Fortran: CASE selector expressions must be scalar

gcc/fortran/ChangeLog:

	PR fortran/103776
	* match.c (match_case_selector): Reject expressions in CASE
	selector which are not scalar.

gcc/testsuite/ChangeLog:

	PR fortran/103776
	* gfortran.dg/select_10.f90: New test.

2 files changed, 38 insertions, 0 deletions

diff --git a/gcc/fortran/match.c b/gcc/fortran/match.c
index 52bc5af..617fb35 100644
--- a/gcc/fortran/match.c
+++ b/gcc/fortran/match.c
@@ -6088,6 +6088,19 @@ match_case_selector (gfc_case **cp)
 	}
     }
 
+  if (c->low && c->low->rank != 0)
+    {
+      gfc_error ("Expression in CASE selector at %L must be scalar",
+		 &c->low->where);
+      goto cleanup;
+    }
+  if (c->high && c->high->rank != 0)
+    {
+      gfc_error ("Expression in CASE selector at %L must be scalar",
+		 &c->high->where);
+      goto cleanup;
+    }
+
   *cp = c;
   return MATCH_YES;
 
diff --git a/gcc/testsuite/gfortran.dg/select_10.f90 b/gcc/testsuite/gfortran.dg/select_10.f90
new file mode 100644
index 0000000..2d9b017
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/select_10.f90
@@ -0,0 +1,25 @@
+! { dg-do compile }
+! PR fortran/103776 - ICE in gfc_compare_string
+! Contributed by G.Steinmetz
+
+program p
+  integer :: n
+  select case (n)
+  case ([1])        ! { dg-error "must be scalar" }
+  end select
+  select case (n)
+  case (:[2])       ! { dg-error "must be scalar" }
+  end select
+  select case (n)
+  case (['1'])      ! { dg-error "must be scalar" }
+  end select
+  select case (n)
+  case (['1']:2)    ! { dg-error "must be scalar" }
+  end select
+  select case (n)
+  case(['1']:['2']) ! { dg-error "must be scalar" }
+  end select
+  select case (n)
+  case(1:['2'])     ! { dg-error "must be scalar" }
+  end select
+end