[clang] Reapply "[clang] Fix name lookup for dependent bases" (PR #118003)
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Thu Nov 28 05:43:38 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Vladislav Belov (vbe-sc)
<details>
<summary>Changes</summary>
Unlike the previous version, this patch also removes an unnecessary assert that causes Clang to crash when compiling such tests. (clang/lib/AST/DeclCXX.cpp)
https://lab.llvm.org/buildbot/#/builders/52/builds/4021
```c++
template <class T>
class X {
public:
X() = default;
virtual ~X() = default;
virtual int foo(int x, int y, T &entry) = 0;
void bar() {
struct Y : public X<T> {
Y() : X() {}
int foo(int, int, T &) override {
return 42;
}
};
}
};
```
the assertions:
```c++
llvm-project/clang/lib/AST/DeclCXX.cpp:2508: void clang::CXXMethodDecl::addOverriddenMethod(const CXXMethodDecl *): Assertion `!MD->getParent()->isDependentContext() && "Can't add an overridden method to a class template!"' failed.
```
I believe that this assert is unnecessary and contradicts the logic of this patch. After its removal, Clang was successfully built using itself, and all tests passed.
---
Full diff: https://github.com/llvm/llvm-project/pull/118003.diff
5 Files Affected:
- (modified) clang/docs/ReleaseNotes.rst (+3)
- (modified) clang/lib/AST/CXXInheritance.cpp (+12-6)
- (modified) clang/lib/AST/DeclCXX.cpp (-2)
- (modified) clang/test/CXX/drs/cwg5xx.cpp (+46-2)
- (modified) clang/www/cxx_dr_status.html (+1-1)
``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 2ecd19bdc39448..c3bb3ea69b03ea 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -308,6 +308,9 @@ Resolutions to C++ Defect Reports
by default.
(`CWG2521: User-defined literals and reserved identifiers <https://cplusplus.github.io/CWG/issues/2521.html>`_).
+- Fix name lookup for a dependent base class that is the current instantiation.
+ (`CWG591: When a dependent base class is the current instantiation <https://cplusplus.github.io/CWG/issues/591.html>`_).
+
C Language Changes
------------------
diff --git a/clang/lib/AST/CXXInheritance.cpp b/clang/lib/AST/CXXInheritance.cpp
index aefc06e9197cfb..10b8d524ff8978 100644
--- a/clang/lib/AST/CXXInheritance.cpp
+++ b/clang/lib/AST/CXXInheritance.cpp
@@ -134,7 +134,7 @@ bool CXXRecordDecl::forallBases(ForallBasesCallback BaseMatches) const {
return false;
CXXRecordDecl *Base =
- cast_or_null<CXXRecordDecl>(Ty->getDecl()->getDefinition());
+ cast_if_present<CXXRecordDecl>(Ty->getDecl()->getDefinition());
if (!Base ||
(Base->isDependentContext() &&
!Base->isCurrentInstantiation(Record))) {
@@ -169,13 +169,21 @@ bool CXXBasePaths::lookupInBases(ASTContext &Context,
QualType BaseType =
Context.getCanonicalType(BaseSpec.getType()).getUnqualifiedType();
+ bool isCurrentInstantiation = isa<InjectedClassNameType>(BaseType);
+ if (!isCurrentInstantiation) {
+ if (auto *BaseRecord = cast_if_present<CXXRecordDecl>(
+ BaseSpec.getType()->getAsRecordDecl()))
+ isCurrentInstantiation = BaseRecord->isDependentContext() &&
+ BaseRecord->isCurrentInstantiation(Record);
+ }
// C++ [temp.dep]p3:
// In the definition of a class template or a member of a class template,
// if a base class of the class template depends on a template-parameter,
// the base class scope is not examined during unqualified name lookup
// either at the point of definition of the class template or member or
// during an instantiation of the class tem- plate or member.
- if (!LookupInDependent && BaseType->isDependentType())
+ if (!LookupInDependent &&
+ (BaseType->isDependentType() && !isCurrentInstantiation))
continue;
// Determine whether we need to visit this base class at all,
@@ -243,9 +251,8 @@ bool CXXBasePaths::lookupInBases(ASTContext &Context,
return FoundPath;
}
} else if (VisitBase) {
- CXXRecordDecl *BaseRecord;
+ CXXRecordDecl *BaseRecord = nullptr;
if (LookupInDependent) {
- BaseRecord = nullptr;
const TemplateSpecializationType *TST =
BaseSpec.getType()->getAs<TemplateSpecializationType>();
if (!TST) {
@@ -264,8 +271,7 @@ bool CXXBasePaths::lookupInBases(ASTContext &Context,
BaseRecord = nullptr;
}
} else {
- BaseRecord = cast<CXXRecordDecl>(
- BaseSpec.getType()->castAs<RecordType>()->getDecl());
+ BaseRecord = cast<CXXRecordDecl>(BaseSpec.getType()->getAsRecordDecl());
}
if (BaseRecord &&
lookupInBases(Context, BaseRecord, BaseMatches, LookupInDependent)) {
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index f2f2835641245e..af73c658d6a0c5 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -2602,8 +2602,6 @@ bool CXXMethodDecl::isMoveAssignmentOperator() const {
void CXXMethodDecl::addOverriddenMethod(const CXXMethodDecl *MD) {
assert(MD->isCanonicalDecl() && "Method is not canonical!");
- assert(!MD->getParent()->isDependentContext() &&
- "Can't add an overridden method to a class template!");
assert(MD->isVirtual() && "Method is not virtual!");
getASTContext().addOverriddenMethod(this, MD);
diff --git a/clang/test/CXX/drs/cwg5xx.cpp b/clang/test/CXX/drs/cwg5xx.cpp
index ed0c7159dfc889..0d53a9d07d76de 100644
--- a/clang/test/CXX/drs/cwg5xx.cpp
+++ b/clang/test/CXX/drs/cwg5xx.cpp
@@ -1178,17 +1178,61 @@ namespace cwg590 { // cwg590: yes
template<typename T> typename A<T>::B::C A<T>::B::C::f(A<T>::B::C) {}
}
-namespace cwg591 { // cwg591: no
+namespace cwg591 { // cwg591: yes
template<typename T> struct A {
typedef int M;
struct B {
typedef void M;
struct C;
+ struct D;
+ };
+ };
+
+ template<typename T> struct G {
+ struct B {
+ typedef int M;
+ struct C {
+ typedef void M;
+ struct D;
+ };
+ };
+ };
+
+ template<typename T> struct H {
+ template<typename U> struct B {
+ typedef int M;
+ template<typename F> struct C {
+ typedef void M;
+ struct D;
+ struct P;
+ };
};
};
template<typename T> struct A<T>::B::C : A<T> {
- // FIXME: Should find member of non-dependent base class A<T>.
+ M m;
+ };
+
+ template<typename T> struct G<T>::B::C::D : B {
+ M m;
+ };
+
+ template<typename T>
+ template<typename U>
+ template<typename F>
+ struct H<T>::B<U>::C<F>::D : B<U> {
+ M m;
+ };
+
+ template<typename T> struct A<T>::B::D : A<T*> {
+ M m;
+ // expected-error at -1 {{field has incomplete type 'M' (aka 'void'}}
+ };
+
+ template<typename T>
+ template<typename U>
+ template<typename F>
+ struct H<T>::B<U>::C<F>::P : B<F> {
M m;
// expected-error at -1 {{field has incomplete type 'M' (aka 'void'}}
};
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index 186f7cc0ace546..c773c58fac4d0f 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -3599,7 +3599,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/591.html">591</a></td>
<td>CD4</td>
<td>When a dependent base class is the current instantiation</td>
- <td class="none" align="center">No</td>
+ <td class="none" align="center">Yes</td>
</tr>
<tr id="592">
<td><a href="https://cplusplus.github.io/CWG/issues/592.html">592</a></td>
``````````
</details>
https://github.com/llvm/llvm-project/pull/118003
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