[Driver][Frontend] -nostdimport and -nostdlibimport should remove the default framework search paths

-nostdimport and -nostdlibimport only remove the toolchain and usr/lib/swift search paths, and they leave the framework search paths intact. That makes it impossible to get a fully custom SDK environment. Make their behavior match clang's -nostdinc/-nostdlibinc behavior: treat framework and non-framework paths the same. In other words, -nostdinc removes *all* compiler provided search paths, and -nostdlibinc removes *all* SDK search paths.

Rename SkipRuntimeLibraryImportPaths to SkipAllImportPaths, and ExcludeSDKPathsFromRuntimeLibraryImportPaths to SkipSDKImportPaths to reflect their updated behavior.

Move the DarwinImplicitFrameworkSearchPaths handling from SearchPathOptions to CompilerInvocation, where RuntimeLibraryImportPaths is managed. Rename it to just ImplicitFrameworkSearchPaths, and filter for Darwin when it's set up so that all of the clients don't have to do Darwin filtering themselves later.

rdar://150557632

Author: ian-twilightcoder

include/swift/AST/ASTContext.h

@@ -1093,10 +1093,6 @@ class ASTContext final {
   /// Retrieve the module interface checker associated with this AST context.
   ModuleInterfaceChecker *getModuleInterfaceChecker() const;
 
-  /// Compute the extra implicit framework search paths on Apple platforms:
-  /// $SDKROOT/System/Library/Frameworks/ and $SDKROOT/Library/Frameworks/.
-  std::vector<std::string> getDarwinImplicitFrameworkSearchPaths() const;
-
   /// Load extensions to the given nominal type from the external
   /// module loaders.
   ///

include/swift/AST/SearchPathOptions.h

@@ -35,7 +35,7 @@ namespace swift {
 enum class ModuleSearchPathKind {
   Import,
   Framework,
-  DarwinImplicitFramework,
+  ImplicitFramework,
   RuntimeLibrary,
 };
 
@@ -361,7 +361,7 @@ class SearchPathOptions {
   /// Computed when the SDK path is set and cached so we can reference the
   /// Darwin implicit framework search paths as \c StringRef from
   /// \c ModuleSearchPath.
-  std::vector<std::string> DarwinImplicitFrameworkSearchPaths;
+  std::vector<std::string> ImplicitFrameworkSearchPaths;
 
   /// Compiler plugin library search paths.
   std::vector<std::string> CompilerPluginLibraryPaths;
@@ -401,21 +401,6 @@ class SearchPathOptions {
 
   void setSDKPath(std::string NewSDKPath) {
     SDKPath = NewSDKPath;
-
-    // Compute Darwin implicit framework search paths.
-    SmallString<128> systemFrameworksScratch(NewSDKPath);
-    llvm::sys::path::append(systemFrameworksScratch, "System", "Library",
-                            "Frameworks");
-    SmallString<128> systemSubFrameworksScratch(NewSDKPath);
-    llvm::sys::path::append(systemSubFrameworksScratch, "System", "Library",
-                            "SubFrameworks");
-    SmallString<128> frameworksScratch(NewSDKPath);
-    llvm::sys::path::append(frameworksScratch, "Library", "Frameworks");
-    DarwinImplicitFrameworkSearchPaths = {systemFrameworksScratch.str().str(),
-                                          systemSubFrameworksScratch.str().str(),
-                                          frameworksScratch.str().str()};
-
-    Lookup.searchPathsDidChange();
   }
 
   /// Retrieves the corresponding parent platform path for the SDK, or
@@ -470,8 +455,14 @@ class SearchPathOptions {
 
   /// The extra implicit framework search paths on Apple platforms:
   /// $SDKROOT/System/Library/Frameworks/ and $SDKROOT/Library/Frameworks/.
-  ArrayRef<std::string> getDarwinImplicitFrameworkSearchPaths() const {
-    return DarwinImplicitFrameworkSearchPaths;
+  ArrayRef<std::string> getImplicitFrameworkSearchPaths() const {
+    return ImplicitFrameworkSearchPaths;
+  }
+
+  void setImplicitFrameworkSearchPaths(
+      std::vector<std::string> NewImplicitFrameworkSearchPaths) {
+    ImplicitFrameworkSearchPaths = NewImplicitFrameworkSearchPaths;
+    Lookup.searchPathsDidChange();
   }
 
   ArrayRef<std::string> getRuntimeLibraryImportPaths() const {
@@ -505,11 +496,11 @@ class SearchPathOptions {
   /// Path to in-process plugin server shared library.
   std::string InProcessPluginServerPath;
 
-  /// Don't look in for compiler-provided modules.
-  bool SkipRuntimeLibraryImportPaths = false;
+  /// Don't automatically add any import paths.
+  bool SkipAllImportPaths = false;
 
-  /// Don't include SDK paths in the RuntimeLibraryImportPaths
-  bool ExcludeSDKPathsFromRuntimeLibraryImportPaths = false;
+  /// Don't automatically add any import paths from the SDK.
+  bool SkipSDKImportPaths = false;
 
   /// Scanner Prefix Mapper.
   std::vector<std::string> ScannerPrefixMapper;

lib/AST/ASTContext.cpp

@@ -2208,12 +2208,6 @@ namespace {
   }
 }
 
-std::vector<std::string> ASTContext::getDarwinImplicitFrameworkSearchPaths()
-const {
-  assert(LangOpts.Target.isOSDarwin());
-  return SearchPathOpts.getDarwinImplicitFrameworkSearchPaths();
-}
-
 void ASTContext::loadExtensions(NominalTypeDecl *nominal,
                                 unsigned previousGeneration) {
   PrettyStackTraceDecl stackTrace("loading extensions for", nominal);

lib/AST/SearchPathOptions.cpp

@@ -58,14 +58,10 @@ void ModuleSearchPathLookup::rebuildLookupTable(const SearchPathOptions *Opts,
                                 Entry.value().IsSystem, Entry.index());
   }
 
-  // Apple platforms have extra implicit framework search paths:
-  // $SDKROOT/System/Library/Frameworks/ and $SDKROOT/Library/Frameworks/.
-  if (IsOSDarwin) {
-    for (auto Entry : llvm::enumerate(Opts->getDarwinImplicitFrameworkSearchPaths())) {
-      addFilesInPathToLookupTable(FS, Entry.value(),
-                                  ModuleSearchPathKind::DarwinImplicitFramework,
-                                  /*isSystem=*/true, Entry.index());
-    }
+  for (auto Entry : llvm::enumerate(Opts->getImplicitFrameworkSearchPaths())) {
+    addFilesInPathToLookupTable(FS, Entry.value(),
+                                ModuleSearchPathKind::ImplicitFramework,
+                                /*isSystem=*/true, Entry.index());
   }
 
   for (auto Entry : llvm::enumerate(Opts->getRuntimeLibraryImportPaths())) {
@@ -123,12 +119,9 @@ void SearchPathOptions::dump(bool isDarwin) const {
                  << Entry.value().Path << "\n";
   }
 
-  if (isDarwin) {
-    llvm::errs() << "Darwin implicit framework search paths:\n";
-    for (auto Entry :
-         llvm::enumerate(getDarwinImplicitFrameworkSearchPaths())) {
-      llvm::errs() << "  [" << Entry.index() << "] " << Entry.value() << "\n";
-    }
+  llvm::errs() << "Implicit framework search paths:\n";
+  for (auto Entry : llvm::enumerate(getImplicitFrameworkSearchPaths())) {
+    llvm::errs() << "  [" << Entry.index() << "] " << Entry.value() << "\n";
   }
 
   llvm::errs() << "Runtime library import search paths:\n";

lib/Frontend/CompilerInvocation.cpp

@@ -43,9 +43,6 @@
 using namespace swift;
 using namespace llvm::opt;
 
-/// The path for Swift libraries in the OS on Darwin.
-#define DARWIN_OS_LIBRARY_PATH "/usr/lib/swift"
-
 static constexpr const char *const localeCodes[] = {
 #define SUPPORTED_LOCALE(Code, Language) #Code,
 #include "swift/AST/LocalizationLanguages.def"
@@ -211,6 +208,12 @@ void CompilerInvocation::setDefaultInProcessPluginServerPathIfNecessary() {
 static void updateRuntimeLibraryPaths(SearchPathOptions &SearchPathOpts,
                                       const FrontendOptions &FrontendOpts,
                                       const LangOptions &LangOpts) {
+  // If this is set, we don't want any runtime import paths.
+  if (SearchPathOpts.SkipAllImportPaths) {
+    SearchPathOpts.setRuntimeLibraryImportPaths({});
+    return;
+  }
+
   const llvm::Triple &Triple = LangOpts.Target;
   llvm::SmallString<128> LibPath(SearchPathOpts.RuntimeResourcePath);
 
@@ -220,44 +223,7 @@ static void updateRuntimeLibraryPaths(SearchPathOptions &SearchPathOpts,
   if (LangOpts.hasFeature(Feature::Embedded))
     LibSubDir = "embedded";
 
-  SearchPathOpts.RuntimeLibraryPaths.clear();
-
-#if defined(_WIN32)
-  // Resource path looks like this:
-  //
-  //   C:\...\Swift\Toolchains\6.0.0+Asserts\usr\lib\swift
-  //
-  // The runtimes are in
-  //
-  //   C:\...\Swift\Runtimes\6.0.0\usr\bin
-  //
-  llvm::SmallString<128> RuntimePath(LibPath);
-
-  llvm::sys::path::remove_filename(RuntimePath);
-  llvm::sys::path::remove_filename(RuntimePath);
-  llvm::sys::path::remove_filename(RuntimePath);
-
-  llvm::SmallString<128> VersionWithAttrs(llvm::sys::path::filename(RuntimePath));
-  size_t MaybePlus = VersionWithAttrs.find_first_of('+');
-  StringRef Version = VersionWithAttrs.substr(0, MaybePlus);
-
-  llvm::sys::path::remove_filename(RuntimePath);
-  llvm::sys::path::remove_filename(RuntimePath);
-  llvm::sys::path::append(RuntimePath, "Runtimes", Version, "usr", "bin");
-
-  SearchPathOpts.RuntimeLibraryPaths.push_back(std::string(RuntimePath.str()));
-#endif
-
   llvm::sys::path::append(LibPath, LibSubDir);
-  SearchPathOpts.RuntimeLibraryPaths.push_back(std::string(LibPath.str()));
-  if (Triple.isOSDarwin())
-    SearchPathOpts.RuntimeLibraryPaths.push_back(DARWIN_OS_LIBRARY_PATH);
-
-  // If this is set, we don't want any runtime import paths.
-  if (SearchPathOpts.SkipRuntimeLibraryImportPaths) {
-    SearchPathOpts.setRuntimeLibraryImportPaths({});
-    return;
-  }
 
   // Set up the import paths containing the swiftmodules for the libraries in
   // RuntimeLibraryPath.
@@ -270,7 +236,7 @@ static void updateRuntimeLibraryPaths(SearchPathOptions &SearchPathOpts,
     RuntimeLibraryImportPaths.push_back(std::string(LibPath.str()));
   }
 
-  if (!SearchPathOpts.ExcludeSDKPathsFromRuntimeLibraryImportPaths && !SearchPathOpts.getSDKPath().empty()) {
+  if (!SearchPathOpts.SkipSDKImportPaths && !SearchPathOpts.getSDKPath().empty()) {
     const char *swiftDir = FrontendOpts.UseSharedResourceFolder
       ? "swift" : "swift_static";
 
@@ -300,6 +266,31 @@ static void updateRuntimeLibraryPaths(SearchPathOptions &SearchPathOpts,
   SearchPathOpts.setRuntimeLibraryImportPaths(RuntimeLibraryImportPaths);
 }
 
+static void
+updateImplicitFrameworkSearchPaths(SearchPathOptions &SearchPathOpts,
+                                   const LangOptions &LangOpts) {
+  std::vector<std::string> ImplicitFrameworkSearchPaths;
+  if (!SearchPathOpts.SkipAllImportPaths &&
+      !SearchPathOpts.SkipSDKImportPaths &&
+      !SearchPathOpts.getSDKPath().empty()) {
+    if (LangOpts.Target.isOSDarwin()) {
+      StringRef SDKPath = SearchPathOpts.getSDKPath();
+      SmallString<128> systemFrameworksScratch(SDKPath);
+      llvm::sys::path::append(systemFrameworksScratch, "System", "Library",
+                              "Frameworks");
+      SmallString<128> systemSubFrameworksScratch(SDKPath);
+      llvm::sys::path::append(systemSubFrameworksScratch, "System", "Library",
+                              "SubFrameworks");
+      SmallString<128> frameworksScratch(SDKPath);
+      llvm::sys::path::append(frameworksScratch, "Library", "Frameworks");
+      ImplicitFrameworkSearchPaths = {systemFrameworksScratch.str().str(),
+                                      systemSubFrameworksScratch.str().str(),
+                                      frameworksScratch.str().str()};
+    }
+  }
+  SearchPathOpts.setImplicitFrameworkSearchPaths(ImplicitFrameworkSearchPaths);
+}
+
 static void
 setIRGenOutputOptsFromFrontendOptions(IRGenOptions &IRGenOpts,
                                       const FrontendOptions &FrontendOpts) {
@@ -411,11 +402,13 @@ void CompilerInvocation::setTargetTriple(StringRef Triple) {
 void CompilerInvocation::setTargetTriple(const llvm::Triple &Triple) {
   LangOpts.setTarget(Triple);
   updateRuntimeLibraryPaths(SearchPathOpts, FrontendOpts, LangOpts);
+  updateImplicitFrameworkSearchPaths(SearchPathOpts, LangOpts);
 }
 
 void CompilerInvocation::setSDKPath(const std::string &Path) {
   SearchPathOpts.setSDKPath(Path);
   updateRuntimeLibraryPaths(SearchPathOpts, FrontendOpts, LangOpts);
+  updateImplicitFrameworkSearchPaths(SearchPathOpts, LangOpts);
 }
 
 bool CompilerInvocation::setModuleAliasMap(std::vector<std::string> args,
@@ -2387,8 +2380,8 @@ static bool ParseSearchPathArgs(SearchPathOptions &Opts, ArgList &Args,
   if (const Arg *A = Args.getLastArg(OPT_resource_dir))
     Opts.RuntimeResourcePath = A->getValue();
 
-  Opts.SkipRuntimeLibraryImportPaths |= Args.hasArg(OPT_nostdimport);
-  Opts.ExcludeSDKPathsFromRuntimeLibraryImportPaths |= Args.hasArg(OPT_nostdlibimport);
+  Opts.SkipAllImportPaths |= Args.hasArg(OPT_nostdimport);
+  Opts.SkipSDKImportPaths |= Args.hasArg(OPT_nostdlibimport);
 
   Opts.DisableModulesValidateSystemDependencies |=
       Args.hasArg(OPT_disable_modules_validate_system_headers);
@@ -4043,6 +4036,7 @@ bool CompilerInvocation::parseArgs(
   }
 
   updateRuntimeLibraryPaths(SearchPathOpts, FrontendOpts, LangOpts);
+  updateImplicitFrameworkSearchPaths(SearchPathOpts, LangOpts);
   setDefaultPrebuiltCacheIfNecessary();
   setDefaultBlocklistsIfNecessary();
   setDefaultInProcessPluginServerPathIfNecessary();

lib/Serialization/SerializedModuleLoader.cpp

@@ -108,14 +108,11 @@ std::optional<bool> forEachModuleSearchPath(
             callback(path.Path, ModuleSearchPathKind::Framework, path.IsSystem))
       return result;
 
-  // Apple platforms have extra implicit framework search paths:
-  // $SDKROOT/System/Library/Frameworks/ and $SDKROOT/Library/Frameworks/.
-  if (Ctx.LangOpts.Target.isOSDarwin()) {
-    for (const auto &path : Ctx.getDarwinImplicitFrameworkSearchPaths())
-      if (auto result =
-              callback(path, ModuleSearchPathKind::DarwinImplicitFramework,
-                       /*isSystem=*/true))
-        return result;
+  for (const auto &path :
+       Ctx.SearchPathOpts.getImplicitFrameworkSearchPaths()) {
+    if (auto result = callback(path, ModuleSearchPathKind::ImplicitFramework,
+                               /*isSystem=*/true))
+      return result;
   }
 
   for (const auto &importPath :
@@ -240,7 +237,7 @@ void SerializedModuleLoaderBase::collectVisibleTopLevelModuleNamesImpl(
       return std::nullopt;
     }
     case ModuleSearchPathKind::Framework:
-    case ModuleSearchPathKind::DarwinImplicitFramework: {
+    case ModuleSearchPathKind::ImplicitFramework: {
       // Look for:
       // $PATH/{name}.framework/Modules/{name}.swiftmodule/{arch}.{extension}
       forEachDirectoryEntryPath(searchPath, [&](StringRef path) {
@@ -964,7 +961,7 @@ bool SerializedModuleLoaderBase::findModule(
       continue;
     }
     case ModuleSearchPathKind::Framework:
-    case ModuleSearchPathKind::DarwinImplicitFramework: {
+    case ModuleSearchPathKind::ImplicitFramework: {
       isFramework = true;
       llvm::sys::path::append(currPath, moduleName + ".framework");
 

test/Frontend/default-search-paths.swift

@@ -0,0 +1,41 @@
+// Standard Apple paths.
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource) -target arm64-apple-darwin24.4 -typecheck %s -Rmodule-loading 2>&1 | %FileCheck -check-prefix=APPLE %s
+// APPLE: Implicit framework search paths:
+// APPLE-NEXT: [0] %clang-importer-sdk-path/System/Library/Frameworks
+// APPLE-NEXT: [1] %clang-importer-sdk-path/System/Library/SubFrameworks
+// APPLE-NEXT: [2] %clang-importer-sdk-path/Library/Frameworks
+// APPLE-NEXT: Runtime library import search paths:
+// APPLE-NEXT: [0] %platform-module-dir
+// APPLE-NEXT: [1] %clang-importer-sdk-path/usr/lib/swift
+// APPLE-NEXT: (End of search path lists.)
+
+// Non-Apple platforms don't have any implicit framework search paths.
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource) -target x86_64-unknown-linux-android -typecheck %s -Rmodule-loading 2>&1 | %FileCheck -check-prefix=ANDROID %s
+// ANDROID: Implicit framework search paths:
+// ANDROID-NEXT: Runtime library import search paths:
+// ANDROID-NEXT: [0] %platform-module-dir
+// ANDROID-NEXT: [1] %platform-module-dir/x86_64
+// ANDROID-NEXT: [2] %clang-importer-sdk-path/usr/lib/swift/android
+// ANDROID-NEXT: [3] %clang-importer-sdk-path/usr/lib/swift/android/x86_64
+// ANDROID-NEXT: (End of search path lists.)
+
+// -nostdimport doesn't set up any standard import paths at all.
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource) -target arm64-apple-darwin24.4 -nostdimport -typecheck %s -Rmodule-loading 2>&1 | %FileCheck -check-prefix=NOSTDIMPORT %s
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource) -target x86_64-unknown-linux-android -nostdimport -typecheck %s -Rmodule-loading 2>&1 | %FileCheck -check-prefix=NOSTDIMPORT %s
+// NOSTDIMPORT: Implicit framework search paths:
+// NOSTDIMPORT-NEXT: Runtime library import search paths:
+// NOSTDIMPORT-NEXT: (End of search path lists.)
+
+// -nostdlibimport removes all of the standard imports from the SDK but leaves the toolchain ones.
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource) -target arm64-apple-darwin24.4 -nostdlibimport -typecheck %s -Rmodule-loading 2>&1 | %FileCheck -check-prefix=APPLE-NOSTDLIBIMPORT %s
+// APPLE-NOSTDLIBIMPORT: Implicit framework search paths:
+// APPLE-NOSTDLIBIMPORT-NEXT: Runtime library import search paths:
+// APPLE-NOSTDLIBIMPORT-NEXT: [0] %platform-module-dir
+// APPLE-NOSTDLIBIMPORT-NEXT: (End of search path lists.)
+
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource) -target x86_64-unknown-linux-android -nostdlibimport -typecheck %s -Rmodule-loading 2>&1 | %FileCheck -check-prefix=ANDROID-NOSTDLIBIMPORT %s
+// ANDROID-NOSTDLIBIMPORT: Implicit framework search paths:
+// ANDROID-NOSTDLIBIMPORT-NEXT: Runtime library import search paths:
+// ANDROID-NOSTDLIBIMPORT-NEXT: [0] %platform-module-dir
+// ANDROID-NOSTDLIBIMPORT-NEXT: [1] %platform-module-dir/x86_64
+// ANDROID-NOSTDLIBIMPORT-NEXT: (End of search path lists.)