Re: [PATCH] c++/modules: Fix missed unwrapping of STAT_HACK in ADL [PR121893]

[Jason Merrill]

On 9/12/25 3:01 PM, Nathaniel Shead wrote:

Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?

OK (obvious).

-- >8 --

My r16-3559-gc2e567a6edb563 reworked ADL for modules, including a change
to allow seeing module-linkage declarations if they only exist on the
instantiation path.  This caused a crash however as I neglected to
unwrap the stat hack wrapper when we were happy to see all declarations,
allowing search_adl to add non-functions to the overload set.

        PR c++/121893

gcc/cp/ChangeLog:

        * name-lookup.cc (name_lookup::adl_namespace_fns): Unwrap the
        STAT_HACK also when on_inst_path.

gcc/testsuite/ChangeLog:

        * g++.dg/modules/adl-10_a.C: New test.
        * g++.dg/modules/adl-10_b.C: New test.

Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
  gcc/cp/name-lookup.cc                   |  4 +++-
  gcc/testsuite/g++.dg/modules/adl-10_a.C | 23 +++++++++++++++++++++++
  gcc/testsuite/g++.dg/modules/adl-10_b.C |  7 +++++++
  3 files changed, 33 insertions(+), 1 deletion(-)
  create mode 100644 gcc/testsuite/g++.dg/modules/adl-10_a.C
  create mode 100644 gcc/testsuite/g++.dg/modules/adl-10_b.C

diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index 43b95bffecf..32af7a6aed9 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -1306,7 +1306,9 @@ name_lookup::adl_namespace_fns (tree scope, bitmap 
imports,
                    /* For lookups on the instantiation path we can see any
                       module-linkage declaration; otherwise we should only
                       see exported decls.  */
-                   if (!on_inst_path)
+                   if (on_inst_path)
+                     bind = STAT_DECL (bind);
+                   else
                      bind = STAT_VISIBLE (bind);
                  }

diff --git a/gcc/testsuite/g++.dg/modules/adl-10_a.C b/gcc/testsuite/g++.dg/modules/adl-10_a.C

new file mode 100644
index 00000000000..eef4ef0f724
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/adl-10_a.C
@@ -0,0 +1,23 @@
+// PR c++/121893
+// { dg-additional-options "-fmodules -Wno-global-module" }
+// { dg-module-cmi M }
+
+module;
+namespace ns {
+  struct S {};
+
+  struct F {
+    template <typename T> void operator()(T) {}
+  };
+  inline constexpr F foo{};
+}
+
+export module M;
+
+namespace ns {
+  export using ns::S;
+  export using ns::foo;
+}
+
+template <typename T> void foo(T) {}
+export template <typename T> void go(T t) { foo(t); }
diff --git a/gcc/testsuite/g++.dg/modules/adl-10_b.C 
b/gcc/testsuite/g++.dg/modules/adl-10_b.C
new file mode 100644
index 00000000000..9be64a96f4e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/adl-10_b.C
@@ -0,0 +1,7 @@
+// PR c++/121893
+// { dg-additional-options "-fmodules" }
+
+import M;
+int main() {
+  ::go(ns::S{});
+}