[gcc r17-2719] fortran: Fix editorial error and new test case

https://gcc.gnu.org/g:4d9a71ceec40da31f781a495368250a1b92d5acb

commit r17-2719-g4d9a71ceec40da31f781a495368250a1b92d5acb
Author: Jerry DeLisle <[email protected]>
Date:   Sun Jul 26 13:33:07 2026 -0700

    fortran: Fix editorial error and new test case
    
    libgfortran/ChangeLog:
    
            * intrinsics/reduce.c (reduce): Fix the mask_present.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/reduce_5.f90: Verify the previously dead
            code error message occurs.

Diff:
---
 gcc/testsuite/gfortran.dg/reduce_5.f90 | 23 +++++++++++++++++++++++
 libgfortran/intrinsics/reduce.c        |  3 +--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/gfortran.dg/reduce_5.f90 b/gcc/testsuite/gfortran.dg/reduce_5.f90
new file mode 100644
index 000000000000..00a7bb2dbead
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/reduce_5.f90
@@ -0,0 +1,23 @@
+! { dg-do run }
+! { dg-shouldfail "foo" }
+
+  implicit none
+  integer :: a(3)
+  logical :: m(2)
+  a = 1
+  m = .true.
+  print *, get_reduce (a, m)
+contains
+  function get_reduce (array, mask) result (res)
+    integer, intent(in) :: array(:)
+    logical, intent(in) :: mask(:)
+    integer :: res
+    res = reduce (array, add, mask = mask, identity = 0)
+  end function get_reduce
+  pure function add (i, j) result (ij)
+    integer, intent(in) :: i, j
+    integer :: ij
+    ij = i + j
+  end function add
+end
+! { dg-output "shape mismatch between ARRAY and MASK in the REDUCE intrinsic \\(3/2\\)" }
diff --git a/libgfortran/intrinsics/reduce.c b/libgfortran/intrinsics/reduce.c
index 28bc834bc731..071d9486d119 100644
--- a/libgfortran/intrinsics/reduce.c
+++ b/libgfortran/intrinsics/reduce.c
@@ -54,7 +54,6 @@ reduce (parray *ret,
   index_type idx0, idx1, idx2;
   index_type dimen, dimen_m1, ldx, ext, str;
   bool started;
-  bool masked = false;
   bool dim_present = dim != NULL;
   bool mask_present = mask != NULL;
   bool identity_present = identity != NULL;
@@ -106,7 +105,7 @@ reduce (parray *ret,
       ext = GFC_DESCRIPTOR_EXTENT (array,i);
       str = GFC_DESCRIPTOR_STRIDE (array,i);
 
-      if (masked && (ext != GFC_DESCRIPTOR_EXTENT (mask, i)))
+      if (mask_present && (ext != GFC_DESCRIPTOR_EXTENT (mask, i)))
 	{
 	  int mext = (int)GFC_DESCRIPTOR_EXTENT (mask, i);
 	  runtime_error ("shape mismatch between ARRAY and MASK in the REDUCE "