| Message ID | 20230209181722.3178411-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: sizeof(expr) in non-templated requires-expr [PR108563] | expand |
On Thu, 9 Feb 2023, Patrick Palka wrote: > When substituting into sizeof(expr), tsubst_copy_and_build elides > substitution into the operand if args is NULL_TREE, and instead > considers the TREE_TYPE of the operand. But here the (templated) > operand is a TEMPLATE_ID_EXPR with empty TREE_TYPE, so we can't elide > substitution in this case. > > Contrary to the associated comment (dating back to r69130) substituting > args=NULL_TREE should generally work since we do exactly that in e.g. > fold_non_dependent_expr, and I don't see why the operand of sizeof would > be an exception. So this patch just removes this special case. > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk? Diff generated with -w to ignore noisy whitespace changes. This time with -w actually passed to format-patch: -- >8 -- PR c++/108563 gcc/cp/ChangeLog: * pt.cc (tsubst_copy_and_build) <case SIZEOF_EXPR>: Remove special case for empty args. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-requires35.C: New test. --- gcc/cp/pt.cc | 11 ----------- gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C | 14 ++++++++++++++ 2 files changed, 14 insertions(+), 11 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 9f3fc1fa089..f21d28263d1 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -20652,16 +20652,6 @@ tsubst_copy_and_build (tree t, op1 = TREE_TYPE (op1); bool std_alignof = (TREE_CODE (t) == ALIGNOF_EXPR && ALIGNOF_EXPR_STD_P (t)); - if (!args) - { - /* When there are no ARGS, we are trying to evaluate a - non-dependent expression from the parser. Trying to do - the substitutions may not work. */ - if (!TYPE_P (op1)) - op1 = TREE_TYPE (op1); - } - else - { ++cp_unevaluated_operand; ++c_inhibit_evaluation_warnings; if (TYPE_P (op1)) @@ -20670,7 +20660,6 @@ tsubst_copy_and_build (tree t, op1 = tsubst_copy_and_build (op1, args, complain, in_decl); --cp_unevaluated_operand; --c_inhibit_evaluation_warnings; - } if (TYPE_P (op1)) r = cxx_sizeof_or_alignof_type (input_location, op1, TREE_CODE (t), std_alignof, diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C b/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C new file mode 100644 index 00000000000..2bb4b2b0b5d --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C @@ -0,0 +1,14 @@ +// PR c++/108563 +// { dg-do compile { target c++20 } } + +template<class T> +struct foo { + static constexpr T value = 0; +}; + +template<class T> +inline constexpr T foo_v = foo<T>::value; + +static_assert(requires { sizeof(foo_v<int>); }); +static_assert(requires { requires sizeof(foo_v<int*>) == sizeof(int*); }); +static_assert(requires { requires sizeof(foo_v<char>) == sizeof(char); });
On 2/9/23 10:22, Patrick Palka wrote: > On Thu, 9 Feb 2023, Patrick Palka wrote: > >> When substituting into sizeof(expr), tsubst_copy_and_build elides >> substitution into the operand if args is NULL_TREE, and instead >> considers the TREE_TYPE of the operand. But here the (templated) >> operand is a TEMPLATE_ID_EXPR with empty TREE_TYPE, so we can't elide >> substitution in this case. >> >> Contrary to the associated comment (dating back to r69130) substituting >> args=NULL_TREE should generally work since we do exactly that in e.g. >> fold_non_dependent_expr, and I don't see why the operand of sizeof would >> be an exception. So this patch just removes this special case. >> >> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for >> trunk? Diff generated with -w to ignore noisy whitespace changes. > > This time with -w actually passed to format-patch: OK. > -- >8 -- > > PR c++/108563 > > gcc/cp/ChangeLog: > > * pt.cc (tsubst_copy_and_build) <case SIZEOF_EXPR>: Remove > special case for empty args. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp2a/concepts-requires35.C: New test. > --- > gcc/cp/pt.cc | 11 ----------- > gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C | 14 ++++++++++++++ > 2 files changed, 14 insertions(+), 11 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index 9f3fc1fa089..f21d28263d1 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -20652,16 +20652,6 @@ tsubst_copy_and_build (tree t, > op1 = TREE_TYPE (op1); > bool std_alignof = (TREE_CODE (t) == ALIGNOF_EXPR > && ALIGNOF_EXPR_STD_P (t)); > - if (!args) > - { > - /* When there are no ARGS, we are trying to evaluate a > - non-dependent expression from the parser. Trying to do > - the substitutions may not work. */ > - if (!TYPE_P (op1)) > - op1 = TREE_TYPE (op1); > - } > - else > - { > ++cp_unevaluated_operand; > ++c_inhibit_evaluation_warnings; > if (TYPE_P (op1)) > @@ -20670,7 +20660,6 @@ tsubst_copy_and_build (tree t, > op1 = tsubst_copy_and_build (op1, args, complain, in_decl); > --cp_unevaluated_operand; > --c_inhibit_evaluation_warnings; > - } > if (TYPE_P (op1)) > r = cxx_sizeof_or_alignof_type (input_location, > op1, TREE_CODE (t), std_alignof, > diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C b/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C > new file mode 100644 > index 00000000000..2bb4b2b0b5d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C > @@ -0,0 +1,14 @@ > +// PR c++/108563 > +// { dg-do compile { target c++20 } } > + > +template<class T> > +struct foo { > + static constexpr T value = 0; > +}; > + > +template<class T> > +inline constexpr T foo_v = foo<T>::value; > + > +static_assert(requires { sizeof(foo_v<int>); }); > +static_assert(requires { requires sizeof(foo_v<int*>) == sizeof(int*); }); > +static_assert(requires { requires sizeof(foo_v<char>) == sizeof(char); });
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 9f3fc1fa089..f21d28263d1 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -20652,25 +20652,14 @@ tsubst_copy_and_build (tree t, op1 = TREE_TYPE (op1); bool std_alignof = (TREE_CODE (t) == ALIGNOF_EXPR && ALIGNOF_EXPR_STD_P (t)); - if (!args) - { - /* When there are no ARGS, we are trying to evaluate a - non-dependent expression from the parser. Trying to do - the substitutions may not work. */ - if (!TYPE_P (op1)) - op1 = TREE_TYPE (op1); - } + ++cp_unevaluated_operand; + ++c_inhibit_evaluation_warnings; + if (TYPE_P (op1)) + op1 = tsubst (op1, args, complain, in_decl); else - { - ++cp_unevaluated_operand; - ++c_inhibit_evaluation_warnings; - if (TYPE_P (op1)) - op1 = tsubst (op1, args, complain, in_decl); - else - op1 = tsubst_copy_and_build (op1, args, complain, in_decl); - --cp_unevaluated_operand; - --c_inhibit_evaluation_warnings; - } + op1 = tsubst_copy_and_build (op1, args, complain, in_decl); + --cp_unevaluated_operand; + --c_inhibit_evaluation_warnings; if (TYPE_P (op1)) r = cxx_sizeof_or_alignof_type (input_location, op1, TREE_CODE (t), std_alignof, diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C b/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C new file mode 100644 index 00000000000..2bb4b2b0b5d --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-requires35.C @@ -0,0 +1,14 @@ +// PR c++/108563 +// { dg-do compile { target c++20 } } + +template<class T> +struct foo { + static constexpr T value = 0; +}; + +template<class T> +inline constexpr T foo_v = foo<T>::value; + +static_assert(requires { sizeof(foo_v<int>); }); +static_assert(requires { requires sizeof(foo_v<int*>) == sizeof(int*); }); +static_assert(requires { requires sizeof(foo_v<char>) == sizeof(char); });