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If a union has explicit initializers for some members, we shouldn't delete
its default constructor.
Fixes https://github.com/llvm/llvm-project/issues/48416.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D145851
Files:
clang/docs/ReleaseNotes.rst
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/SemaCXX/cxx0x-nontrivial-union.cpp
Index: clang/test/SemaCXX/cxx0x-nontrivial-union.cpp
===================================================================
--- clang/test/SemaCXX/cxx0x-nontrivial-union.cpp
+++ clang/test/SemaCXX/cxx0x-nontrivial-union.cpp
@@ -144,3 +144,37 @@
Test2<X> t2x; // expected-error {{call to implicitly-deleted default
constructor of 'Test2<X>'}}
}
+
+namespace GH48416 {
+
+struct non_trivial_constructor {
+ non_trivial_constructor() {}
+};
+
+
+union U1 {
+ int a;
+ non_trivial_constructor b; // expected-note {{has a non-trivial default
constructor}}
+};
+
+union U2 {
+ int a{};
+ non_trivial_constructor b;
+};
+
+union U3 {
+ int a;
+ non_trivial_constructor b{};
+};
+
+union U4 {
+ int a{}; // expected-note {{previous initialization is here}}
+ non_trivial_constructor b{}; // expected-error {{initializing multiple
members of union}}
+};
+
+U1 u1; // expected-error {{call to implicitly-deleted default constructor}}
+U2 u2;
+U3 u3;
+U4 u4;
+
+} // namespace GH48416
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -9157,7 +9157,15 @@
// must be accessible and non-deleted, but need not be trivial. Such a
// destructor is never actually called, but is semantically checked as
// if it were.
- DiagKind = 4;
+ if (CSM == Sema::CXXDefaultConstructor) {
+ // Default constructor of a union can also be valid if one of the
+ // members has an explicit initializer.
+ auto* Constructor = dyn_cast<CXXConstructorDecl>(Decl);
+ auto* RD = dyn_cast<CXXRecordDecl>(Field->getParent());
+ if (!Constructor || !RD || !RD->hasInClassInitializer())
+ DiagKind = 4;
+ } else
+ DiagKind = 4;
}
if (DiagKind == -1)
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -202,6 +202,8 @@
- Fix crash when evaluating consteval constructor of derived class whose base
has more than one field.
(`#60166 <https://github.com/llvm/llvm-project/issues/60166>`_)
+- Fix incorrect deletion of the default constructor of unions in some
+ cases. (`#48416 <https://github.com/llvm/llvm-project/issues/48416>`_)
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
Index: clang/test/SemaCXX/cxx0x-nontrivial-union.cpp
===================================================================
--- clang/test/SemaCXX/cxx0x-nontrivial-union.cpp
+++ clang/test/SemaCXX/cxx0x-nontrivial-union.cpp
@@ -144,3 +144,37 @@
Test2<X> t2x; // expected-error {{call to implicitly-deleted default constructor of 'Test2<X>'}}
}
+
+namespace GH48416 {
+
+struct non_trivial_constructor {
+ non_trivial_constructor() {}
+};
+
+
+union U1 {
+ int a;
+ non_trivial_constructor b; // expected-note {{has a non-trivial default constructor}}
+};
+
+union U2 {
+ int a{};
+ non_trivial_constructor b;
+};
+
+union U3 {
+ int a;
+ non_trivial_constructor b{};
+};
+
+union U4 {
+ int a{}; // expected-note {{previous initialization is here}}
+ non_trivial_constructor b{}; // expected-error {{initializing multiple members of union}}
+};
+
+U1 u1; // expected-error {{call to implicitly-deleted default constructor}}
+U2 u2;
+U3 u3;
+U4 u4;
+
+} // namespace GH48416
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -9157,7 +9157,15 @@
// must be accessible and non-deleted, but need not be trivial. Such a
// destructor is never actually called, but is semantically checked as
// if it were.
- DiagKind = 4;
+ if (CSM == Sema::CXXDefaultConstructor) {
+ // Default constructor of a union can also be valid if one of the
+ // members has an explicit initializer.
+ auto* Constructor = dyn_cast<CXXConstructorDecl>(Decl);
+ auto* RD = dyn_cast<CXXRecordDecl>(Field->getParent());
+ if (!Constructor || !RD || !RD->hasInClassInitializer())
+ DiagKind = 4;
+ } else
+ DiagKind = 4;
}
if (DiagKind == -1)
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -202,6 +202,8 @@
- Fix crash when evaluating consteval constructor of derived class whose base
has more than one field.
(`#60166 <https://github.com/llvm/llvm-project/issues/60166>`_)
+- Fix incorrect deletion of the default constructor of unions in some
+ cases. (`#48416 <https://github.com/llvm/llvm-project/issues/48416>`_)
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
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