From a468c80286c03b55b1a92fdcf640d4fb1bf4e9f9 Mon Sep 17 00:00:00 2001
From: Eric Fiselier <eric@efcs.ca>
Date: Mon, 10 Jul 2017 01:27:22 +0000
Subject: [PATCH] [coroutines] Include the implicit object parameter type when
 looking up coroutine_traits for member functions.

This patch was originally from Toby Allsopp, but I hijacked it and
fixed it up with his permission.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@307513 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaCoroutine.cpp  |  54 ++++++--
 test/SemaCXX/coroutines.cpp | 265 +++++++++++++++++++++++++++++++++++-
 2 files changed, 300 insertions(+), 19 deletions(-)

diff --git a/lib/Sema/SemaCoroutine.cpp b/lib/Sema/SemaCoroutine.cpp
index b05c0998d3..05bf5319a5 100644
--- a/lib/Sema/SemaCoroutine.cpp
+++ b/lib/Sema/SemaCoroutine.cpp
@@ -43,9 +43,10 @@ static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
 
 /// Look up the std::coroutine_traits<...>::promise_type for the given
 /// function type.
-static QualType lookupPromiseType(Sema &S, const FunctionProtoType *FnType,
-                                  SourceLocation KwLoc,
-                                  SourceLocation FuncLoc) {
+static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD,
+                                  SourceLocation KwLoc) {
+  const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
+  const SourceLocation FuncLoc = FD->getLocation();
   // FIXME: Cache std::coroutine_traits once we've found it.
   NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
   if (!StdExp) {
@@ -71,16 +72,35 @@ static QualType lookupPromiseType(Sema &S, const FunctionProtoType *FnType,
     return QualType();
   }
 
-  // Form template argument list for coroutine_traits<R, P1, P2, ...>.
+  // Form template argument list for coroutine_traits<R, P1, P2, ...> according
+  // to [dcl.fct.def.coroutine]3
   TemplateArgumentListInfo Args(KwLoc, KwLoc);
-  Args.addArgument(TemplateArgumentLoc(
-      TemplateArgument(FnType->getReturnType()),
-      S.Context.getTrivialTypeSourceInfo(FnType->getReturnType(), KwLoc)));
-  // FIXME: If the function is a non-static member function, add the type
-  // of the implicit object parameter before the formal parameters.
-  for (QualType T : FnType->getParamTypes())
+  auto AddArg = [&](QualType T) {
     Args.addArgument(TemplateArgumentLoc(
         TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
+  };
+  AddArg(FnType->getReturnType());
+  // If the function is a non-static member function, add the type
+  // of the implicit object parameter before the formal parameters.
+  if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
+    if (MD->isInstance()) {
+      // [over.match.funcs]4
+      // For non-static member functions, the type of the implicit object
+      // parameter is
+      //  — “lvalue reference to cv X” for functions declared without a
+      //    ref-qualifier or with the & ref-qualifier
+      //  — “rvalue reference to cv X” for functions declared with the &&
+      //    ref-qualifier
+      QualType T =
+          MD->getThisType(S.Context)->getAs<PointerType>()->getPointeeType();
+      T = FnType->getRefQualifier() == RQ_RValue
+              ? S.Context.getRValueReferenceType(T)
+              : S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
+      AddArg(T);
+    }
+  }
+  for (QualType T : FnType->getParamTypes())
+    AddArg(T);
 
   // Build the template-id.
   QualType CoroTrait =
@@ -424,12 +444,16 @@ static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
 VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
   assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
   auto *FD = cast<FunctionDecl>(CurContext);
+  bool IsThisDependentType = [&] {
+    if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD))
+      return MD->isInstance() && MD->getThisType(Context)->isDependentType();
+    else
+      return false;
+  }();
 
-  QualType T =
-      FD->getType()->isDependentType()
-          ? Context.DependentTy
-          : lookupPromiseType(*this, FD->getType()->castAs<FunctionProtoType>(),
-                              Loc, FD->getLocation());
+  QualType T = FD->getType()->isDependentType() || IsThisDependentType
+                   ? Context.DependentTy
+                   : lookupPromiseType(*this, FD, Loc);
   if (T.isNull())
     return nullptr;
 
diff --git a/test/SemaCXX/coroutines.cpp b/test/SemaCXX/coroutines.cpp
index 4eedc2162f..6394829f35 100644
--- a/test/SemaCXX/coroutines.cpp
+++ b/test/SemaCXX/coroutines.cpp
@@ -22,8 +22,24 @@ void no_coroutine_traits() {
 
 namespace std {
 namespace experimental {
-template <typename... T>
-struct coroutine_traits; // expected-note {{declared here}}
+
+template <class... Args>
+struct void_t_imp {
+  using type = void;
+};
+template <class... Args>
+using void_t = typename void_t_imp<Args...>::type;
+
+template <class T, class = void>
+struct traits_sfinae_base {};
+
+template <class T>
+struct traits_sfinae_base<T, void_t<typename T::promise_type>> {
+  using promise_type = typename T::promise_type;
+};
+
+template <class Ret, class... Args>
+struct coroutine_traits : public traits_sfinae_base<Ret> {};
 }}  // namespace std::experimental
 
 template<typename Promise> struct coro {};
@@ -50,8 +66,9 @@ struct suspend_never {
   void await_resume() {}
 };
 
-void no_specialization() {
-  co_await a; // expected-error {{implicit instantiation of undefined template 'std::experimental::coroutine_traits<void>'}}
+struct DummyVoidTag {};
+DummyVoidTag no_specialization() { // expected-error {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<DummyVoidTag>' has no member named 'promise_type'}}
+  co_await a;
 }
 
 template <typename... T>
@@ -905,3 +922,243 @@ void test_dependent_param(T t, U) {
   co_return 42;
 }
 template void test_dependent_param(NoCopy<0>, NoCopy<1>); // expected-note {{requested here}}
+
+namespace CoroHandleMemberFunctionTest {
+struct CoroMemberTag {};
+struct BadCoroMemberTag {};
+
+template <class T, class U>
+constexpr bool IsSameV = false;
+template <class T>
+constexpr bool IsSameV<T, T> = true;
+
+template <class T>
+struct TypeTest {
+  template <class U>
+  static constexpr bool IsSame = IsSameV<T, U>;
+
+  template <class... Args>
+  static constexpr bool MatchesArgs = IsSameV<T,
+                                              std::experimental::coroutine_traits<CoroMemberTag, Args...>>;
+};
+
+template <class T>
+struct AwaitReturnsType {
+  bool await_ready() const;
+  void await_suspend(...) const;
+  T await_resume() const;
+};
+
+template <class... CoroTraitsArgs>
+struct CoroMemberPromise {
+  using TraitsT = std::experimental::coroutine_traits<CoroTraitsArgs...>;
+  using TypeTestT = TypeTest<TraitsT>;
+  using AwaitTestT = AwaitReturnsType<TypeTestT>;
+
+  CoroMemberTag get_return_object();
+  suspend_always initial_suspend();
+  suspend_always final_suspend();
+
+  AwaitTestT yield_value(int);
+
+  void return_void();
+  void unhandled_exception();
+};
+
+} // namespace CoroHandleMemberFunctionTest
+
+template <class... Args>
+struct ::std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::CoroMemberTag, Args...> {
+  using promise_type = CoroHandleMemberFunctionTest::CoroMemberPromise<CoroHandleMemberFunctionTest::CoroMemberTag, Args...>;
+};
+
+namespace CoroHandleMemberFunctionTest {
+struct TestType {
+
+  CoroMemberTag test_qual() {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<TestType &>, "");
+    static_assert(!TC.MatchesArgs<TestType>, "");
+    static_assert(!TC.MatchesArgs<TestType *>, "");
+  }
+
+  CoroMemberTag test_sanity(int *) const {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<const TestType &>, ""); // expected-error {{static_assert failed}}
+    static_assert(TC.MatchesArgs<const TestType &>, ""); // expected-error {{static_assert failed}}
+    static_assert(TC.MatchesArgs<const TestType &, int *>, "");
+  }
+
+  CoroMemberTag test_qual(int *, const float &&, volatile void *volatile) const {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<const TestType &, int *, const float &&, volatile void *volatile>, "");
+  }
+
+  CoroMemberTag test_qual() const volatile {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<const volatile TestType &>, "");
+  }
+
+  CoroMemberTag test_ref_qual() & {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<TestType &>, "");
+  }
+  CoroMemberTag test_ref_qual() const & {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<TestType const &>, "");
+  }
+  CoroMemberTag test_ref_qual() && {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<TestType &&>, "");
+  }
+  CoroMemberTag test_ref_qual(const char *&) const volatile && {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<TestType const volatile &&, const char *&>, "");
+  }
+
+  CoroMemberTag test_args(int) {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<TestType &, int>, "");
+  }
+  CoroMemberTag test_args(int, long &, void *) const {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<TestType const &, int, long &, void *>, "");
+  }
+
+  template <class... Args>
+  CoroMemberTag test_member_template(Args...) const && {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<TestType const &&, Args...>, "");
+  }
+
+  static CoroMemberTag test_static() {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<>, "");
+    static_assert(!TC.MatchesArgs<TestType>, "");
+    static_assert(!TC.MatchesArgs<TestType &>, "");
+    static_assert(!TC.MatchesArgs<TestType *>, "");
+  }
+
+  static CoroMemberTag test_static(volatile void *const, char &&) {
+    auto TC = co_yield 0;
+    static_assert(TC.MatchesArgs<volatile void *const, char &&>, "");
+  }
+
+  template <class Dummy>
+  static CoroMemberTag test_static_template(const char *volatile &, unsigned) {
+    auto TC = co_yield 0;
+    using TCT = decltype(TC);
+    static_assert(TCT::MatchesArgs<const char *volatile &, unsigned>, "");
+    static_assert(!TCT::MatchesArgs<TestType &, const char *volatile &, unsigned>, "");
+  }
+
+  BadCoroMemberTag test_diagnostics() {
+    // expected-error@-1 {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::BadCoroMemberTag, CoroHandleMemberFunctionTest::TestType &>' has no member named 'promise_type'}}
+    co_return;
+  }
+  BadCoroMemberTag test_diagnostics(int) const && {
+    // expected-error@-1 {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::BadCoroMemberTag, const CoroHandleMemberFunctionTest::TestType &&, int>' has no member named 'promise_type'}}
+    co_return;
+  }
+
+  static BadCoroMemberTag test_static_diagnostics(long *) {
+    // expected-error@-1 {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::BadCoroMemberTag, long *>' has no member named 'promise_type'}}
+    co_return;
+  }
+};
+
+template CoroMemberTag TestType::test_member_template(long, const char *) const &&;
+template CoroMemberTag TestType::test_static_template<void>(const char *volatile &, unsigned);
+
+template <class... Args>
+struct DepTestType {
+
+  CoroMemberTag test_sanity(int *) const {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<const DepTestType &>, ""); // expected-error {{static_assert failed}}
+    static_assert(TC.template MatchesArgs<>, ""); // expected-error {{static_assert failed}}
+    static_assert(TC.template MatchesArgs<const DepTestType &, int *>, "");
+  }
+
+  CoroMemberTag test_qual() {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType &>, "");
+    static_assert(!TC.template MatchesArgs<DepTestType>, "");
+    static_assert(!TC.template MatchesArgs<DepTestType *>, "");
+  }
+
+  CoroMemberTag test_qual(int *, const float &&, volatile void *volatile) const {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<const DepTestType &, int *, const float &&, volatile void *volatile>, "");
+  }
+
+  CoroMemberTag test_qual() const volatile {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<const volatile DepTestType &>, "");
+  }
+
+  CoroMemberTag test_ref_qual() & {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType &>, "");
+  }
+  CoroMemberTag test_ref_qual() const & {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType const &>, "");
+  }
+  CoroMemberTag test_ref_qual() && {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType &&>, "");
+  }
+  CoroMemberTag test_ref_qual(const char *&) const volatile && {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType const volatile &&, const char *&>, "");
+  }
+
+  CoroMemberTag test_args(int) {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType &, int>, "");
+  }
+  CoroMemberTag test_args(int, long &, void *) const {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType const &, int, long &, void *>, "");
+  }
+
+  template <class... UArgs>
+  CoroMemberTag test_member_template(UArgs...) const && {
+    auto TC = co_yield 0;
+    static_assert(TC.template MatchesArgs<DepTestType const &&, UArgs...>, "");
+  }
+
+  static CoroMemberTag test_static() {
+    auto TC = co_yield 0;
+    using TCT = decltype(TC);
+    static_assert(TCT::MatchesArgs<>, "");
+    static_assert(!TCT::MatchesArgs<DepTestType>, "");
+    static_assert(!TCT::MatchesArgs<DepTestType &>, "");
+    static_assert(!TCT::MatchesArgs<DepTestType *>, "");
+
+    // Ensure diagnostics are actually being generated here
+    static_assert(TCT::MatchesArgs<int>, ""); // expected-error {{static_assert failed}}
+  }
+
+  static CoroMemberTag test_static(volatile void *const, char &&) {
+    auto TC = co_yield 0;
+    using TCT = decltype(TC);
+    static_assert(TCT::MatchesArgs<volatile void *const, char &&>, "");
+  }
+
+  template <class Dummy>
+  static CoroMemberTag test_static_template(const char *volatile &, unsigned) {
+    auto TC = co_yield 0;
+    using TCT = decltype(TC);
+    static_assert(TCT::MatchesArgs<const char *volatile &, unsigned>, "");
+    static_assert(!TCT::MatchesArgs<DepTestType &, const char *volatile &, unsigned>, "");
+  }
+};
+
+template struct DepTestType<int>; // expected-note {{requested here}}
+template CoroMemberTag DepTestType<int>::test_member_template(long, const char *) const &&;
+
+template CoroMemberTag DepTestType<int>::test_static_template<void>(const char *volatile &, unsigned);
+
+} // namespace CoroHandleMemberFunctionTest
-- 
2.40.0