[gcc r14-9961] c++: Only emit exported GMF usings [PR114600]

[Nathaniel Shead via Gcc-cvs]

https://gcc.gnu.org/g:3878e9aeb30cb192f769997c52743daf8190744c

commit r14-9961-g3878e9aeb30cb192f769997c52743daf8190744c
Author: Nathaniel Shead <nathanielosh...@gmail.com>
Date:   Mon Apr 8 23:34:42 2024 +1000

    c++: Only emit exported GMF usings [PR114600]
    
    A typo in r14-6978 made us emit too many things. This ensures that we
    don't emit using-declarations from the GMF that we don't need to.
    
            PR c++/114600
    
    gcc/cp/ChangeLog:
    
            * module.cc (depset::hash::add_binding_entity): Require both
            WMB_Using and WMB_Export for GMF entities.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/modules/using-14.C: New test.
    
    Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
    Co-authored-by: Patrick Palka <ppa...@redhat.com>

Diff:
---
 gcc/cp/module.cc                        |  2 +-
 gcc/testsuite/g++.dg/modules/using-14.C | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 001430a4a8f..d94d8ff4df9 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -13090,7 +13090,7 @@ depset::hash::add_binding_entity (tree decl, WMB_Flags 
flags, void *data_)
        inner = DECL_TEMPLATE_RESULT (inner);
 
       if ((!DECL_LANG_SPECIFIC (inner) || !DECL_MODULE_PURVIEW_P (inner))
-         && !(flags & (WMB_Using | WMB_Export)))
+         && !((flags & WMB_Using) && (flags & WMB_Export)))
        /* Ignore global module fragment entities unless explicitly
           exported with a using declaration.  */
        return false;
diff --git a/gcc/testsuite/g++.dg/modules/using-14.C 
b/gcc/testsuite/g++.dg/modules/using-14.C
new file mode 100644
index 00000000000..0e15a952de5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-14.C
@@ -0,0 +1,14 @@
+// PR c++/114600
+// { dg-additional-options "-fmodules-ts -Wno-global-module 
-fdump-lang-module" }
+// { dg-module-cmi M }
+
+module;
+namespace std {
+  template<class T> struct A { int n; };
+  template<class T> A<T> f();
+  namespace __swappable_details { using std::f; }
+}
+export module M;
+
+// The whole GMF should be discarded here
+// { dg-final { scan-lang-dump "Wrote 0 clusters" module } }