https://gcc.gnu.org/g:fa248a92134c0681719702e60c369b916d4f8bf9
commit r13-9329-gfa248a92134c0681719702e60c369b916d4f8bf9
Author: Simon Martin <si...@nasilyan.com>
Date: Thu Jan 16 16:27:06 2025 +0100
c++: Make sure fold_sizeof_expr returns the correct type [PR117775]
We currently ICE upon the following code, that is valid under
-Wno-pointer-arith:
=== cut here ===
int main() {
decltype( [](auto) { return sizeof(void); } ) x;
return x.operator()(0);
}
=== cut here ===
The problem is that "fold_sizeof_expr (sizeof(void))" returns
size_one_node, that has a different TREE_TYPE from that of the sizeof
expression, which later triggers an assert in cxx_eval_store_expression.
This patch makes sure that fold_sizeof_expr always returns a tree with
the size_type_node type.
PR c++/117775
gcc/cp/ChangeLog:
* decl.cc (fold_sizeof_expr): Make sure the folded result has
type size_type_node.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/constexpr-117775.C: New test.
(cherry picked from commit 37f38b0f97374476a4818b68c8df991886428787)
Diff:
---
gcc/cp/decl.cc | 1 +
gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C | 13 +++++++++++++
2 files changed, 14 insertions(+)
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index dbd1ee664c60..8f902fb1d114 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -11210,6 +11210,7 @@ fold_sizeof_expr (tree t)
false, false);
if (r == error_mark_node)
r = size_one_node;
+ r = cp_fold_convert (size_type_node, r);
return r;
}
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C
b/gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C
new file mode 100644
index 000000000000..59fc0d332b92
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-117775.C
@@ -0,0 +1,13 @@
+// PR c++/117775
+// Check that we don't ICE and have sizeof(void)==1 under -Wno-pointer-arith
+// { dg-do run { target c++20 } }
+// { dg-additional-options "-Wno-pointer-arith" }
+
+int main() {
+ struct why :
+ decltype( [](auto) {
+ return sizeof(void);
+ })
+ {} x;
+ return 1 - x.operator()(0);
+}
