[Lldb-commits] [lldb] [lldb]HostInfoMacOSX] Search CommandLineTools directory when looking up SDK paths (PR #128712)

[Jonas Devlieghere via lldb-commits]

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@@ -581,6 +626,21 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
                                    "XcodeSDK not specified");
   XcodeSDK sdk = *options.XcodeSDKSelection;
   auto key = sdk.GetString();
+
+  // xcrun doesn't search SDKs in the CommandLineTools (CLT) directory. So if
+  // a program was compiled against a CLT SDK, but that SDK wasn't present in
+  // any of the Xcode installations, then xcrun would fail to find the SDK
+  // (which is expensive). To avoid this we first try to find the specified SDK
+  // in the CLT directory.
+  auto clt_root_dir = find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&] {
+    return GetCommandLineToolsSDKRoot(sdk.GetVersion());
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JDevlieghere wrote:

Yeah, you don't know you need the CLT until you know it's not in Xcode, which is exactly the problem this is trying to avoid. 

https://github.com/llvm/llvm-project/pull/128712