royjacobson created this revision.
royjacobson added reviewers: erichkeane, cor3ntin.
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Up to C++20, hasDefaultConstructor and !hasNonTrivialDefaultConstructor
together implied
hasTrivialDefaultConstructor. In C++20, a constructor might be ineligible and
can set
hasDefaultConstructor without setting hasNonTrivialDefaultConstructor.
Fix this by querying hasTrivialDefaultConstructor instead of
hasDefaultConstructor.
I'd like to backport this to Clang 16.
I only change isTrivialType and in a way that should only affect code that uses
constrained constructors, so I think this is relatively safe to backport.
Fixes https://github.com/llvm/llvm-project/issues/60697
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D143891
Files:
clang/lib/AST/Type.cpp
clang/test/SemaCXX/constrained-special-member-functions.cpp
Index: clang/test/SemaCXX/constrained-special-member-functions.cpp
===================================================================
--- clang/test/SemaCXX/constrained-special-member-functions.cpp
+++ clang/test/SemaCXX/constrained-special-member-functions.cpp
@@ -265,3 +265,37 @@
static_assert(__is_trivially_constructible(D), "");
}
+
+namespace GH60697 {
+
+template <class T>
+struct X {
+ X() requires false = default;
+};
+static_assert(!__is_trivial(X<int>));
+
+template <class T>
+struct S {
+ S() requires(__is_trivially_constructible(T)) = default;
+
+ S() requires(!__is_trivially_constructible(T) &&
+ __is_constructible(T)) {}
+
+ T t;
+};
+
+struct D {
+ D(int i) : i(i) {}
+ int i;
+};
+static_assert(!__is_trivially_constructible(D));
+static_assert(!__is_constructible(D));
+static_assert(!__is_trivial(D));
+
+static_assert(!__is_trivially_constructible(S<D>));
+static_assert(!__is_constructible(S<D>));
+
+static_assert(__is_trivial(S<int>));
+static_assert(!__is_trivial(S<D>));
+
+}
Index: clang/lib/AST/Type.cpp
===================================================================
--- clang/lib/AST/Type.cpp
+++ clang/lib/AST/Type.cpp
@@ -2487,11 +2487,13 @@
return true;
if (const auto *RT = CanonicalType->getAs<RecordType>()) {
if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
- // C++11 [class]p6:
- // A trivial class is a class that has a default constructor,
- // has no non-trivial default constructors, and is trivially
- // copyable.
- return ClassDecl->hasDefaultConstructor() &&
+ // C++20 [class]p6:
+ // A trivial class is a class that is trivially copyable, and
+ // has one or more eligible default constructors such that each is
+ // trivial.
+ // FIXME: We should merge this definition of triviality into
+ // CXXRecordDecl::isTrivial. Currently it computes the wrong thing.
+ return ClassDecl->hasTrivialDefaultConstructor() &&
!ClassDecl->hasNonTrivialDefaultConstructor() &&
ClassDecl->isTriviallyCopyable();
}
Index: clang/test/SemaCXX/constrained-special-member-functions.cpp
===================================================================
--- clang/test/SemaCXX/constrained-special-member-functions.cpp
+++ clang/test/SemaCXX/constrained-special-member-functions.cpp
@@ -265,3 +265,37 @@
static_assert(__is_trivially_constructible(D), "");
}
+
+namespace GH60697 {
+
+template <class T>
+struct X {
+ X() requires false = default;
+};
+static_assert(!__is_trivial(X<int>));
+
+template <class T>
+struct S {
+ S() requires(__is_trivially_constructible(T)) = default;
+
+ S() requires(!__is_trivially_constructible(T) &&
+ __is_constructible(T)) {}
+
+ T t;
+};
+
+struct D {
+ D(int i) : i(i) {}
+ int i;
+};
+static_assert(!__is_trivially_constructible(D));
+static_assert(!__is_constructible(D));
+static_assert(!__is_trivial(D));
+
+static_assert(!__is_trivially_constructible(S<D>));
+static_assert(!__is_constructible(S<D>));
+
+static_assert(__is_trivial(S<int>));
+static_assert(!__is_trivial(S<D>));
+
+}
Index: clang/lib/AST/Type.cpp
===================================================================
--- clang/lib/AST/Type.cpp
+++ clang/lib/AST/Type.cpp
@@ -2487,11 +2487,13 @@
return true;
if (const auto *RT = CanonicalType->getAs<RecordType>()) {
if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
- // C++11 [class]p6:
- // A trivial class is a class that has a default constructor,
- // has no non-trivial default constructors, and is trivially
- // copyable.
- return ClassDecl->hasDefaultConstructor() &&
+ // C++20 [class]p6:
+ // A trivial class is a class that is trivially copyable, and
+ // has one or more eligible default constructors such that each is
+ // trivial.
+ // FIXME: We should merge this definition of triviality into
+ // CXXRecordDecl::isTrivial. Currently it computes the wrong thing.
+ return ClassDecl->hasTrivialDefaultConstructor() &&
!ClassDecl->hasNonTrivialDefaultConstructor() &&
ClassDecl->isTriviallyCopyable();
}
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