llvm-project/clang/unittests/AST/DeclTest.cpp

//===- unittests/AST/DeclTest.cpp --- Declaration tests -------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Unit tests for Decl nodes in the AST.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/Decl.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Mangle.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Lexer.h"
#include "clang/Tooling/Tooling.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/Testing/Annotations/Annotations.h"
#include "gtest/gtest.h"

using namespace clang::ast_matchers;
using namespace clang::tooling;
using namespace clang;

TEST(Decl, CleansUpAPValues) {
  MatchFinder Finder;
  std::unique_ptr<FrontendActionFactory> Factory(
      newFrontendActionFactory(&Finder));

  // This is a regression test for a memory leak in APValues for structs that
  // allocate memory. This test only fails if run under valgrind with full leak
  // checking enabled.
  std::vector<std::string> Args(1, "-std=c++11");
  Args.push_back("-fno-ms-extensions");
  ASSERT_TRUE(runToolOnCodeWithArgs(
      Factory->create(),
      "struct X { int a; }; constexpr X x = { 42 };"
      "union Y { constexpr Y(int a) : a(a) {} int a; }; constexpr Y y = { 42 };"
      "constexpr int z[2] = { 42, 43 };"
      "constexpr int __attribute__((vector_size(16))) v1 = {};"
      "\n#ifdef __SIZEOF_INT128__\n"
      "constexpr __uint128_t large_int = 0xffffffffffffffff;"
      "constexpr __uint128_t small_int = 1;"
      "\n#endif\n"
      "constexpr double d1 = 42.42;"
      "constexpr long double d2 = 42.42;"
      "constexpr _Complex long double c1 = 42.0i;"
      "constexpr _Complex long double c2 = 42.0;"
      "template<int N> struct A : A<N-1> {};"
      "template<> struct A<0> { int n; }; A<50> a;"
      "constexpr int &r = a.n;"
      "constexpr int A<50>::*p = &A<50>::n;"
      "void f() { foo: bar: constexpr int k = __builtin_constant_p(0) ?"
      "                         (char*)&&foo - (char*)&&bar : 0; }",
      Args));

  // FIXME: Once this test starts breaking we can test APValue::needsCleanup
  // for ComplexInt.
  ASSERT_FALSE(runToolOnCodeWithArgs(
      Factory->create(),
      "constexpr _Complex __uint128_t c = 0xffffffffffffffff;",
      Args));
}

TEST(Decl, AsmLabelAttr) {
  // Create two method decls: `f` and `g`.
  StringRef Code = R"(
    struct S {
      void f() {}
      void g() {}
    };
  )";
  auto AST =
      tooling::buildASTFromCodeWithArgs(Code, {"-target", "i386-apple-darwin"});
  ASTContext &Ctx = AST->getASTContext();
  assert(Ctx.getTargetInfo().getUserLabelPrefix() == StringRef("_") &&
         "Expected target to have a global prefix");
  DiagnosticsEngine &Diags = AST->getDiagnostics();

  const auto *DeclS =
      selectFirst<CXXRecordDecl>("d", match(cxxRecordDecl().bind("d"), Ctx));
  NamedDecl *DeclF = *DeclS->method_begin();
  NamedDecl *DeclG = *(++DeclS->method_begin());

  // Attach asm labels to the decls: one literal, and one not.
  DeclF->addAttr(AsmLabelAttr::Create(Ctx, "foo", /*LiteralLabel=*/true));
  DeclG->addAttr(AsmLabelAttr::Create(Ctx, "goo", /*LiteralLabel=*/false));

  // Mangle the decl names.
  std::string MangleF, MangleG;
  std::unique_ptr<ItaniumMangleContext> MC(
      ItaniumMangleContext::create(Ctx, Diags));
  {
    llvm::raw_string_ostream OS_F(MangleF);
    llvm::raw_string_ostream OS_G(MangleG);
    MC->mangleName(DeclF, OS_F);
    MC->mangleName(DeclG, OS_G);
  }

  ASSERT_TRUE(0 == MangleF.compare("\x01" "foo"));
  ASSERT_TRUE(0 == MangleG.compare("goo"));
}

TEST(Decl, MangleDependentSizedArray) {
  StringRef Code = R"(
    template <int ...N>
    int A[] = {N...};

    template <typename T, int N>
    struct S {
      T B[N];
    };
  )";
  auto AST =
      tooling::buildASTFromCodeWithArgs(Code, {"-target", "i386-apple-darwin"});
  ASTContext &Ctx = AST->getASTContext();
  assert(Ctx.getTargetInfo().getUserLabelPrefix() == StringRef("_") &&
         "Expected target to have a global prefix");
  DiagnosticsEngine &Diags = AST->getDiagnostics();

  const auto *DeclA =
      selectFirst<VarDecl>("A", match(varDecl().bind("A"), Ctx));
  const auto *DeclB =
      selectFirst<FieldDecl>("B", match(fieldDecl().bind("B"), Ctx));

  std::string MangleA, MangleB;
  llvm::raw_string_ostream OS_A(MangleA), OS_B(MangleB);
  std::unique_ptr<ItaniumMangleContext> MC(
      ItaniumMangleContext::create(Ctx, Diags));

  MC->mangleCanonicalTypeName(DeclA->getType(), OS_A);
  MC->mangleCanonicalTypeName(DeclB->getType(), OS_B);

  ASSERT_TRUE(0 == MangleA.compare("_ZTSA_i"));
  ASSERT_TRUE(0 == MangleB.compare("_ZTSAT0__T_"));
}

TEST(Decl, ConceptDecl) {
  llvm::StringRef Code(R"(
    template<class T>
    concept integral = __is_integral(T);
  )");

  auto AST = tooling::buildASTFromCodeWithArgs(Code, {"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  const auto *Decl =
      selectFirst<ConceptDecl>("decl", match(conceptDecl().bind("decl"), Ctx));
  ASSERT_TRUE(Decl != nullptr);
  EXPECT_EQ(Decl->getName(), "integral");
}

TEST(Decl, EnumDeclRange) {
  llvm::Annotations Code(R"(
    typedef int Foo;
    [[enum Bar : Foo]];)");
  auto AST = tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{});
  ASTContext &Ctx = AST->getASTContext();
  const auto &SM = Ctx.getSourceManager();

  const auto *Bar =
      selectFirst<TagDecl>("Bar", match(enumDecl().bind("Bar"), Ctx));
  auto BarRange =
      Lexer::getAsCharRange(Bar->getSourceRange(), SM, Ctx.getLangOpts());
  EXPECT_EQ(SM.getFileOffset(BarRange.getBegin()), Code.range().Begin);
  EXPECT_EQ(SM.getFileOffset(BarRange.getEnd()), Code.range().End);
}

TEST(Decl, IsInExportDeclContext) {
  llvm::Annotations Code(R"(
    export module m;
    export template <class T>
    void f() {})");
  auto AST =
      tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  const auto *f =
      selectFirst<FunctionDecl>("f", match(functionDecl().bind("f"), Ctx));
  EXPECT_TRUE(f->isInExportDeclContext());
}

TEST(Decl, InConsistLinkageForTemplates) {
  llvm::Annotations Code(R"(
    export module m;
    export template <class T>
    void f() {}

    template <>
    void f<int>() {}

    export template <class T>
    class C {};

    template<>
    class C<int> {};
    )");

  auto AST =
      tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  llvm::SmallVector<ast_matchers::BoundNodes, 2> Funcs =
      match(functionDecl().bind("f"), Ctx);

  EXPECT_EQ(Funcs.size(), 2U);
  const FunctionDecl *TemplateF = Funcs[0].getNodeAs<FunctionDecl>("f");
  const FunctionDecl *SpecializedF = Funcs[1].getNodeAs<FunctionDecl>("f");
  EXPECT_EQ(TemplateF->getLinkageInternal(),
            SpecializedF->getLinkageInternal());

  llvm::SmallVector<ast_matchers::BoundNodes, 1> ClassTemplates =
      match(classTemplateDecl().bind("C"), Ctx);
  llvm::SmallVector<ast_matchers::BoundNodes, 1> ClassSpecializations =
      match(classTemplateSpecializationDecl().bind("C"), Ctx);

  EXPECT_EQ(ClassTemplates.size(), 1U);
  EXPECT_EQ(ClassSpecializations.size(), 1U);
  const NamedDecl *TemplatedC = ClassTemplates[0].getNodeAs<NamedDecl>("C");
  const NamedDecl *SpecializedC = ClassSpecializations[0].getNodeAs<NamedDecl>("C");
  EXPECT_EQ(TemplatedC->getLinkageInternal(),
            SpecializedC->getLinkageInternal());
}

TEST(Decl, ModuleAndInternalLinkage) {
  llvm::Annotations Code(R"(
    export module M;
    static int a;
    static int f(int x);

    int b;
    int g(int x);)");

  auto AST =
      tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  const auto *a =
      selectFirst<VarDecl>("a", match(varDecl(hasName("a")).bind("a"), Ctx));
  const auto *f = selectFirst<FunctionDecl>(
      "f", match(functionDecl(hasName("f")).bind("f"), Ctx));

  EXPECT_EQ(a->getFormalLinkage(), Linkage::Internal);
  EXPECT_EQ(f->getFormalLinkage(), Linkage::Internal);

  const auto *b =
      selectFirst<VarDecl>("b", match(varDecl(hasName("b")).bind("b"), Ctx));
  const auto *g = selectFirst<FunctionDecl>(
      "g", match(functionDecl(hasName("g")).bind("g"), Ctx));

  EXPECT_EQ(b->getFormalLinkage(), Linkage::Module);
  EXPECT_EQ(g->getFormalLinkage(), Linkage::Module);
}

TEST(Decl, GetNonTransparentDeclContext) {
  llvm::Annotations Code(R"(
    export module m3;
    export template <class> struct X {
      template <class Self> friend void f(Self &&self) {
        (Self&)self;
      }
    };)");

  auto AST =
      tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  auto *f = selectFirst<FunctionDecl>(
      "f", match(functionDecl(hasName("f")).bind("f"), Ctx));

  EXPECT_TRUE(f->getNonTransparentDeclContext()->isFileContext());
}

TEST(Decl, MemberFunctionInModules) {
  llvm::Annotations Code(R"(
    module;
    class G {
      void bar() {}
    };
    export module M;
    class A {
      void foo() {}
    };
    )");

  auto AST =
      tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  auto *foo = selectFirst<FunctionDecl>(
      "foo", match(functionDecl(hasName("foo")).bind("foo"), Ctx));

  // The function defined within a class definition is not implicitly inline
  // if it is not attached to global module
  EXPECT_FALSE(foo->isInlined());

  auto *bar = selectFirst<FunctionDecl>(
      "bar", match(functionDecl(hasName("bar")).bind("bar"), Ctx));

  // In global module, the function defined within a class definition is
  // implicitly inline.
  EXPECT_TRUE(bar->isInlined());
}

TEST(Decl, MemberFunctionInHeaderUnit) {
  llvm::Annotations Code(R"(
    class foo {
    public:
      int memFn() {
        return 43;
      }
    };
    )");

  auto AST = tooling::buildASTFromCodeWithArgs(
      Code.code(), {"-std=c++20", " -xc++-user-header ", "-emit-header-unit"});
  ASTContext &Ctx = AST->getASTContext();

  auto *memFn = selectFirst<FunctionDecl>(
      "memFn", match(functionDecl(hasName("memFn")).bind("memFn"), Ctx));

  EXPECT_TRUE(memFn->isInlined());
}

TEST(Decl, FriendFunctionWithinClassInHeaderUnit) {
  llvm::Annotations Code(R"(
    class foo {
      int value;
    public:
      foo(int v) : value(v) {}

      friend int getFooValue(foo f) {
        return f.value;
      }
    };
    )");

  auto AST = tooling::buildASTFromCodeWithArgs(
      Code.code(), {"-std=c++20", " -xc++-user-header ", "-emit-header-unit"});
  ASTContext &Ctx = AST->getASTContext();

  auto *getFooValue = selectFirst<FunctionDecl>(
      "getFooValue",
      match(functionDecl(hasName("getFooValue")).bind("getFooValue"), Ctx));

  EXPECT_TRUE(getFooValue->isInlined());
}

TEST(Decl, FunctionDeclBitsShouldNotOverlapWithCXXConstructorDeclBits) {
  llvm::Annotations Code(R"(
    struct A {
      A() : m() {}
      int m;
    };

    A f() { return A(); }
    )");

  auto AST = tooling::buildASTFromCodeWithArgs(Code.code(), {"-std=c++14"});
  ASTContext &Ctx = AST->getASTContext();

  auto HasCtorInit =
      hasAnyConstructorInitializer(cxxCtorInitializer(isMemberInitializer()));
  auto ImpMoveCtor =
      cxxConstructorDecl(isMoveConstructor(), isImplicit(), HasCtorInit)
          .bind("MoveCtor");

  auto *ToImpMoveCtor =
      selectFirst<CXXConstructorDecl>("MoveCtor", match(ImpMoveCtor, Ctx));

  EXPECT_TRUE(ToImpMoveCtor->getNumCtorInitializers() == 1);
  EXPECT_FALSE(ToImpMoveCtor->FriendConstraintRefersToEnclosingTemplate());
}

TEST(Decl, NoProtoFunctionDeclAttributes) {
  llvm::Annotations Code(R"(
    void f();
    )");

  auto AST = tooling::buildASTFromCodeWithArgs(
      Code.code(),
      /*Args=*/{"-target", "i386-apple-darwin", "-x", "objective-c",
                "-std=c89"});
  ASTContext &Ctx = AST->getASTContext();

  auto *f = selectFirst<FunctionDecl>(
      "f", match(functionDecl(hasName("f")).bind("f"), Ctx));

  const auto *FPT = f->getType()->getAs<FunctionNoProtoType>();

  // Functions without prototypes always have 0 initialized qualifiers
  EXPECT_FALSE(FPT->isConst());
  EXPECT_FALSE(FPT->isVolatile());
  EXPECT_FALSE(FPT->isRestrict());
}

TEST(Decl, ImplicitlyDeclaredAllocationFunctionsInModules) {
  // C++ [basic.stc.dynamic.general]p2:
  //   The library provides default definitions for the global allocation
  //   and deallocation functions. Some global allocation and deallocation
  //   functions are replaceable ([new.delete]); these are attached to the
  //   global module ([module.unit]).

  llvm::Annotations Code(R"(
    export module base;

    export struct Base {
        virtual void hello() = 0;
        virtual ~Base() = default;
    };
  )");

  auto AST =
      tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  // void* operator new(std::size_t);
  auto *SizedOperatorNew = selectFirst<FunctionDecl>(
      "operator new",
      match(functionDecl(hasName("operator new"), parameterCountIs(1),
                         hasParameter(0, hasType(isUnsignedInteger())))
                .bind("operator new"),
            Ctx));
  ASSERT_TRUE(SizedOperatorNew->getOwningModule());
  EXPECT_TRUE(SizedOperatorNew->isFromExplicitGlobalModule());

  // void* operator new(std::size_t, std::align_val_t);
  auto *SizedAlignedOperatorNew = selectFirst<FunctionDecl>(
      "operator new",
      match(functionDecl(
                hasName("operator new"), parameterCountIs(2),
                hasParameter(0, hasType(isUnsignedInteger())),
                hasParameter(1, hasType(enumDecl(hasName("std::align_val_t")))))
                .bind("operator new"),
            Ctx));
  ASSERT_TRUE(SizedAlignedOperatorNew->getOwningModule());
  EXPECT_TRUE(SizedAlignedOperatorNew->isFromExplicitGlobalModule());

  // void* operator new[](std::size_t);
  auto *SizedArrayOperatorNew = selectFirst<FunctionDecl>(
      "operator new[]",
      match(functionDecl(hasName("operator new[]"), parameterCountIs(1),
                         hasParameter(0, hasType(isUnsignedInteger())))
                .bind("operator new[]"),
            Ctx));
  ASSERT_TRUE(SizedArrayOperatorNew->getOwningModule());
  EXPECT_TRUE(SizedArrayOperatorNew->isFromExplicitGlobalModule());

  // void* operator new[](std::size_t, std::align_val_t);
  auto *SizedAlignedArrayOperatorNew = selectFirst<FunctionDecl>(
      "operator new[]",
      match(functionDecl(
                hasName("operator new[]"), parameterCountIs(2),
                hasParameter(0, hasType(isUnsignedInteger())),
                hasParameter(1, hasType(enumDecl(hasName("std::align_val_t")))))
                .bind("operator new[]"),
            Ctx));
  ASSERT_TRUE(SizedAlignedArrayOperatorNew->getOwningModule());
  EXPECT_TRUE(
      SizedAlignedArrayOperatorNew->isFromExplicitGlobalModule());

  // void operator delete(void*) noexcept;
  auto *Delete = selectFirst<FunctionDecl>(
      "operator delete",
      match(functionDecl(
                hasName("operator delete"), parameterCountIs(1),
                hasParameter(0, hasType(pointerType(pointee(voidType())))))
                .bind("operator delete"),
            Ctx));
  ASSERT_TRUE(Delete->getOwningModule());
  EXPECT_TRUE(Delete->isFromExplicitGlobalModule());

  // void operator delete(void*, std::align_val_t) noexcept;
  auto *AlignedDelete = selectFirst<FunctionDecl>(
      "operator delete",
      match(functionDecl(
                hasName("operator delete"), parameterCountIs(2),
                hasParameter(0, hasType(pointerType(pointee(voidType())))),
                hasParameter(1, hasType(enumDecl(hasName("std::align_val_t")))))
                .bind("operator delete"),
            Ctx));
  ASSERT_TRUE(AlignedDelete->getOwningModule());
  EXPECT_TRUE(AlignedDelete->isFromExplicitGlobalModule());

  // Sized deallocation is not enabled by default. So we skip it here.

  // void operator delete[](void*) noexcept;
  auto *ArrayDelete = selectFirst<FunctionDecl>(
      "operator delete[]",
      match(functionDecl(
                hasName("operator delete[]"), parameterCountIs(1),
                hasParameter(0, hasType(pointerType(pointee(voidType())))))
                .bind("operator delete[]"),
            Ctx));
  ASSERT_TRUE(ArrayDelete->getOwningModule());
  EXPECT_TRUE(ArrayDelete->isFromExplicitGlobalModule());

  // void operator delete[](void*, std::align_val_t) noexcept;
  auto *AlignedArrayDelete = selectFirst<FunctionDecl>(
      "operator delete[]",
      match(functionDecl(
                hasName("operator delete[]"), parameterCountIs(2),
                hasParameter(0, hasType(pointerType(pointee(voidType())))),
                hasParameter(1, hasType(enumDecl(hasName("std::align_val_t")))))
                .bind("operator delete[]"),
            Ctx));
  ASSERT_TRUE(AlignedArrayDelete->getOwningModule());
  EXPECT_TRUE(AlignedArrayDelete->isFromExplicitGlobalModule());
}

TEST(Decl, TemplateArgumentDefaulted) {
  llvm::Annotations Code(R"cpp(
    template<typename T1, typename T2>
    struct Alloc {};

    template <typename T1,
              typename T2 = double,
              int      T3 = 42,
              typename T4 = Alloc<T1, T2>>
    struct Foo {
    };

    Foo<char, int, 42, Alloc<char, int>> X;
  )cpp");

  auto AST =
      tooling::buildASTFromCodeWithArgs(Code.code(), /*Args=*/{"-std=c++20"});
  ASTContext &Ctx = AST->getASTContext();

  auto const *CTSD = selectFirst<ClassTemplateSpecializationDecl>(
      "id",
      match(classTemplateSpecializationDecl(hasName("Foo")).bind("id"), Ctx));
  ASSERT_NE(CTSD, nullptr);
  auto const &ArgList = CTSD->getTemplateArgs();

  EXPECT_FALSE(ArgList.get(0).getIsDefaulted());
  EXPECT_FALSE(ArgList.get(1).getIsDefaulted());
  EXPECT_TRUE(ArgList.get(2).getIsDefaulted());
  EXPECT_TRUE(ArgList.get(3).getIsDefaulted());
}

TEST(Decl, CXXDestructorDeclsShouldHaveWellFormedNameInfoRanges) {
  // GH71161
  llvm::Annotations Code(R"cpp(
template <typename T> struct Resource {
  ~Resource(); // 1
};
template <typename T>
Resource<T>::~Resource() {} // 2,3

void instantiate_template() {
  Resource<int> x;
}
)cpp");

  auto AST = tooling::buildASTFromCode(Code.code());
  ASTContext &Ctx = AST->getASTContext();

  const auto &SM = Ctx.getSourceManager();
  auto GetNameInfoRange = [&SM](const BoundNodes &Match) {
    const auto *D = Match.getNodeAs<CXXDestructorDecl>("dtor");
    return D->getNameInfo().getSourceRange().printToString(SM);
  };

  auto Matches = match(findAll(cxxDestructorDecl().bind("dtor")),
                       *Ctx.getTranslationUnitDecl(), Ctx);
  ASSERT_EQ(Matches.size(), 3U);
  EXPECT_EQ(GetNameInfoRange(Matches[0]), "<input.cc:3:3, col:4>");
  EXPECT_EQ(GetNameInfoRange(Matches[1]), "<input.cc:6:14, col:15>");
  EXPECT_EQ(GetNameInfoRange(Matches[2]), "<input.cc:6:14, col:15>");
}

TEST(Decl, CommentsAttachedToDecl1) {
  const SmallVector<StringRef> Sources{
      R"(
        /// Test comment
        void f();
      )",

      R"(
        /// Test comment

        void f();
      )",

      R"(
        /// Test comment
        #if 0
        // tralala
        #endif
        void f();
      )",

      R"(
        /// Test comment

        #if 0
        // tralala
        #endif

        void f();
      )",

      R"(
        /// Test comment
        #ifdef DOCS
        template<typename T>
        #endif
        void f();
      )",

      R"(
        /// Test comment

        #ifdef DOCS
        template<typename T>
        #endif

        void f();
      )",
  };

  for (const auto code : Sources) {
    auto AST = tooling::buildASTFromCodeWithArgs(code, /*Args=*/{"-std=c++20"});
    ASTContext &Ctx = AST->getASTContext();

    auto const *F = selectFirst<FunctionDecl>(
        "id", match(functionDecl(hasName("f")).bind("id"), Ctx));
    ASSERT_NE(F, nullptr);

    auto const *C = Ctx.getRawCommentForDeclNoCache(F);
    ASSERT_NE(C, nullptr);
    EXPECT_EQ(C->getRawText(Ctx.getSourceManager()), "/// Test comment");
  }
}

TEST(Decl, CommentsAttachedToDecl2) {
  const SmallVector<StringRef> Sources{
      R"(
        /** Test comment
         */
        void f();
      )",

      R"(
        /** Test comment
         */

        void f();
      )",

      R"(
        /** Test comment
         */
        #if 0
        /* tralala */
        #endif
        void f();
      )",

      R"(
        /** Test comment
         */

        #if 0
        /* tralala */
        #endif

        void f();
      )",

      R"(
        /** Test comment
         */
        #ifdef DOCS
        template<typename T>
        #endif
        void f();
      )",

      R"(
        /** Test comment
         */

        #ifdef DOCS
        template<typename T>
        #endif

        void f();
      )",
  };

  for (const auto code : Sources) {
    auto AST = tooling::buildASTFromCodeWithArgs(code, /*Args=*/{"-std=c++20"});
    ASTContext &Ctx = AST->getASTContext();

    auto const *F = selectFirst<FunctionDecl>(
        "id", match(functionDecl(hasName("f")).bind("id"), Ctx));
    ASSERT_NE(F, nullptr);

    auto const *C = Ctx.getRawCommentForDeclNoCache(F);
    ASSERT_NE(C, nullptr);
    EXPECT_EQ(C->getRawText(Ctx.getSourceManager()),
              "/** Test comment\n         */");
  }
}

TEST(Decl, CommentsAttachedToDecl3) {
  const SmallVector<StringRef> Sources{
      R"(
        /// @brief Test comment
        void f();
      )",

      R"(
        /// @brief Test comment

        void f();
      )",

      R"(
        /// @brief Test comment
        #if 0
        // tralala
        #endif
        void f();
      )",

      R"(
        /// @brief Test comment

        #if 0
        // tralala
        #endif

        void f();
      )",

      R"(
        /// @brief Test comment
        #ifdef DOCS
        template<typename T>
        #endif
        void f();
      )",

      R"(
        /// @brief Test comment

        #ifdef DOCS
        template<typename T>
        #endif

        void f();
     )",
  };

  for (const auto code : Sources) {
    auto AST = tooling::buildASTFromCodeWithArgs(code, /*Args=*/{"-std=c++20"});
    ASTContext &Ctx = AST->getASTContext();

    auto const *F = selectFirst<FunctionDecl>(
        "id", match(functionDecl(hasName("f")).bind("id"), Ctx));
    ASSERT_NE(F, nullptr);

    auto const *C = Ctx.getRawCommentForDeclNoCache(F);
    ASSERT_NE(C, nullptr);
    EXPECT_EQ(C->getRawText(Ctx.getSourceManager()), "/// @brief Test comment");
  }
}

TEST(Decl, CommentsAttachedToDecl4) {
  const SmallVector<StringRef> Sources{
      R"(
        /** \brief Test comment
         */
        void f();
      )",

      R"(
        /** \brief Test comment
         */

        void f();
      )",

      R"(
        /** \brief Test comment
         */
        #if 0
        /* tralala */
        #endif
        void f();
      )",

      R"(
        /** \brief Test comment
         */

        #if 0
        /* tralala */
        #endif

        void f();
      )",

      R"(
        /** \brief Test comment
         */
        #ifdef DOCS
        template<typename T>
        #endif
        void f();
      )",

      R"(
        /** \brief Test comment
         */

        #ifdef DOCS
        template<typename T>
        #endif

        void f();
     )",
  };

  for (const auto code : Sources) {
    auto AST = tooling::buildASTFromCodeWithArgs(code, /*Args=*/{"-std=c++20"});
    ASTContext &Ctx = AST->getASTContext();

    auto const *F = selectFirst<FunctionDecl>(
        "id", match(functionDecl(hasName("f")).bind("id"), Ctx));
    ASSERT_NE(F, nullptr);

    auto const *C = Ctx.getRawCommentForDeclNoCache(F);
    ASSERT_NE(C, nullptr);
    EXPECT_EQ(C->getRawText(Ctx.getSourceManager()),
              "/** \\brief Test comment\n         */");
  }
}

/// This example intentionally inserts characters between a doc comment and the
/// associated declaration to verify that the comment does not become associated
/// with the FunctionDecl.
/// By default, Clang does not allow for other declarations (aside from
/// preprocessor directives, as shown above) to be placed between a doc comment
/// and a declaration.
TEST(Decl, CommentsAttachedToDecl5) {
  const SmallVector<StringRef> Sources{
      R"(
        /// Test comment
        ;
        void f();
      )",

      R"(
        /// Test comment
        // @
        void f();
      )",

      R"(
        /// Test comment
        // {}
        void f();
      )",
  };

  for (const auto code : Sources) {
    auto AST = tooling::buildASTFromCodeWithArgs(code, /*Args=*/{"-std=c++20"});
    ASTContext &Ctx = AST->getASTContext();

    auto const *F = selectFirst<FunctionDecl>(
        "id", match(functionDecl(hasName("f")).bind("id"), Ctx));
    ASSERT_NE(F, nullptr);

    auto const *C = Ctx.getRawCommentForDeclNoCache(F);
    ASSERT_EQ(C, nullptr);
  }
}