDelegate = LogDelegate()
         IterableLogUtil.sharedInstance = IterableLogUtil(
             dateProvider: SystemDateProvider(),
@@ -41,14 +40,14 @@ class MyAppTests: XCTestCase {
         // Create the persistence container from the bundled CoreData model
         let container: PersistentContainer? = PersistentContainer.initialize()
         XCTAssertNotNil(container)
-        
+
         // Assert that the persistence container was successfully created
         let lastMessage = try XCTUnwrap(logDelegate.messages.last)
         XCTAssert(
             lastMessage.contains("Successfully loaded persistent store at:"),
             "Expected success log message. Found: \(logDelegate.messages.last ?? "nil")"
         )
-        
+
         IterableLogUtil.sharedInstance = nil
     }
 }
@@ -60,18 +59,18 @@ extension Foundation.Bundle {
         let candidates = [
             // Bundle should be present here when the package is linked into an App.
             Bundle.main.resourceURL,
-            
+
             // Bundle should be present here when the package is linked into a framework.
             Bundle(for: BundleFinder.self).resourceURL,
-            
+
             // For command-line tools.
             Bundle.main.bundleURL,
-            
+
             // Bundle should be present here when running previews from a different package (this is the path to "…/Debug-iphonesimulator/").
             Bundle(for: BundleFinder.self).resourceURL?.deletingLastPathComponent().deletingLastPathComponent().deletingLastPathComponent(),
             Bundle(for: BundleFinder.self).resourceURL?.deletingLastPathComponent().deletingLastPathComponent(),
         ]
-        
+
         for candidate in candidates {
             let bundlePath = candidate?.appendingPathComponent(bundleName + ".bundle")
             if let bundle = bundlePath.flatMap(Bundle.init(url:)) {

examples/resources_example/Tests/MyAppTests/MyAppTests.swift

@@ -13,12 +13,30 @@ _PUBLIC_HDR_DIRNAMES = ["include", "public"]
 # https://bazel.build/reference/be/c-cpp#cc_library.srcs
 _HEADER_EXTS = [".h", ".hh", ".hpp", ".hxx", ".inl", ".H"]
 
+# C source extensions
+_C_SRC_EXTS = [".c"]
+
+# C++ source extensions
+_CXX_SRC_EXTS = [".cc", ".cpp"]
+
+# Objective-C source extensions
+_OBJC_SRC_EXTS = [".m"]
+
+_OBJCXX_SRC_EXTS = [".mm"]
+
+# Assembly source extensions
+_ASSEMBLY_SRC_EXTS = [".S"]
+
+# Sources that should be included when constructing other cc_xxx targets
+_OTHER_SRC_EXTS = [".so", ".o", ".inc"]
+
 # Acceptable sources clang and objc:
 # https://bazel.build/reference/be/c-cpp#cc_library.srcs
 # https://bazel.build/reference/be/objective-c#objc_library.srcs
 # NOTE: From examples found so far, .inc files tend to include source, not
 # header declarations.
-_SRC_EXTS = [".c", ".cc", ".cpp", ".S", ".so", ".o", ".m", ".mm", ".inc"]
+_SRC_EXTS = _C_SRC_EXTS + _CXX_SRC_EXTS + _OBJC_SRC_EXTS + _OBJCXX_SRC_EXTS + \
+            _ASSEMBLY_SRC_EXTS + _OTHER_SRC_EXTS
 
 def _is_hdr(path):
     _root, ext = paths.split_extension(path)
@@ -323,6 +341,36 @@ def _collect_files(
         textual_hdrs = sorted(textual_hdrs),
     )
 
+def _organize_srcs(srcs):
+    c_srcs = []
+    cxx_srcs = []
+    objc_srcs = []
+    objcxx_srcs = []
+    assembly_srcs = []
+    other_srcs = []
+    for src in srcs:
+        _root, ext = paths.split_extension(src)
+        if ext in _C_SRC_EXTS:
+            c_srcs.append(src)
+        elif ext in _CXX_SRC_EXTS:
+            cxx_srcs.append(src)
+        elif ext in _OBJC_SRC_EXTS:
+            objc_srcs.append(src)
+        elif ext in _OBJCXX_SRC_EXTS:
+            objcxx_srcs.append(src)
+        elif ext in _ASSEMBLY_SRC_EXTS:
+            assembly_srcs.append(src)
+        else:
+            other_srcs.append(src)
+    return struct(
+        c_srcs = c_srcs,
+        cxx_srcs = cxx_srcs,
+        objc_srcs = objc_srcs,
+        objcxx_srcs = objcxx_srcs,
+        assembly_srcs = assembly_srcs,
+        other_srcs = other_srcs,
+    )
+
 clang_files = struct(
     collect_files = _collect_files,
     find_magical_public_hdr_dir = _find_magical_public_hdr_dir,
@@ -331,6 +379,7 @@ clang_files = struct(
     is_include_hdr = _is_include_hdr,
     is_public_modulemap = _is_public_modulemap,
     is_under_path = _is_under_path,
+    organize_srcs = _organize_srcs,
     reduce_paths = _reduce_paths,
     relativize = _relativize,
 )

swiftpkg/internal/clang_files.bzl

@@ -31,9 +31,12 @@ Generate an ObjC header file with an SPM-specific `SWIFTPM_MODULE_BUNDLE` macro.
 )
 
 def _objc_resource_bundle_accessor_impl_impl(ctx):
-    accessor_impl = ctx.actions.declare_file("{}_ObjcResourceBundleAccessor.m".format(
-        ctx.label.name,
-    ))
+    accessor_impl = ctx.actions.declare_file(
+        "{label}_ObjcResourceBundleAccessor.{ext}".format(
+            ext = ctx.attr.extension,
+            label = ctx.label.name,
+        ),
+    )
     ctx.actions.expand_template(
         template = ctx.file._impl_template,
         output = accessor_impl,
@@ -52,6 +55,10 @@ objc_resource_bundle_accessor_impl = rule(
             mandatory = True,
             doc = "The name of the resource bundle.",
         ),
+        "extension": attr.string(
+            default = "m",
+            doc = "The extension for the accessor implementation file.",
+        ),
         "module_name": attr.string(
             mandatory = True,
             doc = "The name of the module.",

swiftpkg/internal/objc_resource_bundle_accessor.bzl

@@ -7,6 +7,7 @@ _modulemap_suffix = "_modulemap"
 _resource_bundle_suffix = "_resource_bundle"
 _objc_resource_bundle_accessor_hdr_suffix = "_objc_resource_bundle_accessor_hdr"
 _objc_resource_bundle_accessor_impl_suffix = "_objc_resource_bundle_accessor_impl"
+_objc_resource_bundle_accessor_library_suffix = "_objc_resource_bundle_accessor_library"
 _resource_bundle_accessor_suffix = "_resource_bundle_accessor"
 _resource_bundle_infoplist_suffix = "_resource_bundle_infoplist"
 _swift_hint_suffix = "_swift_hint"
@@ -196,6 +197,17 @@ def _objc_resource_bundle_accessor_impl_label_name(target_name):
     """
     return target_name + _objc_resource_bundle_accessor_impl_suffix
 
+def _objc_resource_bundle_accessor_library_label_name(target_name):
+    """Returns the name of the related `objc_library` target.
+
+    Args:
+        target_name: The publicly advertised name for the Swift target.
+
+    Returns:
+        The name of the `objc_library` as a `string`.
+    """
+    return target_name + _objc_resource_bundle_accessor_library_suffix
+
 def _resource_bundle_accessor_label_name(target_name):
     """Returns the name of the related `resource_bundle_accessor` target.
 
@@ -275,6 +287,7 @@ def make_pkginfo_targets(bazel_labels):
         modulemap_label_name = _modulemap_label_name,
         objc_resource_bundle_accessor_hdr_label_name = _objc_resource_bundle_accessor_hdr_label_name,
         objc_resource_bundle_accessor_impl_label_name = _objc_resource_bundle_accessor_impl_label_name,
+        objc_resource_bundle_accessor_library_label_name = _objc_resource_bundle_accessor_library_label_name,
         resource_bundle_accessor_label_name = _resource_bundle_accessor_label_name,
         resource_bundle_infoplist_label_name = _resource_bundle_infoplist_label_name,
         resource_bundle_label_name = _resource_bundle_label_name,

swiftpkg/internal/pkginfo_targets.bzl

@@ -624,6 +624,8 @@ def _new_from_parsed_json(
         targets = targets,
         url = url,
         version = version,
+        c_language_standard = dump_manifest.get("cLanguageStandard"),
+        cxx_language_standard = dump_manifest.get("cxxLanguageStandard"),
     )
 
 # MARK: - Swift Package
@@ -638,7 +640,9 @@ def _new(
         products = [],
         targets = [],
         url = None,
-        version = None):
+        version = None,
+        c_language_standard = None,
+        cxx_language_standard = None):
     """Returns a `struct` representing information about a Swift package.
 
     Args:
@@ -657,6 +661,10 @@ def _new(
             `pkginfos.new_target()`.
         url: Optional. The url of the package (`string`).
         version: Optional. The semantic version of the package (`string`).
+        c_language_standard: Optional. The c language standard (e.g. `c99`,
+            `gnu99`, `c11`).
+        cxx_language_standard: Optional. The c++ language standard (e.g.
+            `c++11`, `c++20`).
 
     Returns:
         A `struct` representing information about a Swift package.
@@ -672,6 +680,8 @@ def _new(
         targets = targets,
         url = url,
         version = version,
+        c_language_standard = c_language_standard,
+        cxx_language_standard = cxx_language_standard,
     )
 
 # MARK: - Platform
@@ -1165,6 +1175,8 @@ def _new_clang_src_info_from_sources(
     srcs = sets.to_list(srcs_set)
     explicit_srcs = sets.to_list(explicit_srcs_set)
 
+    # GH1290: Can I remove explicit_srcs? I believe that it is obsolete.
+
     return _new_clang_src_info(
         srcs = srcs,
         explicit_srcs = explicit_srcs,
@@ -1184,7 +1196,7 @@ def _new_clang_src_info(
         private_includes = [],
         modulemap_path = None):
     return struct(
-        srcs = srcs,
+        organized_srcs = clang_files.organize_srcs(srcs),
         explicit_srcs = explicit_srcs,
         hdrs = hdrs,
         textual_hdrs = textual_hdrs,

swiftpkg/internal/pkginfos.bzl

@@ -97,9 +97,30 @@ def _to_starlark(val):
     fail("Failed to finish processing starlark for value: {}".format(val))
 
 def _process_complex_types(out):
+    def _fail_with_orig_out(msg):
+        def _pad_str(width, value):
+            value = str(value)
+            val_len = len(value)
+            if val_len >= width:
+                return value
+            padding = width - val_len
+            return " " * padding + value
+
+        # buildifier: disable=print
+        print("*** DEBUG _process_complex_types out: ")
+
+        # Not sure why buildifier is complaining about idx not being initialized.
+        # buildifier: disable=uninitialized
+        for idx, item in enumerate(out):
+            # buildifier: disable=print
+            # buildifier: disable=uninitialized
+            print("*** DEBUG", _pad_str(3, idx), ":", _pad_str(7, type(item)), ":", item)
+        fail(msg)
+
     finished = True
     new_out = []
-    for v in out:
+
+    for idx, v in enumerate(out):
         v_type = type(v)
 
         # Check for a with_indent struct and get its indent value and process
@@ -127,10 +148,24 @@ def _process_complex_types(out):
         elif v_type == "struct":
             to_starlark_fn = getattr(v, "to_starlark_parts", None)
             if to_starlark_fn == None:
-                fail("Starlark code gen received a struct without a to_starlark_parts function.", v)
+                _fail_with_orig_out(
+                    """\
+Starlark code gen received a struct without a to_starlark_parts function. \
+idx: {idx}, v: {v}\
+""".format(
+                        idx = idx,
+                        v = v,
+                    ),
+                )
             new_out.extend(to_starlark_fn(v, current_indent))
         else:
-            fail("Starlark code gen received an unsupported type.", v_type, v)
+            _fail_with_orig_out("""\
+Starlark code gen received an unsupported type. idx: {idx}, v_type: {v_type}, v: {v}\
+""".format(
+                idx = idx,
+                v_type = v_type,
+                v = v,
+            ))
 
     return new_out, finished