[PATCH] D158540: Improve error message for constexpr constructors of virtual base classes
Aaron Ballman via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Tue Oct 3 12:06:32 PDT 2023
This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGaf16a4e131c1: Improve error message for constexpr constructors of virtual base classes (authored by NoumanAmir657, committed by aaron.ballman).
Changed prior to commit:
https://reviews.llvm.org/D158540?vs=557571&id=557573#toc
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D158540/new/
https://reviews.llvm.org/D158540
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp
Index: clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp
===================================================================
--- clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp
+++ clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp
@@ -283,3 +283,12 @@
return r;
}
}
+
+struct Base {
+ constexpr Base() = default;
+};
+struct Derived : virtual Base { // expected-note 3{{virtual base class declared here}}
+ constexpr Derived() = default; // expected-error {{default constructor cannot be 'constexpr' in a class with virtual base class}}
+ constexpr Derived(const Derived&) = default; // expected-error {{copy constructor cannot be 'constexpr' in a class with virtual base class}}
+ constexpr Derived(Derived&&) = default; // expected-error {{move constructor cannot be 'constexpr' in a class with virtual base class}}
+};
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -7819,10 +7819,17 @@
: isa<CXXConstructorDecl>(MD))) &&
MD->isConstexpr() && !Constexpr &&
MD->getTemplatedKind() == FunctionDecl::TK_NonTemplate) {
- Diag(MD->getBeginLoc(), MD->isConsteval()
- ? diag::err_incorrect_defaulted_consteval
- : diag::err_incorrect_defaulted_constexpr)
- << CSM;
+ if (!MD->isConsteval() && RD->getNumVBases()) {
+ Diag(MD->getBeginLoc(), diag::err_incorrect_defaulted_constexpr_with_vb)
+ << CSM;
+ for (const auto &I : RD->vbases())
+ Diag(I.getBeginLoc(), diag::note_constexpr_virtual_base_here);
+ } else {
+ Diag(MD->getBeginLoc(), MD->isConsteval()
+ ? diag::err_incorrect_defaulted_consteval
+ : diag::err_incorrect_defaulted_constexpr)
+ << CSM;
+ }
// FIXME: Explain why the special member can't be constexpr.
HadError = true;
}
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -9454,6 +9454,8 @@
def err_incorrect_defaulted_constexpr : Error<
"defaulted definition of %sub{select_special_member_kind}0 "
"is not constexpr">;
+def err_incorrect_defaulted_constexpr_with_vb: Error<
+ "%sub{select_special_member_kind}0 cannot be 'constexpr' in a class with virtual base class">;
def err_incorrect_defaulted_consteval : Error<
"defaulted declaration of %sub{select_special_member_kind}0 "
"cannot be consteval because implicit definition is not constexpr">;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -216,6 +216,9 @@
- The fix-it emitted by ``-Wformat`` for scoped enumerations now take the
enumeration's underlying type into account instead of suggesting a type just
based on the format string specifier being used.
+- Clang now displays an improved diagnostic and a note when a defaulted special
+ member is marked ``constexpr`` in a class with a virtual base class
+ (`#64843: <https://github.com/llvm/llvm-project/issues/64843>`_).
Bug Fixes in This Version
-------------------------
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