InlayHintTests.cpp

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//===-- InlayHintTests.cpp  -------------------------------*- C++ -*-------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "Annotations.h"
#include "Config.h"
#include "InlayHints.h"
#include "Protocol.h"
#include "TestTU.h"
#include "TestWorkspace.h"
#include "XRefs.h"
#include "support/Context.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/ScopedPrinter.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
 
namespace clang {
namespace clangd {
 
llvm::raw_ostream &operator<<(llvm::raw_ostream &Stream,
                              const InlayHint &Hint) {
  return Stream << Hint.label << "@" << Hint.range;
}
 
namespace {
 
using ::testing::ElementsAre;
using ::testing::IsEmpty;
 
std::vector<InlayHint> hintsOfKind(ParsedAST &AST, InlayHintKind Kind) {
  std::vector<InlayHint> Result;
  for (auto &Hint : inlayHints(AST, /*RestrictRange=*/llvm::None)) {
    if (Hint.kind == Kind)
      Result.push_back(Hint);
  }
  return Result;
}
 
enum HintSide { Left, Right };
 
struct ExpectedHint {
  std::string Label;
  std::string RangeName;
  HintSide Side = Left;
 
  friend llvm::raw_ostream &operator<<(llvm::raw_ostream &Stream,
                                       const ExpectedHint &Hint) {
    return Stream << Hint.Label << "@$" << Hint.RangeName;
  }
};
 
MATCHER_P2(HintMatcher, Expected, Code, llvm::to_string(Expected)) {
  llvm::StringRef ExpectedView(Expected.Label);
  if (arg.label != ExpectedView.trim(" ") ||
      arg.paddingLeft != ExpectedView.startswith(" ") ||
      arg.paddingRight != ExpectedView.endswith(" ")) {
    *result_listener << "label is '" << arg.label << "'";
    return false;
  }
  if (arg.range != Code.range(Expected.RangeName)) {
    *result_listener << "range is " << llvm::to_string(arg.range) << " but $"
                     << Expected.RangeName << " is "
                     << llvm::to_string(Code.range(Expected.RangeName));
    return false;
  }
  return true;
}
 
MATCHER_P(labelIs, Label, "") { return arg.label == Label; }
 
Config noHintsConfig() {
  Config C;
  C.InlayHints.Parameters = false;
  C.InlayHints.DeducedTypes = false;
  C.InlayHints.Designators = false;
  return C;
}
 
template <typename... ExpectedHints>
void assertHints(InlayHintKind Kind, llvm::StringRef AnnotatedSource,
                 ExpectedHints... Expected) {
  Annotations Source(AnnotatedSource);
  TestTU TU = TestTU::withCode(Source.code());
  TU.ExtraArgs.push_back("-std=c++20");
  auto AST = TU.build();
 
  EXPECT_THAT(hintsOfKind(AST, Kind),
              ElementsAre(HintMatcher(Expected, Source)...));
  // Sneak in a cross-cutting check that hints are disabled by config.
  // We'll hit an assertion failure if addInlayHint still gets called.
  WithContextValue WithCfg(Config::Key, noHintsConfig());
  EXPECT_THAT(inlayHints(AST, llvm::None), IsEmpty());
}
 
// Hack to allow expression-statements operating on parameter packs in C++14.
template <typename... T> void ignore(T &&...) {}
 
template <typename... ExpectedHints>
void assertParameterHints(llvm::StringRef AnnotatedSource,
                          ExpectedHints... Expected) {
  ignore(Expected.Side = Left...);
  assertHints(InlayHintKind::Parameter, AnnotatedSource, Expected...);
}
 
template <typename... ExpectedHints>
void assertTypeHints(llvm::StringRef AnnotatedSource,
                     ExpectedHints... Expected) {
  ignore(Expected.Side = Right...);
  assertHints(InlayHintKind::Type, AnnotatedSource, Expected...);
}
 
template <typename... ExpectedHints>
void assertDesignatorHints(llvm::StringRef AnnotatedSource,
                           ExpectedHints... Expected) {
  Config Cfg;
  Cfg.InlayHints.Designators = true;
  WithContextValue WithCfg(Config::Key, std::move(Cfg));
  assertHints(InlayHintKind::Designator, AnnotatedSource, Expected...);
}
 
TEST(ParameterHints, Smoke) {
  assertParameterHints(R"cpp(
    void foo(int param);
    void bar() {
      foo($param[[42]]);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, NoName) {
  // No hint for anonymous parameter.
  assertParameterHints(R"cpp(
    void foo(int);
    void bar() {
      foo(42);
    }
  )cpp");
}
 
TEST(ParameterHints, NoNameConstReference) {
  // No hint for anonymous const l-value ref parameter.
  assertParameterHints(R"cpp(
    void foo(const int&);
    void bar() {
      foo(42);
    }
  )cpp");
}
 
TEST(ParameterHints, NoNameReference) {
  // Reference hint for anonymous l-value ref parameter.
  assertParameterHints(R"cpp(
    void foo(int&);
    void bar() {
      int i;
      foo($param[[i]]);
    }
  )cpp",
                       ExpectedHint{"&: ", "param"});
}
 
TEST(ParameterHints, NoNameRValueReference) {
  // No reference hint for anonymous r-value ref parameter.
  assertParameterHints(R"cpp(
    void foo(int&&);
    void bar() {
      foo(42);
    }
  )cpp");
}
 
TEST(ParameterHints, NameInDefinition) {
  // Parameter name picked up from definition if necessary.
  assertParameterHints(R"cpp(
    void foo(int);
    void bar() {
      foo($param[[42]]);
    }
    void foo(int param) {};
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, NameMismatch) {
  // Prefer name from declaration.
  assertParameterHints(R"cpp(
    void foo(int good);
    void bar() {
      foo($good[[42]]);
    }
    void foo(int bad) {};
  )cpp",
                       ExpectedHint{"good: ", "good"});
}
 
TEST(ParameterHints, NameConstReference) {
  // Only name hint for const l-value ref parameter.
  assertParameterHints(R"cpp(
    void foo(const int& param);
    void bar() {
      foo($param[[42]]);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, NameTypeAliasConstReference) {
  // Only name hint for const l-value ref parameter via type alias.
  assertParameterHints(R"cpp(
    using alias = const int&;
    void foo(alias param);
    void bar() {
      int i;
      foo($param[[i]]);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, NameReference) {
  // Reference and name hint for l-value ref parameter.
  assertParameterHints(R"cpp(
    void foo(int& param);
    void bar() {
      int i;
      foo($param[[i]]);
    }
  )cpp",
                       ExpectedHint{"&param: ", "param"});
}
 
TEST(ParameterHints, NameTypeAliasReference) {
  // Reference and name hint for l-value ref parameter via type alias.
  assertParameterHints(R"cpp(
    using alias = int&;
    void foo(alias param);
    void bar() {
      int i;
      foo($param[[i]]);
    }
  )cpp",
                       ExpectedHint{"&param: ", "param"});
}
 
TEST(ParameterHints, NameRValueReference) {
  // Only name hint for r-value ref parameter.
  assertParameterHints(R"cpp(
    void foo(int&& param);
    void bar() {
      foo($param[[42]]);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, Operator) {
  // No hint for operator call with operator syntax.
  assertParameterHints(R"cpp(
    struct S {};
    void operator+(S lhs, S rhs);
    void bar() {
      S a, b;
      a + b;
    }
  )cpp");
}
 
TEST(ParameterHints, Macros) {
  // Handling of macros depends on where the call's argument list comes from.
 
  // If it comes from a macro definition, there's nothing to hint
  // at the invocation site.
  assertParameterHints(R"cpp(
    void foo(int param);
    #define ExpandsToCall() foo(42)
    void bar() {
      ExpandsToCall();
    }
  )cpp");
 
  // The argument expression being a macro invocation shouldn't interfere
  // with hinting.
  assertParameterHints(R"cpp(
    #define PI 3.14
    void foo(double param);
    void bar() {
      foo($param[[PI]]);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
 
  // If the whole argument list comes from a macro parameter, hint it.
  assertParameterHints(R"cpp(
    void abort();
    #define ASSERT(expr) if (!expr) abort()
    int foo(int param);
    void bar() {
      ASSERT(foo($param[[42]]) == 0);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, ConstructorParens) {
  assertParameterHints(R"cpp(
    struct S {
      S(int param);
    };
    void bar() {
      S obj($param[[42]]);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, ConstructorBraces) {
  assertParameterHints(R"cpp(
    struct S {
      S(int param);
    };
    void bar() {
      S obj{$param[[42]]};
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, ConstructorStdInitList) {
  // Do not show hints for std::initializer_list constructors.
  assertParameterHints(R"cpp(
    namespace std {
      template <typename> class initializer_list {};
    }
    struct S {
      S(std::initializer_list<int> param);
    };
    void bar() {
      S obj{42, 43};
    }
  )cpp");
}
 
TEST(ParameterHints, MemberInit) {
  assertParameterHints(R"cpp(
    struct S {
      S(int param);
    };
    struct T {
      S member;
      T() : member($param[[42]]) {}
    };
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, ImplicitConstructor) {
  assertParameterHints(R"cpp(
    struct S {
      S(int param);
    };
    void bar(S);
    S foo() {
      // Do not show hint for implicit constructor call in argument.
      bar(42);
      // Do not show hint for implicit constructor call in return.
      return 42;
    }
  )cpp");
}
 
TEST(ParameterHints, ArgMatchesParam) {
  assertParameterHints(R"cpp(
    void foo(int param);
    struct S {
      static const int param = 42;
    };
    void bar() {
      int param = 42;
      // Do not show redundant "param: param".
      foo(param);
      // But show it if the argument is qualified.
      foo($param[[S::param]]);
    }
    struct A {
      int param;
      void bar() {
        // Do not show "param: param" for member-expr.
        foo(param);
      }
    };
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, ArgMatchesParamReference) {
  assertParameterHints(R"cpp(
    void foo(int& param);
    void foo2(const int& param);
    void bar() {
      int param;
      // show reference hint on mutable reference
      foo($param[[param]]);
      // but not on const reference
      foo2(param);
    }
  )cpp",
                       ExpectedHint{"&: ", "param"});
}
 
TEST(ParameterHints, LeadingUnderscore) {
  assertParameterHints(R"cpp(
    void foo(int p1, int _p2, int __p3);
    void bar() {
      foo($p1[[41]], $p2[[42]], $p3[[43]]);
    }
  )cpp",
                       ExpectedHint{"p1: ", "p1"}, ExpectedHint{"p2: ", "p2"},
                       ExpectedHint{"p3: ", "p3"});
}
 
TEST(ParameterHints, DependentCalls) {
  assertParameterHints(R"cpp(
    template <typename T>
    void nonmember(T par1);
 
    template <typename T>
    struct A {
      void member(T par2);
      static void static_member(T par3);
    };
 
    void overload(int anInt);
    void overload(double aDouble);
 
    template <typename T>
    struct S {
      void bar(A<T> a, T t) {
        nonmember($par1[[t]]);
        a.member($par2[[t]]);
        A<T>::static_member($par3[[t]]);
        // We don't want to arbitrarily pick between
        // "anInt" or "aDouble", so just show no hint.
        overload(T{});
      }
    };
  )cpp",
                       ExpectedHint{"par1: ", "par1"},
                       ExpectedHint{"par2: ", "par2"},
                       ExpectedHint{"par3: ", "par3"});
}
 
TEST(ParameterHints, VariadicFunction) {
  assertParameterHints(R"cpp(
    template <typename... T>
    void foo(int fixed, T... variadic);
 
    void bar() {
      foo($fixed[[41]], 42, 43);
    }
  )cpp",
                       ExpectedHint{"fixed: ", "fixed"});
}
 
TEST(ParameterHints, VarargsFunction) {
  assertParameterHints(R"cpp(
    void foo(int fixed, ...);
 
    void bar() { 
      foo($fixed[[41]], 42, 43);
    }
  )cpp",
                       ExpectedHint{"fixed: ", "fixed"});
}
 
TEST(ParameterHints, CopyOrMoveConstructor) {
  // Do not show hint for parameter of copy or move constructor.
  assertParameterHints(R"cpp(
    struct S {
      S();
      S(const S& other);
      S(S&& other);
    };
    void bar() {
      S a;
      S b(a);    // copy
      S c(S());  // move
    }
  )cpp");
}
 
TEST(ParameterHints, AggregateInit) {
  // FIXME: This is not implemented yet, but it would be a natural
  // extension to show member names as hints here.
  assertParameterHints(R"cpp(
    struct Point {
      int x;
      int y;
    };
    void bar() {
      Point p{41, 42};
    }
  )cpp");
}
 
TEST(ParameterHints, UserDefinedLiteral) {
  // Do not hint call to user-defined literal operator.
  assertParameterHints(R"cpp(
    long double operator"" _w(long double param);
    void bar() {
      1.2_w;
    }
  )cpp");
}
 
TEST(ParameterHints, ParamNameComment) {
  // Do not hint an argument which already has a comment
  // with the parameter name preceding it.
  assertParameterHints(R"cpp(
    void foo(int param);
    void bar() {
      foo(/*param*/42);
      foo( /* param = */ 42);
      foo(/* the answer */$param[[42]]);
    }
  )cpp",
                       ExpectedHint{"param: ", "param"});
}
 
TEST(ParameterHints, SetterFunctions) {
  assertParameterHints(R"cpp(
    struct S {
      void setParent(S* parent);
      void set_parent(S* parent);
      void setTimeout(int timeoutMillis);
      void setTimeoutMillis(int timeout_millis);
    };
    void bar() {
      S s;
      // Parameter name matches setter name - omit hint.
      s.setParent(nullptr);
      // Support snake_case
      s.set_parent(nullptr);
      // Parameter name may contain extra info - show hint.
      s.setTimeout($timeoutMillis[[120]]);
      // FIXME: Ideally we'd want to omit this.
      s.setTimeoutMillis($timeout_millis[[120]]);
    }
  )cpp",
                       ExpectedHint{"timeoutMillis: ", "timeoutMillis"},
                       ExpectedHint{"timeout_millis: ", "timeout_millis"});
}
 
TEST(ParameterHints, BuiltinFunctions) {
  // This prototype of std::forward is sufficient for clang to recognize it
  assertParameterHints(R"cpp(
    namespace std { template <typename T> T&& forward(T&); }
    void foo() {
      int i;
      std::forward(i);
    }
  )cpp");
}
 
TEST(ParameterHints, IncludeAtNonGlobalScope) {
  Annotations FooInc(R"cpp(
    void bar() { foo(42); }
  )cpp");
  Annotations FooCC(R"cpp(
    struct S {
      void foo(int param);
      #include "foo.inc"
    };
  )cpp");
 
  TestWorkspace Workspace;
  Workspace.addSource("foo.inc", FooInc.code());
  Workspace.addMainFile("foo.cc", FooCC.code());
 
  auto AST = Workspace.openFile("foo.cc");
  ASSERT_TRUE(bool(AST));
 
  // Ensure the hint for the call in foo.inc is NOT materialized in foo.cc.
  EXPECT_EQ(hintsOfKind(*AST, InlayHintKind::Parameter).size(), 0u);
}
 
TEST(TypeHints, Smoke) {
  assertTypeHints(R"cpp(
    auto $waldo[[waldo]] = 42;
  )cpp",
                  ExpectedHint{": int", "waldo"});
}
 
TEST(TypeHints, Decorations) {
  assertTypeHints(R"cpp(
    int x = 42;
    auto* $var1[[var1]] = &x;
    auto&& $var2[[var2]] = x;
    const auto& $var3[[var3]] = x;
  )cpp",
                  ExpectedHint{": int *", "var1"},
                  ExpectedHint{": int &", "var2"},
                  ExpectedHint{": const int &", "var3"});
}
 
TEST(TypeHints, DecltypeAuto) {
  assertTypeHints(R"cpp(
    int x = 42;
    int& y = x;
    decltype(auto) $z[[z]] = y;
  )cpp",
                  ExpectedHint{": int &", "z"});
}
 
TEST(TypeHints, NoQualifiers) {
  assertTypeHints(R"cpp(
    namespace A {
      namespace B {
        struct S1 {};
        S1 foo();
        auto $x[[x]] = foo();
 
        struct S2 {
          template <typename T>
          struct Inner {};
        };
        S2::Inner<int> bar();
        auto $y[[y]] = bar();
      }
    }
  )cpp",
                  ExpectedHint{": S1", "x"},
                  // FIXME: We want to suppress scope specifiers
                  //        here because we are into the whole
                  //        brevity thing, but the ElaboratedType
                  //        printer does not honor the SuppressScope
                  //        flag by design, so we need to extend the
                  //        PrintingPolicy to support this use case.
                  ExpectedHint{": S2::Inner<int>", "y"});
}
 
TEST(TypeHints, Lambda) {
  // Do not print something overly verbose like the lambda's location.
  // Show hints for init-captures (but not regular captures).
  assertTypeHints(R"cpp(
    void f() {
      int cap = 42;
      auto $L[[L]] = [cap, $init[[init]] = 1 + 1](int a$ret[[)]] { 
        return a + cap + init; 
      };
    }
  )cpp",
                  ExpectedHint{": (lambda)", "L"},
                  ExpectedHint{": int", "init"}, ExpectedHint{"-> int", "ret"});
 
  // Lambda return hint shown even if no param list.
  // (The digraph :> is just a ] that doesn't conflict with the annotations).
  assertTypeHints("auto $L[[x]] = <:$ret[[:>]]{return 42;};",
                  ExpectedHint{": (lambda)", "L"},
                  ExpectedHint{"-> int", "ret"});
}
 
// Structured bindings tests.
// Note, we hint the individual bindings, not the aggregate.
 
TEST(TypeHints, StructuredBindings_PublicStruct) {
  assertTypeHints(R"cpp(
    // Struct with public fields.
    struct Point {
      int x;
      int y;
    };
    Point foo();
    auto [$x[[x]], $y[[y]]] = foo();
  )cpp",
                  ExpectedHint{": int", "x"}, ExpectedHint{": int", "y"});
}
 
TEST(TypeHints, StructuredBindings_Array) {
  assertTypeHints(R"cpp(
    int arr[2];
    auto [$x[[x]], $y[[y]]] = arr;
  )cpp",
                  ExpectedHint{": int", "x"}, ExpectedHint{": int", "y"});
}
 
TEST(TypeHints, StructuredBindings_TupleLike) {
  assertTypeHints(R"cpp(
    // Tuple-like type.
    struct IntPair {
      int a;
      int b;
    };
    namespace std {
      template <typename T>
      struct tuple_size {};
      template <>
      struct tuple_size<IntPair> {
        constexpr static unsigned value = 2;
      };
      template <unsigned I, typename T>
      struct tuple_element {};
      template <unsigned I>
      struct tuple_element<I, IntPair> {
        using type = int;
      };
    }
    template <unsigned I>
    int get(const IntPair& p) {
      if constexpr (I == 0) {
        return p.a;
      } else if constexpr (I == 1) {
        return p.b;
      }
    }
    IntPair bar();
    auto [$x[[x]], $y[[y]]] = bar();
  )cpp",
                  ExpectedHint{": int", "x"}, ExpectedHint{": int", "y"});
}
 
TEST(TypeHints, StructuredBindings_NoInitializer) {
  assertTypeHints(R"cpp(
    // No initializer (ill-formed).
    // Do not show useless "NULL TYPE" hint.    
    auto [x, y];  /*error-ok*/
  )cpp");
}
 
TEST(TypeHints, ReturnTypeDeduction) {
  assertTypeHints(
      R"cpp(
    auto f1(int x$ret1a[[)]];  // Hint forward declaration too
    auto f1(int x$ret1b[[)]] { return x + 1; }
 
    // Include pointer operators in hint
    int s;
    auto& f2($ret2[[)]] { return s; }
 
    // Do not hint `auto` for trailing return type.
    auto f3() -> int;
 
    // Do not hint when a trailing return type is specified.
    auto f4() -> auto* { return "foo"; }
 
    auto f5($noreturn[[)]] {}
 
    // `auto` conversion operator
    struct A {
      operator auto($retConv[[)]] { return 42; }
    };
 
    // FIXME: Dependent types do not work yet.
    template <typename T>
    struct S {
      auto method() { return T(); }
    };
  )cpp",
      ExpectedHint{"-> int", "ret1a"}, ExpectedHint{"-> int", "ret1b"},
      ExpectedHint{"-> int &", "ret2"}, ExpectedHint{"-> void", "noreturn"},
      ExpectedHint{"-> int", "retConv"});
}
 
TEST(TypeHints, DependentType) {
  assertTypeHints(R"cpp(
    template <typename T>
    void foo(T arg) {
      // The hint would just be "auto" and we can't do any better.
      auto var1 = arg.method();
      // FIXME: It would be nice to show "T" as the hint.
      auto $var2[[var2]] = arg;
    }
  )cpp");
}
 
TEST(TypeHints, LongTypeName) {
  assertTypeHints(R"cpp(
    template <typename, typename, typename>
    struct A {};
    struct MultipleWords {};
    A<MultipleWords, MultipleWords, MultipleWords> foo();
    // Omit type hint past a certain length (currently 32)
    auto var = foo();
  )cpp");
}
 
TEST(TypeHints, DefaultTemplateArgs) {
  assertTypeHints(R"cpp(
    template <typename, typename = int>
    struct A {};
    A<float> foo();
    auto $var[[var]] = foo();
  )cpp",
                  ExpectedHint{": A<float>", "var"});
}
 
TEST(TypeHints, Deduplication) {
  assertTypeHints(R"cpp(
    template <typename T>
    void foo() {
      auto $var[[var]] = 42;
    }
    template void foo<int>();
    template void foo<float>();
  )cpp",
                  ExpectedHint{": int", "var"});
}
 
TEST(TypeHints, SinglyInstantiatedTemplate) {
  assertTypeHints(R"cpp(
    auto $lambda[[x]] = [](auto *$param[[y]], auto) { return 42; };
    int m = x("foo", 3);
  )cpp",
                  ExpectedHint{": (lambda)", "lambda"},
                  ExpectedHint{": const char *", "param"});
 
  // No hint for packs, or auto params following packs
  assertTypeHints(R"cpp(
    int x(auto $a[[a]], auto... b, auto c) { return 42; }
    int m = x<void*, char, float>(nullptr, 'c', 2.0, 2);
  )cpp",
                  ExpectedHint{": void *", "a"});
}
 
TEST(TypeHints, Aliased) {
  // Check that we don't crash for functions without a FunctionTypeLoc.
  // https://github.com/clangd/clangd/issues/1140
  TestTU TU = TestTU::withCode("void foo(void){} extern typeof(foo) foo;");
  TU.ExtraArgs.push_back("-xc");
  auto AST = TU.build();
 
  EXPECT_THAT(hintsOfKind(AST, InlayHintKind::Type), IsEmpty());
}
 
TEST(DesignatorHints, Basic) {
  assertDesignatorHints(R"cpp(
    struct S { int x, y, z; };
    S s {$x[[1]], $y[[2+2]]};
 
    int x[] = {$0[[0]], $1[[1]]};
  )cpp",
                        ExpectedHint{".x=", "x"}, ExpectedHint{".y=", "y"},
                        ExpectedHint{"[0]=", "0"}, ExpectedHint{"[1]=", "1"});
}
 
TEST(DesignatorHints, Nested) {
  assertDesignatorHints(R"cpp(
    struct Inner { int x, y; };
    struct Outer { Inner a, b; };
    Outer o{ $a[[{ $x[[1]], $y[[2]] }]], $bx[[3]] };
  )cpp",
                        ExpectedHint{".a=", "a"}, ExpectedHint{".x=", "x"},
                        ExpectedHint{".y=", "y"}, ExpectedHint{".b.x=", "bx"});
}
 
TEST(DesignatorHints, AnonymousRecord) {
  assertDesignatorHints(R"cpp(
    struct S {
      union {
        struct {
          struct {
            int y;
          };
        } x;
      };
    };
    S s{$xy[[42]]};
  )cpp",
                        ExpectedHint{".x.y=", "xy"});
}
 
TEST(DesignatorHints, Suppression) {
  assertDesignatorHints(R"cpp(
    struct Point { int a, b, c, d, e, f, g, h; };
    Point p{/*a=*/1, .c=2, /* .d = */3, $e[[4]]};
  )cpp",
                        ExpectedHint{".e=", "e"});
}
 
TEST(DesignatorHints, StdArray) {
  // Designators for std::array should be [0] rather than .__elements[0].
  // While technically correct, the designator is useless and horrible to read.
  assertDesignatorHints(R"cpp(
    template <typename T, int N> struct Array { T __elements[N]; };
    Array<int, 2> x = {$0[[0]], $1[[1]]};
  )cpp",
                        ExpectedHint{"[0]=", "0"}, ExpectedHint{"[1]=", "1"});
}
 
TEST(DesignatorHints, OnlyAggregateInit) {
  assertDesignatorHints(R"cpp(
    struct Copyable { int x; } c;
    Copyable d{c};
 
    struct Constructible { Constructible(int x); };
    Constructible x{42};
  )cpp" /*no designator hints expected (but param hints!)*/);
}
 
TEST(InlayHints, RestrictRange) {
  Annotations Code(R"cpp(
    auto a = false;
    [[auto b = 1;
    auto c = '2';]]
    auto d = 3.f;
  )cpp");
  auto AST = TestTU::withCode(Code.code()).build();
  EXPECT_THAT(inlayHints(AST, Code.range()),
              ElementsAre(labelIs(": int"), labelIs(": char")));
}
 
// FIXME: Low-hanging fruit where we could omit a type hint:
//  - auto x = TypeName(...);
//  - auto x = (TypeName) (...);
//  - auto x = static_cast<TypeName>(...);  // and other built-in casts
 
// Annoyances for which a heuristic is not obvious:
//  - auto x = llvm::dyn_cast<LongTypeName>(y);  // and similar
//  - stdlib algos return unwieldy __normal_iterator<X*, ...> type
//    (For this one, perhaps we should omit type hints that start
//     with a double underscore.)
 
} // namespace
} // namespace clangd
} // namespace clang