Workaround dyld warning about SwiftSyntax classes (realm#4901)

This uses a recent but unannounced (also read as private) feature of
dyld where it ignores duplicate Objective-C classes when they're in a
special format in the binary. https://github.com/apple-oss-distributions/dyld/blob/c8a445f88f9fc1713db34674e79b00e30723e79d/dyld/PrebuiltLoader.cpp#L1660-L1662

I think this is generally safe because hopefully people aren't actually
using the SwiftSyntax classes through the Objective-C runtime, but if
they are we'd still probably prefer to silence the noise and accept the
UB.

Fixes realm#4782

BUILD

@@ -21,13 +21,13 @@ swift_library(
     module_name = "SwiftLintFramework",
     visibility = ["//visibility:public"],
     deps = [
-        "@com_github_jpsim_sourcekitten//:SourceKittenFramework",
         "@com_github_apple_swift_syntax//:optlibs",
+        "@com_github_jpsim_sourcekitten//:SourceKittenFramework",
         "@sourcekitten_com_github_jpsim_yams//:Yams",
         "@swiftlint_com_github_scottrhoyt_swifty_text_table//:SwiftyTextTable",
     ] + select({
         "@platforms//os:linux": ["@com_github_krzyzanowskim_cryptoswift//:CryptoSwift"],
-        "//conditions:default": [],
+        "//conditions:default": [":DyldWarningWorkaround"],
     }),
 )
 
@@ -64,6 +64,16 @@ apple_universal_binary(
     visibility = ["//visibility:public"],
 )
 
+cc_library(
+    name = "DyldWarningWorkaround",
+    srcs = [
+        "Source/DyldWarningWorkaround/DyldWarningWorkaround.c",
+        "Source/DyldWarningWorkaround/include/objc_dupclass.h",
+    ],
+    includes = ["Source/DyldWarningWorkaround/include"],
+    alwayslink = True,
+)
+
 # Linting
 
 filegroup(
@@ -80,9 +90,9 @@ filegroup(
 filegroup(
     name = "release_files",
     srcs = [
-        "MODULE.bazel",
         "BUILD",
         "LICENSE",
+        "MODULE.bazel",
         "//:LintInputs",
         "//Tests:BUILD",
         "//bazel:release_files",

CHANGELOG.md

@@ -60,6 +60,10 @@
   [SimplyDanny](https://github.com/SimplyDanny)
   [#4894](https://github.com/realm/SwiftLint/issues/4894)
 
+* Workaround dyld warning about SwiftSyntax classes.  
+  [keith](https://github.com/keith)
+  [#4782](https://github.com/realm/SwiftLint/issues/4782)
+
 ## 0.51.0: bzllint
 
 #### Breaking

Package.swift

@@ -52,10 +52,12 @@ let package = Package(
                 .product(name: "SwiftParser", package: "swift-syntax"),
                 .product(name: "SwiftOperators", package: "swift-syntax"),
                 "SwiftyTextTable",
+                .target(name: "DyldWarningWorkaround", condition: .when(platforms: [.macOS])),
                 "Yams",
                 .product(name: "CryptoSwift", package: "CryptoSwift", condition: .when(platforms: [.linux]))
             ]
         ),
+        .target(name: "DyldWarningWorkaround"),
         .target(
             name: "SwiftLintTestHelpers",
             dependencies: [

Source/DyldWarningWorkaround/DyldWarningWorkaround.c

@@ -0,0 +1,15 @@
+#ifdef __APPLE__
+
+#include "objc_dupclass.h"
+
+OBJC_DUPCLASS(_TtC11SwiftSyntax11SyntaxArena);
+OBJC_DUPCLASS(_TtC11SwiftSyntax13SyntaxVisitor);
+OBJC_DUPCLASS(_TtC11SwiftSyntax14SyntaxRewriter);
+OBJC_DUPCLASS(_TtC11SwiftSyntax16BumpPtrAllocator);
+OBJC_DUPCLASS(_TtC11SwiftSyntax16SyntaxAnyVisitor);
+OBJC_DUPCLASS(_TtC11SwiftSyntax18ParsingSyntaxArena);
+OBJC_DUPCLASS(_TtC11SwiftSyntax23SourceLocationConverter);
+OBJC_DUPCLASS(_TtC11SwiftSyntax26IncrementalParseTransition);
+OBJC_DUPCLASS(_TtC11SwiftSyntax35IncrementalParseReusedNodeCollector);
+
+#endif // __APPLE__

Source/DyldWarningWorkaround/include/objc_dupclass.h

@@ -0,0 +1,19 @@
+// https://github.com/keith/objc_dupclass
+#include <stdint.h>
+
+// TODO: This isn't entirely accurate, but I'm not sure how to more accurately determine
+#if (defined(__arm64__) || defined(DUPCLASS_FORCE_DATA_CONST)) && !defined(DUPCLASS_FORCE_DATA)
+#define SECTION "__DATA_CONST"
+#else
+#define SECTION "__DATA"
+#endif
+
+// Struct layout from https://github.com/apple-oss-distributions/objc4/blob/8701d5672d3fd3cd817aeb84db1077aafe1a1604/runtime/objc-abi.h#L175-L183
+#define OBJC_DUPCLASS(kclass) \
+    __attribute__((used)) __attribute__((visibility("hidden"))) \
+      static struct { uint32_t version; uint32_t flags; const char name[64]; } \
+      const __duplicate_class_##kclass = { 0, 0, #kclass }; \
+    \
+    __attribute__((used)) __attribute__((visibility("hidden"))) \
+      __attribute__((section (SECTION",__objc_dupclass"))) \
+      const void* __set___objc_dupclass_sym___duplicate_class_##kclass = &__duplicate_class_##kclass