On Thu, Mar 21, 2019 at 04:00:41PM -0400, Jason Merrill wrote:
> On 3/19/19 11:45 AM, Marek Polacek wrote:
> > On Thu, Mar 14, 2019 at 04:22:41PM -0400, Jason Merrill wrote:
> > > On 3/7/19 4:52 PM, 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.
>
> > > How does it make sense to instantiate the noexcept-specifier of a
> > > template?
> > > We should only get there for fully-instantiated function decls.
> >
> > Hmm, but duplicate_decls calls check_redeclaration_exception_specification
> > even
> > for DECL_FUNCTION_TEMPLATE_Ps.
> > ...
> > Note the crash happens in tsubst_friend_function. I wouldn't know when to
> > check the noexcept-specifier of such a TEMPLATE_DECL for a template friend
> > if not there.
>
> Hmm, true, I guess we do need to do a partial instantiation of the
> noexcept-specifier in order to compare it.
*nod*
> > 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.
>
> What about uses of non-'this' parameters in the noexcept-specification?
>
> template <typename T>
> struct C {
> template <int N>
> friend void foo(T t) noexcept(sizeof(decltype(t)) > 1);
> };
>
> template <int N>
> void foo(int i) noexcept { }
>
> C<int> c;
Still works. I extended the test to see if we detect the scenario when the
noexcept-specifiers don't match, and we do. It's noexcept39.C.
> > > > 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).
> > >
> > > This spot should probably also use build_converted_constant_expr.
> >
> > Ok, I'll address this.
>
> I'm finding this repeated pattern awkward. Earlier you changed
> check_narrowing to use maybe_constant_value instead of
> fold_non_dependent_expr, but perhaps whatever that fixed should have been
> fixed instead with a processing_template_decl_sentinel in the enclosing code
> that already instantiated the expression. That ought to avoid any need to
> change this spot or r269131.
So this also came up in the other patch. Why don't I drop this part (and the
noexcept1.C test) and open a new PR for this issue, so that we don't conflate
two problems? The following patch fixes the original issue.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2019-03-28 Marek Polacek <pola...@redhat.com>
PR c++/89612 - ICE with member friend template with noexcept.
* 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/noexcept38.C: New test.
* g++.dg/cpp0x/noexcept39.C: New test.
* g++.dg/cpp1z/noexcept-type21.C: New test.
diff --git gcc/cp/pt.c gcc/cp/pt.c
index 05d5371d8a6..fa30a7f00c8 100644
--- gcc/cp/pt.c
+++ gcc/cp/pt.c
@@ -24192,6 +24192,17 @@ 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);
@@ -24228,37 +24239,41 @@ 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);
@@ -24278,6 +24293,8 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t
complain)
}
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/noexcept38.C
gcc/testsuite/g++.dg/cpp0x/noexcept38.C
new file mode 100644
index 00000000000..ecab59df694
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/noexcept38.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/cpp0x/noexcept39.C
gcc/testsuite/g++.dg/cpp0x/noexcept39.C
new file mode 100644
index 00000000000..fbebbed5e4c
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/noexcept39.C
@@ -0,0 +1,19 @@
+// PR c++/89612
+// { dg-do compile { target c++11 } }
+
+template <typename T>
+struct C {
+ template <int N>
+ friend void foo(T t) noexcept(sizeof(decltype(t)) > 1);
+
+ template <int N>
+ friend void foo2(T t) noexcept(sizeof(decltype(t)) < 1); // { dg-error
"different exception" }
+};
+
+template <int N>
+void foo(int i) noexcept { }
+
+template <int N>
+void foo2(int i) noexcept { }
+
+C<int> c;
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, [] {});
+}
