shafik created this revision.
shafik added reviewers: rsmith, aaron.ballman, erichkeane.
Herald added a project: All.
shafik requested review of this revision.
Prior to P2448R2 <http://wg21.link/P2448R2> we were more aggressive in
diagnosing ill-formed `constexpr` functions. Many of these restrictions were
relaxed and now it is not required for defaulted comparison operators to call
`constexpr` functions.
This behavior is extended to before C++23 and diagnostic for it's use can be
enabled w/ `-pedantic` or `-Wc++2b-default-comp-relaxed-constexpr`
This fixes: https://github.com/llvm/llvm-project/issues/61238
https://reviews.llvm.org/D146090
Files:
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/CXX/class/class.compare/class.compare.default/p3.cpp
clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
Index: clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
===================================================================
--- clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
+++ clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
@@ -1,7 +1,9 @@
// RUN: %clang_cc1 -std=c++2a -verify %s
+// RUN: %clang_cc1 -std=c++2a -Wc++2b-default-comp-relaxed-constexpr -verify=expected,extension %s
// This test is for [class.compare.default]p3 as modified and renumbered to p4
// by P2002R0.
+// Also covers modifications made by P2448R2 and extension warnings
namespace std {
struct strong_ordering {
@@ -76,14 +78,13 @@
}
struct H {
- bool operator==(const H&) const; // expected-note {{here}}
+ bool operator==(const H&) const; // extension-note {{non-constexpr comparison function declared here}}
constexpr std::strong_ordering operator<=>(const H&) const { return std::strong_ordering::equal; }
};
struct I {
- H h; // expected-note {{used to compare}}
- // expected-error@+1 {{defaulted definition of three-way comparison operator cannot be declared constexpr because the corresponding implicit 'operator==' invokes a non-constexpr comparison function}}
- constexpr std::strong_ordering operator<=>(const I&) const = default;
+ H h; // extension-note {{non-constexpr comparison function would be used to compare member 'h'}}
+ constexpr std::strong_ordering operator<=>(const I&) const = default; // extension-warning {{implicit 'operator==' invokes a non-constexpr comparison function are a C++2b extension}}
};
struct J {
@@ -144,3 +145,19 @@
};
bool test_d = D() == D();
}
+
+namespace GH61238 {
+template <typename A> struct my_struct {
+ A value; // extension-note {{non-constexpr comparison function would be used to compare member 'value'}}
+
+ constexpr friend bool operator==(const my_struct &, const my_struct &) noexcept = default; // no diagnostic extension-warning {{declared constexpr but it invokes a non-constexpr comparison function are a C++2b extension}}
+};
+
+struct non_constexpr_type {
+ friend bool operator==(non_constexpr_type, non_constexpr_type) noexcept { // extension-note {{non-constexpr comparison function declared here}}
+ return false;
+ }
+};
+
+my_struct<non_constexpr_type> obj; // extension-note {{in instantiation of template class 'GH61238::my_struct<GH61238::non_constexpr_type>' requested here}}
+}
Index: clang/test/CXX/class/class.compare/class.compare.default/p3.cpp
===================================================================
--- clang/test/CXX/class/class.compare/class.compare.default/p3.cpp
+++ clang/test/CXX/class/class.compare/class.compare.default/p3.cpp
@@ -80,10 +80,10 @@
};
struct C {
- friend bool operator==(const C&, const C&); // expected-note {{previous}} expected-note 2{{here}}
+ friend bool operator==(const C&, const C&); // expected-note {{previous}}
friend bool operator!=(const C&, const C&) = default; // expected-note {{previous}}
- friend std::strong_ordering operator<=>(const C&, const C&); // expected-note {{previous}} expected-note 2{{here}}
+ friend std::strong_ordering operator<=>(const C&, const C&); // expected-note {{previous}}
friend bool operator<(const C&, const C&) = default; // expected-note {{previous}}
friend bool operator<=(const C&, const C&) = default; // expected-note {{previous}}
friend bool operator>(const C&, const C&) = default; // expected-note {{previous}}
@@ -127,23 +127,23 @@
struct E {
A a;
- C c; // expected-note 2{{non-constexpr comparison function would be used to compare member 'c'}}
+ C c;
A b;
- friend constexpr bool operator==(const E&, const E&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
+ friend constexpr bool operator==(const E&, const E&) = default;
friend constexpr bool operator!=(const E&, const E&) = default;
- friend constexpr std::strong_ordering operator<=>(const E&, const E&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
+ friend constexpr std::strong_ordering operator<=>(const E&, const E&) = default;
friend constexpr bool operator<(const E&, const E&) = default;
friend constexpr bool operator<=(const E&, const E&) = default;
friend constexpr bool operator>(const E&, const E&) = default;
friend constexpr bool operator>=(const E&, const E&) = default;
};
-struct E2 : A, C { // expected-note 2{{non-constexpr comparison function would be used to compare base class 'C'}}
- friend constexpr bool operator==(const E2&, const E2&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
+struct E2 : A, C {
+ friend constexpr bool operator==(const E2&, const E2&) = default;
friend constexpr bool operator!=(const E2&, const E2&) = default;
- friend constexpr std::strong_ordering operator<=>(const E2&, const E2&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
+ friend constexpr std::strong_ordering operator<=>(const E2&, const E2&) = default;
friend constexpr bool operator<(const E2&, const E2&) = default;
friend constexpr bool operator<=(const E2&, const E2&) = default;
friend constexpr bool operator>(const E2&, const E2&) = default;
@@ -151,14 +151,14 @@
};
struct F {
- friend bool operator==(const F&, const F&); // expected-note {{here}}
- friend constexpr bool operator!=(const F&, const F&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
-
- friend std::strong_ordering operator<=>(const F&, const F&); // expected-note 4{{here}}
- friend constexpr bool operator<(const F&, const F&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
- friend constexpr bool operator<=(const F&, const F&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
- friend constexpr bool operator>(const F&, const F&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
- friend constexpr bool operator>=(const F&, const F&) = default; // expected-error {{cannot be declared constexpr because it invokes a non-constexpr comparison function}}
+ friend bool operator==(const F&, const F&);
+ friend constexpr bool operator!=(const F&, const F&) = default;
+
+ friend std::strong_ordering operator<=>(const F&, const F&);
+ friend constexpr bool operator<(const F&, const F&) = default;
+ friend constexpr bool operator<=(const F&, const F&) = default;
+ friend constexpr bool operator>(const F&, const F&) = default;
+ friend constexpr bool operator>=(const F&, const F&) = default;
};
// No implicit 'constexpr' if it's not the first declaration.
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -8809,7 +8809,8 @@
CheckConstexprParameterTypes(*this, FD, CheckConstexprKind::Diagnose) &&
!Info.Constexpr) {
Diag(FD->getBeginLoc(),
- diag::err_incorrect_defaulted_comparison_constexpr)
+ (getLangOpts().CPlusPlus2b ? diag::warn_cxx2b_incorrect_defaulted_comparison_constexpr :
+ diag::ext_incorrect_defaulted_comparison_constexpr ))
<< FD->isImplicit() << (int)DCK << FD->isConsteval();
DefaultedComparisonAnalyzer(*this, RD, FD, DCK,
DefaultedComparisonAnalyzer::ExplainConstexpr)
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -9407,12 +9407,18 @@
"%select{|member|base class}0 %1 declared here">;
def note_defaulted_comparison_cannot_deduce_callee : Note<
"selected 'operator<=>' for %select{|member|base class}0 %1 declared here">;
-def err_incorrect_defaulted_comparison_constexpr : Error<
+def ext_incorrect_defaulted_comparison_constexpr : Extension<
"defaulted definition of %select{%sub{select_defaulted_comparison_kind}1|"
"three-way comparison operator}0 "
- "cannot be declared %select{constexpr|consteval}2 because "
+ "declared %select{constexpr|consteval}2 but "
"%select{it|the corresponding implicit 'operator=='}0 "
- "invokes a non-constexpr comparison function">;
+ "invokes a non-constexpr comparison function are a C++2b extension">, InGroup<CXX2bDefCompCallsNonConstexpr>;
+def warn_cxx2b_incorrect_defaulted_comparison_constexpr : Warning<
+ "defaulted definition of %select{%sub{select_defaulted_comparison_kind}1|"
+ "three-way comparison operator}0 "
+ "declared %select{constexpr|consteval}2 but "
+ "%select{it|the corresponding implicit 'operator=='}0 "
+ "invokes a non-constexpr comparison function are a C++2b extension">, InGroup<CXXPre2bCompat>, DefaultIgnore;
def note_defaulted_comparison_not_constexpr : Note<
"non-constexpr comparison function would be used to compare "
"%select{|member %1|base class %1}0">;
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -228,6 +228,7 @@
DiagCategory<"Deprecations">;
def CXX20Designator : DiagGroup<"c++20-designator">;
+def CXX2bDefCompCallsNonConstexpr : DiagGroup<"c++2b-default-comp-relaxed-constexpr">;
// Allow -Wno-c99-designator to be used to turn off all warnings on valid C99
// designators (including the warning controlled by -Wc++20-designator).
def C99Designator : DiagGroup<"c99-designator", [CXX20Designator]>;
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
