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diff --git a/gcc/testsuite/gfortran.dg/transpose_optimization_1.f90 b/gcc/testsuite/gfortran.dg/transpose_optimization_1.f90
new file mode 100644
index 000000000..885ff7c20
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+++ b/gcc/testsuite/gfortran.dg/transpose_optimization_1.f90
@@ -0,0 +1,106 @@
+! { dg-do compile }
+! { dg-options "-Warray-temporaries -fdump-tree-original" }
+!
+! PR fortran/45648
+! Non-copying descriptor transpose optimization (for function call args).
+!
+! Contributed by Richard Sandiford <richard@codesourcery.com>
+
+module foo
+  interface
+    subroutine ext1 (a, b)
+      real, intent (in), dimension (:, :) :: a, b
+    end subroutine ext1
+    subroutine ext2 (a, b)
+      real, intent (in), dimension (:, :) :: a
+      real, intent (out), dimension (:, :) :: b
+    end subroutine ext2
+    subroutine ext3 (a, b)
+      real, dimension (:, :) :: a, b
+    end subroutine ext3
+  end interface
+contains
+  ! No temporary needed here.
+  subroutine test1 (n, a, b, c)
+    integer :: n
+    real, dimension (n, n) :: a, b, c
+    a = matmul (transpose (b), c)
+  end subroutine test1
+
+  ! No temporary either, as we know the arguments to matmul are intent(in)
+  subroutine test2 (n, a, b)
+    integer :: n
+    real, dimension (n, n) :: a, b
+    a = matmul (transpose (b), b)
+  end subroutine test2
+
+  ! No temporary needed.
+  subroutine test3 (n, a, b, c)
+    integer :: n
+    real, dimension (n, n) :: a, c
+    real, dimension (n+4, n+4) :: b
+    a = matmul (transpose (b (2:n+1, 3:n+2)), c)
+  end subroutine test3
+
+  ! A temporary is needed for the result of either the transpose or matmul.
+  subroutine test4 (n, a, b)
+    integer :: n
+    real, dimension (n, n) :: a, b
+    a = matmul (transpose (a), b)       ! { dg-warning "Creating array temporary" }
+  end subroutine test4
+
+  ! The temporary is needed here since the second argument to imp1
+  ! has unknown intent.
+  subroutine test5 (n, a)
+    integer :: n
+    real, dimension (n, n) :: a
+    call imp1 (transpose (a), a)        ! { dg-warning "Creating array temporary" }
+  end subroutine test5
+
+  ! No temporaries are needed here; imp1 can't modify either argument.
+  ! We have to pack the arguments, however. 
+  subroutine test6 (n, a, b)
+    integer :: n
+    real, dimension (n, n) :: a, b
+    call imp1 (transpose (a), transpose (b))    ! { dg-warning "Creating array temporary" }
+  end subroutine test6
+
+  ! No temporaries are needed here; imp1 can't modify either argument.
+  ! We don't have to pack the arguments. 
+  subroutine test6_bis (n, a, b)
+    integer :: n
+    real, dimension (n, n) :: a, b
+    call ext3 (transpose (a), transpose (b))
+  end subroutine test6_bis
+
+  ! No temporary is neede here; the second argument is intent(in).
+  subroutine test7 (n, a)
+    integer :: n
+    real, dimension (n, n) :: a
+    call ext1 (transpose (a), a)
+  end subroutine test7
+
+  ! The temporary is needed here though.
+  subroutine test8 (n, a)
+    integer :: n
+    real, dimension (n, n) :: a
+    call ext2 (transpose (a), a)        ! { dg-warning "Creating array temporary" } 
+  end subroutine test8
+
+  ! Silly, but we don't need any temporaries here.
+  subroutine test9 (n, a)
+    integer :: n
+    real, dimension (n, n) :: a
+    call ext1 (transpose (transpose (a)), a)
+  end subroutine test9
+
+  ! The outer transpose needs a temporary; the inner one doesn't.
+  subroutine test10 (n, a)
+    integer :: n
+    real, dimension (n, n) :: a
+    call ext2 (transpose (transpose (a)), a)    ! { dg-warning "Creating array temporary" }
+  end subroutine test10
+end module foo
+
+! { dg-final { scan-tree-dump-times "struct\[^\\n\]*atmp" 4 "original" } }
+! { dg-final { cleanup-tree-dump "original" } }