[gcc r12-10022] Fortran: avoid obsolescence warning for COMMON with submodule [PR111880]

[Harald Anlauf]

https://gcc.gnu.org/g:17cbec6e8ea8817b6240837bb1f1bf74f1b9bdcd

commit r12-10022-g17cbec6e8ea8817b6240837bb1f1bf74f1b9bdcd
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Thu Nov 23 22:48:38 2023 +0100

    Fortran: avoid obsolescence warning for COMMON with submodule [PR111880]
    
    gcc/fortran/ChangeLog:
    
            PR fortran/111880
            * resolve.cc (resolve_common_vars): Do not call gfc_add_in_common
            for symbols that are USE associated or used in a submodule.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/111880
            * gfortran.dg/pr111880.f90: New test.
    
    (cherry picked from commit c9d029ba2ceb435e31492c1f3f0fd3edf0e386be)

Diff:
---
 gcc/fortran/resolve.cc                 |  4 ++--
 gcc/testsuite/gfortran.dg/pr111880.f90 | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 426eb3dead3..9264322f671 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -965,8 +965,8 @@ resolve_common_vars (gfc_common_head *common_block, bool named_common)
 
       /* gfc_add_in_common may have been called before, but the reported errors
 	 have been ignored to continue parsing.
-	 We do the checks again here.  */
-      if (!csym->attr.use_assoc)
+	 We do the checks again here, unless the symbol is USE associated.  */
+      if (!csym->attr.use_assoc && !csym->attr.used_in_submodule)
 	{
 	  gfc_add_in_common (&csym->attr, csym->name, &common_block->where);
 	  gfc_notify_std (GFC_STD_F2018_OBS, "COMMON block at %L",
diff --git a/gcc/testsuite/gfortran.dg/pr111880.f90 b/gcc/testsuite/gfortran.dg/pr111880.f90
new file mode 100644
index 00000000000..c0cd98a93d4
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr111880.f90
@@ -0,0 +1,22 @@
+! { dg-do compile }
+! { dg-options "-std=f2018" }
+! PR fortran/111880 - redundant warning of obsolescent COMMON with submodule
+
+module third_party_module
+  integer :: some_param
+  common /not_my_code/ some_param   ! { dg-warning "COMMON block" }
+end module third_party_module
+
+module foo
+  use third_party_module
+  interface
+    module subroutine bar()
+    end subroutine bar
+  end interface
+end module foo
+
+submodule (foo) foo_submod      ! We do not need a warning here!
+contains
+  module procedure bar
+  end procedure bar
+end submodule foo_submod