From: Jason Merrill <jason@redhat.com>
Date: Fri, 14 Nov 2025 17:59:38 +0000 (+0530)
Subject: c++/modules: using builtin
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=feccb9c9cd6ccab3fa75e2ca3f533e02de15750f;p=thirdparty%2Fgcc.git

c++/modules: using builtin

Here, when we try to bring "memset" back into the global namespace, we find
the built-in, see that it's the same declaration (because the module brought
it into the other namespace with a using-declaration), and decide that we
don't need to do anything.  But we still need a non-hidden overload.

gcc/cp/ChangeLog:

	* name-lookup.cc (do_nonmember_using_decl): Handle hidden better.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/using-33_a.C: New test.
	* g++.dg/modules/using-33_b.C: New test.
---

diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index 984d37c2089..abb0d48fb66 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -5404,7 +5404,11 @@ do_nonmember_using_decl (name_lookup &lookup, bool fn_scope_p,
 		     namespace.  We will still want to insert it if
 		     it is revealing a not-revealed thing.  */
 		  found = true;
-		  if (!revealing_p)
+		  if (old.hidden_p ())
+		    /* The function was merged with a hidden built-in;
+		       insert it again as not hidden.  */
+		    found = false;
+		  else if (!revealing_p)
 		    ;
 		  else if (old.using_p ())
 		    {
diff --git a/gcc/testsuite/g++.dg/modules/using-33_a.C b/gcc/testsuite/g++.dg/modules/using-33_a.C
new file mode 100644
index 00000000000..949eade2cd9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-33_a.C
@@ -0,0 +1,10 @@
+// { dg-additional-options "-fmodules" }
+module;
+
+#include <string.h>
+
+export module M;
+
+namespace N {
+  export using ::memset;
+}
diff --git a/gcc/testsuite/g++.dg/modules/using-33_b.C b/gcc/testsuite/g++.dg/modules/using-33_b.C
new file mode 100644
index 00000000000..342014666ca
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-33_b.C
@@ -0,0 +1,10 @@
+// { dg-additional-options "-fmodules" }
+import M;
+
+using N::memset;
+
+int main()
+{
+  int i = 1;
+  memset (&i, 42, 1);
+}