[Lldb-commits] [lldb] [lldb][ClangExpressionParser] Set BuiltinHeadersInSystemModules depending on SDK version (PR #101778)

[Adrian Prantl via lldb-commits]

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@@ -561,7 +562,85 @@ static void SetupLangOpts(CompilerInstance &compiler,
   lang_opts.NoBuiltin = true;
 }
 
-static void SetupImportStdModuleLangOpts(CompilerInstance &compiler) {
+// NOTE: should be kept in sync with sdkSupportsBuiltinModules in
+// Toolchains/Darwin.cpp
+static bool
+sdkSupportsBuiltinModulesImpl(const llvm::Triple &triple,
+                              const std::optional<DarwinSDKInfo> &SDKInfo) {
+  if (!SDKInfo)
+    return false;
+
+  VersionTuple SDKVersion = SDKInfo->getVersion();
+  switch (triple.getOS()) {
+  case Triple::OSType::MacOSX:
+    return SDKVersion >= VersionTuple(15U);
+  case Triple::OSType::IOS:
+    return SDKVersion >= VersionTuple(18U);
+  case Triple::OSType::TvOS:
+    return SDKVersion >= VersionTuple(18U);
+  case Triple::OSType::WatchOS:
+    return SDKVersion >= VersionTuple(11U);
+  case Triple::OSType::XROS:
+    return SDKVersion >= VersionTuple(2U);
+  default:
+    // New SDKs support builtin modules from the start.
+    return true;
+  }
+}
+
+/// Returns true if the SDK for the specified triple supports
+/// builtin modules in system headers. This is used to decide
+/// whether to pass -fbuiltin-headers-in-system-modules to
+/// the compiler instance when compiling the `std` module.
+///
+/// This function assumes one of the directories in \ref include_dirs
+/// is an SDK path that exists on the host. The SDK version is
+/// read from the SDKSettings.json in that directory.
+///
+/// \param[in] triple The target triple.
+/// \param[in] include_dirs The include directories the compiler will use
+///                         during header search.
+///
+static bool
+sdkSupportsBuiltinModules(llvm::Triple const &triple,
+                          std::vector<std::string> const &include_dirs) {
+  // Find an SDK directory.
+  static constexpr std::string_view s_sdk_suffix = ".sdk";
+  auto it = llvm::find_if(include_dirs, [](std::string const &path) {
+    return path.find(s_sdk_suffix) != std::string::npos;
+  });
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adrian-prantl wrote:

There is also this, which might be shorter. https://llvm.org/doxygen/namespacellvm_1_1sys_1_1path.html#ad7c38f73fbf2f1a4ed9578621c6bfe8b

https://github.com/llvm/llvm-project/pull/101778