[unittests] Extend Sema testing fixture to load stdlib (+ shims)

Setup module importers, load stdlib, establish separate testing
module and load a single main file there which imports standard
library.

Author: xedin

unittests/Sema/CMakeLists.txt

@@ -4,4 +4,9 @@ add_swift_unittest(swiftSemaTests
 
 target_link_libraries(swiftSemaTests
   PRIVATE
-    swiftSema)
+    swiftAST
+    swiftSema
+    swiftSerialization)
+
+target_compile_definitions(swiftSemaTests PRIVATE
+  SWIFTLIB_DIR=\"${SWIFTLIB_DIR}\")

unittests/Sema/SemaFixture.cpp

@@ -13,24 +13,42 @@
 #include "SemaFixture.h"
 #include "swift/AST/Module.h"
 #include "swift/AST/ParseRequests.h"
-#include "swift/Strings.h"
+#include "swift/AST/SourceFile.h"
+#include "swift/Basic/LLVMInitialize.h"
+#include "swift/ClangImporter/ClangImporter.h"
+#include "swift/Serialization/SerializedModuleLoader.h"
 #include "swift/Subsystems.h"
 
 using namespace swift;
 using namespace swift::unittest;
 
+using ModuleDecl = SourceFile::ImportedModuleDesc;
+
 SemaTest::SemaTest()
     : Context(*ASTContext::get(LangOpts, TypeCheckerOpts, SearchPathOpts,
                                ClangImporterOpts, SourceMgr, Diags)) {
+  INITIALIZE_LLVM();
+
   registerParseRequestFunctions(Context.evaluator);
   registerTypeCheckerRequestFunctions(Context.evaluator);
-  auto stdlibID = Context.getIdentifier(STDLIB_NAME);
-  auto *module = ModuleDecl::create(stdlibID, Context);
-  Context.addLoadedModule(module);
 
-  FileForLookups = new (Context) SourceFile(*module, SourceFileKind::Library,
-                                            /*buffer*/ None);
-  module->addFile(*FileForLookups);
+  Context.addModuleLoader(ImplicitSerializedModuleLoader::create(Context));
+  Context.addModuleLoader(ClangImporter::create(Context), /*isClang=*/true);
+
+  auto *stdlib = Context.getStdlibModule(/*loadIfAbsent=*/true);
+  assert(stdlib && "Failed to load standard library");
+
+  auto *module =
+      ModuleDecl::create(Context.getIdentifier("SemaTests"), Context);
+
+  MainFile = new (Context) SourceFile(*module, SourceFileKind::Main,
+                                      /*buffer=*/None);
+
+  auto stdlibImport =
+      ModuleDesc({ImportPath::Access(), stdlib}, /*options=*/{});
+
+  MainFile->setImports(stdlibImport);
+  module->addFile(*MainFile);
 
   DC = module;
 }

unittests/Sema/SemaFixture.h

@@ -15,9 +15,14 @@
 #include "swift/AST/Module.h"
 #include "swift/AST/SourceFile.h"
 #include "swift/Basic/LangOptions.h"
+#include "swift/Basic/Platform.h"
 #include "swift/Basic/SourceManager.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Host.h"
+#include "llvm/Support/Path.h"
 #include "gtest/gtest.h"
+#include <string>
 
 namespace swift {
 namespace unittest {
@@ -33,12 +38,20 @@ class SemaTestBase : public ::testing::Test {
 
   SemaTestBase() : Diags(SourceMgr) {
     LangOpts.Target = llvm::Triple(llvm::sys::getProcessTriple());
+
+    llvm::SmallString<128> libDir(SWIFTLIB_DIR);
+    llvm::sys::path::append(libDir, getPlatformNameForTriple(LangOpts.Target));
+
+    SearchPathOpts.RuntimeResourcePath = SWIFTLIB_DIR;
+    SearchPathOpts.RuntimeLibraryPaths.push_back(std::string(libDir.str()));
+    SearchPathOpts.RuntimeLibraryImportPaths.push_back(
+        std::string(libDir.str()));
   }
 };
 
 /// Owns an ASTContext and the associated types.
 class SemaTest : public SemaTestBase {
-  SourceFile *FileForLookups;
+  SourceFile *MainFile;
 
 public:
   ASTContext &Context;