c++: friend vs inherited guide confusion [PR117855]
We recently started using the lang_decl_fn::context field to track
inheritedness of a deduction guide (for C++23 inherited CTAD). This
new overloading of the field accidentally made DECL_FRIEND_CONTEXT
return non-NULL for inherited guides, which breaks the below testcase
during overload resolution with an inherited guide.
This patch fixes this by refining DECL_FRIEND_CONTEXT appropriately.
PR c++/117855
gcc/cp/ChangeLog:
* cp-tree.h (DECL_FRIEND_CONTEXT): Exclude deduction guides.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/class-deduction-inherited7.C: New test.
Reviewed-by: Jason Merrill <jason@redhat.com>
(cherry picked from commit ea578dd251eaf6304b0c95acc107f9a4d63bee8f)
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index ab2b090..a9a4a7a 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -3575,7 +3575,8 @@
the DECL_FRIEND_CONTEXT for `f' will be `S'. */
#define DECL_FRIEND_CONTEXT(NODE) \
((DECL_DECLARES_FUNCTION_P (NODE) && !DECL_VIRTUAL_P (NODE) \
- && !DECL_CONSTRUCTOR_P (NODE)) \
+ && !DECL_CONSTRUCTOR_P (NODE) \
+ && (cxx_dialect < cxx23 || !deduction_guide_p (NODE))) \
? LANG_DECL_FN_CHECK (NODE)->context \
: NULL_TREE)
diff --git a/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited7.C b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited7.C
new file mode 100644
index 0000000..b1d5e89
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited7.C
@@ -0,0 +1,12 @@
+// PR c++/117855
+// { dg-do compile { target c++20 } }
+
+template <typename T, int _Extent = -1> struct span { span(T&&);};
+template <typename T> span(T &&) -> span<T>;
+template <typename et, int e = -1>
+struct this_span : span<et, e> {
+ using span<et, e>::span;
+};
+template <typename T> this_span(T &&) -> this_span<T>;
+int vec;
+this_span a = vec;
