[SyntaxTree] Fix crash on functions with default arguments.

[eduucaldas]

Summary

• Do not visit CXXDefaultArgExpr
• To build CallArguments nodes, just go through non-default arguments

[gribozavr2]

Please also add tests for calls to constructors without arguments and calls to implicit constructors 1 argument, as requested in https://reviews.llvm.org/D86700.

[eduucaldas]

Add tests for constructor calls

[gribozavr2]

clang/unittests/Tooling/Syntax/BuildTreeTest.cpp

3931

Please also add tests that use this syntax:

X x1;
X x2(1);
X x3(1, '2');

[eduucaldas]

Test init declarator with default arguments

clang/lib/Tooling/Syntax/BuildTree.cpp

template <class PtrLoc> SourceLocation HandlePointer(PtrLoc T) {
     auto L = Visit(T.getPointeeLoc());
     if (L.isValid())
       return L;
     return T.getLocalSourceRange().getBegin();
   }
 };
 } // namespace
 
+static CallExpr::arg_range dropDefaultArgs(CallExpr::arg_range Args) {
+  auto firstDefaultArg = std::find_if(Args.begin(), Args.end(), [](auto it) {
+    return isa<CXXDefaultArgExpr>(it);
+  });
+  return llvm::make_range(Args.begin(), firstDefaultArg);
+}
+
 static syntax::NodeKind getOperatorNodeKind(const CXXOperatorCallExpr &E) {
   switch (E.getOperator()) {
   // Comparison
   case OO_EqualEqual:
   case OO_ExclaimEqual:
   case OO_Greater:
   case OO_GreaterEqual:
   case OO_Less:
bool WalkUpFromBinaryOperator(BinaryOperator *S) {
     Builder.markChildToken(S->getOperatorLoc(),
                            syntax::NodeRole::OperatorToken);
     Builder.markExprChild(S->getRHS(), syntax::NodeRole::RightHandSide);
     Builder.foldNode(Builder.getExprRange(S),
                      new (allocator()) syntax::BinaryOperatorExpression, S);
     return true;
   }
 
-  syntax::CallArguments *buildCallArguments(CallExpr::arg_range Args) {
+  /// Builds `CallArguments` syntax node from arguments that appear in source
+  /// code, i.e. not default arguments.
+  syntax::CallArguments *
+  buildCallArguments(CallExpr::arg_range ArgsAndDefaultArgs) {
+    auto Args = dropDefaultArgs(ArgsAndDefaultArgs);
     for (const auto &Arg : Args) {
       Builder.markExprChild(Arg, syntax::NodeRole::ListElement);
       const auto *DelimiterToken =
           std::next(Builder.findToken(Arg->getEndLoc()));
       if (DelimiterToken->kind() == clang::tok::TokenKind::comma)
         Builder.markChildToken(DelimiterToken, syntax::NodeRole::ListDelimiter);
     }
 
bool WalkUpFromCXXOperatorCallExpr(CXXOperatorCallExpr *S) {
     }
     case syntax::NodeKind::UnknownExpression:
       return WalkUpFromExpr(S);
     default:
       llvm_unreachable("getOperatorNodeKind() does not return this value");
     }
   }
 
+  bool WalkUpFromCXXDefaultArgExpr(CXXDefaultArgExpr *S) { return true; }
+
   bool WalkUpFromNamespaceDecl(NamespaceDecl *S) {
     auto Tokens = Builder.getDeclarationRange(S);
     if (Tokens.front().kind() == tok::coloncolon) {
       // Handle nested namespace definitions. Those start at '::' token, e.g.
       // namespace a^::b {}
       // FIXME: build corresponding nodes for the name of this namespace.
       return true;
     }

clang/unittests/Tooling/Syntax/BuildTreeTest.cpp

 |   |-IdExpression
 |   | `-UnqualifiedId UnqualifiedId
 |   |   `-'args'
 |   `-'...'
 `-')' CloseParen
 )txt"}));
 }
 
+TEST_P(SyntaxTreeTest, CallExpression_DefaultArguments) {
+  if (!GetParam().isCXX11OrLater()) {
+    return;
+  }
+  EXPECT_TRUE(treeDumpEqualOnAnnotations(
+      R"cpp(
+void f(int i = 1, char c = '2');
+void test() {
+  [[f()]];
+  [[f(1)]];
+  [[f(1, '2')]];
+}
+)cpp",
+      {R"txt(
+CallExpression Expression
+|-IdExpression Callee
+| `-UnqualifiedId UnqualifiedId
+|   `-'f'
+|-'(' OpenParen
+`-')' CloseParen
+      )txt",
+       R"txt(
+CallExpression Expression
+|-IdExpression Callee
+| `-UnqualifiedId UnqualifiedId
+|   `-'f'
+|-'(' OpenParen
+|-CallArguments Arguments
+| `-IntegerLiteralExpression ListElement
+|   `-'1' LiteralToken
+`-')' CloseParen
+      )txt",
+       R"txt(
+CallExpression Expression
+|-IdExpression Callee
+| `-UnqualifiedId UnqualifiedId
+|   `-'f'
+|-'(' OpenParen
+|-CallArguments Arguments
+| |-IntegerLiteralExpression ListElement
+| | `-'1' LiteralToken
+| |-',' ListDelimiter
+| `-CharacterLiteralExpression ListElement
+|   `-''2'' LiteralToken
+`-')' CloseParen
+)txt"}));
+}
+
 TEST_P(SyntaxTreeTest, MultipleDeclaratorsGrouping) {
   EXPECT_TRUE(treeDumpEqual(
       R"cpp(
 int *a, b;
 int *c, d;
 )cpp",
       R"txt(
 TranslationUnit Detached

 )cpp",
       R"txt(
 TranslationUnit Detached
 `-SimpleDeclaration
   |-'int'
   |-SimpleDeclarator Declarator
   | |-'a'
   | `-ArraySubscript
   |   |-'[' OpenParen
   |   |-IntegerLiteralExpression Size
   |   | `-'10' LiteralToken
   |   `-']' CloseParen
   `-';'
 )txt"));
 }
 
 TEST_P(SyntaxTreeTest, ArrayDeclarator_Multidimensional) {
`-SimpleDeclaration
   |   | |-',' ListDelimiter
   |   | `-SimpleDeclaration ListElement
   |   |   `-'float'
   |   `-')' CloseParen
   `-';'
 )txt"));
 }
 
+TEST_P(SyntaxTreeTest, ParametersAndQualifiers_InFreeFunctions_Default_One) {
+  if (!GetParam().isCXX()) {
+    return;
+  }
+  EXPECT_TRUE(treeDumpEqualOnAnnotations(
+      R"cpp(
+int func1([[int a = 1]]);
+)cpp",
+      {R"txt(
+ParameterDeclarationList Parameters
+`-SimpleDeclaration ListElement
+  |-'int'
+  `-SimpleDeclarator Declarator
+    |-'a'
+    |-'='
+    `-IntegerLiteralExpression
+      `-'1' LiteralToken
+)txt"}));
+}
+
+TEST_P(SyntaxTreeTest,
+       ParametersAndQualifiers_InFreeFunctions_Default_Multiple) {
+  if (!GetParam().isCXX()) {
+    return;
+  }
+  EXPECT_TRUE(treeDumpEqualOnAnnotations(
+      R"cpp(
+int func2([[int *ap, int a = 1, char c = '2']]);
+)cpp",
+      {R"txt(
+ParameterDeclarationList Parameters
+|-SimpleDeclaration ListElement
+| |-'int'
+| `-SimpleDeclarator Declarator
+|   |-'*'
+|   `-'ap'
+|-',' ListDelimiter
+|-SimpleDeclaration ListElement
+| |-'int'
+| `-SimpleDeclarator Declarator
+|   |-'a'
+|   |-'='
+|   `-IntegerLiteralExpression
+|     `-'1' LiteralToken
+|-',' ListDelimiter
+`-SimpleDeclaration ListElement
+  |-'char'
+  `-SimpleDeclarator Declarator
+    |-'c'
+    |-'='
+    `-CharacterLiteralExpression
+      `-''2'' LiteralToken
+)txt"}));
+}
+
 TEST_P(SyntaxTreeTest,
        ParametersAndQualifiers_InVariadicFunctionTemplate_ParameterPack) {
   if (!GetParam().isCXX11OrLater() || GetParam().hasDelayedTemplateParsing()) {
     return;
   }
   EXPECT_TRUE(treeDumpEqualOnAnnotations(
       R"cpp(
 template<typename T, typename... Args>