https://gcc.gnu.org/g:fa99002538bc91c869f3b1fd9af7f14e410e1e1a
commit r15-6369-gfa99002538bc91c869f3b1fd9af7f14e410e1e1a
Author: Marek Polacek <pola...@redhat.com>
Date: Tue Dec 10 18:43:56 2024 -0500
c++: ICE in TARGET_EXPR evaluation in cp_fold_r [PR117980]
This ICE started with the recent prvalue optimization (r15-6052). In
cp_fold_r we have:
if (tree &init = TARGET_EXPR_INITIAL (stmt))
{
cp_walk_tree (&init, cp_fold_r, data, NULL);
// ...
tree folded = maybe_constant_init (init, TARGET_EXPR_SLOT (stmt));
What can happen here is that originally the TARGET_EXPR is:
TARGET_EXPR <D.2747, <<< Unknown tree: aggr_init_expr
5
__ct_comp
D.2747
(struct subrange *) <<< Unknown tree: void_cst >>>
&TARGET_EXPR <D.2707, {.it=TARGET_EXPR <D.2695, ...>}> >>>>
but after the first cp_walk_tree we fold the D.2707 TARGET_EXPR into:
TARGET_EXPR <D.2707, <<< Unknown tree: expr_stmt
D.2707.it = TARGET_EXPR <D.2695, ...> >>>>
and then we pass the EXPR_STMT to maybe_constant_init, with D.2707 as
the object. But their types don't match anymore, so we crash. We'd
have to pass D.2707.it as the object for it to work.
This patch adjusts cxx_eval_outermost_constant_expr to take the object's
type if available.
constexpr-prvalue3.C is reduced from a large std::ranges libstdc++ test.
PR c++/117980
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_outermost_constant_expr): If there's
an object to initialize, take its type. Don't set the type
in the constexpr dtor case.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-prvalue2.C: New test.
* g++.dg/cpp0x/constexpr-prvalue3.C: New test.
Co-authored-by: Jason Merrill <ja...@redhat.com>
Diff:
---
gcc/cp/constexpr.cc | 9 ++++-----
gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue2.C | 15 ++++++++++++++
gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue3.C | 26 +++++++++++++++++++++++++
3 files changed, 45 insertions(+), 5 deletions(-)
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index c16597dfaece..d699020ff9db 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -8870,15 +8870,14 @@ cxx_eval_outermost_constant_expr (tree t, bool
allow_non_constant,
/* Turn off -frounding-math for manifestly constant evaluation. */
warning_sentinel rm (flag_rounding_math,
ctx.manifestly_const_eval == mce_true);
- tree type = initialized_type (t);
+ tree type = (object
+ ? cv_unqualified (TREE_TYPE (object))
+ : initialized_type (t));
tree r = t;
bool is_consteval = false;
if (VOID_TYPE_P (type))
{
- if (constexpr_dtor)
- /* Used for destructors of array elements. */
- type = TREE_TYPE (object);
- else
+ if (!constexpr_dtor)
{
if (cxx_dialect < cxx20)
return t;
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue2.C
b/gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue2.C
new file mode 100644
index 000000000000..46053231cf83
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue2.C
@@ -0,0 +1,15 @@
+// PR c++/117980
+// { dg-do compile { target c++11 } }
+// { dg-options "-O" }
+
+struct S {
+ constexpr S(S &); // { dg-warning "used but never defined" }
+ ~S();
+};
+struct B {
+ S s;
+};
+struct A {
+ B b;
+};
+void fn(B b) { A{b}; }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue3.C
b/gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue3.C
new file mode 100644
index 000000000000..a2eb12c02d74
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-prvalue3.C
@@ -0,0 +1,26 @@
+// PR c++/117980
+// { dg-do compile { target c++11 } }
+// { dg-options "-O" }
+
+struct _Safe_iterator {
+ _Safe_iterator();
+ ~_Safe_iterator();
+};
+template <typename _Tp>
+struct vector {
+ vector(int) {}
+ constexpr _Safe_iterator end() {
+ return _Safe_iterator();
+ }
+};
+template <typename It> struct sentinel {
+ It it;
+};
+template <typename _Sent>
+struct subrange {
+ subrange(sentinel<_Safe_iterator>) {}
+};
+void test01() {
+ vector<int> v{0};
+ subrange<sentinel<_Safe_iterator>>{sentinel<_Safe_iterator>{v.end()}};
+}
