Re: [PATCH 2/3] c++/modules: Propagate using decls from partitions

[Jason Merrill]

On 4/11/24 20:40, Nathaniel Shead wrote:

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

-- >8 --

The modules code currently neglects to set OVL_USING_P on the dependency
created for a using-decl, which causes it not to remember that the
OVL_EXPORT_P flag had been set on it when emitted from the primary
interface unit. This patch ensures that it occurs.

gcc/cp/ChangeLog:

        * module.cc (depset::hash::add_binding_entity): Propagate
        OVL_USING_P for using-declarations.

gcc/testsuite/ChangeLog:

        * g++.dg/modules/using-15_a.C: New test.
        * g++.dg/modules/using-15_b.C: New test.
        * g++.dg/modules/using-15_c.C: New test.

Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
  gcc/cp/module.cc                          |  4 ++++
  gcc/testsuite/g++.dg/modules/using-15_a.C | 13 +++++++++++++
  gcc/testsuite/g++.dg/modules/using-15_b.C |  5 +++++
  gcc/testsuite/g++.dg/modules/using-15_c.C |  7 +++++++
  4 files changed, 29 insertions(+)
  create mode 100644 gcc/testsuite/g++.dg/modules/using-15_a.C
  create mode 100644 gcc/testsuite/g++.dg/modules/using-15_b.C
  create mode 100644 gcc/testsuite/g++.dg/modules/using-15_c.C

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 9d054c4c792..527c9046c67 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -12915,10 +12915,12 @@ depset::hash::add_binding_entity (tree decl, 
WMB_Flags flags, void *data_)
        /* Ignore NTTP objects.  */
        return false;

+ bool unscoped_enum_const_p = false;

        if (!(flags & WMB_Using) && CP_DECL_CONTEXT (decl) != data->ns)
        {
          /* A using that lost its wrapper or an unscoped enum
             constant.  */
+         unscoped_enum_const_p = (TREE_CODE (decl) == CONST_DECL);

How does this interact with C++20 using enum?

          flags = WMB_Flags (flags | WMB_Using);
          if (DECL_MODULE_EXPORT_P (TREE_CODE (decl) == CONST_DECL
                                    ? TYPE_NAME (TREE_TYPE (decl))
@@ -12979,6 +12981,8 @@ depset::hash::add_binding_entity (tree decl, WMB_Flags 
flags, void *data_)
        if (flags & WMB_Using)
        {
          decl = ovl_make (decl, NULL_TREE);
+         if (!unscoped_enum_const_p)
+           OVL_USING_P (decl) = true;
          if (flags & WMB_Export)
            OVL_EXPORT_P (decl) = true;
        }
diff --git a/gcc/testsuite/g++.dg/modules/using-15_a.C 
b/gcc/testsuite/g++.dg/modules/using-15_a.C
new file mode 100644
index 00000000000..23895bd8c4a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-15_a.C
@@ -0,0 +1,13 @@
+// { dg-additional-options "-fmodules-ts -Wno-global-module" }
+// { dg-module-cmi M:a }
+
+module;
+namespace foo {
+  void a();
+};
+export module M:a;
+
+namespace bar {
+  // propagate usings from partitions
+  export using foo::a;
+};
diff --git a/gcc/testsuite/g++.dg/modules/using-15_b.C 
b/gcc/testsuite/g++.dg/modules/using-15_b.C
new file mode 100644
index 00000000000..a88f86af61f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-15_b.C
@@ -0,0 +1,5 @@
+// { dg-additional-options "-fmodules-ts" }
+// { dg-module-cmi M }
+
+export module M;
+export import :a;
diff --git a/gcc/testsuite/g++.dg/modules/using-15_c.C 
b/gcc/testsuite/g++.dg/modules/using-15_c.C
new file mode 100644
index 00000000000..0651efffc91
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-15_c.C
@@ -0,0 +1,7 @@
+// { dg-additional-options "-fmodules-ts" }
+import M;
+
+int main() {
+  bar::a();
+  foo::a();  // { dg-error "not been declared" }
+}