[clang] When checking for covariant return types, make sure the pointers or references are to *classes* #111856
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…ers or references are to *classes*. https://eel.is/c++draft/class.virtual#8.1 This prevents overriding methods with non class return types that have less cv-qualification.
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@llvm/pr-subscribers-clang Author: Boaz Brickner (bricknerb) Changeshttps://eel.is/c++draft/class.virtual#8.1 This prevents overriding methods with non class return types that have less cv-qualification. Fixes: #111742 Full diff: https://github.com/llvm/llvm-project/pull/111856.diff 2 Files Affected:
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 9cb2ed02a3f764..6195b62b8afa16 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -18273,7 +18273,7 @@ bool Sema::CheckOverridingFunctionReturnType(const CXXMethodDecl *New,
}
// The return types aren't either both pointers or references to a class type.
- if (NewClassTy.isNull()) {
+ if (NewClassTy.isNull() || !NewClassTy->isStructureOrClassType()) {
Diag(New->getLocation(),
diag::err_different_return_type_for_overriding_virtual_function)
<< New->getDeclName() << NewTy << OldTy
@@ -18296,7 +18296,7 @@ bool Sema::CheckOverridingFunctionReturnType(const CXXMethodDecl *New,
diag::err_covariant_return_incomplete,
New->getDeclName()))
return true;
- }
+ }
// Check if the new class derives from the old class.
if (!IsDerivedFrom(New->getLocation(), NewClassTy, OldClassTy)) {
diff --git a/clang/test/SemaCXX/virtual-override.cpp b/clang/test/SemaCXX/virtual-override.cpp
index 72abfc3cf51e1f..6008b8ed063f20 100644
--- a/clang/test/SemaCXX/virtual-override.cpp
+++ b/clang/test/SemaCXX/virtual-override.cpp
@@ -289,3 +289,13 @@ namespace PR8168 {
static void foo() {} // expected-error{{'static' member function 'foo' overrides a virtual function}}
};
}
+
+namespace T13 {
+ struct A {
+ virtual const int *f() const; // expected-note{{overridden virtual function is here}}
+ };
+
+ struct B : A {
+ int *f() const override; // expected-error{{virtual function 'f' has a different return type ('int *') than the function it overrides (which has return type 'const int *')}}
+ };
+}
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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Implementation seems fine, but this is still missing a release note (in clang/docs/ReleaseNotes.rst, probably somewhere in the ‘Potentially Breaking Changes’ section).
CC @AaronBallman @cor3ntin Do we want to make this a warning that defaults to an error instead? Imo it’s probably fine as-is because I don’t imagine too many people would write code that abuses us not diagnosing this...
…en return type doesn't point to a class to release notes.
…e pointers to non classes when calculating covariance.
It looks fine to me as is. Code that would do something like If people scream we have plenty of time to reconsider making it a warning |
bricknerb
changed the title
…ts into T2 and T6. In T2, we check that return types that are pointers to different non-class types fail. In T6, we check that unlike class return types, non-class return types do not allow to change qualifiers at all (add or remove).
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https://eel.is/c++draft/class.virtual#8.1
This prevents overriding methods with non class return types that have less cv-qualification.
Fixes: #111742