swift-api-digester: teach the tool to compare two SDKs directly

With module stability from the compiler, we can now use an earlier version
of the SDK as the baseline and compare the new SDK with it. This patch
adds a new -bsdk flag to the tool to specify the baseline SDK path.

test/api-digester/Inputs/mock-sdk-baseline.sdk/System/Library/Frameworks/Foo.framework/Frameworks/FooSub.framework/Headers/FooSub.h

@@ -0,0 +1,15 @@
+#if !defined(__FOOSUB_H__)
+#define __FOOSUB_H__ 1
+
+int fooSubFunc1(int a);
+
+enum FooSubEnum1 {
+  FooSubEnum1X,
+  FooSubEnum1Y
+};
+
+enum {
+  FooSubUnnamedEnumeratorA1
+};
+
+#endif /* ! __FOOSUB_H__ */

test/api-digester/Inputs/mock-sdk-baseline.sdk/System/Library/Frameworks/Foo.framework/Headers/Foo.h

@@ -0,0 +1,11 @@
+/*  Foo.h
+  Copyright (c) 1815, Napoleon Bonaparte. All rights reserved.
+*/
+#if !defined(__FOO_H__)
+#define __FOO_H__ 1
+
+#import <FooSub/FooSub.h>
+
+void removedFunction(void);
+
+#endif /* ! __FOO_H__ */

test/api-digester/Inputs/mock-sdk-baseline.sdk/System/Library/Frameworks/Foo.framework/module.map

@@ -0,0 +1,9 @@
+framework module Foo {
+  umbrella header "Foo.h"
+  export *
+  framework module FooSub {
+    umbrella header "FooSub.h"
+    export *
+  }
+}
+

test/api-digester/Inputs/mock-sdk-modules.txt

@@ -0,0 +1 @@
+Foo

test/api-digester/Inputs/mock-sdk.sdk/System/Library/Frameworks/Foo.framework/Frameworks/FooSub.framework/Headers/FooSub.h

@@ -0,0 +1,15 @@
+#if !defined(__FOOSUB_H__)
+#define __FOOSUB_H__ 1
+
+int fooSubFunc1(int a);
+
+enum FooSubEnum1 {
+  FooSubEnum1X,
+  FooSubEnum1Y
+};
+
+enum {
+  FooSubUnnamedEnumeratorA1
+};
+
+#endif /* ! __FOOSUB_H__ */

test/api-digester/Inputs/mock-sdk.sdk/System/Library/Frameworks/Foo.framework/Headers/Foo.h

@@ -0,0 +1,9 @@
+/*  Foo.h
+  Copyright (c) 1815, Napoleon Bonaparte. All rights reserved.
+*/
+#if !defined(__FOO_H__)
+#define __FOO_H__ 1
+
+#import <FooSub/FooSub.h>
+
+#endif /* ! __FOO_H__ */

test/api-digester/Inputs/mock-sdk.sdk/System/Library/Frameworks/Foo.framework/module.map

@@ -0,0 +1,9 @@
+framework module Foo {
+  umbrella header "Foo.h"
+  export *
+  framework module FooSub {
+    umbrella header "FooSub.h"
+    export *
+  }
+}
+

test/api-digester/Outputs/mock-sdk-api.txt

@@ -0,0 +1 @@
+Foo(Foo.h): Func removedFunction() has been removed

test/api-digester/compare-dump-abi-parsable-interface.swift

@@ -5,7 +5,7 @@
 
 // RUN: %target-swift-frontend -typecheck -emit-parseable-module-interface-path %t.mod1/cake.swiftinterface %S/Inputs/cake_baseline/cake.swift -I %S/Inputs/APINotesLeft %clang-importer-sdk-nosource -parse-as-library -enable-library-evolution -disable-objc-attr-requires-foundation-module -module-cache-path %t.module-cache
 // RUN: %target-swift-frontend -typecheck -emit-parseable-module-interface-path %t.mod2/cake.swiftinterface %S/Inputs/cake_current/cake.swift -I %S/Inputs/APINotesRight %clang-importer-sdk-nosource -parse-as-library -enable-library-evolution -disable-objc-attr-requires-foundation-module -module-cache-path %t.module-cache
-// RUN: %api-digester -diagnose-sdk -print-module -module cake -BI %t.mod1 -BI %S/Inputs/APINotesLeft -I %t.mod2 -I %S/Inputs/APINotesRight %clang-importer-sdk-nosource -module-cache-path %t.module-cache -o %t.result -abi
+// RUN: %api-digester -diagnose-sdk -print-module -module cake -BI %t.mod1 -BI %S/Inputs/APINotesLeft -I %t.mod2 -I %S/Inputs/APINotesRight -sdk %clang-importer-sdk-path -bsdk %clang-importer-sdk-path -module-cache-path %t.module-cache -o %t.result -abi
 
 // RUN: %clang -E -P -x c %S/Outputs/Cake-abi.txt -o - | sed '/^\s*$/d' > %t.expected
 // RUN: %clang -E -P -x c %t.result -o - | sed '/^\s*$/d' > %t.result.tmp

test/api-digester/compare-dump-parsable-interface.swift

@@ -5,7 +5,7 @@
 
 // RUN: %target-swift-frontend -typecheck -emit-parseable-module-interface-path %t.mod1/cake.swiftinterface %S/Inputs/cake_baseline/cake.swift -I %S/Inputs/APINotesLeft %clang-importer-sdk-nosource -parse-as-library -enable-library-evolution -disable-objc-attr-requires-foundation-module -module-cache-path %t.module-cache
 // RUN: %target-swift-frontend -typecheck -emit-parseable-module-interface-path %t.mod2/cake.swiftinterface %S/Inputs/cake_current/cake.swift -I %S/Inputs/APINotesRight %clang-importer-sdk-nosource -parse-as-library -enable-library-evolution -disable-objc-attr-requires-foundation-module -module-cache-path %t.module-cache
-// RUN: %api-digester -diagnose-sdk -print-module -module cake -BI %t.mod1 -BI %S/Inputs/APINotesLeft -I %t.mod2 -I %S/Inputs/APINotesRight %clang-importer-sdk-nosource -module-cache-path %t.module-cache -o %t.result
+// RUN: %api-digester -diagnose-sdk -print-module -module cake -BI %t.mod1 -BI %S/Inputs/APINotesLeft -I %t.mod2 -I %S/Inputs/APINotesRight -sdk %clang-importer-sdk-path -bsdk %clang-importer-sdk-path -module-cache-path %t.module-cache -o %t.result
 
 // RUN: %clang -E -P -x c %S/Outputs/Cake.txt -o - | sed '/^\s*$/d' > %t.expected
 // RUN: %clang -E -P -x c %t.result -o - | sed '/^\s*$/d' > %t.result.tmp

test/api-digester/compare-two-sdks.swift

@@ -0,0 +1,10 @@
+// RUN: %empty-directory(%t.mod1)
+// RUN: %empty-directory(%t.mod2)
+// RUN: %empty-directory(%t.sdk)
+// RUN: %empty-directory(%t.module-cache)
+
+// RUN: %api-digester -diagnose-sdk -print-module -module-list-file %S/Inputs/mock-sdk-modules.txt -sdk %S/Inputs/mock-sdk.sdk -bsdk %S/Inputs/mock-sdk-baseline.sdk -module-cache-path %t.module-cache -o %t.result 
+
+// RUN: %clang -E -P -x c %S/Outputs/mock-sdk-api.txt -o - | sed '/^\s*$/d' > %t.expected
+// RUN: %clang -E -P -x c %t.result -o - | sed '/^\s*$/d' > %t.result.tmp
+// RUN: diff -u %t.expected %t.result.tmp

tools/swift-api-digester/swift-api-digester.cpp

@@ -81,6 +81,10 @@ static llvm::cl::opt<std::string>
 SDK("sdk", llvm::cl::desc("path to the SDK to build against"),
     llvm::cl::cat(Category));
 
+static llvm::cl::opt<std::string>
+BaselineSDK("bsdk", llvm::cl::desc("path to the baseline SDK to import frameworks"),
+    llvm::cl::cat(Category));
+
 static llvm::cl::opt<std::string>
 Triple("target", llvm::cl::desc("target triple"),
        llvm::cl::cat(Category));
@@ -98,6 +102,10 @@ static llvm::cl::list<std::string>
 FrameworkPaths("F", llvm::cl::desc("add a directory to the framework search path"),
                llvm::cl::cat(Category));
 
+static llvm::cl::list<std::string>
+BaselineFrameworkPaths("BF", llvm::cl::desc("add a directory to the baseline framework search path"),
+                       llvm::cl::cat(Category));
+
 static llvm::cl::list<std::string>
 BaselineModuleInputPaths("BI", llvm::cl::desc("add a module for baseline input"),
                          llvm::cl::cat(Category));
@@ -2084,6 +2092,10 @@ static int diagnoseModuleChange(SDKContext &Ctx, SDKNodeRoot *LeftModule,
   assert(LeftModule);
   assert(RightModule);
   llvm::raw_ostream *OS = &llvm::errs();
+  if (!LeftModule || !RightModule) {
+    *OS << "Cannot diagnose null SDKNodeRoot";
+    exit(1);
+  }
   std::unique_ptr<llvm::raw_ostream> FileOS;
   if (!OutputPath.empty()) {
     std::error_code EC;
@@ -2270,13 +2282,14 @@ static int readFileLineByLine(StringRef Path, llvm::StringSet<> &Lines) {
 // without being given the address of a function in the main executable).
 void anchorForGetMainExecutable() {}
 
-static int prepareForDump(const char *Main,
-                          CompilerInvocation &InitInvok,
-                          llvm::StringSet<> &Modules,
-                          bool IsBaseline = false) {
-  InitInvok.setMainExecutablePath(fs::getMainExecutable(Main,
-    reinterpret_cast<void *>(&anchorForGetMainExecutable)));
-  InitInvok.setModuleName("swift_ide_test");
+static void setSDKPath(CompilerInvocation &InitInvok, bool IsBaseline) {
+  if (IsBaseline) {
+    // Set baseline SDK
+    if (!options::BaselineSDK.empty()) {
+      InitInvok.setSDKPath(options::BaselineSDK);
+    }
+  } else {
+    // Set current SDK
     if (!options::SDK.empty()) {
       InitInvok.setSDKPath(options::SDK);
     } else if (const char *SDKROOT = getenv("SDKROOT")) {
@@ -2284,8 +2297,19 @@ static int prepareForDump(const char *Main,
     } else {
       llvm::errs() << "Provide '-sdk <path>' option or run with 'xcrun -sdk <..>\
       swift-api-digester'\n";
-    return 1;
+      exit(1);
     }
+  }
+}
+
+static int prepareForDump(const char *Main,
+                          CompilerInvocation &InitInvok,
+                          llvm::StringSet<> &Modules,
+                          bool IsBaseline = false) {
+  InitInvok.setMainExecutablePath(fs::getMainExecutable(Main,
+    reinterpret_cast<void *>(&anchorForGetMainExecutable)));
+  InitInvok.setModuleName("swift_ide_test");
+  setSDKPath(InitInvok, IsBaseline);
 
   if (!options::Triple.empty())
     InitInvok.setTargetTriple(options::Triple);
@@ -2308,7 +2332,7 @@ static int prepareForDump(const char *Main,
     }
     if (!isValid) {
       llvm::errs() << "Unsupported Swift Version.\n";
-      return 1;
+      exit(1);
     }
   }
 
@@ -2316,28 +2340,31 @@ static int prepareForDump(const char *Main,
     InitInvok.setRuntimeResourcePath(options::ResourceDir);
   }
   std::vector<SearchPathOptions::FrameworkSearchPath> FramePaths;
-  for (const auto &path : options::FrameworkPaths) {
-    FramePaths.push_back({path, /*isSystem=*/false});
-  }
   for (const auto &path : options::CCSystemFrameworkPaths) {
     FramePaths.push_back({path, /*isSystem=*/true});
   }
-  InitInvok.setFrameworkSearchPaths(FramePaths);
   if (IsBaseline) {
+    for (const auto &path : options::BaselineFrameworkPaths) {
+      FramePaths.push_back({path, /*isSystem=*/false});
+    }
     InitInvok.setImportSearchPaths(options::BaselineModuleInputPaths);
   } else {
+    for (const auto &path : options::FrameworkPaths) {
+      FramePaths.push_back({path, /*isSystem=*/false});
+    }
     InitInvok.setImportSearchPaths(options::ModuleInputPaths);
   }
+  InitInvok.setFrameworkSearchPaths(FramePaths);
   if (!options::ModuleList.empty()) {
     if (readFileLineByLine(options::ModuleList, Modules))
-      return 1;
+      exit(1);
   }
   for (auto M : options::ModuleNames) {
     Modules.insert(M);
   }
   if (Modules.empty()) {
     llvm::errs() << "Need to specify -include-all or -module <name>\n";
-    return 1;
+    exit(1);
   }
   return 0;
 }
@@ -2406,6 +2433,11 @@ static SDKNodeRoot *getSDKRoot(const char *Main, SDKContext &Ctx,
   return getSDKNodeRoot(Ctx, Invok, Modules, Opts);
 }
 
+static bool hasBaselineInput() {
+  return !options::BaselineModuleInputPaths.empty() ||
+    !options::BaselineFrameworkPaths.empty() || !options::BaselineSDK.empty();
+}
+
 int main(int argc, char *argv[]) {
   PROGRAM_START(argc, argv);
   INITIALIZE_LLVM();
@@ -2428,7 +2460,7 @@ int main(int argc, char *argv[]) {
   case ActionType::MigratorGen:
   case ActionType::DiagnoseSDKs: {
     bool CompareJson = options::SDKJsonPaths.size() == 2;
-    if (!CompareJson && options::BaselineModuleInputPaths.empty()) {
+    if (!CompareJson && !hasBaselineInput()) {
       llvm::errs() << "Only two SDK versions can be compared\n";
       llvm::cl::PrintHelpMessage();
       return 1;