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];
+}
