[ASTImporter] Refactor ASTImporter to support custom downstream tests

Summary:
The purpose of this change is to do a small refactoring of code in
ASTImporterTest.cpp by moving it to ASTImporterFixtures.h in order to
support tests of downstream custom types and minimize the "living
downstream burden" of frequent integrations from community to a
downstream repo that implements custom AST import tests.

Reviewers: martong, a.sidorin, shafik

Reviewed By: martong

Subscribers: balazske, dkrupp, bjope, rnkovacs, teemperor, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83970

clang/unittests/AST/ASTImporterFixtures.h

@@ -24,6 +24,7 @@
 #include "llvm/Support/ErrorHandling.h"
 
 #include "DeclMatcher.h"
+#include "MatchVerifier.h"
 
 #include <sstream>
 
@@ -202,6 +203,229 @@ class ASTImporterOptionSpecificTestBase
   std::vector<std::string> getExtraArgs() const override { return GetParam(); }
 };
 
+// Base class for those tests which use the family of `testImport` functions.
+class TestImportBase
+    : public CompilerOptionSpecificTest,
+      public ::testing::WithParamInterface<std::vector<std::string>> {
+
+  template <typename NodeType>
+  llvm::Expected<NodeType> importNode(ASTUnit *From, ASTUnit *To,
+                                      ASTImporter &Importer, NodeType Node) {
+    ASTContext &ToCtx = To->getASTContext();
+
+    // Add 'From' file to virtual file system so importer can 'find' it
+    // while importing SourceLocations. It is safe to add same file multiple
+    // times - it just isn't replaced.
+    StringRef FromFileName = From->getMainFileName();
+    createVirtualFileIfNeeded(To, FromFileName,
+                              From->getBufferForFile(FromFileName));
+
+    auto Imported = Importer.Import(Node);
+
+    if (Imported) {
+      // This should dump source locations and assert if some source locations
+      // were not imported.
+      SmallString<1024> ImportChecker;
+      llvm::raw_svector_ostream ToNothing(ImportChecker);
+      ToCtx.getTranslationUnitDecl()->print(ToNothing);
+
+      // This traverses the AST to catch certain bugs like poorly or not
+      // implemented subtrees.
+      (*Imported)->dump(ToNothing);
+    }
+
+    return Imported;
+  }
+
+  template <typename NodeType>
+  testing::AssertionResult
+  testImport(const std::string &FromCode,
+             const std::vector<std::string> &FromArgs,
+             const std::string &ToCode, const std::vector<std::string> &ToArgs,
+             MatchVerifier<NodeType> &Verifier,
+             const internal::BindableMatcher<NodeType> &SearchMatcher,
+             const internal::BindableMatcher<NodeType> &VerificationMatcher) {
+    const char *const InputFileName = "input.cc";
+    const char *const OutputFileName = "output.cc";
+
+    std::unique_ptr<ASTUnit> FromAST = tooling::buildASTFromCodeWithArgs(
+                                 FromCode, FromArgs, InputFileName),
+                             ToAST = tooling::buildASTFromCodeWithArgs(
+                                 ToCode, ToArgs, OutputFileName);
+
+    ASTContext &FromCtx = FromAST->getASTContext(),
+               &ToCtx = ToAST->getASTContext();
+
+    ASTImporter Importer(ToCtx, ToAST->getFileManager(), FromCtx,
+                         FromAST->getFileManager(), false);
+
+    auto FoundNodes = match(SearchMatcher, FromCtx);
+    if (FoundNodes.size() != 1)
+      return testing::AssertionFailure()
+             << "Multiple potential nodes were found!";
+
+    auto ToImport = selectFirst<NodeType>(DeclToImportID, FoundNodes);
+    if (!ToImport)
+      return testing::AssertionFailure() << "Node type mismatch!";
+
+    // Sanity check: the node being imported should match in the same way as
+    // the result node.
+    internal::BindableMatcher<NodeType> WrapperMatcher(VerificationMatcher);
+    EXPECT_TRUE(Verifier.match(ToImport, WrapperMatcher));
+
+    auto Imported = importNode(FromAST.get(), ToAST.get(), Importer, ToImport);
+    if (!Imported) {
+      std::string ErrorText;
+      handleAllErrors(
+          Imported.takeError(),
+          [&ErrorText](const ImportError &Err) { ErrorText = Err.message(); });
+      return testing::AssertionFailure()
+             << "Import failed, error: \"" << ErrorText << "\"!";
+    }
+
+    return Verifier.match(*Imported, WrapperMatcher);
+  }
+
+  template <typename NodeType>
+  testing::AssertionResult
+  testImport(const std::string &FromCode,
+             const std::vector<std::string> &FromArgs,
+             const std::string &ToCode, const std::vector<std::string> &ToArgs,
+             MatchVerifier<NodeType> &Verifier,
+             const internal::BindableMatcher<NodeType> &VerificationMatcher) {
+    return testImport(
+        FromCode, FromArgs, ToCode, ToArgs, Verifier,
+        translationUnitDecl(
+            has(namedDecl(hasName(DeclToImportID)).bind(DeclToImportID))),
+        VerificationMatcher);
+  }
+
+protected:
+  std::vector<std::string> getExtraArgs() const override { return GetParam(); }
+
+public:
+  /// Test how AST node named "declToImport" located in the translation unit
+  /// of "FromCode" virtual file is imported to "ToCode" virtual file.
+  /// The verification is done by running AMatcher over the imported node.
+  template <typename NodeType, typename MatcherType>
+  void testImport(const std::string &FromCode, TestLanguage FromLang,
+                  const std::string &ToCode, TestLanguage ToLang,
+                  MatchVerifier<NodeType> &Verifier,
+                  const MatcherType &AMatcher) {
+    std::vector<std::string> FromArgs = getCommandLineArgsForLanguage(FromLang);
+    std::vector<std::string> ToArgs = getCommandLineArgsForLanguage(ToLang);
+    EXPECT_TRUE(
+        testImport(FromCode, FromArgs, ToCode, ToArgs, Verifier, AMatcher));
+  }
+
+  struct ImportAction {
+    StringRef FromFilename;
+    StringRef ToFilename;
+    // FIXME: Generalize this to support other node kinds.
+    internal::BindableMatcher<Decl> ImportPredicate;
+
+    ImportAction(StringRef FromFilename, StringRef ToFilename,
+                 DeclarationMatcher ImportPredicate)
+        : FromFilename(FromFilename), ToFilename(ToFilename),
+          ImportPredicate(ImportPredicate) {}
+
+    ImportAction(StringRef FromFilename, StringRef ToFilename,
+                 const std::string &DeclName)
+        : FromFilename(FromFilename), ToFilename(ToFilename),
+          ImportPredicate(namedDecl(hasName(DeclName))) {}
+  };
+
+  using SingleASTUnit = std::unique_ptr<ASTUnit>;
+  using AllASTUnits = llvm::StringMap<SingleASTUnit>;
+
+  struct CodeEntry {
+    std::string CodeSample;
+    TestLanguage Lang;
+  };
+
+  using CodeFiles = llvm::StringMap<CodeEntry>;
+
+  /// Builds an ASTUnit for one potential compile options set.
+  SingleASTUnit createASTUnit(StringRef FileName, const CodeEntry &CE) const {
+    std::vector<std::string> Args = getCommandLineArgsForLanguage(CE.Lang);
+    auto AST = tooling::buildASTFromCodeWithArgs(CE.CodeSample, Args, FileName);
+    EXPECT_TRUE(AST.get());
+    return AST;
+  }
+
+  /// Test an arbitrary sequence of imports for a set of given in-memory files.
+  /// The verification is done by running VerificationMatcher against a
+  /// specified AST node inside of one of given files.
+  /// \param CodeSamples Map whose key is the file name and the value is the
+  /// file content.
+  /// \param ImportActions Sequence of imports. Each import in sequence
+  /// specifies "from file" and "to file" and a matcher that is used for
+  /// searching a declaration for import in "from file".
+  /// \param FileForFinalCheck Name of virtual file for which the final check is
+  /// applied.
+  /// \param FinalSelectPredicate Matcher that specifies the AST node in the
+  /// FileForFinalCheck for which the verification will be done.
+  /// \param VerificationMatcher Matcher that will be used for verification
+  /// after all imports in sequence are done.
+  void testImportSequence(const CodeFiles &CodeSamples,
+                          const std::vector<ImportAction> &ImportActions,
+                          StringRef FileForFinalCheck,
+                          internal::BindableMatcher<Decl> FinalSelectPredicate,
+                          internal::BindableMatcher<Decl> VerificationMatcher) {
+    AllASTUnits AllASTs;
+    using ImporterKey = std::pair<const ASTUnit *, const ASTUnit *>;
+    llvm::DenseMap<ImporterKey, std::unique_ptr<ASTImporter>> Importers;
+
+    auto GenASTsIfNeeded = [this, &AllASTs, &CodeSamples](StringRef Filename) {
+      if (!AllASTs.count(Filename)) {
+        auto Found = CodeSamples.find(Filename);
+        assert(Found != CodeSamples.end() && "Wrong file for import!");
+        AllASTs[Filename] = createASTUnit(Filename, Found->getValue());
+      }
+    };
+
+    for (const ImportAction &Action : ImportActions) {
+      StringRef FromFile = Action.FromFilename, ToFile = Action.ToFilename;
+      GenASTsIfNeeded(FromFile);
+      GenASTsIfNeeded(ToFile);
+
+      ASTUnit *From = AllASTs[FromFile].get();
+      ASTUnit *To = AllASTs[ToFile].get();
+
+      // Create a new importer if needed.
+      std::unique_ptr<ASTImporter> &ImporterRef = Importers[{From, To}];
+      if (!ImporterRef)
+        ImporterRef.reset(new ASTImporter(
+            To->getASTContext(), To->getFileManager(), From->getASTContext(),
+            From->getFileManager(), false));
+
+      // Find the declaration and import it.
+      auto FoundDecl = match(Action.ImportPredicate.bind(DeclToImportID),
+                             From->getASTContext());
+      EXPECT_TRUE(FoundDecl.size() == 1);
+      const Decl *ToImport = selectFirst<Decl>(DeclToImportID, FoundDecl);
+      auto Imported = importNode(From, To, *ImporterRef, ToImport);
+      EXPECT_TRUE(static_cast<bool>(Imported));
+      if (!Imported)
+        llvm::consumeError(Imported.takeError());
+    }
+
+    // Find the declaration and import it.
+    auto FoundDecl = match(FinalSelectPredicate.bind(DeclToVerifyID),
+                           AllASTs[FileForFinalCheck]->getASTContext());
+    EXPECT_TRUE(FoundDecl.size() == 1);
+    const Decl *ToVerify = selectFirst<Decl>(DeclToVerifyID, FoundDecl);
+    MatchVerifier<Decl> Verifier;
+    EXPECT_TRUE(Verifier.match(
+        ToVerify, internal::BindableMatcher<Decl>(VerificationMatcher)));
+  }
+};
+
+template <typename T> RecordDecl *getRecordDecl(T *D) {
+  auto *ET = cast<ElaboratedType>(D->getType().getTypePtr());
+  return cast<RecordType>(ET->getNamedType().getTypePtr())->getDecl();
+}
+
 template <class T>
 ::testing::AssertionResult isSuccess(llvm::Expected<T> &ValOrErr) {
   if (ValOrErr)