[gcc r15-11041] fortran: Fix creation of reference to C_FUNLOC argument [PR117303]

[Harald Anlauf]

https://gcc.gnu.org/g:ff40dfb9543c859e39a957d8599630999bc7aca0

commit r15-11041-gff40dfb9543c859e39a957d8599630999bc7aca0
Author: Kirill Chilikin <chilikin.k@gmail.com>
Date:   Sun Jan 25 14:43:08 2026 +0700

    fortran: Fix creation of reference to C_FUNLOC argument [PR117303]
    
    The reference returned by C_FUNLOC is assigned to a variable. Without that,
    no reference from the calling subprogram to the argument of C_FUNLOC
    was created in the call graph, resulting in an undefined-reference error
    with link-time optimization. Please see PR 117303 for more details.
    
            PR fortran/117303
    
    gcc/fortran/ChangeLog:
    
            * trans-intrinsic.cc (conv_isocbinding_function):
            Assign the reference returned by C_FUNLOC to a variable.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/c_funloc_tests_7.f90:
            Updated test due to changed code generation.
            * gfortran.dg/c_funloc_tests_9.f90: New test.
    
    Signed-off-by: Kirill Chilikin <chilikin.k@gmail.com>
    (cherry picked from commit 3c3c7f6519f54d26afdb9bd810cc7bc11b395a53)

Diff:
---
 gcc/fortran/trans-intrinsic.cc                 |  9 ++++++-
 gcc/testsuite/gfortran.dg/c_funloc_tests_7.f90 |  2 +-
 gcc/testsuite/gfortran.dg/c_funloc_tests_9.f90 | 34 ++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/gcc/fortran/trans-intrinsic.cc b/gcc/fortran/trans-intrinsic.cc
index 4b68f5759488..22115ef791c2 100644
--- a/gcc/fortran/trans-intrinsic.cc
+++ b/gcc/fortran/trans-intrinsic.cc
@@ -9677,7 +9677,14 @@ conv_isocbinding_function (gfc_se *se, gfc_expr *expr)
       se->expr = gfc_evaluate_now (se->expr, &se->pre);
     }
   else if (expr->value.function.isym->id == GFC_ISYM_C_FUNLOC)
-    gfc_conv_expr_reference (se, arg->expr);
+    {
+      gfc_conv_expr_reference (se, arg->expr);
+      /* The code below is necessary to create a reference from the calling
+	 subprogram to the argument of C_FUNLOC() in the call graph.
+	 Please see PR 117303 for more details. */
+      se->expr = convert (pvoid_type_node, se->expr);
+      se->expr = gfc_evaluate_now (se->expr, &se->pre);
+    }
   else if (expr->value.function.isym->id == GFC_ISYM_C_ASSOCIATED)
     {
       gfc_se arg1se;
diff --git a/gcc/testsuite/gfortran.dg/c_funloc_tests_7.f90 b/gcc/testsuite/gfortran.dg/c_funloc_tests_7.f90
index 7a4464ab5528..1e199b4503be 100644
--- a/gcc/testsuite/gfortran.dg/c_funloc_tests_7.f90
+++ b/gcc/testsuite/gfortran.dg/c_funloc_tests_7.f90
@@ -16,6 +16,6 @@ cfp = c_funloc (noCsub)
 call c_f_procpointer (cfp, fint)
 end
 
-! { dg-final { scan-tree-dump-times "cfp =\[^;\]+ nocsub;" 1 "original" } }
+! { dg-final { scan-tree-dump-times "D.\[0-9\]* =\[^;\]+ nocsub;" 1 "original" } }
 ! { dg-final { scan-tree-dump-times "fint =\[^;\]+ cfp;" 1 "original" } }
 
diff --git a/gcc/testsuite/gfortran.dg/c_funloc_tests_9.f90 b/gcc/testsuite/gfortran.dg/c_funloc_tests_9.f90
new file mode 100644
index 000000000000..2ebb951a6fc0
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/c_funloc_tests_9.f90
@@ -0,0 +1,34 @@
+! { dg-do link }
+! { dg-options "-O1 -flto" }
+! PR 117303
+
+MODULE M1
+  USE, INTRINSIC :: ISO_C_BINDING
+
+  TYPE T
+    TYPE(C_FUNPTR) FUNPTR
+  END TYPE
+
+  TYPE(T), POINTER :: T_POINTER
+
+CONTAINS
+
+  SUBROUTINE SET_FUNPTR(F)
+    TYPE(C_FUNPTR), INTENT(IN) :: F
+    T_POINTER%FUNPTR = F
+  END SUBROUTINE
+
+  SUBROUTINE S1() BIND(C)
+  END SUBROUTINE
+
+END MODULE
+
+PROGRAM TEST
+  USE M1
+  INTEGER(C_INTPTR_T) I
+  ALLOCATE(T_POINTER)
+  ! There was no reference from TEST to S1 in the call graph,
+  ! resulting in undefined-reference error with link-time optimization.
+  CALL SET_FUNPTR(C_FUNLOC(S1))
+  PRINT *, TRANSFER(T_POINTER%FUNPTR, I)
+END PROGRAM