[llvm-branch-commits] [clang] release/19.x: [Clang][Sema] Use the correct lookup context when building overloaded 'operator->' in the current instantiation (#104458) (PR #107886)
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Mon Sep 9 09:13:40 PDT 2024
https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/107886
Backport 3cdb30e
Requested by: @cor3ntin
>From e64fc4127deca57ace68d7ad634b926d10858ab5 Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian at gmail.com>
Date: Mon, 9 Sep 2024 12:06:45 -0400
Subject: [PATCH] [Clang][Sema] Use the correct lookup context when building
overloaded 'operator->' in the current instantiation (#104458)
Currently, clang erroneously rejects the following:
```
struct A
{
template<typename T>
void f();
};
template<typename T>
struct B
{
void g()
{
(*this)->template f<int>(); // error: no member named 'f' in 'B<T>'
}
A* operator->();
};
```
This happens because `Sema::ActOnStartCXXMemberReference` does not adjust the `ObjectType` parameter when `ObjectType` is a dependent type (except when the type is a `PointerType` and the class member access is the `->` form). Since the (possibly adjusted) `ObjectType` parameter (`B<T>` in the above example) is passed to `Parser::ParseOptionalCXXScopeSpecifier`, we end up looking up `f` in `B` rather than `A`.
This patch fixes the issue by identifying cases where the type of the object expression `T` is a dependent, non-pointer type and:
- `T` is the current instantiation and lookup for `operator->` finds a member of the current instantiation, or
- `T` has at least one dependent base case, and `operator->` is not found in the current instantiation
and using `ASTContext::DependentTy` as the type of the object expression when the optional _nested-name-specifier_ is parsed.
Fixes #104268.
(cherry picked from commit 3cdb30ebbc18fa894d3bd67aebcff76ce7c741ac)
---
clang/include/clang/Sema/Sema.h | 6 +--
clang/lib/Sema/SemaExprCXX.cpp | 37 +++++++++++--------
clang/lib/Sema/SemaOverload.cpp | 24 +++++++++---
clang/lib/Sema/TreeTransform.h | 8 +++-
.../temp.res/temp.dep/temp.dep.type/p4.cpp | 24 ++++++------
5 files changed, 62 insertions(+), 37 deletions(-)
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 7bfdaaae45a93e..f1e31f52de0ef5 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -10615,9 +10615,9 @@ class Sema final : public SemaBase {
/// BuildOverloadedArrowExpr - Build a call to an overloaded @c operator->
/// (if one exists), where @c Base is an expression of class type and
/// @c Member is the name of the member we're trying to find.
- ExprResult BuildOverloadedArrowExpr(Scope *S, Expr *Base,
- SourceLocation OpLoc,
- bool *NoArrowOperatorFound = nullptr);
+ ExprResult BuildOverloadedArrowExpr(Expr *Base, SourceLocation OpLoc,
+ bool *NoArrowOperatorFound,
+ bool &IsDependent);
ExprResult BuildCXXMemberCallExpr(Expr *Exp, NamedDecl *FoundDecl,
CXXConversionDecl *Method,
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 14d1f395af90e3..9061cb5a957f2e 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -7850,18 +7850,6 @@ ExprResult Sema::ActOnStartCXXMemberReference(Scope *S, Expr *Base,
QualType BaseType = Base->getType();
MayBePseudoDestructor = false;
- if (BaseType->isDependentType()) {
- // If we have a pointer to a dependent type and are using the -> operator,
- // the object type is the type that the pointer points to. We might still
- // have enough information about that type to do something useful.
- if (OpKind == tok::arrow)
- if (const PointerType *Ptr = BaseType->getAs<PointerType>())
- BaseType = Ptr->getPointeeType();
-
- ObjectType = ParsedType::make(BaseType);
- MayBePseudoDestructor = true;
- return Base;
- }
// C++ [over.match.oper]p8:
// [...] When operator->returns, the operator-> is applied to the value
@@ -7876,7 +7864,8 @@ ExprResult Sema::ActOnStartCXXMemberReference(Scope *S, Expr *Base,
SmallVector<FunctionDecl*, 8> OperatorArrows;
CTypes.insert(Context.getCanonicalType(BaseType));
- while (BaseType->isRecordType()) {
+ while (
+ isa<InjectedClassNameType, RecordType>(BaseType.getCanonicalType())) {
if (OperatorArrows.size() >= getLangOpts().ArrowDepth) {
Diag(OpLoc, diag::err_operator_arrow_depth_exceeded)
<< StartingType << getLangOpts().ArrowDepth << Base->getSourceRange();
@@ -7886,15 +7875,26 @@ ExprResult Sema::ActOnStartCXXMemberReference(Scope *S, Expr *Base,
return ExprError();
}
+ bool IsDependent;
Result = BuildOverloadedArrowExpr(
- S, Base, OpLoc,
+ Base, OpLoc,
// When in a template specialization and on the first loop iteration,
// potentially give the default diagnostic (with the fixit in a
// separate note) instead of having the error reported back to here
// and giving a diagnostic with a fixit attached to the error itself.
(FirstIteration && CurFD && CurFD->isFunctionTemplateSpecialization())
? nullptr
- : &NoArrowOperatorFound);
+ : &NoArrowOperatorFound,
+ IsDependent);
+
+ if (IsDependent) {
+ // BuildOverloadedArrowExpr sets IsDependent to indicate that we need
+ // to build a dependent overloaded arrow expression.
+ assert(BaseType->isDependentType());
+ BaseType = Context.DependentTy;
+ break;
+ }
+
if (Result.isInvalid()) {
if (NoArrowOperatorFound) {
if (FirstIteration) {
@@ -7914,6 +7914,7 @@ ExprResult Sema::ActOnStartCXXMemberReference(Scope *S, Expr *Base,
}
return ExprError();
}
+
Base = Result.get();
if (CXXOperatorCallExpr *OpCall = dyn_cast<CXXOperatorCallExpr>(Base))
OperatorArrows.push_back(OpCall->getDirectCallee());
@@ -7951,7 +7952,7 @@ ExprResult Sema::ActOnStartCXXMemberReference(Scope *S, Expr *Base,
// it's legal for the type to be incomplete if this is a pseudo-destructor
// call. We'll do more incomplete-type checks later in the lookup process,
// so just skip this check for ObjC types.
- if (!BaseType->isRecordType()) {
+ if (!isa<InjectedClassNameType, RecordType>(BaseType.getCanonicalType())) {
ObjectType = ParsedType::make(BaseType);
MayBePseudoDestructor = true;
return Base;
@@ -7969,6 +7970,10 @@ ExprResult Sema::ActOnStartCXXMemberReference(Scope *S, Expr *Base,
return CreateRecoveryExpr(Base->getBeginLoc(), Base->getEndLoc(), {Base});
}
+ // We can't implicitly declare the destructor for a templated class.
+ if (BaseType->isDependentType())
+ MayBePseudoDestructor = true;
+
// C++ [basic.lookup.classref]p2:
// If the id-expression in a class member access (5.2.5) is an
// unqualified-id, and the type of the object expression is of a class
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 28fd3b06156b9b..6fd01064f1012b 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -15805,12 +15805,14 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
return CheckForImmediateInvocation(MaybeBindToTemporary(TheCall), Method);
}
-ExprResult
-Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
- bool *NoArrowOperatorFound) {
- assert(Base->getType()->isRecordType() &&
+ExprResult Sema::BuildOverloadedArrowExpr(Expr *Base, SourceLocation OpLoc,
+ bool *NoArrowOperatorFound,
+ bool &IsDependent) {
+ assert(Base->getType()->getAsRecordDecl() &&
"left-hand side must have class type");
+ IsDependent = false;
+
if (checkPlaceholderForOverload(*this, Base))
return ExprError();
@@ -15831,7 +15833,19 @@ Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
return ExprError();
LookupResult R(*this, OpName, OpLoc, LookupOrdinaryName);
- LookupQualifiedName(R, Base->getType()->castAs<RecordType>()->getDecl());
+ LookupParsedName(R, /*S=*/nullptr, /*SS=*/nullptr, Base->getType());
+
+ // If the expression is dependent and we either:
+ // - found a member of the current instantiation named 'operator->', or
+ // - found nothing, and the lookup context has no dependent base classes
+ //
+ // then we should build a dependent class member access expression.
+ if (R.wasNotFoundInCurrentInstantiation() ||
+ (Base->isTypeDependent() && !R.empty())) {
+ IsDependent = true;
+ return Base;
+ }
+
R.suppressAccessDiagnostics();
for (LookupResult::iterator Oper = R.begin(), OperEnd = R.end();
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 51e6a4845bf6fd..690e3835e8cac1 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -16376,10 +16376,14 @@ ExprResult TreeTransform<Derived>::RebuildCXXOperatorCallExpr(
} else if (Op == OO_Arrow) {
// It is possible that the type refers to a RecoveryExpr created earlier
// in the tree transformation.
- if (First->getType()->isDependentType())
+ if (First->containsErrors())
return ExprError();
+ bool IsDependent;
// -> is never a builtin operation.
- return SemaRef.BuildOverloadedArrowExpr(nullptr, First, OpLoc);
+ ExprResult Result = SemaRef.BuildOverloadedArrowExpr(
+ First, OpLoc, /*NoArrowOperatorFound=*/nullptr, IsDependent);
+ assert(!IsDependent);
+ return Result;
} else if (Second == nullptr || isPostIncDec) {
if (!First->getType()->isOverloadableType() ||
(Op == OO_Amp && getSema().isQualifiedMemberAccess(First))) {
diff --git a/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p4.cpp b/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p4.cpp
index f32f49ef4539a5..89c22a0bc137d9 100644
--- a/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p4.cpp
+++ b/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p4.cpp
@@ -484,16 +484,19 @@ namespace N4 {
template<typename T>
struct A {
void not_instantiated(A a, A<T> b, T c) {
- a->x;
- b->x;
+ a->x; // expected-error {{member reference type 'A<T>' is not a pointer; did you mean to use '.'?}}
+ b->x; // expected-error {{member reference type 'A<T>' is not a pointer; did you mean to use '.'?}}
c->x;
}
void instantiated(A a, A<T> b, T c) {
- a->x; // expected-error {{member reference type 'A<int>' is not a pointer; did you mean to use '.'?}}
- // expected-error at -1 {{no member named 'x' in 'N4::A<int>'}}
- b->x; // expected-error {{member reference type 'A<int>' is not a pointer; did you mean to use '.'?}}
- // expected-error at -1 {{no member named 'x' in 'N4::A<int>'}}
+ // FIXME: We should only emit a single diagnostic suggesting to use '.'!
+ a->x; // expected-error {{member reference type 'A<T>' is not a pointer; did you mean to use '.'?}}
+ // expected-error at -1 {{member reference type 'A<int>' is not a pointer; did you mean to use '.'?}}
+ // expected-error at -2 {{no member named 'x' in 'N4::A<int>'}}
+ b->x; // expected-error {{member reference type 'A<T>' is not a pointer; did you mean to use '.'?}}
+ // expected-error at -1 {{member reference type 'A<int>' is not a pointer; did you mean to use '.'?}}
+ // expected-error at -2 {{no member named 'x' in 'N4::A<int>'}}
c->x; // expected-error {{member reference type 'int' is not a pointer}}
}
};
@@ -540,11 +543,10 @@ namespace N4 {
a->T::f();
a->T::g();
- // FIXME: 'U' should be a dependent name, and its lookup context should be 'a.operator->()'!
- a->U::x; // expected-error {{use of undeclared identifier 'U'}}
- a->U::y; // expected-error {{use of undeclared identifier 'U'}}
- a->U::f(); // expected-error {{use of undeclared identifier 'U'}}
- a->U::g(); // expected-error {{use of undeclared identifier 'U'}}
+ a->U::x;
+ a->U::y;
+ a->U::f();
+ a->U::g();
}
void instantiated(D a) {
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