https://github.com/Maetveis created
https://github.com/llvm/llvm-project/pull/116965
The original code assumed that only special methods might be defined as
defaulted. Since C++20 comparison operators might be defaulted too, and we *do*
want to consider those as using the fields of the class.
Fixes: #116961
From 0dd94643cd32992e4b54463eea8a73d377b9169e Mon Sep 17 00:00:00 2001
From: Gergely Meszaros <gergely.mesza...@intel.com>
Date: Wed, 20 Nov 2024 12:55:59 +0000
Subject: [PATCH] [Clang] Only ignore special methods for unused private fields
in BuildFieldReferenceExpr
The original code assumed that only special methods might be defined
as defaulted. Since C++20 comparison operators might be defaulted too,
and we *do* want to consider those as using the fields of the class.
Fixes: #116961
---
clang/lib/Sema/SemaExprMember.cpp | 12 ++++++++++--
clang/test/SemaCXX/warn-unused-private-field.cpp | 14 ++++++++++++++
2 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/clang/lib/Sema/SemaExprMember.cpp
b/clang/lib/Sema/SemaExprMember.cpp
index c32df607692813..46821dc8746b2a 100644
--- a/clang/lib/Sema/SemaExprMember.cpp
+++ b/clang/lib/Sema/SemaExprMember.cpp
@@ -1874,8 +1874,16 @@ Sema::BuildFieldReferenceExpr(Expr *BaseExpr, bool
IsArrow,
Context.getAttributedType(attr::NoDeref, MemberType, MemberType);
}
- auto *CurMethod = dyn_cast<CXXMethodDecl>(CurContext);
- if (!(CurMethod && CurMethod->isDefaulted()))
+ auto isDefaultedSpecialMember = [this](const DeclContext *Ctx) {
+ auto *Method = dyn_cast<CXXMethodDecl>(CurContext);
+ if (!Method || !Method->isDefaulted())
+ return false;
+
+ return getDefaultedFunctionKind(Method).isSpecialMember();
+ };
+
+ // Implicit special members should not mark fields as used.
+ if (!isDefaultedSpecialMember(CurContext))
UnusedPrivateFields.remove(Field);
ExprResult Base = PerformObjectMemberConversion(BaseExpr, SS.getScopeRep(),
diff --git a/clang/test/SemaCXX/warn-unused-private-field.cpp
b/clang/test/SemaCXX/warn-unused-private-field.cpp
index 1128eacc309d9f..9913dbaafb7a57 100644
--- a/clang/test/SemaCXX/warn-unused-private-field.cpp
+++ b/clang/test/SemaCXX/warn-unused-private-field.cpp
@@ -20,6 +20,20 @@ class SpaceShipDefaultCompare {
int operator<=>(const SpaceShipDefaultCompare &) const = default;
};
+class EqDefaultCompareOutOfClass {
+ int used;
+ bool operator==(const EqDefaultCompareOutOfClass &) const;
+};
+
+bool EqDefaultCompareOutOfClass::operator==(const EqDefaultCompareOutOfClass
&) const = default;
+
+class FriendEqDefaultCompareOutOfClass {
+ int used;
+ friend bool operator==(const FriendEqDefaultCompareOutOfClass &, const
FriendEqDefaultCompareOutOfClass &);
+};
+
+bool operator==(const FriendEqDefaultCompareOutOfClass &, const
FriendEqDefaultCompareOutOfClass &) = default;
+
#endif
class NotFullyDefined {
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