Add libSwiftScan entry-points to query supported compiler flags and compiler features

For the client library (`libSwiftDriver`), this is critical for multiplexing library instances, and for compatibility with different versions of `libSwiftDrvier`.

Resolves rdar://73631930

Author: artemcm

include/swift-c/DependencyScan/DependencyScan.h

@@ -27,7 +27,7 @@
 /// SWIFTSCAN_VERSION_MINOR should increase when there are API additions.
 /// SWIFTSCAN_VERSION_MAJOR is intended for "major" source/ABI breaking changes.
 #define SWIFTSCAN_VERSION_MAJOR 0
-#define SWIFTSCAN_VERSION_MINOR 1
+#define SWIFTSCAN_VERSION_MINOR 2
 
 SWIFTSCAN_BEGIN_DECLS
 
@@ -292,6 +292,13 @@ swiftscan_batch_scan_result_dispose(swiftscan_batch_scan_result_t *result);
 SWIFTSCAN_PUBLIC void
 swiftscan_scan_invocation_dispose(swiftscan_scan_invocation_t invocation);
 
+//=== Feature-Query Functions -----------------------------------------===//
+SWIFTSCAN_PUBLIC swiftscan_string_set_t *
+swiftscan_compiler_supported_arguments_query();
+
+SWIFTSCAN_PUBLIC swiftscan_string_set_t *
+swiftscan_compiler_supported_features_query();
+
 //=== Scanner Functions ---------------------------------------------------===//
 
 /// Container of the configuration state and shared cache for dependency

tools/libSwiftScan/libSwiftScan.cpp

@@ -18,6 +18,7 @@
 #include "swift/DependencyScan/DependencyScanImpl.h"
 #include "swift/DependencyScan/DependencyScanningTool.h"
 #include "swift/DependencyScan/StringUtils.h"
+#include "swift/Option/Options.h"
 
 using namespace swift::dependencies;
 
@@ -461,3 +462,34 @@ void swiftscan_scan_invocation_dispose(swiftscan_scan_invocation_t invocation) {
   swiftscan_string_set_dispose(invocation->argv);
   delete invocation;
 }
+
+//=== Feature-Query Functions -----------------------------------------===//
+static void addFrontendFlagOption(llvm::opt::OptTable &table,
+                                  swift::options::ID id,
+                                  std::vector<std::string> &frontendOptions) {
+  if (table.getOption(id).hasFlag(swift::options::FrontendOption)) {
+    auto name = table.getOptionName(id);
+    if (strlen(name) > 0) {
+      frontendOptions.push_back(std::string(name));
+    }
+  }
+}
+
+// use" swiftscan_string_set_t *create_set(const std::vector<std::string> &strings) {
+swiftscan_string_set_t *
+swiftscan_compiler_supported_arguments_query() {
+  std::unique_ptr<llvm::opt::OptTable> table = swift::createSwiftOptTable();
+  std::vector<std::string> frontendFlags;
+#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \
+               HELPTEXT, METAVAR, VALUES)                                      \
+  addFrontendFlagOption(*table, swift::options::OPT_##ID, frontendFlags);
+#include "swift/Option/Options.inc"
+#undef OPTION
+  return create_set(frontendFlags);
+}
+
+swiftscan_string_set_t *
+swiftscan_compiler_supported_features_query() {
+  // TODO: We are yet to figure out how "Features" will be organized.
+  return nullptr;
+}

tools/libSwiftScan/libSwiftScan.exports

@@ -51,3 +51,5 @@ swiftscan_dependency_graph_dispose
 swiftscan_batch_scan_result_dispose
 swiftscan_import_set_dispose
 swiftscan_scanner_dispose
+swiftscan_compiler_supported_arguments_query
+swiftscan_compiler_supported_features_query

unittests/DependencyScan/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_swift_unittest(swiftScanTests
   ScanFixture.cpp
+  Features.cpp
   ModuleDeps.cpp)
 
 target_link_libraries(swiftScanTests

unittests/DependencyScan/Features.cpp

@@ -0,0 +1,67 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#include "ScanFixture.h"
+#include "swift-c/DependencyScan/DependencyScan.h"
+#include "swift/Basic/LLVM.h"
+#include "swift/Option/Options.h"
+#include "llvm/ADT/StringRef.h"
+#include <vector>
+#include <unordered_set>
+#include "gtest/gtest.h"
+
+using namespace swift;
+using namespace swift::unittest;
+
+static void
+testHasOption(llvm::opt::OptTable &table, options::ID id,
+              const std::unordered_set<std::string> &optionSet) {
+  if (table.getOption(id).hasFlag(swift::options::FrontendOption)) {
+    auto name = table.getOptionName(id);
+    if (strlen(name) > 0) {
+      auto nameStr = std::string(name);
+      bool setContainsOption = optionSet.find(nameStr) != optionSet.end();
+      EXPECT_EQ(setContainsOption, true);
+    }
+  }
+}
+
+TEST_F(ScanTest, TestHasArgumentQuery) {
+  std::unique_ptr<llvm::opt::OptTable> table = swift::createSwiftOptTable();
+  auto supported_args_set = swiftscan_compiler_supported_arguments_query();
+  std::unordered_set<std::string> optionSet;
+  for (size_t i = 0; i < supported_args_set->count; ++i) {
+    swiftscan_string_ref_t option = supported_args_set->strings[i];
+    const char* data = static_cast<const char*>(option.data);
+    optionSet.insert(std::string(data, option.length));
+  }
+#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \
+               HELPTEXT, METAVAR, VALUES)                                      \
+  testHasOption(*table, swift::options::OPT_##ID, optionSet);
+#include "swift/Option/Options.inc"
+#undef OPTION
+}
+
+TEST_F(ScanTest, TestDoesNotHaveArgumentQuery) {
+  auto supported_args_set = swiftscan_compiler_supported_arguments_query();
+  std::unordered_set<std::string> optionSet;
+  for (size_t i = 0; i < supported_args_set->count; ++i) {
+    swiftscan_string_ref_t option = supported_args_set->strings[i];
+    const char* data = static_cast<const char*>(option.data);
+    optionSet.insert(std::string(data, option.length));
+  }
+  bool hasOption;
+  hasOption = optionSet.find("-clearly-not-a-compiler-flag") != optionSet.end();
+  EXPECT_EQ(hasOption, false);
+  hasOption = optionSet.find("-emit-modul") != optionSet.end();
+  EXPECT_EQ(hasOption, false);
+}

unittests/DependencyScan/ModuleDeps.cpp

@@ -56,7 +56,6 @@ TEST_F(ScanTest, TestModuleDeps) {
   // Create test input file
   std::string TestPathStr = createFilename(tempDir, "foo.swift");
   ASSERT_FALSE(emitFileWithContents(tempDir, "foo.swift", "import A\n"));
-  llvm::dbgs() << "Input File: " << TestPathStr << "\n";
 
   // Create includes
   std::string IncludeDirPath = createFilename(tempDir, "include");
@@ -172,10 +171,8 @@ export *\n\
   }
 
   std::vector<const char*> Command;
-  llvm::dbgs() << "Compiler Command: \n";
   for (auto &command : CommandStrArr) {
     Command.push_back(command.c_str());
-    llvm::dbgs() << command.c_str() << "\n";
   }
   auto DependenciesOrErr = ScannerTool.getDependencies(Command, {});
   ASSERT_FALSE(DependenciesOrErr.getError());