fortran: Fix ICE with implicit variable in iterator depend clause [PR107425]

An implicitly typed variable used as a subscript in an OpenMP iterator
depend clause (e.g., x(j) where j is implicit and only referenced in
the clause) caused an ICE in gimplify_var_or_parm_decl because the
variable's decl was never associated with a BIND_EXPR.

The root cause is that gfc_match_iterator creates a block namespace
(via gfc_build_block_ns) for iterator variables.  When the locator
expression x(j) is parsed with gfc_current_ns set to this iterator
namespace, the implicit variable j is created there rather than in the
enclosing program namespace.  In gfc_finish_var_decl, the FL_LABEL
check for BLOCK constructs matched before the omp_affinity_iterators
check, routing j through add_decl_as_local.  Unlike real BLOCK
construct variables, these never get a proper BIND_EXPR, so the
gimplifier rejects them.

Fixed by checking for omp_affinity_iterators before the FL_LABEL
BLOCK construct check, and only treating actual iterator variables
(those on the omp_affinity_iterators chain) as block-local.  Other
variables in the iterator namespace are added to the enclosing
function scope.

2026-04-07  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
	PR fortran/107425
	* trans-decl.cc (gfc_finish_var_decl): Check for
	omp_affinity_iterators namespace before FL_LABEL BLOCK check.
	Only route actual iterator variables through add_decl_as_local;
	add other variables to the enclosing function.

gcc/testsuite
	PR fortran/107425
	* gfortran.dg/gomp/pr107425.f90: New test.

Signed-off-by: Christopher Albert <albert@tugraz.at>

diff --git a/gcc/fortran/trans-decl.cc b/gcc/fortran/trans-decl.cc
index 0080e83fc369a182366020746579512e1b7b0686..f0b46d0b841393fff8ee66a16e426be349dc5a94 100644 (file)
--- a/gcc/fortran/trans-decl.cc
+++ b/gcc/fortran/trans-decl.cc
@@ -666,13 +666,26 @@ gfc_finish_var_decl (tree decl, gfc_symbol * sym)
          && (sym->ns->proc_name->backend_decl == current_function_decl
              || sym->result == sym))
        gfc_add_decl_to_function (decl);
+      else if (sym->ns->omp_affinity_iterators)
+       {
+         /* Iterator variables are block-local; other variables in the
+            iterator namespace (e.g. implicitly typed host-associated
+            ones used in locator expressions) belong in the enclosing
+            function.  */
+         gfc_symbol *iter;
+         for (iter = sym->ns->omp_affinity_iterators; iter;
+              iter = iter->tlink)
+           if (iter == sym)
+             break;
+         if (iter)
+           add_decl_as_local (decl);
+         else
+           gfc_add_decl_to_function (decl);
+       }
       else if (sym->ns->proc_name
               && sym->ns->proc_name->attr.flavor == FL_LABEL)
        /* This is a BLOCK construct.  */
        add_decl_as_local (decl);
-      else if (sym->ns->omp_affinity_iterators)
-       /* This is a block-local iterator.  */
-       add_decl_as_local (decl);
       else
        gfc_add_decl_to_parent_function (decl);
     }

diff --git a/gcc/testsuite/gfortran.dg/gomp/pr107425.f90 b/gcc/testsuite/gfortran.dg/gomp/pr107425.f90
new file mode 100644 (file)
index 0000000..77c31c2
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/pr107425.f90
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! { dg-options "-fopenmp" }
+!
+! PR fortran/107425
+! ICE in gimplify_var_or_parm_decl when an implicitly typed variable
+! is used as a subscript in an iterator depend clause.
+
+program p
+   integer :: x(8)
+   !$omp taskwait depend(iterator(i=1:8), in:x(j))
+end