Regtested on x86_64-pc-linux-gnu, OK for trunk?
-- >8 --
When processing inherited CTAD in C++23, type_targs_deducible_from can
be called with a synthetic alias template whose TREE_VALUE is a type
alias like std::string_view. Since type aliases don't have their own
TEMPLATE_INFO, calling TI_TEMPLATE on a NULL
TYPE_TEMPLATE_INFO_MAYBE_ALIAS result caused a segfault.
This fix adds a NULL check and returns NULL_TREE when the type lacks
template info, indicating it can't be deduced.
PR c++/122070
gcc/cp/ChangeLog:
* pt.cc (type_targs_deducible_from): Add NULL check for
TYPE_TEMPLATE_INFO_MAYBE_ALIAS to prevent ICE with type aliases.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/class-deduction-inherited-ice.C: New test.
Signed-off-by: Egas Ribeiro <[email protected]>
---
gcc/cp/pt.cc | 5 ++-
.../cpp23/class-deduction-inherited-ice.C | 34 +++++++++++++++++++
2 files changed, 38 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp23/class-deduction-inherited-ice.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 8498730b6e4..c99df255dd7 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -31630,7 +31630,10 @@ type_targs_deducible_from (tree tmpl, tree type)
per alias_ctad_tweaks. */
tparms = INNERMOST_TEMPLATE_PARMS (TREE_PURPOSE (tmpl));
ttype = TREE_VALUE (tmpl);
- tmpl = TI_TEMPLATE (TYPE_TEMPLATE_INFO_MAYBE_ALIAS (ttype));
+ tree ti = TYPE_TEMPLATE_INFO_MAYBE_ALIAS (ttype);
+ if (!ti)
+ return NULL_TREE;
+ tmpl = TI_TEMPLATE (ti);
}
int len = TREE_VEC_LENGTH (tparms);
diff --git a/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited-ice.C
b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited-ice.C
new file mode 100644
index 00000000000..6724ce303d8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited-ice.C
@@ -0,0 +1,34 @@
+// { dg-do compile { target c++23 } }
+// PR c++/122070
+
+namespace std {
+ template<typename T, T v> struct integral_constant { static constexpr T
value = v; };
+ using size_t = decltype(sizeof(0));
+
+ template<typename CharT>
+ struct basic_string_view {
+ const CharT* ptr;
+ size_t len;
+ constexpr basic_string_view(const CharT* p) : ptr(p), len(0) { while
(p && p[len]) ++len; }
+ };
+ using string_view = basic_string_view<char>;
+}
+
+template<std::size_t N>
+struct sized_string_view: std::string_view {
+ using std::string_view::string_view;
+};
+template<std::size_t N>
+sized_string_view(const char (&str)[N]) -> sized_string_view<N - 1>;
+
+
+constexpr auto string_builder(auto first, auto second, auto... trailing) {
+ constexpr auto is_last = sizeof...(trailing) == 0;
+ auto buffer = 1;
+ if constexpr (is_last) {
+ return buffer;
+ } else
+ return string_builder(buffer, trailing...);
+}
+
+constexpr auto copyright = string_builder(sized_string_view("a"),
sized_string_view("b"), sized_string_view("c"));
--
2.52.0
