A union can have a constexpr defaulted default constructor, if it has an
in-class initializer for one of its fields. Value-initialization of such
a type should use the in-class initializer!
The former was just a bug, the latter is a (reported) standard defect.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156274 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 7f3ec4c..54d4d7b 100644
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -357,6 +357,9 @@
/// \brief True if there no non-field members declared by the user.
bool HasOnlyCMembers : 1;
+ /// \brief True if any field has an in-class initializer.
+ bool HasInClassInitializer : 1;
+
/// HasTrivialDefaultConstructor - True when, if this class has a default
/// constructor, this default constructor is trivial.
///
@@ -1040,6 +1043,10 @@
/// no base classes, and no virtual functions (C++ [dcl.init.aggr]p1).
bool isAggregate() const { return data().Aggregate; }
+ /// hasInClassInitializer - Whether this class has any in-class initializers
+ /// for non-static data members.
+ bool hasInClassInitializer() const { return data().HasInClassInitializer; }
+
/// isPOD - Whether this class is a POD-type (C++ [class]p4), which is a class
/// that is an aggregate that has no non-static non-POD data members, no
/// reference data members, no user-defined copy assignment operator and no
@@ -1091,7 +1098,8 @@
/// defaultedDefaultConstructorIsConstexpr - Whether a defaulted default
/// constructor for this class would be constexpr.
bool defaultedDefaultConstructorIsConstexpr() const {
- return data().DefaultedDefaultConstructorIsConstexpr;
+ return data().DefaultedDefaultConstructorIsConstexpr &&
+ (!isUnion() || hasInClassInitializer());
}
/// defaultedCopyConstructorIsConstexpr - Whether a defaulted copy
@@ -1111,7 +1119,7 @@
bool hasConstexprDefaultConstructor() const {
return data().HasConstexprDefaultConstructor ||
(!data().UserDeclaredConstructor &&
- data().DefaultedDefaultConstructorIsConstexpr && isLiteral());
+ defaultedDefaultConstructorIsConstexpr() && isLiteral());
}
/// hasConstexprCopyConstructor - Whether this class has a constexpr copy
diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index 6ecc489..87e5e53 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -1852,6 +1852,7 @@
ToData.HasPublicFields = FromData.HasPublicFields;
ToData.HasMutableFields = FromData.HasMutableFields;
ToData.HasOnlyCMembers = FromData.HasOnlyCMembers;
+ ToData.HasInClassInitializer = FromData.HasInClassInitializer;
ToData.HasTrivialDefaultConstructor = FromData.HasTrivialDefaultConstructor;
ToData.HasConstexprNonCopyMoveConstructor
= FromData.HasConstexprNonCopyMoveConstructor;
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index e27d880..0c78abb 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -43,6 +43,7 @@
Abstract(false), IsStandardLayout(true), HasNoNonEmptyBases(true),
HasPrivateFields(false), HasProtectedFields(false), HasPublicFields(false),
HasMutableFields(false), HasOnlyCMembers(true),
+ HasInClassInitializer(false),
HasTrivialDefaultConstructor(true),
HasConstexprNonCopyMoveConstructor(false),
DefaultedDefaultConstructorIsConstexpr(true),
@@ -818,17 +819,19 @@
data().HasNonLiteralTypeFieldsOrBases = true;
if (Field->hasInClassInitializer()) {
- // C++0x [class]p5:
+ data().HasInClassInitializer = true;
+
+ // C++11 [class]p5:
// A default constructor is trivial if [...] no non-static data member
// of its class has a brace-or-equal-initializer.
data().HasTrivialDefaultConstructor = false;
- // C++0x [dcl.init.aggr]p1:
+ // C++11 [dcl.init.aggr]p1:
// An aggregate is a [...] class with [...] no
// brace-or-equal-initializers for non-static data members.
data().Aggregate = false;
- // C++0x [class]p10:
+ // C++11 [class]p10:
// A POD struct is [...] a trivial class.
data().PlainOldData = false;
}
@@ -920,7 +923,7 @@
// -- every constructor involved in initializing non-static data
// members [...] shall be a constexpr constructor
if (!Field->hasInClassInitializer() &&
- !FieldRec->hasConstexprDefaultConstructor())
+ !FieldRec->hasConstexprDefaultConstructor() && !isUnion())
// The standard requires any in-class initializer to be a constant
// expression. We consider this to be a defect.
data().DefaultedDefaultConstructorIsConstexpr = false;
@@ -944,7 +947,7 @@
data().DefaultedDefaultConstructorIsConstexpr = false;
data().DefaultedCopyConstructorIsConstexpr = false;
data().DefaultedMoveConstructorIsConstexpr = false;
- } else if (!Field->hasInClassInitializer())
+ } else if (!Field->hasInClassInitializer() && !isUnion())
data().DefaultedDefaultConstructorIsConstexpr = false;
}
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 0ef1b1e..66cc1e1 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -3642,11 +3642,10 @@
// user-provided or deleted default constructor, then the object is
// zero-initialized and, if T has a non-trivial default constructor,
// default-initialized;
- if ((ClassDecl->getTagKind() == TTK_Class ||
- ClassDecl->getTagKind() == TTK_Struct)) {
- Sequence.AddZeroInitializationStep(Entity.getType());
- return TryConstructorInitialization(S, Entity, Kind, 0, 0, T, Sequence);
- }
+ // FIXME: The 'non-union' here is a defect (not yet assigned an issue
+ // number). Update the quotation when the defect is resolved.
+ Sequence.AddZeroInitializationStep(Entity.getType());
+ return TryConstructorInitialization(S, Entity, Kind, 0, 0, T, Sequence);
}
}
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 1c5b658..9ead794 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -1090,6 +1090,7 @@
Data.HasPublicFields = Record[Idx++];
Data.HasMutableFields = Record[Idx++];
Data.HasOnlyCMembers = Record[Idx++];
+ Data.HasInClassInitializer = Record[Idx++];
Data.HasTrivialDefaultConstructor = Record[Idx++];
Data.HasConstexprNonCopyMoveConstructor = Record[Idx++];
Data.DefaultedDefaultConstructorIsConstexpr = Record[Idx++];
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 29ea01b..62154ed 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -4310,6 +4310,7 @@
Record.push_back(Data.HasPublicFields);
Record.push_back(Data.HasMutableFields);
Record.push_back(Data.HasOnlyCMembers);
+ Record.push_back(Data.HasInClassInitializer);
Record.push_back(Data.HasTrivialDefaultConstructor);
Record.push_back(Data.HasConstexprNonCopyMoveConstructor);
Record.push_back(Data.DefaultedDefaultConstructorIsConstexpr);
diff --git a/test/CXX/special/class.ctor/p6-0x.cpp b/test/CXX/special/class.ctor/p6-0x.cpp
index 8c8800f..9860317 100644
--- a/test/CXX/special/class.ctor/p6-0x.cpp
+++ b/test/CXX/special/class.ctor/p6-0x.cpp
@@ -55,3 +55,42 @@
struct B {
friend A::A(); // expected-error {{non-constexpr declaration of 'A' follows constexpr declaration}}
};
+
+namespace UnionCtors {
+ union A { // expected-note {{here}}
+ int a;
+ int b;
+ };
+ union B {
+ int a;
+ int b = 5;
+ };
+ union C {
+ int a = 5;
+ int b;
+ };
+ struct D {
+ union {
+ int a = 5;
+ int b;
+ };
+ union {
+ int c;
+ int d = 5;
+ };
+ };
+ struct E { // expected-note {{here}}
+ union {
+ int a;
+ int b;
+ };
+ };
+
+ struct Test {
+ friend constexpr A::A() noexcept; // expected-error {{follows non-constexpr declaration}}
+ friend constexpr B::B() noexcept;
+ friend constexpr C::C() noexcept;
+ friend constexpr D::D() noexcept;
+ friend constexpr E::E() noexcept; // expected-error {{follows non-constexpr declaration}}
+ };
+}
diff --git a/test/CodeGenCXX/const-init-cxx11.cpp b/test/CodeGenCXX/const-init-cxx11.cpp
index 62a345a..d1b91ba 100644
--- a/test/CodeGenCXX/const-init-cxx11.cpp
+++ b/test/CodeGenCXX/const-init-cxx11.cpp
@@ -49,6 +49,17 @@
// CHECK: @_ZN11StructUnion1fE = global {{.*}} { i32 5 }
D f;
+
+ union E {
+ int a;
+ void *b = &f;
+ };
+
+ // CHECK: @_ZN11StructUnion1gE = global {{.*}} @_ZN11StructUnion1fE
+ E g;
+
+ // CHECK: @_ZN11StructUnion1hE = global {{.*}} @_ZN11StructUnion1fE
+ E h = E();
}
namespace BaseClass {
diff --git a/test/CodeGenCXX/member-init-anon-union.cpp b/test/CodeGenCXX/member-init-anon-union.cpp
index 1ff7537..4db31f0 100644
--- a/test/CodeGenCXX/member-init-anon-union.cpp
+++ b/test/CodeGenCXX/member-init-anon-union.cpp
@@ -2,8 +2,10 @@
// PR10531.
+int make_a();
+
static union {
- int a = 42;
+ int a = make_a();
char *b;
};
@@ -32,4 +34,4 @@
// CHECK: define {{.*}}@"[[CONSTRUCT_GLOBAL]]C2Ev"
// CHECK-NOT: }
-// CHECK: store i32 42
+// CHECK: call {{.*}}@_Z6make_a
