ClangImporter: don't import clang SPI attributes by default

include/swift/Basic/LangOptions.h

@@ -740,6 +740,9 @@ namespace swift {
     /// When set, don't look for or load overlays.
     bool DisableOverlayModules = false;
 
+    /// When set, import SPI_AVAILABLE symbols with Swift SPI attribtues.
+    bool EnableClangSPI = false;
+
     /// When set, don't enforce warnings with -Werror.
     bool DebuggerSupport = false;
 
@@ -767,7 +770,8 @@ namespace swift {
                           DetailedPreprocessingRecord,
                           ImportForwardDeclarations,
                           DisableSwiftBridgeAttr,
-                          DisableOverlayModules);
+                          DisableOverlayModules,
+                          EnableClangSPI);
     }
   };
 

include/swift/Option/FrontendOptions.td

@@ -138,6 +138,10 @@ def disable_testable_attr_requires_testable_module :
   Flag<["-"], "disable-testable-attr-requires-testable-module">,
   HelpText<"Disable checking of @testable">;
 
+def enable_clang_spi :
+  Flag<["-"], "enable-clang-spi">,
+  HelpText<"Import Clang SPIs as Swift SPIs">;
+
 def enable_target_os_checking :
   Flag<["-"], "enable-target-os-checking">,
   HelpText<"Enable checking the target OS of serialized modules">;

lib/ClangImporter/ClangImporter.cpp

@@ -2197,6 +2197,7 @@ ClangImporter::Implementation::Implementation(
       DisableSwiftBridgeAttr(ctx.ClangImporterOpts.DisableSwiftBridgeAttr),
       BridgingHeaderExplicitlyRequested(!ctx.ClangImporterOpts.BridgingHeader.empty()),
       DisableOverlayModules(ctx.ClangImporterOpts.DisableOverlayModules),
+      EnableClangSPI(ctx.ClangImporterOpts.EnableClangSPI),
       IsReadingBridgingPCH(false),
       CurrentVersion(ImportNameVersion::fromOptions(ctx.LangOpts)),
       BridgingHeaderLookupTable(new SwiftLookupTable(nullptr)),

lib/ClangImporter/ImportDecl.cpp

@@ -8711,15 +8711,17 @@ void ClangImporter::Implementation::importAttributes(
         AnyUnavailable = true;
       }
 
-      if (isUsingMacroName(getClangASTContext().getSourceManager(),
-                            avail->getLoc(), "SPI_AVAILABLE") ||
-           isUsingMacroName(getClangASTContext().getSourceManager(),
-                            avail->getLoc(), "__SPI_AVAILABLE")) {
-        // The decl has been marked as SPI in the header by using the SPI macro,
-        // thus we add the SPI attribute to it with a default group name.
-        MappedDecl->getAttrs().add(SPIAccessControlAttr::create(SwiftContext,
-          SourceLoc(), SourceRange(),
-          SwiftContext.getIdentifier(CLANG_MODULE_DEFUALT_SPI_GROUP_NAME)));
+      if (EnableClangSPI) {
+        if (isUsingMacroName(getClangASTContext().getSourceManager(),
+                              avail->getLoc(), "SPI_AVAILABLE") ||
+             isUsingMacroName(getClangASTContext().getSourceManager(),
+                              avail->getLoc(), "__SPI_AVAILABLE")) {
+          // The decl has been marked as SPI in the header by using the SPI macro,
+          // thus we add the SPI attribute to it with a default group name.
+          MappedDecl->getAttrs().add(SPIAccessControlAttr::create(SwiftContext,
+            SourceLoc(), SourceRange(),
+            SwiftContext.getIdentifier(CLANG_MODULE_DEFUALT_SPI_GROUP_NAME)));
+        }
       }
 
       StringRef message = avail->getMessage();

lib/ClangImporter/ImporterImpl.h

@@ -337,6 +337,7 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
   const bool DisableSwiftBridgeAttr;
   const bool BridgingHeaderExplicitlyRequested;
   const bool DisableOverlayModules;
+  const bool EnableClangSPI;
 
   bool IsReadingBridgingPCH;
   llvm::SmallVector<clang::serialization::SubmoduleID, 2> PCHImportedSubmodules;

lib/Frontend/CompilerInvocation.cpp

@@ -1052,6 +1052,8 @@ static bool ParseClangImporterArgs(ClangImporterOptions &Opts,
 
   Opts.DisableOverlayModules |= Args.hasArg(OPT_emit_imported_modules);
 
+  Opts.EnableClangSPI |= Args.hasArg(OPT_enable_clang_spi);
+
   Opts.ExtraArgsOnly |= Args.hasArg(OPT_extra_clang_options_only);
 
   if (const Arg *A = Args.getLastArg(OPT_pch_output_dir)) {

test/ClangImporter/availability_spi_as_unavailable.swift

@@ -1,6 +1,6 @@
 // REQUIRES: OS=macosx
-// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -verify -DNOT_UNDERLYING
-// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -module-name SPIContainer -import-underlying-module -verify
+// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -enable-clang-spi -verify -DNOT_UNDERLYING
+// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -module-name SPIContainer -import-underlying-module -enable-clang-spi -verify
 
 #if NOT_UNDERLYING
 import SPIContainer

test/ClangImporter/availability_spi_as_unavailable_bridging_header.swift

@@ -1,5 +1,5 @@
 // REQUIRES: OS=macosx
-// RUN: %target-swift-frontend -typecheck %s -import-objc-header %S/Inputs/frameworks/SPIContainer.framework/Headers/SPIContainer.h -verify
+// RUN: %target-swift-frontend -typecheck %s -import-objc-header %S/Inputs/frameworks/SPIContainer.framework/Headers/SPIContainer.h -enable-clang-spi -verify
 
 
 @_spi(a) public let a: SPIInterface1