[Driver] Read SDK version information to pass to the Darwin linker.

Recent-ish SDKs for Darwin platforms include an SDKSettings.json
file with version information and Catalyst SDK version mappings. Read
these (when available) and use them to pass the appropriate SDK
version down to the Darwin linker via `-platform_version`.

Finishes rdar://problem/55972144.

Author: DougGregor

include/swift/AST/DiagnosticsDriver.def

@@ -207,6 +207,10 @@ ERROR(cannot_find_migration_script, none,
 ERROR(error_darwin_static_stdlib_not_supported, none,
       "-static-stdlib is no longer supported on Apple platforms", ())
 
+WARNING(warn_drv_darwin_sdk_invalid_settings, none,
+    "SDK settings were ignored because 'SDKSettings.json' could not be parsed",
+    ())
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

include/swift/Driver/ToolChain.h

@@ -318,6 +318,13 @@ class ToolChain {
                                  const llvm::opt::ArgList &args,
                                  StringRef defaultTarget) const {}
 
+  /// Validate the output information.
+  ///
+  /// An override point for platform-specific subclasses to customize their
+  /// behavior once the outputs are known.
+  virtual void validateOutputInfo(DiagnosticEngine &diags,
+                                  const OutputInfo &outputInfo) const { }
+
   llvm::Expected<file_types::ID>
   remarkFileTypeFromArgs(const llvm::opt::ArgList &Args) const;
 };

lib/Driver/DarwinToolChains.cpp

@@ -21,6 +21,7 @@
 #include "swift/Basic/TaskQueue.h"
 #include "swift/Config.h"
 #include "swift/Driver/Compilation.h"
+#include "clang/Driver/DarwinSDKInfo.h"
 #include "swift/Driver/Driver.h"
 #include "swift/Driver/Job.h"
 #include "swift/Option/Options.h"
@@ -481,10 +482,45 @@ toolchains::Darwin::addProfileGenerationArgs(ArgStringList &Arguments,
   }
 }
 
+/// Remap the given version number via the version map, or produce \c None if
+/// there is no mapping for this version.
+static Optional<llvm::VersionTuple> remapVersion(
+    const llvm::StringMap<llvm::VersionTuple> &versionMap,
+    llvm::VersionTuple version) {
+  // The build number is never used in the lookup.
+  version = version.withoutBuild();
+
+  // Look for this specific version.
+  auto known = versionMap.find(version.getAsString());
+  if (known != versionMap.end())
+    return known->second;
+
+  // If an extra ".0" was specified (in the subminor version), drop that
+  // and look again.
+  if (!version.getSubminor() || *version.getSubminor() != 0)
+    return None;
+
+  version = llvm::VersionTuple(version.getMajor(), *version.getMinor());
+  known = versionMap.find(version.getAsString());
+  if (known != versionMap.end())
+    return known->second;
+
+  // If another extra ".0" wa specified (in the minor version), drop that
+  // and look again.
+  if (!version.getMinor() || *version.getMinor() != 0)
+    return None;
+
+  version = llvm::VersionTuple(version.getMajor());
+  known = versionMap.find(version.getAsString());
+  if (known != versionMap.end())
+    return known->second;
+
+  return None;
+}
+
 void
 toolchains::Darwin::addDeploymentTargetArgs(ArgStringList &Arguments,
                                             const JobContext &context) const {
-
   auto addPlatformVersionArg = [&](const llvm::Triple &triple) {
     // Compute the name of the platform for the linker.
     const char *platformName;
@@ -546,10 +582,31 @@ toolchains::Darwin::addDeploymentTargetArgs(ArgStringList &Arguments,
       }
     }
 
+    // Compute the SDK version.
+    unsigned sdkMajor = 0, sdkMinor = 0, sdkMicro = 0;
+    if (SDKInfo) {
+      // Retrieve the SDK version.
+      auto SDKVersion = SDKInfo->getVersion();
+
+      // For the Mac Catalyst environment, we have a macOS SDK with a macOS
+      // SDK version. Map that to the corresponding iOS version number to pass
+      // down to the linker.
+      if (tripleIsMacCatalystEnvironment(triple)) {
+        SDKVersion = remapVersion(
+            SDKInfo->getVersionMap().MacOS2iOSMacMapping, SDKVersion)
+              .getValueOr(llvm::VersionTuple(0, 0, 0));
+      }
+
+      // Extract the version information.
+      sdkMajor = SDKVersion.getMajor();
+      sdkMinor = SDKVersion.getMinor().getValueOr(0);
+      sdkMicro = SDKVersion.getSubminor().getValueOr(0);
+    }
+
     Arguments.push_back("-platform_version");
     Arguments.push_back(platformName);
     addVersionString(context.Args, Arguments, major, minor, micro);
-    addVersionString(context.Args, Arguments, 0, 0, 0);
+    addVersionString(context.Args, Arguments, sdkMajor, sdkMinor, sdkMicro);
   };
 
   addPlatformVersionArg(getTriple());
@@ -799,3 +856,20 @@ toolchains::Darwin::validateArguments(DiagnosticEngine &diags,
     diags.diagnose(SourceLoc(), diag::error_darwin_static_stdlib_not_supported);
   }
 }
+
+void
+toolchains::Darwin::validateOutputInfo(DiagnosticEngine &diags,
+                                       const OutputInfo &outputInfo) const {
+  // If we are linking and have been provided with an SDK, go read the SDK
+  // information.
+  if (outputInfo.shouldLink() && !outputInfo.SDKPath.empty()) {
+    auto SDKInfoOrErr = clang::driver::parseDarwinSDKInfo(
+        *llvm::vfs::getRealFileSystem(), outputInfo.SDKPath);
+    if (SDKInfoOrErr) {
+      SDKInfo = *SDKInfoOrErr;
+    } else {
+      llvm::consumeError(SDKInfoOrErr.takeError());
+      diags.diagnose(SourceLoc(), diag::warn_drv_darwin_sdk_invalid_settings);
+    }
+  }
+}

lib/Driver/Driver.cpp

@@ -883,6 +883,10 @@ Driver::buildCompilation(const ToolChain &TC,
   assert(OI.CompilerOutputType != file_types::ID::TY_INVALID &&
          "buildOutputInfo() must set a valid output type!");
 
+  TC.validateOutputInfo(Diags, OI);
+  if (Diags.hadAnyError())
+    return nullptr;
+
   validateEmbedBitcode(*TranslatedArgList, OI, Diags);
 
   if (OI.CompilerMode == OutputInfo::Mode::REPL)

lib/Driver/ToolChains.h

@@ -15,6 +15,7 @@
 
 #include "swift/Basic/LLVM.h"
 #include "swift/Driver/ToolChain.h"
+#include "clang/Driver/DarwinSDKInfo.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/Compiler.h"
 
@@ -58,10 +59,18 @@ class LLVM_LIBRARY_VISIBILITY Darwin : public ToolChain {
                          const llvm::opt::ArgList &args,
                          StringRef defaultTarget) const override;
 
+  void validateOutputInfo(DiagnosticEngine &diags,
+                          const OutputInfo &outputInfo) const override;
+
   std::string findProgramRelativeToSwiftImpl(StringRef name) const override;
 
   bool shouldStoreInvocationInDebugInfo() const override;
 
+  /// Information about the SDK that the application is being built against.
+  /// This information is only used by the linker, so it is only populated
+  /// when there will be a linker job.
+  mutable Optional<clang::driver::DarwinSDKInfo> SDKInfo;
+
   const Optional<llvm::Triple> TargetVariant;
 
 public:

test/Driver/Inputs/MacOSX10.15.4.versioned.sdk/SDKSettings.json

@@ -0,0 +1,27 @@
+{
+  "Version":"10.15.4",
+  "VersionMap" : {
+      "macOS_iOSMac" : {
+          "10.14.4" : "12.4",
+          "10.14.3" : "12.3",
+          "10.14.2" : "12.2",
+          "10.14.1" : "12.1",
+          "10.15" : "13.0",
+          "10.14" : "12.0",
+          "10.14.5" : "12.5",
+          "10.15.1" : "13.2",
+          "10.15.4" : "13.4"
+      },
+      "iOSMac_macOS" : {
+          "13.0" : "10.15",
+          "12.3" : "10.14.3",
+          "12.0" : "10.14",
+          "12.4" : "10.14.4",
+          "12.1" : "10.14.1",
+          "12.5" : "10.14.5",
+          "12.2" : "10.14.2",
+          "13.2" : "10.15.1",
+          "13.4" : "10.15.4"
+      }
+  }
+}

test/Driver/Inputs/MacOSX10.15.versioned.sdk/SDKSettings.json

@@ -0,0 +1,13 @@
+{
+  "Version":"10.15",
+  "VersionMap" : {
+      "macOS_iOSMac" : {
+          "10.15" : "13.1",
+          "10.15.1" : "13.2"
+      },
+      "iOSMac_macOS" : {
+          "13.1" : "10.15",
+          "13.2" : "10.15.1"
+      }
+  }
+}

test/Driver/linker.swift

@@ -101,6 +101,15 @@
 // INFERRED_NAMED_DARWIN tests above: 'libLINKER.dylib'.
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.9 -emit-library %s -o libLINKER.dylib | %FileCheck -check-prefix INFERRED_NAME_DARWIN %s
 
+// Check reading the SDKSettings.json from an SDK
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.9 -sdk %S/Inputs/MacOSX10.15.versioned.sdk %s 2>&1 | %FileCheck -check-prefix MACOS_10_15 %s
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.9 -sdk %S/Inputs/MacOSX10.15.4.versioned.sdk %s 2>&1 | %FileCheck -check-prefix MACOS_10_15_4 %s
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.9 -sdk %S/Inputs/MacOSX10.15.sdk %s 2>&1 | %FileCheck -check-prefix MACOS_UNVERSIONED %s
+
+// MACOS_10_15: -platform_version macos 10.9.0 10.15.0
+// MACOS_10_15_4: -platform_version macos 10.9.0 10.15.4
+// MACOS_UNVERSIONED: -platform_version macos 10.9.0 0.0.0
+
 // There are more RUN lines further down in the file.
 
 // CHECK: swift

test/Driver/macabi-environment.swift

@@ -97,3 +97,19 @@
 // IOS13-NO-MACABI-DAG: -L {{[^ ]+/lib/swift/iphoneos}}
 // IOS13-NO-MACABI-DAG: -L {{[^ ]+/clang-importer-sdk/usr/lib/swift}}
 // IOS13-NO-MACABI-DAG: -platform_version ios 13.0.0
+
+// Check reading the SDKSettings.json from an SDK and using it to map Catalyst
+// SDK version information.
+
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.14 -target-variant x86_64-apple-ios13.0-macabi -sdk %S/Inputs/MacOSX10.15.versioned.sdk %s 2>&1 | %FileCheck -check-prefix MACOS_10_15_ZIPPERED %s
+// MACOS_10_15_ZIPPERED: -platform_version macos 10.14.0 10.15.0
+// MACOS_10_15_ZIPPERED: -platform_version "mac catalyst" 13.0.0 13.1.0
+
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.14 -target-variant x86_64-apple-ios13.0-macabi -sdk %S/Inputs/MacOSX10.15.4.versioned.sdk %s 2>&1 | %FileCheck -check-prefix MACOS_10_15_4_ZIPPERED %s
+// MACOS_10_15_4_ZIPPERED: -platform_version macos 10.14.0 10.15.4
+// MACOS_10_15_4_ZIPPERED: -platform_version "mac catalyst" 13.0.0 13.4.0
+
+// RUN: %swiftc_driver -driver-print-jobs -target-variant x86_64-apple-macosx10.14 -target x86_64-apple-ios13.0-macabi -sdk %S/Inputs/MacOSX10.15.4.versioned.sdk %s 2>&1 | %FileCheck -check-prefix MACOS_10_15_4_REVERSE_ZIPPERED %s
+// MACOS_10_15_4_REVERSE_ZIPPERED: -platform_version "mac catalyst" 13.0.0 13.4.0
+// MACOS_10_15_4_REVERSE_ZIPPERED: -platform_version macos 10.14.0 10.15.4
+