| Message ID | 65e7a11e.050a0220.6580e.c8c8@mx.google.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: Fix template deduction for conversion operators with xobj parameters [PR113629] | expand |
On 3/5/24 17:47, Nathaniel Shead wrote: > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? > > -- >8 -- > > Unification for conversion operators (DEDUCE_CONV) doesn't perform > transformations like handling forwarding references. This is correct in > general, but not for xobj parameters, which should be handled "normally" > for the purposes of deduction: [temp.deduct.conv] only applies to the > return type of the conversion function. > > PR c++/113629 > > gcc/cp/ChangeLog: > > * pt.cc (type_unification_real): Use DEDUCE_CALL for xobj > parameters of conversion functions. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp23/explicit-obj-conv-op.C: New test. > > Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com> > --- > gcc/cp/pt.cc | 15 +++++- > .../g++.dg/cpp23/explicit-obj-conv-op.C | 49 +++++++++++++++++++ > 2 files changed, 63 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/cpp23/explicit-obj-conv-op.C > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index c4bc54a8fdb..632437d3424 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -23281,6 +23281,10 @@ type_unification_real (tree tparms, > in TARGS. */ > NON_DEFAULT_TEMPLATE_ARGS_COUNT (targs) = NULL_TREE; > > + bool is_xobj_conv_fn > + = (strict == DEDUCE_CONV > + && DECL_XOBJ_MEMBER_FUNCTION_P (TREE_TYPE (tparms))); > + > again: > parms = xparms; > args = xargs; > @@ -23312,10 +23316,17 @@ type_unification_real (tree tparms, > parameter pack is a non-deduced context. */ > continue; > > + /* For explicit object parameters, unification should behave like > + normal function calls, even for conversion functions. This > + corresponds to the second (that is, last) argument. */ > + unification_kind_t kind = strict; > + if (is_xobj_conv_fn && ia > 0) Is it necessary to check the xobj flag? Or can this just be if (strict == DEDUCE_CONV && ia > 0) ? Jason
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index c4bc54a8fdb..632437d3424 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -23281,6 +23281,10 @@ type_unification_real (tree tparms, in TARGS. */ NON_DEFAULT_TEMPLATE_ARGS_COUNT (targs) = NULL_TREE; + bool is_xobj_conv_fn + = (strict == DEDUCE_CONV + && DECL_XOBJ_MEMBER_FUNCTION_P (TREE_TYPE (tparms))); + again: parms = xparms; args = xargs; @@ -23312,10 +23316,17 @@ type_unification_real (tree tparms, parameter pack is a non-deduced context. */ continue; + /* For explicit object parameters, unification should behave like + normal function calls, even for conversion functions. This + corresponds to the second (that is, last) argument. */ + unification_kind_t kind = strict; + if (is_xobj_conv_fn && ia > 0) + kind = DEDUCE_CALL; + arg = args[ia]; ++ia; - if (unify_one_argument (tparms, full_targs, parm, arg, subr, strict, + if (unify_one_argument (tparms, full_targs, parm, arg, subr, kind, explain_p)) return 1; } @@ -23324,6 +23335,8 @@ type_unification_real (tree tparms, && parms != void_list_node && TREE_CODE (TREE_VALUE (parms)) == TYPE_PACK_EXPANSION) { + gcc_assert (strict != DEDUCE_CONV); + /* Unify the remaining arguments with the pack expansion type. */ tree argvec; tree parmvec = make_tree_vec (1); diff --git a/gcc/testsuite/g++.dg/cpp23/explicit-obj-conv-op.C b/gcc/testsuite/g++.dg/cpp23/explicit-obj-conv-op.C new file mode 100644 index 00000000000..a6ae4ea1dda --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp23/explicit-obj-conv-op.C @@ -0,0 +1,49 @@ +// PR c++/113629 +// { dg-do compile { target c++23 } } + +template <typename T> constexpr bool is_lvalue = false; +template <typename T> constexpr bool is_lvalue<T&> = true; + +struct A { + constexpr operator bool(this auto&& self) { + return is_lvalue<decltype(self)>; + } +}; + +constexpr A a; +static_assert(static_cast<bool>(a)); +static_assert((bool)a); +static_assert(!static_cast<bool>(A{})); +static_assert(!(bool)A{}); + +struct B : A {}; + +constexpr B b; +static_assert(static_cast<bool>(b)); +static_assert((bool)b); +static_assert(!static_cast<bool>(B{})); +static_assert(!(bool)B{}); + +struct C { + template <typename R, typename T> + explicit constexpr operator R(this T&&) { + return is_lvalue<T>; + } +}; + +constexpr C c; +static_assert(static_cast<bool>(c)); +static_assert((bool)c); +static_assert(!static_cast<bool>(C{})); +static_assert(!(bool)C{}); + +struct D { + explicit constexpr operator bool(this const D&) { return true; } + explicit constexpr operator bool(this const D&&) { return false; } +}; + +constexpr D d; +static_assert(static_cast<bool>(d)); +static_assert((bool)d); +static_assert(!static_cast<bool>(D{})); +static_assert(!(bool)D{});
Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? -- >8 -- Unification for conversion operators (DEDUCE_CONV) doesn't perform transformations like handling forwarding references. This is correct in general, but not for xobj parameters, which should be handled "normally" for the purposes of deduction: [temp.deduct.conv] only applies to the return type of the conversion function. PR c++/113629 gcc/cp/ChangeLog: * pt.cc (type_unification_real): Use DEDUCE_CALL for xobj parameters of conversion functions. gcc/testsuite/ChangeLog: * g++.dg/cpp23/explicit-obj-conv-op.C: New test. Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com> --- gcc/cp/pt.cc | 15 +++++- .../g++.dg/cpp23/explicit-obj-conv-op.C | 49 +++++++++++++++++++ 2 files changed, 63 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp23/explicit-obj-conv-op.C