[clang][ASTImporter] Add support for importing CXXFoldExpr.

[balazske]

There is a related bug report:
https://bugs.llvm.org/show_bug.cgi?id=48004

[shafik]

clang/unittests/AST/ASTImporterTest.cpp

655

Is it possible to check that we imported four fold expressions and maybe also check the operator of each one?

[balazske]

Improved test.

[balazske]

clang/unittests/AST/ASTImporterTest.cpp

655

Added more exact checks.

[martong]

Looks good to me! Thanks!

clang/lib/AST/ASTImporter.cpp

8019

Could you please address the Lint messages? Making it auto * has sense.

clang/unittests/AST/ASTImporterTest.cpp

642–649

Perhaps we could add this directly to ASTMatchers.h ?

[balazske]

Removed use of auto.

[martong]

Thanks for the update!

[shafik]

LGTM, thank you for expanding the test!

[balazske]

clang/unittests/AST/ASTImporterTest.cpp

642–649

It would make sense, CXXFoldExpr could be needed by other users.

[balazske]

clang/unittests/AST/ASTImporterTest.cpp

642–649

But I plan to commit this as is, there are other matchers in this file that could be put into ASTMatchers.h, it should be checked why these are not there and which ones to put into the header.

clang/lib/AST/ASTImporter.cpp

public:
     ExpectedStmt VisitCXXInheritedCtorInitExpr(CXXInheritedCtorInitExpr *E);
     ExpectedStmt VisitArrayInitLoopExpr(ArrayInitLoopExpr *E);
     ExpectedStmt VisitArrayInitIndexExpr(ArrayInitIndexExpr *E);
     ExpectedStmt VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E);
     ExpectedStmt VisitCXXNamedCastExpr(CXXNamedCastExpr *E);
     ExpectedStmt VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E);
     ExpectedStmt VisitTypeTraitExpr(TypeTraitExpr *E);
     ExpectedStmt VisitCXXTypeidExpr(CXXTypeidExpr *E);
+    ExpectedStmt VisitCXXFoldExpr(CXXFoldExpr *E);
 
     template<typename IIter, typename OIter>
     Error ImportArrayChecked(IIter Ibegin, IIter Iend, OIter Obegin) {
       using ItemT = std::remove_reference_t<decltype(*Obegin)>;
       for (; Ibegin != Iend; ++Ibegin, ++Obegin) {
         Expected<ItemT> ToOrErr = import(*Ibegin);
         if (!ToOrErr)
           return ToOrErr.takeError();
ExpectedStmt ASTNodeImporter::VisitCXXTypeidExpr(CXXTypeidExpr *E) {
   ExpectedExpr ToExprOperandOrErr = import(E->getExprOperand());
   if (!ToExprOperandOrErr)
     return ToExprOperandOrErr.takeError();
 
   return new (Importer.getToContext()) CXXTypeidExpr(
       *ToTypeOrErr, *ToExprOperandOrErr, *ToSourceRangeOrErr);
 }
 
+ExpectedStmt ASTNodeImporter::VisitCXXFoldExpr(CXXFoldExpr *E) {
+  Error Err = Error::success();
+
+  QualType ToType = importChecked(Err, E->getType());
+  UnresolvedLookupExpr *ToCallee = importChecked(Err, E->getCallee());
+  SourceLocation ToLParenLoc = importChecked(Err, E->getLParenLoc());
+  Expr *ToLHS = importChecked(Err, E->getLHS());
+  SourceLocation ToEllipsisLoc = importChecked(Err, E->getEllipsisLoc());
+  Expr *ToRHS = importChecked(Err, E->getRHS());
+  SourceLocation ToRParenLoc = importChecked(Err, E->getRParenLoc());
+
+  if (Err)
+    return std::move(Err);
+
+  return new (Importer.getToContext())
+      CXXFoldExpr(ToType, ToCallee, ToLParenLoc, ToLHS, E->getOperator(),
+                  ToEllipsisLoc, ToRHS, ToRParenLoc, E->getNumExpansions());
+}
+
 Error ASTNodeImporter::ImportOverriddenMethods(CXXMethodDecl *ToMethod,
                                                CXXMethodDecl *FromMethod) {
   Error ImportErrors = Error::success();
   for (auto *FromOverriddenMethod : FromMethod->overridden_methods()) {
     if (auto ImportedOrErr = import(FromOverriddenMethod))
       ToMethod->getCanonicalDecl()->addOverriddenMethod(cast<CXXMethodDecl>(
           (*ImportedOrErr)->getCanonicalDecl()));
     else

clang/unittests/AST/ASTImporterTest.cpp

testImport(
       "  X<Us..., int, double, int, Us...> f;"
       "};"
       "Y<float, int> declToImport;",
       Lang_CXX11, "", Lang_CXX11, Verifier,
       varDecl(hasType(classTemplateSpecializationDecl(has(fieldDecl(hasType(
           hasUnqualifiedDesugaredType(constantArrayType(hasSize(7))))))))));
 }
 
+const internal::VariadicDynCastAllOfMatcher<Stmt, CXXFoldExpr> cxxFoldExpr;
+
+AST_MATCHER_P(CXXFoldExpr, hasOperator, BinaryOperatorKind, Op) {
+  return Node.getOperator() == Op;
+}
+AST_MATCHER(CXXFoldExpr, hasInit) { return Node.getInit(); }
+AST_MATCHER(CXXFoldExpr, isRightFold) { return Node.isRightFold(); }
+AST_MATCHER(CXXFoldExpr, isLeftFold) { return Node.isLeftFold(); }
+
+TEST_P(ImportExpr, ImportCXXFoldExpr) {
+  auto Match1 =
+      cxxFoldExpr(hasOperator(BO_Add), isLeftFold(), unless(hasInit()));
+  auto Match2 = cxxFoldExpr(hasOperator(BO_Sub), isLeftFold(), hasInit());
+  auto Match3 =
+      cxxFoldExpr(hasOperator(BO_Mul), isRightFold(), unless(hasInit()));
+  auto Match4 = cxxFoldExpr(hasOperator(BO_Div), isRightFold(), hasInit());
+
+  MatchVerifier<Decl> Verifier;
+  testImport("template <typename... Ts>"
+             "void declToImport(Ts... args) {"
+             "  const int i1 = (... + args);"
+             "  const int i2 = (1 - ... - args);"
+             "  const int i3 = (args * ...);"
+             "  const int i4 = (args / ... / 1);"
+             "};"
+             "void g() { declToImport(1, 2, 3, 4, 5); }",
+             Lang_CXX17, "", Lang_CXX17, Verifier,
+             functionTemplateDecl(hasDescendant(Match1), hasDescendant(Match2),
+                                  hasDescendant(Match3),
+                                  hasDescendant(Match4)));
+}
+
 /// \brief Matches __builtin_types_compatible_p:
 /// GNU extension to check equivalent types
 /// Given
 /// \code
 ///   __builtin_types_compatible_p(int, int)
 /// \endcode
 //  will generate TypeTraitExpr <...> 'int'
 const internal::VariadicDynCastAllOfMatcher<Stmt, TypeTraitExpr> typeTraitExpr;