OK.
On Thu, Apr 12, 2018 at 1:47 PM, Marek Polacek <pola...@redhat.com> wrote:
> This is a crash on invalid which started when we changed
> decl_maybe_constant_var_p
> to say true for references. Then in tsubst_copy we take this branch:
> if (decl_maybe_constant_var_p (r))
> {
> /* We can't call cp_finish_decl, so handle the
> initializer by hand. */
> tree init = tsubst_init (DECL_INITIAL (t), r, args,
> complain, in_decl);
> but tsubst_init can return NULL_TREE, which potential_constant_expression
> knows how to handle, but reduced_constant_expression_p didn't. So the
> following patch will fix the ICE.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-04-12 Marek Polacek <pola...@redhat.com>
>
> PR c++/85258
> * constexpr.c (reduced_constant_expression_p): Return false for null
> trees.
>
> * g++.dg/parse/error61.C: New test.
>
> diff --git gcc/cp/constexpr.c gcc/cp/constexpr.c
> index 75f56df4465..82f14baaefd 100644
> --- gcc/cp/constexpr.c
> +++ gcc/cp/constexpr.c
> @@ -1773,6 +1773,9 @@ cxx_eval_call_expression (const constexpr_ctx *ctx,
> tree t,
> bool
> reduced_constant_expression_p (tree t)
> {
> + if (t == NULL_TREE)
> + return false;
> +
> switch (TREE_CODE (t))
> {
> case PTRMEM_CST:
> @@ -1794,9 +1797,8 @@ reduced_constant_expression_p (tree t)
> field = NULL_TREE;
> FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (t), i, idx, val)
> {
> - if (!val)
> - /* We're in the middle of initializing this element. */
> - return false;
> + /* If VAL is null, we're in the middle of initializing this
> + element. */
> if (!reduced_constant_expression_p (val))
> return false;
> if (field)
> diff --git gcc/testsuite/g++.dg/parse/error61.C
> gcc/testsuite/g++.dg/parse/error61.C
> index e69de29bb2d..199e1aa721c 100644
> --- gcc/testsuite/g++.dg/parse/error61.C
> +++ gcc/testsuite/g++.dg/parse/error61.C
> @@ -0,0 +1,14 @@
> +// PR c++/85258
> +// { dg-do compile { target c++11 } }
> +
> +template<int> void foo()
> +{
> + int x[8];
> + for (int& i, j : x) // { dg-error "multiple" }
> + i = 0; // { dg-error "local variable" }
> +}
> +
> +void bar()
> +{
> + foo<0>();
> +}
>
> Marek
