[lldb][NFC] Inline ResolveSDKPathFromDebugInfo in one of its call site (#146062)

This patch is part of an effort to remove the
`ResolveSDKPathFromDebugInfo` method, and more specifically the variant
which takes a Module as argument.

See the following PR for a follow up on what to do:
- #144913.

---------

Co-authored-by: Michael Buch <[email protected]>

Author: charles-zablit

lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp

@@ -1030,6 +1030,40 @@ PlatformDarwin::ExtractAppSpecificInfo(Process &process) {
   return dict_sp;
 }
 
+static llvm::Expected<lldb_private::FileSpec>
+ResolveSDKPathFromDebugInfo(lldb_private::Target *target) {
+
+  ModuleSP exe_module_sp = target->GetExecutableModule();
+  if (!exe_module_sp)
+    return llvm::createStringError("Failed to get module from target");
+
+  SymbolFile *sym_file = exe_module_sp->GetSymbolFile();
+  if (!sym_file)
+    return llvm::createStringError("Failed to get symbol file from module");
+
+  XcodeSDK merged_sdk;
+  for (unsigned i = 0; i < sym_file->GetNumCompileUnits(); ++i) {
+    if (auto cu_sp = sym_file->GetCompileUnitAtIndex(i)) {
+      auto cu_sdk = sym_file->ParseXcodeSDK(*cu_sp);
+      merged_sdk.Merge(cu_sdk);
+    }
+  }
+
+  // TODO: The result of this loop is almost equivalent to deriving the SDK
+  // from the target triple, which would be a lot cheaper.
+  FileSpec sdk_path = merged_sdk.GetSysroot();
+  if (FileSystem::Instance().Exists(sdk_path)) {
+    return sdk_path;
+  }
+  auto path_or_err = HostInfo::GetSDKRoot(HostInfo::SDKOptions{merged_sdk});
+  if (!path_or_err)
+    return llvm::createStringError(
+        llvm::formatv("Failed to resolve SDK path: {0}",
+                      llvm::toString(path_or_err.takeError())));
+
+  return FileSpec(*path_or_err);
+}
+
 void PlatformDarwin::AddClangModuleCompilationOptionsForSDKType(
     Target *target, std::vector<std::string> &options, XcodeSDK::Type sdk_type) {
   const std::vector<std::string> apple_arguments = {
@@ -1129,15 +1163,13 @@ void PlatformDarwin::AddClangModuleCompilationOptionsForSDKType(
   FileSpec sysroot_spec;
 
   if (target) {
-    if (ModuleSP exe_module_sp = target->GetExecutableModule()) {
-      auto path_or_err = ResolveSDKPathFromDebugInfo(*exe_module_sp);
-      if (path_or_err) {
-        sysroot_spec = FileSpec(*path_or_err);
-      } else {
-        LLDB_LOG_ERROR(GetLog(LLDBLog::Types | LLDBLog::Host),
-                       path_or_err.takeError(),
-                       "Failed to resolve SDK path: {0}");
-      }
+    auto sysroot_spec_or_err = ::ResolveSDKPathFromDebugInfo(target);
+    if (!sysroot_spec_or_err) {
+      LLDB_LOG_ERROR(GetLog(LLDBLog::Types | LLDBLog::Host),
+                     sysroot_spec_or_err.takeError(),
+                     "Failed to resolve sysroot: {0}");
+    } else {
+      sysroot_spec = *sysroot_spec_or_err;
     }
   }