From 3032ebf0c9b769f02f494e97417a1b68ad59c884 Mon Sep 17 00:00:00 2001
From: Nathaniel Shead <nathanieloshead@gmail.com>
Date: Tue, 9 Apr 2024 21:52:38 +1000
Subject: c++: Propagate hidden flag on decls from partitions

While working on some other fixes I noticed that the partition handling
code used the wrong flag to propagate OVL_HIDDEN_P on exported bindings
from partitions. This patch fixes that, and renames the flag to be
clearer.

gcc/cp/ChangeLog:

	* name-lookup.cc (walk_module_binding): Use the
	partition-specific hidden flag instead of the top-level
	decl_hidden.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/using-16_a.C: New test.
	* g++.dg/modules/using-16_b.C: New test.
	* g++.dg/modules/using-16_c.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---
 gcc/cp/name-lookup.cc                     | 10 +++++-----
 gcc/testsuite/g++.dg/modules/using-16_a.C | 11 +++++++++++
 gcc/testsuite/g++.dg/modules/using-16_b.C | 12 ++++++++++++
 gcc/testsuite/g++.dg/modules/using-16_c.C | 11 +++++++++++
 4 files changed, 39 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/modules/using-16_a.C
 create mode 100644 gcc/testsuite/g++.dg/modules/using-16_b.C
 create mode 100644 gcc/testsuite/g++.dg/modules/using-16_c.C

diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index 5d2319db43d..78f08acffaa 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -4290,19 +4290,19 @@ walk_module_binding (tree binding, bitmap partitions,
 
 			count += callback (btype, flags, data);
 		      }
-		    bool hidden = STAT_DECL_HIDDEN_P (bind);
+		    bool part_hidden = STAT_DECL_HIDDEN_P (bind);
 		    for (ovl_iterator iter (MAYBE_STAT_DECL (STAT_DECL (bind)));
 			 iter; ++iter)
 		      {
 			if (iter.hidden_p ())
-			  hidden = true;
+			  part_hidden = true;
 			gcc_checking_assert
-			  (!(hidden && DECL_IS_UNDECLARED_BUILTIN (*iter)));
+			  (!(part_hidden && DECL_IS_UNDECLARED_BUILTIN (*iter)));
 
 			WMB_Flags flags = WMB_None;
 			if (maybe_dups)
 			  flags = WMB_Flags (flags | WMB_Dups);
-			if (decl_hidden)
+			if (part_hidden)
 			  flags = WMB_Flags (flags | WMB_Hidden);
 			if (iter.using_p ())
 			  {
@@ -4311,7 +4311,7 @@ walk_module_binding (tree binding, bitmap partitions,
 			      flags = WMB_Flags (flags | WMB_Export);
 			  }
 			count += callback (*iter, flags, data);
-			hidden = false;
+			part_hidden = false;
 		      }
 		  }
 	      }
diff --git a/gcc/testsuite/g++.dg/modules/using-16_a.C b/gcc/testsuite/g++.dg/modules/using-16_a.C
new file mode 100644
index 00000000000..25d8bca5d1c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-16_a.C
@@ -0,0 +1,11 @@
+// { dg-additional-options "-fmodules-ts" }
+// { dg-module-cmi M:S }
+
+export module M:S;
+
+namespace foo {
+  // propagate hidden from partitions
+  export struct S {
+    friend void f(S);
+  };
+};
diff --git a/gcc/testsuite/g++.dg/modules/using-16_b.C b/gcc/testsuite/g++.dg/modules/using-16_b.C
new file mode 100644
index 00000000000..3f704a913f4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-16_b.C
@@ -0,0 +1,12 @@
+// { dg-additional-options "-fmodules-ts -Wno-global-module" }
+// { dg-module-cmi M }
+
+module;
+namespace bar {
+  void f(int);
+}
+export module M;
+export import :S;
+namespace foo {
+  export using bar::f;
+}
diff --git a/gcc/testsuite/g++.dg/modules/using-16_c.C b/gcc/testsuite/g++.dg/modules/using-16_c.C
new file mode 100644
index 00000000000..5e46cd16013
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-16_c.C
@@ -0,0 +1,11 @@
+// { dg-additional-options "-fmodules-ts" }
+import M;
+
+int main() {
+  // this should be hidden and fail
+  foo::f(foo::S{});  // { dg-error "cannot convert" }
+
+  // but these should be legal
+  foo::f(10);
+  f(foo::S{});
+}
-- 
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