OK.
On Wed, May 23, 2018 at 4:27 PM, Marek Polacek <pola...@redhat.com> wrote:
> On Wed, May 23, 2018 at 03:24:20PM -0400, Jason Merrill wrote:
>> On Wed, May 23, 2018 at 2:50 PM, Marek Polacek <pola...@redhat.com> wrote:
>> > On Wed, May 23, 2018 at 12:45:11PM -0400, Jason Merrill wrote:
>> >> On Wed, May 23, 2018 at 9:46 AM, Marek Polacek <pola...@redhat.com> wrote:
>> >> > The diagnostic code in build_new{,_1} was using maybe_constant_value to
>> >> > fold
>> >> > the array length, but that breaks while parsing a template, because we
>> >> > might
>> >> > then leak template codes to the constexpr machinery.
>> >> >
>> >> > Bootstrapped/regtested on x86_64-linux, ok for trunk/8?
>> >> >
>> >> > 2018-05-23 Marek Polacek <pola...@redhat.com>
>> >> >
>> >> > PR c++/85847
>> >> > * init.c (build_new_1): Use fold_non_dependent_expr.
>> >> > (build_new): Likewise.
>> >> >
>> >> > * g++.dg/cpp0x/new3.C: New test.
>> >> >
>> >> > @@ -2860,7 +2860,7 @@ build_new_1 (vec<tree, va_gc> **placement, tree
>> >> > type, tree nelts,
>> >> > /* Lots of logic below. depends on whether we have a constant number
>> >> > of
>> >> > elements, so go ahead and fold it now. */
>> >> > if (outer_nelts)
>> >> > - outer_nelts = maybe_constant_value (outer_nelts);
>> >> > + outer_nelts = fold_non_dependent_expr (outer_nelts);
>> >>
>> >> If outer_nelts is non-constant, this will mean that it ends up
>> >> instantiated but still non-constant, which can lead to problems when
>> >> the result is used in building up other expressions.
>> >>
>> >> I think we want to put the result of folding in a separate variable
>> >> for use with things that want to know about a constant size, and keep
>> >> the original outer_nelts for use in building outer_nelts_check.
>> >>
>> >> > /* Try to determine the constant value only for the purposes
>> >> > of the diagnostic below but continue to use the original
>> >> > value and handle const folding later. */
>> >> > - const_tree cst_nelts = maybe_constant_value (nelts);
>> >> > + const_tree cst_nelts = fold_non_dependent_expr (nelts);
>> >>
>> >> ...like we do here.
>> >
>> > Like this?
>> >
>> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
>> >
>> > 2018-05-23 Marek Polacek <pola...@redhat.com>
>> >
>> > PR c++/85847
>> > * init.c (build_new_1): Use fold_non_dependent_expr. Use a
>> > dedicated
>> > variable for its result. Fix a condition.
>> > (build_new): Use fold_non_dependent_expr. Tweak a condition.
>> >
>> > * g++.dg/cpp0x/new3.C: New test.
>> >
>> > diff --git gcc/cp/init.c gcc/cp/init.c
>> > index b558742abf6..cd0110a1e19 100644
>> > --- gcc/cp/init.c
>> > +++ gcc/cp/init.c
>> > @@ -2857,10 +2857,9 @@ build_new_1 (vec<tree, va_gc> **placement, tree
>> > type, tree nelts,
>> > outer_nelts_from_type = true;
>> > }
>> >
>> > - /* Lots of logic below. depends on whether we have a constant number of
>> > + /* Lots of logic below depends on whether we have a constant number of
>> > elements, so go ahead and fold it now. */
>> > - if (outer_nelts)
>> > - outer_nelts = maybe_constant_value (outer_nelts);
>> > + const_tree cst_outer_nelts = fold_non_dependent_expr (outer_nelts);
>> >
>> > /* If our base type is an array, then make sure we know how many
>> > elements
>> > it has. */
>> > @@ -2912,11 +2911,12 @@ build_new_1 (vec<tree, va_gc> **placement, tree
>> > type, tree nelts,
>> > /* Warn if we performed the (T[N]) to T[N] transformation and N is
>> > variable. */
>> > if (outer_nelts_from_type
>> > - && !TREE_CONSTANT (outer_nelts))
>> > + && cst_outer_nelts != NULL_TREE
>> > + && !TREE_CONSTANT (cst_outer_nelts))
>>
>> Why add the comparisons with NULL_TREE? fold_non_dependent_expr only
>> returns null if its argument is null.
>
> True, and it seemed to me that the argument can be null when NELTS is null,
> which, according to the comment for build_new_1 could happen. So I was just
> being cautious. But I dropped the checks and nothing in the testsuite broke.
>
>> > - pedwarn (EXPR_LOC_OR_LOC (outer_nelts, input_location), OPT_Wvla,
>> > + pedwarn (EXPR_LOC_OR_LOC (cst_outer_nelts, input_location),
>> > OPT_Wvla,
>>
>> Let's drop this change, the original expression has the location we want.
>
> Okay.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk/8?
>
> 2018-05-23 Marek Polacek <pola...@redhat.com>
>
> PR c++/85847
> * init.c (build_new_1): Use fold_non_dependent_expr. Use a dedicated
> variable for its result. Fix a condition.
> (build_new): Use fold_non_dependent_expr. Tweak a condition.
>
> * g++.dg/cpp0x/new3.C: New test.
>
> diff --git gcc/cp/init.c gcc/cp/init.c
> index b558742abf6..5bfd0848fc4 100644
> --- gcc/cp/init.c
> +++ gcc/cp/init.c
> @@ -2857,10 +2857,9 @@ build_new_1 (vec<tree, va_gc> **placement, tree type,
> tree nelts,
> outer_nelts_from_type = true;
> }
>
> - /* Lots of logic below. depends on whether we have a constant number of
> + /* Lots of logic below depends on whether we have a constant number of
> elements, so go ahead and fold it now. */
> - if (outer_nelts)
> - outer_nelts = maybe_constant_value (outer_nelts);
> + const_tree cst_outer_nelts = fold_non_dependent_expr (outer_nelts);
>
> /* If our base type is an array, then make sure we know how many elements
> it has. */
> @@ -2912,7 +2911,7 @@ build_new_1 (vec<tree, va_gc> **placement, tree type,
> tree nelts,
> /* Warn if we performed the (T[N]) to T[N] transformation and N is
> variable. */
> if (outer_nelts_from_type
> - && !TREE_CONSTANT (outer_nelts))
> + && !TREE_CONSTANT (cst_outer_nelts))
> {
> if (complain & tf_warning_or_error)
> {
> @@ -3011,9 +3010,9 @@ build_new_1 (vec<tree, va_gc> **placement, tree type,
> tree nelts,
>
> size = size_binop (MULT_EXPR, size, fold_convert (sizetype, nelts));
>
> - if (INTEGER_CST == TREE_CODE (outer_nelts))
> + if (TREE_CODE (cst_outer_nelts) == INTEGER_CST)
> {
> - if (tree_int_cst_lt (max_outer_nelts_tree, outer_nelts))
> + if (tree_int_cst_lt (max_outer_nelts_tree, cst_outer_nelts))
> {
> /* When the array size is constant, check it at compile time
> to make sure it doesn't exceed the implementation-defined
> @@ -3639,13 +3638,13 @@ build_new (vec<tree, va_gc> **placement, tree type,
> tree nelts,
> /* Try to determine the constant value only for the purposes
> of the diagnostic below but continue to use the original
> value and handle const folding later. */
> - const_tree cst_nelts = maybe_constant_value (nelts);
> + const_tree cst_nelts = fold_non_dependent_expr (nelts);
>
> /* The expression in a noptr-new-declarator is erroneous if it's of
> non-class type and its value before converting to std::size_t is
> less than zero. ... If the expression is a constant expression,
> the program is ill-fomed. */
> - if (INTEGER_CST == TREE_CODE (cst_nelts)
> + if (TREE_CODE (cst_nelts) == INTEGER_CST
> && tree_int_cst_sgn (cst_nelts) == -1)
> {
> if (complain & tf_error)
> diff --git gcc/testsuite/g++.dg/cpp0x/new3.C gcc/testsuite/g++.dg/cpp0x/new3.C
> index e69de29bb2d..c388acf552e 100644
> --- gcc/testsuite/g++.dg/cpp0x/new3.C
> +++ gcc/testsuite/g++.dg/cpp0x/new3.C
> @@ -0,0 +1,11 @@
> +// PR c++/85847
> +// { dg-do compile { target c++11 } }
> +
> +template <class>
> +int f(int b) { return b; }
> +
> +template <class>
> +void g()
> +{
> + auto a = new int[f<int>(2), 2];
> +}
