swiftlang · owenv · Dec 11, 2025
@@ -1556,7 +1556,7 @@ def Xfrontend : Separate<["-"], "Xfrontend">, Flags<[HelpHidden]>,
 
 def Xcc : Separate<["-"], "Xcc">,
   Flags<[FrontendOption, SwiftSymbolGraphExtractOption,
-         SwiftSynthesizeInterfaceOption]>,
+         SwiftSynthesizeInterfaceOption, SwiftAPIDigesterOption]>,
   MetaVarName<"<arg>">,
   HelpText<"Pass <arg> to the C/C++/Objective-C compiler">;
 

@@ -2273,6 +2273,7 @@ class SwiftAPIDigesterInvocation {
   std::string ResourceDir;
   std::string ModuleCachePath;
   bool DisableFailOnError;
+  std::vector<std::string> ClangImporterArgs;
 
 public:
   SwiftAPIDigesterInvocation(const std::string &ExecPath)
@@ -2375,6 +2376,7 @@ class SwiftAPIDigesterInvocation {
         ParsedArgs.getAllArgValues(OPT_use_interface_for_module);
     ResourceDir = ParsedArgs.getLastArgValue(OPT_resource_dir).str();
     ModuleCachePath = ParsedArgs.getLastArgValue(OPT_module_cache_path).str();
+    ClangImporterArgs = ParsedArgs.getAllArgValues(OPT_Xcc);
     DebugMapping = ParsedArgs.hasArg(OPT_debug_mapping);
     DisableFailOnError = ParsedArgs.hasArg(OPT_disable_fail_on_error);
 
@@ -2456,6 +2458,11 @@ class SwiftAPIDigesterInvocation {
         InitInvoke.getLangOptions().Target.isOSDarwin();
     InitInvoke.getClangImporterOptions().ModuleCachePath = ModuleCachePath;
 
+    // Pass -Xcc arguments to the Clang importer
+    for (const auto &arg : ClangImporterArgs) {
+      InitInvoke.getClangImporterOptions().ExtraArgs.push_back(arg);
+    }
+
     if (!SwiftVersion.empty()) {
       using version::Version;
       bool isValid = false;

diff --git a/lib/Option/features.json b/lib/Option/features.json
@@ -53,6 +53,9 @@
     },
     {
        "name": "internal-import-bridging-header"
+    },
+    {
+       "name": "api-digester-Xcc"
     }
   ]
 }
diff --git a/test/api-digester/Inputs/XccTest/XccTest.h b/test/api-digester/Inputs/XccTest/XccTest.h
@@ -0,0 +1,9 @@
+@import ObjectiveC;
+
+#ifdef MY_MACRO
+@interface Hidden : NSObject
+@end
+#endif
+
+@interface NotHidden : NSObject
+@end
diff --git a/test/api-digester/Inputs/XccTest/module.modulemap b/test/api-digester/Inputs/XccTest/module.modulemap
@@ -0,0 +1,4 @@
+module XccTest {
+  header "XccTest.h"
+  export *
+}
diff --git a/test/api-digester/Xcc-preprocessor-define.swift b/test/api-digester/Xcc-preprocessor-define.swift
@@ -0,0 +1,13 @@
+// REQUIRES: VENDOR=apple
+
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t.module-cache)
+
+// RUN: %api-digester -dump-sdk -module XccTest -o %t.with-define.json -module-cache-path %t.module-cache %clang-importer-sdk-nosource -I %S/Inputs/XccTest -Xcc -DMY_MACRO
+// RUN: %api-digester -dump-sdk -module XccTest -o %t.without-define.json -module-cache-path %t.module-cache %clang-importer-sdk-nosource -I %S/Inputs/XccTest
+
+// RUN: grep -q "Hidden" %t.with-define.json
+// RUN: grep -q "NotHidden" %t.with-define.json
+
+// RUN: not grep -q "Hidden" %t.without-define.json
+// RUN: grep -q "NotHidden" %t.without-define.json
-Original file line number
+Diff line change
@@ Expand Up / @@ -53,6 +53,9 @@ @@
         },
         {
            "name": "internal-import-bridging-header"
+        },
+        {
+           "name": "api-digester-Xcc"
         }
       ]
     }