[clang] static operators should evaluate object argument (reland)

[SuperSodaSea]

Description

clang don't evaluate the object argument of static operator() and static operator[] currently, for example:

#include <iostream>

struct Foo {
    static int operator()(int x, int y) {
        std::cout << "Foo::operator()" << std::endl;
        return x + y;
    }
    static int operator[](int x, int y) {
        std::cout << "Foo::operator[]" << std::endl;
        return x + y;
    }
};
Foo getFoo() {
    std::cout << "getFoo()" << std::endl;
    return {};
}
int main() {
    std::cout << getFoo()(1, 2) << std::endl;
    std::cout << getFoo()[1, 2] << std::endl;
}

getFoo() is expected to be called, but clang don't call it currently (17.0.6). This PR fixes this issue.

Fixes #67976, reland #68485.

Walkthrough

• clang/lib/Sema/SemaOverload.cpp
  • Sema::CreateOverloadedArraySubscriptExpr & Sema::BuildCallToObjectOfClassType
    Previously clang generate CallExpr for static operators, ignoring the object argument. In this PR CXXOperatorCallExpr is generated for static operators instead, with the object argument as the first argument.
  • TryObjectArgumentInitialization
const / volatile objects are allowed for static methods, so that we can call static operators on them.
• clang/lib/CodeGen/CGExpr.cpp
  • CodeGenFunction::EmitCall
    CodeGen changes for CXXOperatorCallExpr with static operators: emit and ignore the object argument first, then emit the operator call.
• clang/lib/AST/ExprConstant.cpp
  • ‎ExprEvaluatorBase::handleCallExpr‎
    Evaluation of static operators in constexpr also need some small changes to work, so that the arguments won't be out of position.
• clang/lib/Sema/SemaChecking.cpp
  • Sema::CheckFunctionCall
    Code for argument checking also need to be modify, or it will fail the test clang/test/SemaCXX/overloaded-operator-decl.cpp.
• clang-tools-extra/clangd/InlayHints.cpp
  • InlayHintVisitor::VisitCallExpr
    Now that the CXXOperatorCallExpr for static operators also have object argument, we should also take care of this situation in clangd.

Tests

• Added:
  • clang/test/AST/ast-dump-static-operators.cpp
    Verify the AST generated for static operators.
  • clang/test/SemaCXX/cxx2b-static-operator.cpp
    Static operators should be able to be called on const / volatile objects.
• Modified:
  • clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp
  • clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp
    Matching the new CodeGen.

Documentation

• clang/docs/ReleaseNotes.rst
  Update release notes.

[llvmbot]

@llvm/pr-subscribers-clangd

@llvm/pr-subscribers-clang-codegen

Author: Tianlan Zhou (SuperSodaSea)

Changes

Description

clang don't evaluate the object argument of static operator() and static operator[] currently, for example:

#include <iostream>

struct Foo {
    static int operator()(int x, int y) {
        std::cout << "Foo::operator()" << std::endl;
        return x + y;
    }
    static int operator[](int x, int y) {
        std::cout << "Foo::operator[]" << std::endl;
        return x + y;
    }
};
Foo getFoo() {
    std::cout << "getFoo()" << std::endl;
    return {};
}
int main() {
    std::cout << getFoo()(1, 2) << std::endl;
    std::cout << getFoo()[1, 2] << std::endl;
}

getFoo() is expected to be called, but clang don't call it currently (17.0.6). This PR fixes this issue.

Fixes #67976, reland #68485.

Walkthrough

• clang/lib/Sema/SemaOverload.cpp
  • Sema::CreateOverloadedArraySubscriptExpr & Sema::BuildCallToObjectOfClassType
    Previously clang generate CallExpr for static operators, ignoring the object argument. In this PR CXXOperatorCallExpr is generated for static operators instead, with the object argument as the first argument.
  • TryObjectArgumentInitialization
const / volatile objects are allowed for static methods, so that we can call static operators on them.
• clang/lib/CodeGen/CGExpr.cpp
  • CodeGenFunction::EmitCall
    CodeGen changes for CXXOperatorCallExpr with static operators: emit and ignore the object argument first, then emit the operator call.
• clang/lib/AST/ExprConstant.cpp
  • ‎ExprEvaluatorBase::handleCallExpr‎
    Evaluation of static operators in constexpr also need some small changes to work, so that the arguments won't be out of position.
• clang/lib/Sema/SemaChecking.cpp
  • Sema::CheckFunctionCall
    Code for argument checking also need to be modify, or it will fail the test clang/test/SemaCXX/overloaded-operator-decl.cpp.
• clang-tools-extra/clangd/InlayHints.cpp
  • InlayHintVisitor::VisitCallExpr
    Now that the CXXOperatorCallExpr for static operators also have object argument, we should also take care of this situation in clangd.

Tests

• Added:
  • clang/test/AST/ast-dump-static-operators.cpp
    Verify the AST generated for static operators.
  • clang/test/SemaCXX/cxx2b-static-operator.cpp
    Static operators should be able to be called on const / volatile objects.
• Modified:
  • clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp
  • clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp
    Matching the new CodeGen.

Documentation

• clang/docs/ReleaseNotes.rst
  Update release notes.

---

Full diff: https://github.com/llvm/llvm-project/pull/80108.diff

10 Files Affected:

• (modified) clang-tools-extra/clangd/InlayHints.cpp (+1-5)
• (modified) clang/docs/ReleaseNotes.rst (+2)
• (modified) clang/lib/AST/ExprConstant.cpp (+7-2)
• (modified) clang/lib/CodeGen/CGExpr.cpp (+15-2)
• (modified) clang/lib/Sema/SemaChecking.cpp (+2-3)
• (modified) clang/lib/Sema/SemaOverload.cpp (+18-26)
• (added) clang/test/AST/ast-dump-static-operators.cpp (+55)
• (modified) clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp (+19-7)
• (modified) clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp (+9-2)
• (added) clang/test/SemaCXX/cxx2b-static-operator.cpp (+31)

diff --git a/clang-tools-extra/clangd/InlayHints.cpp b/clang-tools-extra/clangd/InlayHints.cpp
index c7dce041474a1..671a9c30ffa95 100644
--- a/clang-tools-extra/clangd/InlayHints.cpp
+++ b/clang-tools-extra/clangd/InlayHints.cpp
@@ -651,16 +651,12 @@ class InlayHintVisitor : public RecursiveASTVisitor<InlayHintVisitor> {
     // implied object argument ([over.call.func]), the list of provided
     // arguments is preceded by the implied object argument for the purposes of
     // this correspondence...
-    //
-    // However, we don't have the implied object argument
-    // for static operator() per clang::Sema::BuildCallToObjectOfClassType.
     llvm::ArrayRef<const Expr *> Args = {E->getArgs(), E->getNumArgs()};
     // We don't have the implied object argument through a function pointer
     // either.
     if (const CXXMethodDecl *Method =
             dyn_cast_or_null<CXXMethodDecl>(Callee.Decl))
-      if (Method->isInstance() &&
-          (IsFunctor || Method->hasCXXExplicitFunctionObjectParameter()))
+      if (IsFunctor || Method->hasCXXExplicitFunctionObjectParameter())
         Args = Args.drop_front(1);
     processCall(Callee, Args);
     return true;
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index f0dea0c9bc89b..891623eb13c45 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -147,6 +147,8 @@ Bug Fixes to C++ Support
 - Fix for crash when using a erroneous type in a return statement.
   Fixes (`#63244 <https://github.com/llvm/llvm-project/issues/63244>`_)
   and (`#79745 <https://github.com/llvm/llvm-project/issues/79745>`_)
+- Fix incorrect code generation caused by the object argument of ``static operator()`` and ``static operator[]`` calls not being evaluated.
+  Fixes (`#67976 <https://github.com/llvm/llvm-project/issues/67976>`_)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index a41bdac46c814..63453890d9879 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -7951,7 +7951,8 @@ class ExprEvaluatorBase
       // Overloaded operator calls to member functions are represented as normal
       // calls with '*this' as the first argument.
       const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
-      if (MD && MD->isImplicitObjectMemberFunction()) {
+      if (MD &&
+          (MD->isImplicitObjectMemberFunction() || (OCE && MD->isStatic()))) {
         // FIXME: When selecting an implicit conversion for an overloaded
         // operator delete, we sometimes try to evaluate calls to conversion
         // operators without a 'this' parameter!
@@ -7960,7 +7961,11 @@ class ExprEvaluatorBase
 
         if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
           return false;
-        This = &ThisVal;
+
+        // If we are calling a static operator, the 'this' argument needs to be
+        // ignored after being evaluated.
+        if (MD->isInstance())
+          This = &ThisVal;
 
         // If this is syntactically a simple assignment using a trivial
         // assignment operator, start the lifetimes of union members as needed,
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 8c8c937b512ac..4a2f3caad6588 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -5848,6 +5848,7 @@ RValue CodeGenFunction::EmitCall(QualType CalleeType, const CGCallee &OrigCallee
   // destruction order is not necessarily reverse construction order.
   // FIXME: Revisit this based on C++ committee response to unimplementability.
   EvaluationOrder Order = EvaluationOrder::Default;
+  bool StaticOperator = false;
   if (auto *OCE = dyn_cast<CXXOperatorCallExpr>(E)) {
     if (OCE->isAssignmentOp())
       Order = EvaluationOrder::ForceRightToLeft;
@@ -5865,10 +5866,22 @@ RValue CodeGenFunction::EmitCall(QualType CalleeType, const CGCallee &OrigCallee
         break;
       }
     }
+
+    if (const auto *MD =
+            dyn_cast_if_present<CXXMethodDecl>(OCE->getCalleeDecl());
+        MD && MD->isStatic())
+      StaticOperator = true;
   }
 
-  EmitCallArgs(Args, dyn_cast<FunctionProtoType>(FnType), E->arguments(),
-               E->getDirectCallee(), /*ParamsToSkip*/ 0, Order);
+  auto Arguments = E->arguments();
+  if (StaticOperator) {
+    // If we're calling a static operator, we need to emit the object argument
+    // and ignore it.
+    EmitIgnoredExpr(E->getArg(0));
+    Arguments = drop_begin(Arguments, 1);
+  }
+  EmitCallArgs(Args, dyn_cast<FunctionProtoType>(FnType), Arguments,
+               E->getDirectCallee(), /*ParamsToSkip=*/0, Order);
 
   const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeFreeFunctionCall(
       Args, FnType, /*ChainCall=*/Chain);
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 502b24bcdf8b4..fc91f5d3f8f88 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -7611,9 +7611,8 @@ bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
   unsigned NumArgs = TheCall->getNumArgs();
 
   Expr *ImplicitThis = nullptr;
-  if (IsMemberOperatorCall && !FDecl->isStatic() &&
-      !FDecl->hasCXXExplicitFunctionObjectParameter()) {
-    // If this is a call to a non-static member operator, hide the first
+  if (IsMemberOperatorCall && !FDecl->hasCXXExplicitFunctionObjectParameter()) {
+    // If this is a call to a member operator, hide the first
     // argument from checkCall.
     // FIXME: Our choice of AST representation here is less than ideal.
     ImplicitThis = Args[0];
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index c9eb678983563..940bcccb9e261 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -5664,10 +5664,15 @@ static ImplicitConversionSequence TryObjectArgumentInitialization(
   assert(FromType->isRecordType());
 
   QualType ClassType = S.Context.getTypeDeclType(ActingContext);
-  // [class.dtor]p2: A destructor can be invoked for a const, volatile or
-  //                 const volatile object.
+  // C++98 [class.dtor]p2:
+  //   A destructor can be invoked for a const, volatile or const volatile
+  //   object.
+  // C++98 [over.match.funcs]p4:
+  //   For static member functions, the implicit object parameter is considered
+  //   to match any object (since if the function is selected, the object is
+  //   discarded).
   Qualifiers Quals = Method->getMethodQualifiers();
-  if (isa<CXXDestructorDecl>(Method)) {
+  if (isa<CXXDestructorDecl>(Method) || Method->isStatic()) {
     Quals.addConst();
     Quals.addVolatile();
   }
@@ -15061,7 +15066,7 @@ ExprResult Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
         CXXMethodDecl *Method = cast<CXXMethodDecl>(FnDecl);
         SmallVector<Expr *, 2> MethodArgs;
 
-        // Handle 'this' parameter if the selected function is not static.
+        // Initialize the object parameter.
         if (Method->isExplicitObjectMemberFunction()) {
           ExprResult Res =
               InitializeExplicitObjectArgument(*this, Args[0], Method);
@@ -15069,7 +15074,7 @@ ExprResult Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
             return ExprError();
           Args[0] = Res.get();
           ArgExpr = Args;
-        } else if (Method->isInstance()) {
+        } else {
           ExprResult Arg0 = PerformImplicitObjectArgumentInitialization(
               Args[0], /*Qualifier=*/nullptr, Best->FoundDecl, Method);
           if (Arg0.isInvalid())
@@ -15097,15 +15102,9 @@ ExprResult Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
         ExprValueKind VK = Expr::getValueKindForType(ResultTy);
         ResultTy = ResultTy.getNonLValueExprType(Context);
 
-        CallExpr *TheCall;
-        if (Method->isInstance())
-          TheCall = CXXOperatorCallExpr::Create(
-              Context, OO_Subscript, FnExpr.get(), MethodArgs, ResultTy, VK,
-              RLoc, CurFPFeatureOverrides());
-        else
-          TheCall =
-              CallExpr::Create(Context, FnExpr.get(), MethodArgs, ResultTy, VK,
-                               RLoc, CurFPFeatureOverrides());
+        CallExpr *TheCall = CXXOperatorCallExpr::Create(
+            Context, OO_Subscript, FnExpr.get(), MethodArgs, ResultTy, VK, RLoc,
+            CurFPFeatureOverrides());
 
         if (CheckCallReturnType(FnDecl->getReturnType(), LLoc, TheCall, FnDecl))
           return ExprError();
@@ -15733,15 +15732,13 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
 
   bool IsError = false;
 
-  // Initialize the implicit object parameter if needed.
-  // Since C++23, this could also be a call to a static call operator
-  // which we emit as a regular CallExpr.
+  // Initialize the object parameter.
   llvm::SmallVector<Expr *, 8> NewArgs;
   if (Method->isExplicitObjectMemberFunction()) {
     // FIXME: we should do that during the definition of the lambda when we can.
     DiagnoseInvalidExplicitObjectParameterInLambda(Method);
     PrepareExplicitObjectArgument(*this, Method, Obj, Args, NewArgs);
-  } else if (Method->isInstance()) {
+  } else {
     ExprResult ObjRes = PerformImplicitObjectArgumentInitialization(
         Object.get(), /*Qualifier=*/nullptr, Best->FoundDecl, Method);
     if (ObjRes.isInvalid())
@@ -15775,14 +15772,9 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
   ExprValueKind VK = Expr::getValueKindForType(ResultTy);
   ResultTy = ResultTy.getNonLValueExprType(Context);
 
-  CallExpr *TheCall;
-  if (Method->isInstance())
-    TheCall = CXXOperatorCallExpr::Create(Context, OO_Call, NewFn.get(),
-                                          MethodArgs, ResultTy, VK, RParenLoc,
-                                          CurFPFeatureOverrides());
-  else
-    TheCall = CallExpr::Create(Context, NewFn.get(), MethodArgs, ResultTy, VK,
-                               RParenLoc, CurFPFeatureOverrides());
+  CallExpr *TheCall = CXXOperatorCallExpr::Create(
+      Context, OO_Call, NewFn.get(), MethodArgs, ResultTy, VK, RParenLoc,
+      CurFPFeatureOverrides());
 
   if (CheckCallReturnType(Method->getReturnType(), LParenLoc, TheCall, Method))
     return true;
diff --git a/clang/test/AST/ast-dump-static-operators.cpp b/clang/test/AST/ast-dump-static-operators.cpp
new file mode 100644
index 0000000000000..e8454bdac02f7
--- /dev/null
+++ b/clang/test/AST/ast-dump-static-operators.cpp
@@ -0,0 +1,55 @@
+// RUN: %clang_cc1 -std=c++23 %s -ast-dump -triple x86_64-unknown-unknown -o - | FileCheck -strict-whitespace %s
+
+struct Functor {
+  static int operator()(int x, int y) {
+    return x + y;
+  }
+  static int operator[](int x, int y) {
+    return x + y;
+  }
+};
+
+Functor& get_functor() {
+  static Functor functor;
+  return functor;
+}
+
+void call_static_operators() {
+  Functor functor;
+
+  int z1 = functor(1, 2);
+  // CHECK:      CXXOperatorCallExpr {{.*}} 'int' '()'
+  // CHECK-NEXT: |-ImplicitCastExpr {{.*}} <col:19, col:24> 'int (*)(int, int)' <FunctionToPointerDecay>
+  // CHECK-NEXT: | `-DeclRefExpr {{.*}} <col:19, col:24> 'int (int, int)' lvalue CXXMethod {{.*}} 'operator()' 'int (int, int)'
+  // CHECK-NEXT: |-DeclRefExpr {{.*}} <col:12> 'Functor' lvalue Var {{.*}} 'functor' 'Functor'
+  // CHECK-NEXT: |-IntegerLiteral {{.*}} <col:20> 'int' 1
+  // CHECK-NEXT: `-IntegerLiteral {{.*}} <col:23> 'int' 2
+
+  int z2 = functor[1, 2];
+  // CHECK:      CXXOperatorCallExpr {{.*}} 'int' '[]'
+  // CHECK-NEXT: |-ImplicitCastExpr {{.*}} <col:19, col:24> 'int (*)(int, int)' <FunctionToPointerDecay>
+  // CHECK-NEXT: | `-DeclRefExpr {{.*}} <col:19, col:24> 'int (int, int)' lvalue CXXMethod {{.*}} 'operator[]' 'int (int, int)'
+  // CHECK-NEXT: |-DeclRefExpr {{.*}} <col:12> 'Functor' lvalue Var {{.*}} 'functor' 'Functor'
+  // CHECK-NEXT: |-IntegerLiteral {{.*}} <col:20> 'int' 1
+  // CHECK-NEXT: `-IntegerLiteral {{.*}} <col:23> 'int' 2
+
+  int z3 = get_functor()(1, 2);
+  // CHECK:      CXXOperatorCallExpr {{.*}} 'int' '()'
+  // CHECK-NEXT: |-ImplicitCastExpr {{.*}} <col:25, col:30> 'int (*)(int, int)' <FunctionToPointerDecay>
+  // CHECK-NEXT: | `-DeclRefExpr {{.*}} <col:25, col:30> 'int (int, int)' lvalue CXXMethod {{.*}} 'operator()' 'int (int, int)'
+  // CHECK-NEXT: |-CallExpr {{.*}} <col:12, col:24> 'Functor' lvalue
+  // CHECK-NEXT: | `-ImplicitCastExpr {{.*}} <col:12> 'Functor &(*)()' <FunctionToPointerDecay>
+  // CHECK-NEXT: |   `-DeclRefExpr {{.*}} <col:12> 'Functor &()' lvalue Function {{.*}} 'get_functor' 'Functor &()'
+  // CHECK-NEXT: |-IntegerLiteral {{.*}} <col:26> 'int' 1
+  // CHECK-NEXT: `-IntegerLiteral {{.*}} <col:29> 'int' 2
+
+  int z4 = get_functor()[1, 2];
+  // CHECK:      CXXOperatorCallExpr {{.*}} 'int' '[]'
+  // CHECK-NEXT: |-ImplicitCastExpr {{.*}} <col:25, col:30> 'int (*)(int, int)' <FunctionToPointerDecay>
+  // CHECK-NEXT: | `-DeclRefExpr {{.*}} <col:25, col:30> 'int (int, int)' lvalue CXXMethod {{.*}} 'operator[]' 'int (int, int)'
+  // CHECK-NEXT: |-CallExpr {{.*}} <col:12, col:24> 'Functor' lvalue
+  // CHECK-NEXT: | `-ImplicitCastExpr {{.*}} <col:12> 'Functor &(*)()' <FunctionToPointerDecay>
+  // CHECK-NEXT: |   `-DeclRefExpr {{.*}} <col:12> 'Functor &()' lvalue Function {{.*}} 'get_functor' 'Functor &()'
+  // CHECK-NEXT: |-IntegerLiteral {{.*}} <col:26> 'int' 1
+  // CHECK-NEXT: `-IntegerLiteral {{.*}} <col:29> 'int' 2
+}
diff --git a/clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp b/clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp
index fd53649c9b061..9cf5a7e00e7b4 100644
--- a/clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp
+++ b/clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp
@@ -19,16 +19,22 @@ void CallsTheLambda() {
 
 // CHECK:      define {{.*}}CallsTheLambda{{.*}}
 // CHECK-NEXT: entry:
-// CHECK-NEXT:   %call = call noundef i32 {{.*}}(i32 noundef 1, i32 noundef 2)
+// CHECK:        {{.*}}call {{.*}}GetALambda{{.*}}()
+// CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}(i32 noundef 1, i32 noundef 2)
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }
 
+Functor GetAFunctor() {
+  return {};
+}
+
 void call_static_call_operator() {
   Functor f;
   f(101, 102);
   f.operator()(201, 202);
   Functor{}(301, 302);
   Functor::operator()(401, 402);
+  GetAFunctor()(501, 502);
 }
 
 // CHECK:      define {{.*}}call_static_call_operator{{.*}}
@@ -37,6 +43,8 @@ void call_static_call_operator() {
 // CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 201, i32 noundef 202)
 // CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 301, i32 noundef 302)
 // CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 401, i32 noundef 402)
+// CHECK:        {{.*}}call {{.*}}GetAFunctor{{.*}}()
+// CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 501, i32 noundef 502)
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }
 
@@ -106,12 +114,16 @@ void test_dep_functors() {
 
 // CHECK:      define {{.*}}test_dep_functors{{.*}}
 // CHECK-NEXT: entry:
-// CHECK:        %call = call noundef i32 {{.*}}DepFunctor{{.*}}(float noundef 1.000000e+00)
-// CHECK:        %call1 = call noundef i32 {{.*}}DepFunctor{{.*}}(i1 noundef zeroext true)
-// CHECK:        %call2 = call noundef i32 {{.*}}dep_lambda1{{.*}}(float noundef 1.000000e+00)
-// CHECK:        %call3 = call noundef i32 {{.*}}dep_lambda1{{.*}}(i1 noundef zeroext true)
-// CHECK:        %call4 = call noundef i32 {{.*}}dep_lambda2{{.*}}(float noundef 1.000000e+00)
-// CHECK:        %call5 = call noundef i32 {{.*}}dep_lambda2{{.*}}(i1 noundef zeroext true)
+// CHECK:        {{.*}} = call noundef i32 {{.*}}DepFunctor{{.*}}(float noundef 1.000000e+00)
+// CHECK:        {{.*}} = call noundef i32 {{.*}}DepFunctor{{.*}}(i1 noundef zeroext true)
+// CHECK:        {{.*}}call {{.*}}dep_lambda1{{.*}}()
+// CHECK:        {{.*}} = call noundef i32 {{.*}}dep_lambda1{{.*}}(float noundef 1.000000e+00)
+// CHECK:        {{.*}}call {{.*}}dep_lambda1{{.*}}()
+// CHECK:        {{.*}} = call noundef i32 {{.*}}dep_lambda1{{.*}}(i1 noundef zeroext true)
+// CHECK:        {{.*}}call {{.*}}dep_lambda2{{.*}}()
+// CHECK:        {{.*}} = call noundef i32 {{.*}}dep_lambda2{{.*}}(float noundef 1.000000e+00)
+// CHECK:        {{.*}}call {{.*}}dep_lambda2{{.*}}()
+// CHECK:        {{.*}} = call noundef i32 {{.*}}dep_lambda2{{.*}}(i1 noundef zeroext true)
 // CHECK:        ret void
 // CHECK-NEXT: }
 
diff --git a/clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp b/clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp
index 5dbd2c50cc56b..5d8258978c50d 100644
--- a/clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp
+++ b/clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp
@@ -7,12 +7,17 @@ struct Functor {
   }
 };
 
+Functor GetAFunctor() {
+  return {};
+}
+
 void call_static_subscript_operator() {
   Functor f;
   f[101, 102];
   f.operator[](201, 202);
   Functor{}[301, 302];
   Functor::operator[](401, 402);
+  GetAFunctor()[501, 502];
 }
 
 // CHECK:      define {{.*}}call_static_subscript_operator{{.*}}
@@ -21,6 +26,8 @@ void call_static_subscript_operator() {
 // CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 201, i32 noundef 202)
 // CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 301, i32 noundef 302)
 // CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 401, i32 noundef 402)
+// CHECK:        {{.*}}call {{.*}}GetAFunctor{{.*}}()
+// CHECK-NEXT:   {{.*}} = call noundef i32 {{.*}}Functor{{.*}}(i32 noundef 501, i32 noundef 502)
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }
 
@@ -60,7 +67,7 @@ void test_dep_functors() {
 
 // CHECK:      define {{.*}}test_dep_functors{{.*}}
 // CHECK-NEXT: entry:
-// CHECK:        %call = call noundef i32 {{.*}}DepFunctor{{.*}}(float noundef 1.000000e+00)
-// CHECK:        %call1 = call noundef i32 {{.*}}DepFunctor{{.*}}(i1 noundef zeroext true)
+// CHECK:        {{.*}} = call noundef i32 {{.*}}DepFunctor{{.*}}(float noundef 1.000000e+00)
+// CHECK:        {{.*}} = call noundef i32 {{.*}}DepFunctor{{.*}}(i1 noundef zeroext true)
 // CHECK:        ret void
 // CHECK-NEXT: }
diff --git a/clang/test/SemaCXX/cxx2b-static-operator.cpp b/clang/test/SemaCXX/cxx2b-static-operator.cpp
new file mode 100644
index 0000000000000..4d6f1f76d1315
--- /dev/null
+++ b/clang/test/SemaCXX/cxx2b-static-operator.cpp
@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++23 %s
+
+// expected-no-diagnostics
+
+namespace A {
+
+struct Foo {
+  static int operator()(int a, int b) { return a + b; }
+  static int operator[](int a, int b) { return a + b; }
+};
+
+void ok() {
+  // Should pass regardless of const / volatile
+  Foo foo;
+  foo(1, 2);
+  foo[1, 2];
+
+  const Foo fooC;
+  fooC(1, 2);
+  fooC[1, 2];
+
+  const Foo fooV;
+  fooV(1, 2);
+  fooV[1, 2];
+
+  const volatile Foo fooCV;
+  fooCV(1, 2);
+  fooCV[1, 2];
+}
+
+}

[cor3ntin]

I don;t understand where the change is. isInstance is implied by hasCXXExplicitFunctionObjectParameter so isn't that change doing... nothing?

[SuperSodaSea]

IsFunctor can be true when isInstance() is false, this is the situation (static functor) we are dealing with.

[zyn0217]

See https://github.com/llvm/llvm-project/pull/68485/files#diff-19c518dbc68b30c66e1a2b6bd523c005fb2050dcf1a0e92305df7ab3e1b9e9f3L15744-L15751. The patch actually changes the behavior when we put an implied object argument. (I was replying at wrong place in that PR...)

[zyn0217]

So we may have an implied object argument for static operator() calls without an explicit object parameter, while it was only applied previously to non-static (isInstance()) operator() calls.

[zyn0217]

Thanks again for working on it. The clangd part LGTM, and since the other part was left as-is and had been accepted in our previous attempt #68485, I believe we can now reland the patch.

Please keep an eye on the CI in case we have missed anything else.