C++ PATCH for c++/89612 - ICE with member friend template with noexcept
Marek Polacek
polacek@redhat.com
Thu Mar 14 13:08:00 GMT 2019
Ping.
On Thu, Mar 07, 2019 at 04:52:55PM -0500, Marek Polacek wrote:
> This was one of those PRs where the more you poke, the more ICEs turn up.
> This patch fixes the ones I could find. The original problem was that
> maybe_instantiate_noexcept got a TEMPLATE_DECL created for the member
> friend template in do_friend. Its noexcept-specification was deferred,
> so we went to the block with push_access_scope, but that crashes on a
> TEMPLATE_DECL. One approach could be to somehow not defer noexcept-specs
> for friend templates, I guess, but I didn't want to do that.
>
> So the approach I did take in the end was to handle TEMPLATE_DECLs in
> maybe_instantiate_noexcept.
>
> That broke in register_parameter_specializations but we don't need this
> code anyway, so let's do away with it -- the current_class_{ref,ptr}
> code is enough to fix the PR that register_parameter_specializations was
> introduced for.
>
> Another issue was that since here we are instantiating a deferred noexcept,
> in a instantiate_class_template context, processing_template_decl was 0.
> Let's pretend it's on for the tsubst purposes here, and for build_noexcept_spec
> too, so that the *_dependent_expression_p functions work.
>
> Lastly, I found an invalid testcase that was breaking because a template code
> leaked to constexpr functions. This I fixed similarly to the recent explicit
> PR fix (r269131).
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2019-03-07 Marek Polacek <polacek@redhat.com>
>
> PR c++/89612 - ICE with member friend template with noexcept.
> * except.c (build_noexcept_spec): Call instantiate_non_dependent_expr
> before perform_implicit_conversion_flags. Add processing_template_decl
> sentinel.
> * pt.c (maybe_instantiate_noexcept): For function templates, use their
> template result (function decl). Don't set up local specializations.
> Temporarily turn on processing_template_decl. Update the template type
> too.
>
> * g++.dg/cpp0x/noexcept36.C: New test.
> * g++.dg/cpp1y/noexcept1.C: New test.
> * g++.dg/cpp1z/noexcept-type21.C: New test.
>
> diff --git gcc/cp/except.c gcc/cp/except.c
> index 139e871d7a7..d97b8d40542 100644
> --- gcc/cp/except.c
> +++ gcc/cp/except.c
> @@ -1285,10 +1285,13 @@ build_noexcept_spec (tree expr, tsubst_flags_t complain)
> if (TREE_CODE (expr) != DEFERRED_NOEXCEPT
> && !value_dependent_expression_p (expr))
> {
> + expr = instantiate_non_dependent_expr_sfinae (expr, complain);
> + /* Don't let perform_implicit_conversion_flags create more template
> + codes. */
> + processing_template_decl_sentinel s;
> expr = perform_implicit_conversion_flags (boolean_type_node, expr,
> complain,
> LOOKUP_NORMAL);
> - expr = instantiate_non_dependent_expr (expr);
> expr = cxx_constant_value (expr);
> }
> if (TREE_CODE (expr) == INTEGER_CST)
> diff --git gcc/cp/pt.c gcc/cp/pt.c
> index 906cfe0a58c..44a2c4606f8 100644
> --- gcc/cp/pt.c
> +++ gcc/cp/pt.c
> @@ -24174,6 +24174,17 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t complain)
>
> if (DECL_CLONED_FUNCTION_P (fn))
> fn = DECL_CLONED_FUNCTION (fn);
> +
> + tree orig_fn = NULL_TREE;
> + /* For a member friend template we can get a TEMPLATE_DECL. Let's use
> + its FUNCTION_DECL for the rest of this function -- push_access_scope
> + doesn't accept TEMPLATE_DECLs. */
> + if (DECL_FUNCTION_TEMPLATE_P (fn))
> + {
> + orig_fn = fn;
> + fn = DECL_TEMPLATE_RESULT (fn);
> + }
> +
> fntype = TREE_TYPE (fn);
> spec = TYPE_RAISES_EXCEPTIONS (fntype);
>
> @@ -24204,37 +24215,41 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t complain)
> push_deferring_access_checks (dk_no_deferred);
> input_location = DECL_SOURCE_LOCATION (fn);
>
> - /* A new stack interferes with pop_access_scope. */
> - {
> - /* Set up the list of local specializations. */
> - local_specialization_stack lss (lss_copy);
> -
> - tree save_ccp = current_class_ptr;
> - tree save_ccr = current_class_ref;
> - /* If needed, set current_class_ptr for the benefit of
> - tsubst_copy/PARM_DECL. */
> - tree tdecl = DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (fn));
> - if (DECL_NONSTATIC_MEMBER_FUNCTION_P (tdecl))
> - {
> - tree this_parm = DECL_ARGUMENTS (tdecl);
> - current_class_ptr = NULL_TREE;
> - current_class_ref = cp_build_fold_indirect_ref (this_parm);
> - current_class_ptr = this_parm;
> - }
> + tree save_ccp = current_class_ptr;
> + tree save_ccr = current_class_ref;
> + /* If needed, set current_class_ptr for the benefit of
> + tsubst_copy/PARM_DECL. */
> + tree tdecl = DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (fn));
> + if (DECL_NONSTATIC_MEMBER_FUNCTION_P (tdecl))
> + {
> + tree this_parm = DECL_ARGUMENTS (tdecl);
> + current_class_ptr = NULL_TREE;
> + current_class_ref = cp_build_fold_indirect_ref (this_parm);
> + current_class_ptr = this_parm;
> + }
>
> - /* Create substitution entries for the parameters. */
> - register_parameter_specializations (tdecl, fn);
> + /* If this function is represented by a TEMPLATE_DECL, then
> + the deferred noexcept-specification might still contain
> + dependent types, even after substitution. And we need the
> + dependency check functions to work in build_noexcept_spec. */
> + if (orig_fn)
> + ++processing_template_decl;
>
> - /* Do deferred instantiation of the noexcept-specifier. */
> - noex = tsubst_copy_and_build (DEFERRED_NOEXCEPT_PATTERN (noex),
> - DEFERRED_NOEXCEPT_ARGS (noex),
> - tf_warning_or_error, fn,
> - /*function_p=*/false,
> - /*i_c_e_p=*/true);
> - current_class_ptr = save_ccp;
> - current_class_ref = save_ccr;
> - spec = build_noexcept_spec (noex, tf_warning_or_error);
> - }
> + /* Do deferred instantiation of the noexcept-specifier. */
> + noex = tsubst_copy_and_build (DEFERRED_NOEXCEPT_PATTERN (noex),
> + DEFERRED_NOEXCEPT_ARGS (noex),
> + tf_warning_or_error, fn,
> + /*function_p=*/false,
> + /*i_c_e_p=*/true);
> +
> + current_class_ptr = save_ccp;
> + current_class_ref = save_ccr;
> +
> + /* Build up the noexcept-specification. */
> + spec = build_noexcept_spec (noex, tf_warning_or_error);
> +
> + if (orig_fn)
> + --processing_template_decl;
>
> pop_deferring_access_checks ();
> pop_access_scope (fn);
> @@ -24250,6 +24265,8 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t complain)
> return false;
>
> TREE_TYPE (fn) = build_exception_variant (fntype, spec);
> + if (orig_fn)
> + TREE_TYPE (orig_fn) = TREE_TYPE (fn);
> }
>
> FOR_EACH_CLONE (clone, fn)
> diff --git gcc/testsuite/g++.dg/cpp0x/noexcept36.C gcc/testsuite/g++.dg/cpp0x/noexcept36.C
> new file mode 100644
> index 00000000000..ecab59df694
> --- /dev/null
> +++ gcc/testsuite/g++.dg/cpp0x/noexcept36.C
> @@ -0,0 +1,19 @@
> +// PR c++/89612
> +// { dg-do compile { target c++11 } }
> +
> +template <typename>
> +struct C {
> + template <int N>
> + friend int foo() noexcept(N);
> +
> + template <int N>
> + friend int foo2() noexcept(N); // { dg-error "different exception" }
> +};
> +
> +template <int N>
> +int foo() noexcept(N);
> +
> +template <int N>
> +int foo2() noexcept(N + 1);
> +
> +C<int> c;
> diff --git gcc/testsuite/g++.dg/cpp1y/noexcept1.C gcc/testsuite/g++.dg/cpp1y/noexcept1.C
> new file mode 100644
> index 00000000000..2344b1ba92c
> --- /dev/null
> +++ gcc/testsuite/g++.dg/cpp1y/noexcept1.C
> @@ -0,0 +1,13 @@
> +// PR c++/89612
> +// { dg-do compile { target c++14 } }
> +
> +template <int> bool b;
> +
> +template <typename>
> +struct C {
> + template <typename> friend int foo() noexcept(b<1>); // { dg-error "not usable in a constant expression|different exception specifier" }
> +};
> +
> +template <typename> int foo() noexcept(b<1>);
> +
> +auto a = C<int>();
> diff --git gcc/testsuite/g++.dg/cpp1z/noexcept-type21.C gcc/testsuite/g++.dg/cpp1z/noexcept-type21.C
> new file mode 100644
> index 00000000000..d0a61d95e87
> --- /dev/null
> +++ gcc/testsuite/g++.dg/cpp1z/noexcept-type21.C
> @@ -0,0 +1,16 @@
> +// PR c++/89612
> +// { dg-do compile { target c++17 } }
> +
> +template <typename a> using b = typename a ::c;
> +template <typename> bool d;
> +template <typename, typename> struct e {
> + template <typename f, typename g> e(f, g) {}
> + template <typename h, typename i, typename j>
> + friend auto k(h &&, const j &, i &&) noexcept(d<b<h>, h> &&d<b<i>, i>);
> +};
> +template <typename l, typename m> e(l, m)->e<l, m>;
> +template <typename l, typename m, typename j>
> +auto k(l &&, const j &, m &&) noexcept(d<b<l>, l> &&d<b<m>, m>);
> +int main() {
> + e(0, [] {});
> +}
Marek
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