[AST] Store "UsesADL" information in CallExpr.

Summary:
Currently the Clang AST doesn't store information about how the callee of a CallExpr was found. Specifically if it was found using ADL.

However, this information is invaluable to tooling. Consider a tool which renames usages of a function. If the originally CallExpr was formed using ADL, then the tooling may need to additionally qualify the replacement.
Without information about how the callee was found, the tooling is left scratching it's head. Additionally, we want to be able to match ADL calls as quickly as possible, which means avoiding computing the answer on the fly.

This patch changes `CallExpr` to store whether it's callee was found using ADL. It does not change the size of any AST nodes.


Reviewers: fowles, rsmith, klimek, shafik

Reviewed By: rsmith

Subscribers: aaron.ballman, riccibruno, calabrese, titus, cfe-commits

Differential Revision: https://reviews.llvm.org/D55534

llvm-svn: 348977

19 files changed, 264 insertions, 81 deletions

diff --git a/clang/docs/LibASTMatchersReference.html b/clang/docs/LibASTMatchersReference.html
index b5e6199c314..0a8a5a95faf 100644
--- a/clang/docs/LibASTMatchersReference.html
+++ b/clang/docs/LibASTMatchersReference.html
@@ -2562,6 +2562,28 @@ Example matches f(0, 0) (matcher = callExpr(argumentCountIs(2)))
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1CallExpr.html">CallExpr</a>&gt;</td><td class="name" onclick="toggle('usesADL0')"><a name="usesADL0Anchor">usesADL</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="usesADL0"><pre>Matches call expressions which were resolved using ADL.
+
+Example matches y(x) but not y(42) or NS::y(x).
+  namespace NS {
+    struct X {};
+    void y(X);
+  }
+
+  void y(...);
+
+  void test() {
+    NS::X x;
+    y(x); // Matches
+    NS::y(x); // Doesn't match
+    y(42); // Doesn't match
+    using NS::y;
+    y(x); // Found by both unqualified lookup and ADL, doesn't match
+   }
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1CastExpr.html">CastExpr</a>&gt;</td><td class="name" onclick="toggle('hasCastKind0')"><a name="hasCastKind0Anchor">hasCastKind</a></td><td>CastKind Kind</td></tr>
 <tr><td colspan="4" class="doc" id="hasCastKind0"><pre>Matches casts that has a given cast kind.
 
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index d082fdd1cc3..d57c45eec04 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -2412,14 +2412,20 @@ class CallExpr : public Expr {
 
   void updateDependenciesFromArg(Expr *Arg);
 
+public:
+  enum class ADLCallKind : bool { NotADL, UsesADL };
+  static constexpr ADLCallKind NotADL = ADLCallKind::NotADL;
+  static constexpr ADLCallKind UsesADL = ADLCallKind::UsesADL;
+
 protected:
   // These versions of the constructor are for derived classes.
   CallExpr(const ASTContext &C, StmtClass SC, Expr *fn,
            ArrayRef<Expr *> preargs, ArrayRef<Expr *> args, QualType t,
-           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0);
+           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0,
+           ADLCallKind UsesADL = NotADL);
   CallExpr(const ASTContext &C, StmtClass SC, Expr *fn, ArrayRef<Expr *> args,
            QualType t, ExprValueKind VK, SourceLocation rparenloc,
-           unsigned MinNumArgs = 0);
+           unsigned MinNumArgs = 0, ADLCallKind UsesADL = NotADL);
   CallExpr(const ASTContext &C, StmtClass SC, unsigned NumPreArgs,
            unsigned NumArgs, EmptyShell Empty);
 
@@ -2443,7 +2449,8 @@ public:
   /// arguments. The actual number of arguments will be the greater of
   /// args.size() and MinNumArgs.
   CallExpr(const ASTContext &C, Expr *fn, ArrayRef<Expr *> args, QualType t,
-           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0);
+           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0,
+           ADLCallKind UsesADL = NotADL);
 
   /// Build an empty call expression.
   CallExpr(const ASTContext &C, unsigned NumArgs, EmptyShell Empty);
@@ -2452,6 +2459,14 @@ public:
   Expr *getCallee() { return cast<Expr>(SubExprs[FN]); }
   void setCallee(Expr *F) { SubExprs[FN] = F; }
 
+  ADLCallKind getADLCallKind() const {
+    return static_cast<ADLCallKind>(CallExprBits.UsesADL);
+  }
+  void setADLCallKind(ADLCallKind V = UsesADL) {
+    CallExprBits.UsesADL = static_cast<bool>(V);
+  }
+  bool usesADL() const { return getADLCallKind() == UsesADL; }
+
   Decl *getCalleeDecl();
   const Decl *getCalleeDecl() const {
     return const_cast<CallExpr*>(this)->getCalleeDecl();
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index 33c014e068e..f39bddb040e 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -90,10 +90,12 @@ public:
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
 
-  CXXOperatorCallExpr(ASTContext& C, OverloadedOperatorKind Op, Expr *fn,
-                      ArrayRef<Expr*> args, QualType t, ExprValueKind VK,
-                      SourceLocation operatorloc, FPOptions FPFeatures)
-      : CallExpr(C, CXXOperatorCallExprClass, fn, args, t, VK, operatorloc),
+  CXXOperatorCallExpr(ASTContext &C, OverloadedOperatorKind Op, Expr *fn,
+                      ArrayRef<Expr *> args, QualType t, ExprValueKind VK,
+                      SourceLocation operatorloc, FPOptions FPFeatures,
+                      ADLCallKind UsesADL = NotADL)
+      : CallExpr(C, CXXOperatorCallExprClass, fn, args, t, VK, operatorloc,
+                 /*MinNumArgs=*/0, UsesADL),
         Operator(Op), FPFeatures(FPFeatures) {
     Range = getSourceRangeImpl();
   }
@@ -168,7 +170,8 @@ public:
   CXXMemberCallExpr(ASTContext &C, Expr *fn, ArrayRef<Expr *> args, QualType t,
                     ExprValueKind VK, SourceLocation RP,
                     unsigned MinNumArgs = 0)
-      : CallExpr(C, CXXMemberCallExprClass, fn, args, t, VK, RP, MinNumArgs) {}
+      : CallExpr(C, CXXMemberCallExprClass, fn, args, t, VK, RP, MinNumArgs,
+                 NotADL) {}
 
   CXXMemberCallExpr(ASTContext &C, unsigned NumArgs, EmptyShell Empty)
       : CallExpr(C, CXXMemberCallExprClass, /*NumPreArgs=*/0, NumArgs, Empty) {}
@@ -212,7 +215,7 @@ public:
                      ArrayRef<Expr *> args, QualType t, ExprValueKind VK,
                      SourceLocation RP, unsigned MinNumArgs = 0)
       : CallExpr(C, CUDAKernelCallExprClass, fn, Config, args, t, VK, RP,
-                 MinNumArgs) {}
+                 MinNumArgs, NotADL) {}
 
   CUDAKernelCallExpr(ASTContext &C, unsigned NumArgs, EmptyShell Empty)
       : CallExpr(C, CUDAKernelCallExprClass, /*NumPreArgs=*/END_PREARG, NumArgs,
@@ -487,16 +490,17 @@ public:
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
 
-  UserDefinedLiteral(const ASTContext &C, Expr *Fn, ArrayRef<Expr*> Args,
+  UserDefinedLiteral(const ASTContext &C, Expr *Fn, ArrayRef<Expr *> Args,
                      QualType T, ExprValueKind VK, SourceLocation LitEndLoc,
                      SourceLocation SuffixLoc)
-      : CallExpr(C, UserDefinedLiteralClass, Fn, Args, T, VK, LitEndLoc),
+      : CallExpr(C, UserDefinedLiteralClass, Fn, Args, T, VK, LitEndLoc,
+                 /*MinNumArgs=*/0, NotADL),
         UDSuffixLoc(SuffixLoc) {}
 
   explicit UserDefinedLiteral(const ASTContext &C, unsigned NumArgs,
                               EmptyShell Empty)
-      : CallExpr(C, UserDefinedLiteralClass, /*NumPreArgs=*/0, NumArgs,
-                 Empty) {}
+      : CallExpr(C, UserDefinedLiteralClass, /*NumPreArgs=*/0, NumArgs, Empty) {
+  }
 
   /// The kind of literal operator which is invoked.
   enum LiteralOperatorKind {
diff --git a/clang/include/clang/AST/Stmt.h b/clang/include/clang/AST/Stmt.h
index 0d1ca0a406b..23ac5af7ae0 100644
--- a/clang/include/clang/AST/Stmt.h
+++ b/clang/include/clang/AST/Stmt.h
@@ -430,6 +430,9 @@ protected:
     unsigned : NumExprBits;
 
     unsigned NumPreArgs : 1;
+
+    /// True if the callee of the call expression was found using ADL.
+    unsigned UsesADL : 1;
   };
 
   class MemberExprBitfields {
diff --git a/clang/include/clang/ASTMatchers/ASTMatchers.h b/clang/include/clang/ASTMatchers/ASTMatchers.h
index ea3448ac62f..e06bda7d3ef 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchers.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -1257,6 +1257,28 @@ extern const internal::VariadicDynCastAllOfMatcher<Stmt,
 /// \endcode
 extern const internal::VariadicDynCastAllOfMatcher<Stmt, CallExpr> callExpr;
 
+/// Matches call expressions which were resolved using ADL.
+///
+/// Example matches y(x) but not y(42) or NS::y(x).
+/// \code
+///   namespace NS {
+///     struct X {};
+///     void y(X);
+///   }
+///
+///   void y(...);
+///
+///   void test() {
+///     NS::X x;
+///     y(x); // Matches
+///     NS::y(x); // Doesn't match
+///     y(42); // Doesn't match
+///     using NS::y;
+///     y(x); // Found by both unqualified lookup and ADL, doesn't match
+//    }
+/// \endcode
+AST_MATCHER(CallExpr, usesADL) { return Node.usesADL(); }
+
 /// Matches lambda expressions.
 ///
 /// Example matches [&](){return 5;}
diff --git a/clang/include/clang/Sema/Overload.h b/clang/include/clang/Sema/Overload.h
index 6ded010ee8e..96fd5892daa 100644
--- a/clang/include/clang/Sema/Overload.h
+++ b/clang/include/clang/Sema/Overload.h
@@ -755,12 +755,12 @@ class Sema;
     ConversionFixItGenerator Fix;
 
     /// Viable - True to indicate that this overload candidate is viable.
-    bool Viable;
+    bool Viable : 1;
 
     /// IsSurrogate - True to indicate that this candidate is a
     /// surrogate for a conversion to a function pointer or reference
     /// (C++ [over.call.object]).
-    bool IsSurrogate;
+    bool IsSurrogate : 1;
 
     /// IgnoreObjectArgument - True to indicate that the first
     /// argument's conversion, which for this function represents the
@@ -769,7 +769,10 @@ class Sema;
     /// implicit object argument is just a placeholder) or a
     /// non-static member function when the call doesn't have an
     /// object argument.
-    bool IgnoreObjectArgument;
+    bool IgnoreObjectArgument : 1;
+
+    /// True if the candidate was found using ADL.
+    CallExpr::ADLCallKind IsADLCandidate : 1;
 
     /// FailureKind - The reason why this candidate is not viable.
     /// Actually an OverloadFailureKind.
@@ -823,6 +826,10 @@ class Sema;
         return Function->getNumParams();
       return ExplicitCallArguments;
     }
+
+  private:
+    friend class OverloadCandidateSet;
+    OverloadCandidate() : IsADLCandidate(CallExpr::NotADL) {}
   };
 
   /// OverloadCandidateSet - A set of overload candidates, used in C++
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index e67e918e99c..8a8af52b932 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -2749,13 +2749,15 @@ public:
   typedef llvm::SmallSetVector<DeclContext   *, 16> AssociatedNamespaceSet;
   typedef llvm::SmallSetVector<CXXRecordDecl *, 16> AssociatedClassSet;
 
-  void AddOverloadCandidate(FunctionDecl *Function,
-                            DeclAccessPair FoundDecl,
+  using ADLCallKind = CallExpr::ADLCallKind;
+
+  void AddOverloadCandidate(FunctionDecl *Function, DeclAccessPair FoundDecl,
                             ArrayRef<Expr *> Args,
                             OverloadCandidateSet &CandidateSet,
                             bool SuppressUserConversions = false,
                             bool PartialOverloading = false,
                             bool AllowExplicit = false,
+                            ADLCallKind IsADLCandidate = ADLCallKind::NotADL,
                             ConversionSequenceList EarlyConversions = None);
   void AddFunctionCandidates(const UnresolvedSetImpl &Functions,
                       ArrayRef<Expr *> Args,
@@ -2789,13 +2791,12 @@ public:
                                   OverloadCandidateSet& CandidateSet,
                                   bool SuppressUserConversions = false,
                                   bool PartialOverloading = false);
-  void AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
-                                    DeclAccessPair FoundDecl,
-                                 TemplateArgumentListInfo *ExplicitTemplateArgs,
-                                    ArrayRef<Expr *> Args,
-                                    OverloadCandidateSet& CandidateSet,
-                                    bool SuppressUserConversions = false,
-                                    bool PartialOverloading = false);
+  void AddTemplateOverloadCandidate(
+      FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
+      TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
+      OverloadCandidateSet &CandidateSet, bool SuppressUserConversions = false,
+      bool PartialOverloading = false,
+      ADLCallKind IsADLCandidate = ADLCallKind::NotADL);
   bool CheckNonDependentConversions(FunctionTemplateDecl *FunctionTemplate,
                                     ArrayRef<QualType> ParamTypes,
                                     ArrayRef<Expr *> Args,
@@ -4387,12 +4388,11 @@ public:
                            MultiExprArg ArgExprs, SourceLocation RParenLoc,
                            Expr *ExecConfig = nullptr,
                            bool IsExecConfig = false);
-  ExprResult BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
-                                   SourceLocation LParenLoc,
-                                   ArrayRef<Expr *> Arg,
-                                   SourceLocation RParenLoc,
-                                   Expr *Config = nullptr,
-                                   bool IsExecConfig = false);
+  ExprResult
+  BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl, SourceLocation LParenLoc,
+                        ArrayRef<Expr *> Arg, SourceLocation RParenLoc,
+                        Expr *Config = nullptr, bool IsExecConfig = false,
+                        ADLCallKind UsesADL = ADLCallKind::NotADL);
 
   ExprResult ActOnCUDAExecConfigExpr(Scope *S, SourceLocation LLLLoc,
                                      MultiExprArg ExecConfig,
diff --git a/clang/lib/AST/ASTDumper.cpp b/clang/lib/AST/ASTDumper.cpp
index 8137c81d0c4..92cd2396089 100644
--- a/clang/lib/AST/ASTDumper.cpp
+++ b/clang/lib/AST/ASTDumper.cpp
@@ -382,6 +382,7 @@ namespace  {
     void VisitOMPExecutableDirective(const OMPExecutableDirective *Node);
 
     // Exprs
+    void VisitCallExpr(const CallExpr *Node);
     void VisitCastExpr(const CastExpr *Node);
     void VisitImplicitCastExpr(const ImplicitCastExpr *Node);
     void VisitDeclRefExpr(const DeclRefExpr *Node);
@@ -1876,6 +1877,11 @@ static void dumpBasePath(raw_ostream &OS, const CastExpr *Node) {
   OS << ')';
 }
 
+void ASTDumper::VisitCallExpr(const CallExpr *Node) {
+  if (Node->usesADL())
+    OS << " adl";
+}
+
 void ASTDumper::VisitCastExpr(const CastExpr *Node) {
   OS << " <";
   {
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 90724241dbb..6ba80cdaa76 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -7383,12 +7383,13 @@ ExpectedStmt ASTNodeImporter::VisitCallExpr(CallExpr *E) {
   if (const auto *OCE = dyn_cast<CXXOperatorCallExpr>(E)) {
     return new (Importer.getToContext()) CXXOperatorCallExpr(
         Importer.getToContext(), OCE->getOperator(), ToCallee, ToArgs, ToType,
-        OCE->getValueKind(), ToRParenLoc, OCE->getFPFeatures());
+        OCE->getValueKind(), ToRParenLoc, OCE->getFPFeatures(),
+        OCE->getADLCallKind());
   }
 
   return new (Importer.getToContext()) CallExpr(
       Importer.getToContext(), ToCallee, ToArgs, ToType, E->getValueKind(),
-      ToRParenLoc);
+      ToRParenLoc, /*MinNumArgs=*/0, E->getADLCallKind());
 }
 
 ExpectedStmt ASTNodeImporter::VisitLambdaExpr(LambdaExpr *E) {
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 8ff967e26db..751d9137e6b 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1223,11 +1223,13 @@ OverloadedOperatorKind UnaryOperator::getOverloadedOperator(Opcode Opc) {
 CallExpr::CallExpr(const ASTContext &C, StmtClass SC, Expr *fn,
                    ArrayRef<Expr *> preargs, ArrayRef<Expr *> args, QualType t,
                    ExprValueKind VK, SourceLocation rparenloc,
-                   unsigned MinNumArgs)
+                   unsigned MinNumArgs, ADLCallKind UsesADL)
     : Expr(SC, t, VK, OK_Ordinary, fn->isTypeDependent(),
            fn->isValueDependent(), fn->isInstantiationDependent(),
            fn->containsUnexpandedParameterPack()),
       RParenLoc(rparenloc) {
+  CallExprBits.UsesADL = static_cast<bool>(UsesADL);
+
   NumArgs = std::max<unsigned>(args.size(), MinNumArgs);
   unsigned NumPreArgs = preargs.size();
   CallExprBits.NumPreArgs = NumPreArgs;
@@ -1249,15 +1251,16 @@ CallExpr::CallExpr(const ASTContext &C, StmtClass SC, Expr *fn,
 
 CallExpr::CallExpr(const ASTContext &C, StmtClass SC, Expr *fn,
                    ArrayRef<Expr *> args, QualType t, ExprValueKind VK,
-                   SourceLocation rparenloc, unsigned MinNumArgs)
+                   SourceLocation rparenloc, unsigned MinNumArgs,
+                   ADLCallKind UsesADL)
     : CallExpr(C, SC, fn, ArrayRef<Expr *>(), args, t, VK, rparenloc,
-               MinNumArgs) {}
+               MinNumArgs, UsesADL) {}
 
 CallExpr::CallExpr(const ASTContext &C, Expr *fn, ArrayRef<Expr *> args,
                    QualType t, ExprValueKind VK, SourceLocation rparenloc,
-                   unsigned MinNumArgs)
-    : CallExpr(C, CallExprClass, fn, ArrayRef<Expr *>(), args, t, VK,
-               rparenloc, MinNumArgs) {}
+                   unsigned MinNumArgs, ADLCallKind UsesADL)
+    : CallExpr(C, CallExprClass, fn, ArrayRef<Expr *>(), args, t, VK, rparenloc,
+               MinNumArgs, UsesADL) {}
 
 CallExpr::CallExpr(const ASTContext &C, StmtClass SC, unsigned NumPreArgs,
                    unsigned NumArgs, EmptyShell Empty)
diff --git a/clang/lib/ASTMatchers/Dynamic/Registry.cpp b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
index 3ed189a524c..edebb5c43a5 100644
--- a/clang/lib/ASTMatchers/Dynamic/Registry.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
@@ -493,6 +493,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(unresolvedUsingTypenameDecl);
   REGISTER_MATCHER(unresolvedUsingValueDecl);
   REGISTER_MATCHER(userDefinedLiteral);
+  REGISTER_MATCHER(usesADL);
   REGISTER_MATCHER(usingDecl);
   REGISTER_MATCHER(usingDirectiveDecl);
   REGISTER_MATCHER(valueDecl);
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 3ea9c7c8f95..d4180c89da7 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -5585,12 +5585,11 @@ ExprResult Sema::ActOnConvertVectorExpr(Expr *E, ParsedType ParsedDestTy,
 /// block-pointer type.
 ///
 /// \param NDecl the declaration being called, if available
-ExprResult
-Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
-                            SourceLocation LParenLoc,
-                            ArrayRef<Expr *> Args,
-                            SourceLocation RParenLoc,
-                            Expr *Config, bool IsExecConfig) {
+ExprResult Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
+                                       SourceLocation LParenLoc,
+                                       ArrayRef<Expr *> Args,
+                                       SourceLocation RParenLoc, Expr *Config,
+                                       bool IsExecConfig, ADLCallKind UsesADL) {
   FunctionDecl *FDecl = dyn_cast_or_null<FunctionDecl>(NDecl);
   unsigned BuiltinID = (FDecl ? FDecl->getBuiltinID() : 0);
 
@@ -5670,13 +5669,16 @@ Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
   unsigned NumParams = Proto ? Proto->getNumParams() : 0;
 
   CallExpr *TheCall;
-  if (Config)
+  if (Config) {
+    assert(UsesADL == ADLCallKind::NotADL &&
+           "CUDAKernelCallExpr should not use ADL");
     TheCall = new (Context)
         CUDAKernelCallExpr(Context, Fn, cast<CallExpr>(Config), Args, ResultTy,
                            VK_RValue, RParenLoc, NumParams);
-  else
-    TheCall = new (Context)
-        CallExpr(Context, Fn, Args, ResultTy, VK_RValue, RParenLoc, NumParams);
+  } else {
+    TheCall = new (Context) CallExpr(Context, Fn, Args, ResultTy, VK_RValue,
+                                     RParenLoc, NumParams, UsesADL);
+  }
 
   if (!getLangOpts().CPlusPlus) {
     // C cannot always handle TypoExpr nodes in builtin calls and direct
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 22514ee2420..8c4f124b8e6 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -5946,15 +5946,13 @@ static bool IsAcceptableNonMemberOperatorCandidate(ASTContext &Context,
 /// \param PartialOverloading true if we are performing "partial" overloading
 /// based on an incomplete set of function arguments. This feature is used by
 /// code completion.
-void
-Sema::AddOverloadCandidate(FunctionDecl *Function,
-                           DeclAccessPair FoundDecl,
-                           ArrayRef<Expr *> Args,
-                           OverloadCandidateSet &CandidateSet,
-                           bool SuppressUserConversions,
-                           bool PartialOverloading,
-                           bool AllowExplicit,
-                           ConversionSequenceList EarlyConversions) {
+void Sema::AddOverloadCandidate(FunctionDecl *Function,
+                                DeclAccessPair FoundDecl, ArrayRef<Expr *> Args,
+                                OverloadCandidateSet &CandidateSet,
+                                bool SuppressUserConversions,
+                                bool PartialOverloading, bool AllowExplicit,
+                                ADLCallKind IsADLCandidate,
+                                ConversionSequenceList EarlyConversions) {
   const FunctionProtoType *Proto
     = dyn_cast<FunctionProtoType>(Function->getType()->getAs<FunctionType>());
   assert(Proto && "Functions without a prototype cannot be overloaded");
@@ -6013,6 +6011,7 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
   Candidate.Function = Function;
   Candidate.Viable = true;
   Candidate.IsSurrogate = false;
+  Candidate.IsADLCandidate = IsADLCandidate;
   Candidate.IgnoreObjectArgument = false;
   Candidate.ExplicitCallArguments = Args.size();
 
@@ -6715,14 +6714,11 @@ Sema::AddMethodTemplateCandidate(FunctionTemplateDecl *MethodTmpl,
 /// Add a C++ function template specialization as a candidate
 /// in the candidate set, using template argument deduction to produce
 /// an appropriate function template specialization.
-void
-Sema::AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
-                                   DeclAccessPair FoundDecl,
-                                 TemplateArgumentListInfo *ExplicitTemplateArgs,
-                                   ArrayRef<Expr *> Args,
-                                   OverloadCandidateSet& CandidateSet,
-                                   bool SuppressUserConversions,
-                                   bool PartialOverloading) {
+void Sema::AddTemplateOverloadCandidate(
+    FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
+    TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
+    OverloadCandidateSet &CandidateSet, bool SuppressUserConversions,
+    bool PartialOverloading, ADLCallKind IsADLCandidate) {
   if (!CandidateSet.isNewCandidate(FunctionTemplate))
     return;
 
@@ -6751,6 +6747,7 @@ Sema::AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
     Candidate.Function = FunctionTemplate->getTemplatedDecl();
     Candidate.Viable = false;
     Candidate.IsSurrogate = false;
+    Candidate.IsADLCandidate = IsADLCandidate;
     // Ignore the object argument if there is one, since we don't have an object
     // type.
     Candidate.IgnoreObjectArgument =
@@ -6772,7 +6769,7 @@ Sema::AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
   assert(Specialization && "Missing function template specialization?");
   AddOverloadCandidate(Specialization, FoundDecl, Args, CandidateSet,
                        SuppressUserConversions, PartialOverloading,
-                       /*AllowExplicit*/false, Conversions);
+                       /*AllowExplicit*/ false, IsADLCandidate, Conversions);
 }
 
 /// Check that implicit conversion sequences can be formed for each argument
@@ -8935,17 +8932,19 @@ Sema::AddArgumentDependentLookupCandidates(DeclarationName Name,
   // set.
   for (ADLResult::iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
     DeclAccessPair FoundDecl = DeclAccessPair::make(*I, AS_none);
+
     if (FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
       if (ExplicitTemplateArgs)
         continue;
 
       AddOverloadCandidate(FD, FoundDecl, Args, CandidateSet,
-                           /*SupressUserConversions=*/false,
-                           PartialOverloading);
+                           /*SupressUserConversions=*/false, PartialOverloading,
+                           /*AllowExplicit=*/false, ADLCallKind::UsesADL);
     } else {
-     AddTemplateOverloadCandidate(
-          cast<FunctionTemplateDecl>(*I), FoundDecl, ExplicitTemplateArgs, Args,
-          CandidateSet, /*SupressUserConversions=*/false, PartialOverloading);
+      AddTemplateOverloadCandidate(cast<FunctionTemplateDecl>(*I), FoundDecl,
+                                   ExplicitTemplateArgs, Args, CandidateSet,
+                                   /*SupressUserConversions=*/false,
+                                   PartialOverloading, ADLCallKind::UsesADL);
     }
   }
 }
@@ -12023,7 +12022,8 @@ static ExprResult FinishOverloadedCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
       return ExprError();
     Fn = SemaRef.FixOverloadedFunctionReference(Fn, (*Best)->FoundDecl, FDecl);
     return SemaRef.BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, RParenLoc,
-                                         ExecConfig);
+                                         ExecConfig, /*IsExecConfig=*/false,
+                                         (*Best)->IsADLCandidate);
   }
 
   case OR_No_Viable_Function: {
@@ -12075,7 +12075,8 @@ static ExprResult FinishOverloadedCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
     FunctionDecl *FDecl = (*Best)->Function;
     Fn = SemaRef.FixOverloadedFunctionReference(Fn, (*Best)->FoundDecl, FDecl);
     return SemaRef.BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, RParenLoc,
-                                         ExecConfig);
+                                         ExecConfig, /*IsExecConfig=*/false,
+                                         (*Best)->IsADLCandidate);
   }
   }
 
@@ -12264,9 +12265,9 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
       ResultTy = ResultTy.getNonLValueExprType(Context);
 
       Args[0] = Input;
-      CallExpr *TheCall =
-        new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.get(), ArgsArray,
-                                          ResultTy, VK, OpLoc, FPOptions());
+      CallExpr *TheCall = new (Context)
+          CXXOperatorCallExpr(Context, Op, FnExpr.get(), ArgsArray, ResultTy,
+                              VK, OpLoc, FPOptions(), Best->IsADLCandidate);
 
       if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall, FnDecl))
         return ExprError();
@@ -12496,10 +12497,9 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
         ExprValueKind VK = Expr::getValueKindForType(ResultTy);
         ResultTy = ResultTy.getNonLValueExprType(Context);
 
-        CXXOperatorCallExpr *TheCall =
-          new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.get(),
-                                            Args, ResultTy, VK, OpLoc,
-                                            FPFeatures);
+        CXXOperatorCallExpr *TheCall = new (Context)
+            CXXOperatorCallExpr(Context, Op, FnExpr.get(), Args, ResultTy, VK,
+                                OpLoc, FPFeatures, Best->IsADLCandidate);
 
         if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall,
                                 FnDecl))
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index a32e3fc505b..88e7bb64719 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -737,6 +737,7 @@ void ASTStmtReader::VisitCallExpr(CallExpr *E) {
   E->setCallee(Record.readSubExpr());
   for (unsigned I = 0; I != NumArgs; ++I)
     E->setArg(I, Record.readSubExpr());
+  E->setADLCallKind(static_cast<CallExpr::ADLCallKind>(Record.readInt()));
 }
 
 void ASTStmtReader::VisitCXXMemberCallExpr(CXXMemberCallExpr *E) {
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index edc66c57bee..3a14c39fa1d 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -651,6 +651,7 @@ void ASTStmtWriter::VisitCallExpr(CallExpr *E) {
   for (CallExpr::arg_iterator Arg = E->arg_begin(), ArgEnd = E->arg_end();
        Arg != ArgEnd; ++Arg)
     Record.AddStmt(*Arg);
+  Record.push_back(static_cast<unsigned>(E->getADLCallKind()));
   Code = serialization::EXPR_CALL;
 }
 
diff --git a/clang/test/AST/ast-dump-expr.cpp b/clang/test/AST/ast-dump-expr.cpp
index e847fc61647..5d668aad4ae 100644
--- a/clang/test/AST/ast-dump-expr.cpp
+++ b/clang/test/AST/ast-dump-expr.cpp
@@ -508,3 +508,46 @@ void PrimaryExpressions(Ts... a) {
   // CHECK-NEXT: DeclRefExpr 0x{{[^ ]*}} <col:4> 'Ts...' lvalue ParmVar 0x{{[^ ]*}} 'a' 'Ts...'
   // CHECK-NEXT: DeclRefExpr 0x{{[^ ]*}} <col:14> 'int' lvalue Var 0x{{[^ ]*}} 'b' 'int'
 }
+
+
+namespace NS {
+struct X {};
+void f(X);
+void y(...);
+} // namespace NS
+
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}ADLCall 'void ()'
+void ADLCall() {
+  NS::X x;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void' adl{{$}}
+  f(x);
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void' adl{{$}}
+  y(x);
+}
+
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}NonADLCall 'void ()'
+void NonADLCall() {
+  NS::X x;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void'{{$}}
+  NS::f(x);
+}
+
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}NonADLCall2 'void ()'
+void NonADLCall2() {
+  NS::X x;
+  using NS::f;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void'{{$}}
+  f(x);
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void' adl{{$}}
+  y(x);
+}
+
+namespace test_adl_call_three {
+using namespace NS;
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}NonADLCall3 'void ()'
+void NonADLCall3() {
+  X x;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void'{{$}}
+  f(x);
+}
+} // namespace test_adl_call_three
\ No newline at end of file
diff --git a/clang/test/Import/call-expr/Inputs/F.cpp b/clang/test/Import/call-expr/Inputs/F.cpp
new file mode 100644
index 00000000000..bd88df99ba4
--- /dev/null
+++ b/clang/test/Import/call-expr/Inputs/F.cpp
@@ -0,0 +1,10 @@
+namespace NS {
+struct X {};
+void f(X) {}
+void operator+(X, X) {}
+} // namespace NS
+void f() {
+  NS::X x;
+  f(x);
+  x + x;
+}
diff --git a/clang/test/Import/call-expr/test.cpp b/clang/test/Import/call-expr/test.cpp
new file mode 100644
index 00000000000..86c1b50c47d
--- /dev/null
+++ b/clang/test/Import/call-expr/test.cpp
@@ -0,0 +1,8 @@
+// RUN: clang-import-test -dump-ast -import %S/Inputs/F.cpp -expression %s | FileCheck %s
+void expr() {
+  f();
+}
+
+// CHECK: FunctionDecl 0x{{[^ ]*}} <{{[^>]*}}> line:{{.*}}:{{[^ ]*}} used f 'void ()'
+// CHECK: -CallExpr 0x{{[^ ]*}} <{{[^>]*}}> 'void' adl
+// CHECK: -CXXOperatorCallExpr 0x{{[^ ]*}} <{{[^>]*}}> 'void' adl
diff --git a/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
index 9278987cb0b..1bd4e09e776 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
@@ -199,6 +199,40 @@ TEST(Matcher, UnresolvedLookupExpr) {
                                    "-fno-delayed-template-parsing"));
 }
 
+TEST(Matcher, ADLCall) {
+  StatementMatcher ADLMatch = callExpr(usesADL());
+  StatementMatcher ADLMatchOper = cxxOperatorCallExpr(usesADL());
+  auto NS_Str = R"cpp(
+  namespace NS {
+    struct X {};
+    void f(X);
+    void operator+(X, X);
+  }
+  struct MyX {};
+  void f(...);
+  void operator+(MyX, MyX);
+)cpp";
+
+  auto MkStr = [&](std::string Body) -> std::string {
+    std::string S = NS_Str;
+    S += "void test_fn() { " + Body + " }";
+    return S;
+  };
+
+  EXPECT_TRUE(matches(MkStr("NS::X x; f(x);"), ADLMatch));
+  EXPECT_TRUE(notMatches(MkStr("NS::X x; NS::f(x);"), ADLMatch));
+  EXPECT_TRUE(notMatches(MkStr("MyX x; f(x);"), ADLMatch));
+  EXPECT_TRUE(notMatches(MkStr("NS::X x; using NS::f; f(x);"), ADLMatch));
+
+  // Operator call expressions
+  EXPECT_TRUE(matches(MkStr("NS::X x; x + x;"), ADLMatch));
+  EXPECT_TRUE(matches(MkStr("NS::X x; x + x;"), ADLMatchOper));
+  EXPECT_TRUE(notMatches(MkStr("MyX x; x + x;"), ADLMatch));
+  EXPECT_TRUE(notMatches(MkStr("MyX x; x + x;"), ADLMatchOper));
+  EXPECT_TRUE(matches(MkStr("NS::X x; operator+(x, x);"), ADLMatch));
+  EXPECT_TRUE(notMatches(MkStr("NS::X x; NS::operator+(x, x);"), ADLMatch));
+}
+
 TEST(Matcher, Call) {
   // FIXME: Do we want to overload Call() to directly take
   // Matcher<Decl>, too?