[InstallAPI] capture compatibility versions (#85261)

clang/test/InstallAPI/basic.test

@@ -2,7 +2,8 @@
 // RUN: split-file %s %t
 /// Check basic arguments are captured.
 // RUN: clang-installapi -x objective-c -target arm64-apple-ios13.0.0 \
-// RUN: -fapplication-extension -current_version 1 -install_name /usr/lib/basic.dylib \
+// RUN: -fapplication-extension -current_version 1 -compatibility_version 1 \
+// RUN: -install_name /usr/lib/basic.dylib \
 // RUN: %t/basic_inputs.json -o %t/basic.tbd 2>&1 | FileCheck %s --allow-empty
 // RUN: llvm-readtapi -compare %t/basic.tbd %t/expected.tbd 2>&1 | FileCheck %s --allow-empty
 
@@ -25,11 +26,6 @@
 //--- expected.tbd
 {
   "main_library": {
-    "compatibility_versions": [
-      {
-        "version": "0"
-      }
-    ],
     "install_names": [
       {
         "name": "/usr/lib/basic.dylib"

clang/tools/clang-installapi/Options.cpp

@@ -85,6 +85,9 @@ bool Options::processLinkerOptions(InputArgList &Args) {
   if (auto *Arg = Args.getLastArg(OPT_current__version))
     LinkerOpts.CurrentVersion.parse64(Arg->getValue());
 
+  if (auto *Arg = Args.getLastArg(OPT_compatibility__version))
+    LinkerOpts.CompatVersion.parse64(Arg->getValue());
+
   LinkerOpts.IsDylib = Args.hasArg(OPT_dynamiclib);
 
   LinkerOpts.AppExtensionSafe =
@@ -159,6 +162,7 @@ InstallAPIContext Options::createContext() {
 
   Ctx.BA.InstallName = LinkerOpts.InstallName;
   Ctx.BA.CurrentVersion = LinkerOpts.CurrentVersion;
+  Ctx.BA.CompatVersion = LinkerOpts.CompatVersion;
   Ctx.BA.AppExtensionSafe = LinkerOpts.AppExtensionSafe;
   Ctx.FT = DriverOpts.OutFT;
   Ctx.OutputLoc = DriverOpts.OutputPath;

clang/tools/clang-installapi/Options.h

@@ -49,6 +49,9 @@ struct LinkerOptions {
   /// \brief The current version to use for the dynamic library.
   PackedVersion CurrentVersion;
 
+  /// \brief The compatibility version to use for the dynamic library.
+  PackedVersion CompatVersion;
+
   /// \brief Is application extension safe.
   bool AppExtensionSafe = false;