OK.
On Tue, Jun 12, 2018 at 3:02 PM, Marek Polacek <pola...@redhat.com> wrote: > As [class.copy.ctor] says, the type of an implicitly declared copy constructor > will be either > > X::X(const X&) > > if each potentially constructed subobject of a class type M (or array thereof) > has a copy constructor whose first parameter is of type const M& or const > volatile M&. Otherwise, the implicitly-declared copy constructor will > have the form > > X::X(X&) > > Similarly for implicitly-declared copy assignment operator: it will be either > > X& operator=(const X&) > > or > > X& operator=(X&) > > Previously, the declared type of an explicitly defaulted function had to be > the > same as if it had been implicitly declared, otherwise the code was ill-formed. > But Core Issue 1331 [1] changes this in such a way that it be defined as > deleted > instead, with two exceptions for an assignment operator with a mismatched > return > type, and an assignment operator with a parameter type that's not a reference. > > The change itself seems trivial (unless I'm missing something), so most of my > effort went into writing testcases for various scenarios I could think of. > We already give errors for cases that are still considered ill-formed. > > [1] http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0641r2.html > > Bootstrapped/regtested on x86_64-linux, ok for trunk? > > 2018-06-12 Marek Polacek <pola...@redhat.com> > > Core issue 1331 - const mismatch with defaulted copy constructor > * class.c (check_bases_and_members): When checking a defaulted > function, mark it as deleted rather than giving an error. > > * g++.dg/cpp0x/defaulted15.C (struct F): Remove dg-error. > * g++.dg/cpp0x/defaulted52.C: New test. > * g++.dg/cpp0x/defaulted53.C: New test. > * g++.dg/cpp0x/defaulted54.C: New test. > * g++.dg/cpp0x/defaulted55.C: New test. > * g++.dg/cpp0x/defaulted56.C: New test. > * g++.dg/cpp0x/defaulted57.C: New test. > * g++.dg/cpp0x/defaulted58.C: New test. > * g++.dg/cpp0x/defaulted59.C: New test. > * g++.dg/cpp0x/defaulted60.C: New test. > > diff --git gcc/cp/class.c gcc/cp/class.c > index fbf39035e18..b6e78c6377d 100644 > --- gcc/cp/class.c > +++ gcc/cp/class.c > @@ -5660,9 +5660,9 @@ check_bases_and_members (tree t) > > if (fn_const_p && !imp_const_p) > /* If the function is defaulted outside the class, we just > - give the synthesis error. */ > - error ("%q+D declared to take const reference, but implicit " > - "declaration would take non-const", fn); > + give the synthesis error. Core Issue #1331 says this is > + no longer ill-formed, it is defined as deleted instead. */ > + DECL_DELETED_FN (fn) = true; > } > defaulted_late_check (fn); > } > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted15.C > gcc/testsuite/g++.dg/cpp0x/defaulted15.C > index fabcc23a150..1e0b3545840 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted15.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted15.C > @@ -48,8 +48,7 @@ struct F > > struct G: public F > { > - // Can't be const because F copy ctor isn't. > - G(const G&) = default; // { dg-error "const" } > + G(const G&) = default; > }; > > struct H > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted52.C > gcc/testsuite/g++.dg/cpp0x/defaulted52.C > index e69de29bb2d..c617230b493 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted52.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted52.C > @@ -0,0 +1,20 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +struct M > +{ > + M(); > + // So that W wouldn't have had "const W&" copy ctor if it were > + // implicitly declared. > + M(M&); > +}; > + > +template<typename T> struct W > +{ > + W(); > + // This should now compile and be =deleted. > + W(const W&) = default; > + T t; > +}; > + > +W<M> w; > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted53.C > gcc/testsuite/g++.dg/cpp0x/defaulted53.C > index e69de29bb2d..8147e7e2ad1 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted53.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted53.C > @@ -0,0 +1,35 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +struct M > +{ > + M& operator=(M&); > +}; > + > +struct R > +{ > + R& operator=(R&) = default; > + M m; > +}; > + > +struct S > +{ > + S& operator=(const S&) = default; > + M m; > +}; > + > +struct T > +{ > + // If F is an assignment operator, and the return type of T1 > + // differs from the return type of T2 the program is ill-formed. > + T operator=(T&) = default; // { dg-error "defaulted" } > + M m; > +}; > + > +struct U > +{ > + // If F is an assignment operator, and T1's parameter type is > + // not a reference, the program is ill-formed. > + U& operator=(U) = default; // { dg-error "defaulted" } > + M m; > +}; > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted54.C > gcc/testsuite/g++.dg/cpp0x/defaulted54.C > index e69de29bb2d..f8ddc4e47ce 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted54.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted54.C > @@ -0,0 +1,18 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +struct M > +{ > + M(); > + M(M&); > +}; > + > +template<typename T> struct W > +{ > + W(); > + W(const W&) = default; // { dg-error "binding" } > + T t; > +}; > + > +W<M> w; > +W<M> w2 = w; // { dg-error "use of deleted function" } > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted55.C > gcc/testsuite/g++.dg/cpp0x/defaulted55.C > index e69de29bb2d..04cfc172000 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted55.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted55.C > @@ -0,0 +1,19 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +struct M > +{ > + M(); > + M(M&); > +}; > + > +template<typename T> struct W > +{ > + W(); > + W(W&) = default; > + // T1 and T2 may have differing ref-qualifiers (copy assign op). > + constexpr W& operator=(const W&) && = default; // { dg-error "defaulted" > "" { target c++11_down } } > + T t; > +}; > + > +W<M> w; > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted56.C > gcc/testsuite/g++.dg/cpp0x/defaulted56.C > index e69de29bb2d..e7ce12c5566 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted56.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted56.C > @@ -0,0 +1,25 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +// If T2 (what would be the implicit declaration) has a parameter of > +// type const C&, the corresponding parameter of T1 may be of type C&. > + > +struct S > +{ > + constexpr S(S &) = default; > +}; > + > +struct T > +{ > + constexpr T(volatile T &) = default; // { dg-error "defaulted" } > +}; > + > +struct U > +{ > + constexpr U(const volatile U &) = default; // { dg-error "defaulted" } > +}; > + > +struct V > +{ > + constexpr V(const V &) = default; > +}; > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted57.C > gcc/testsuite/g++.dg/cpp0x/defaulted57.C > index e69de29bb2d..37fb7dd6e1d 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted57.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted57.C > @@ -0,0 +1,25 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +// If T2 (what would be the implicit declaration) has a parameter of > +// type const C&, the corresponding parameter of T1 may be of type C&. > + > +struct S > +{ > + S& operator=(S &) = default; > +}; > + > +struct T > +{ > + T& operator=(volatile T &) = default; // { dg-error "defaulted" } > +}; > + > +struct U > +{ > + U& operator=(const volatile U &) = default; // { dg-error "defaulted" } > +}; > + > +struct V > +{ > + V& operator=(const V &) = default; > +}; > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted58.C > gcc/testsuite/g++.dg/cpp0x/defaulted58.C > index e69de29bb2d..920a4ad0c6d 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted58.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted58.C > @@ -0,0 +1,22 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +struct M > +{ > + M() = default; > + M& operator=(M&); > +}; > + > +template<typename T> struct W > +{ > + W() = default; > + W& operator=(const W&) = default; // { dg-error "binding" } > + T t; > +}; > + > +int > +main () > +{ > + W<M> w1, w2; > + w1 = w2; // { dg-error "use of deleted function" } > +} > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted59.C > gcc/testsuite/g++.dg/cpp0x/defaulted59.C > index e69de29bb2d..4f871d7f5b1 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted59.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted59.C > @@ -0,0 +1,12 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +struct M > +{ > + M(M&) = default; > +}; > + > +struct W : public M > +{ > + W(const W&) = default; > +}; > diff --git gcc/testsuite/g++.dg/cpp0x/defaulted60.C > gcc/testsuite/g++.dg/cpp0x/defaulted60.C > index e69de29bb2d..ad025236cce 100644 > --- gcc/testsuite/g++.dg/cpp0x/defaulted60.C > +++ gcc/testsuite/g++.dg/cpp0x/defaulted60.C > @@ -0,0 +1,18 @@ > +// Core Issue #1331 (const mismatch with defaulted copy constructor) > +// { dg-do compile { target c++11 } } > + > +struct M > +{ > + M(M&); > +}; > + > +struct W > +{ > + W(); > + W(const W&); > + M m; > +}; > + > +// Not first declaration. > +W::W(const W&) = default; // { dg-error "binding" } > +W w;
