Minor update pure/elemental in string_type module

doc/specs/stdlib_string_type.md

@@ -1993,7 +1993,7 @@ An unallocated `string_type` instance is equivalent to an empty string.
 
 #### Class
 
-Pure Subroutine.
+Pure subroutine (Elemental subroutine, only when both `from` and `to` are `type(string_type)`)
 
 #### Argument
 

src/stdlib_string_type.fypp

@@ -52,18 +52,18 @@ module stdlib_string_type
 
     !> Constructor for new string instances
     interface string_type
-        pure elemental module function new_string(string) result(new)
+        elemental module function new_string(string) result(new)
             character(len=*), intent(in), optional :: string
             type(string_type) :: new
         end function new_string
         #:for kind in INT_KINDS
-        pure elemental module function new_string_from_integer_${kind}$(val) result(new)
+        elemental module function new_string_from_integer_${kind}$(val) result(new)
             integer(${kind}$), intent(in) :: val
             type(string_type) :: new
         end function new_string_from_integer_${kind}$
         #:endfor
         #:for kind in LOG_KINDS
-        pure elemental module function new_string_from_logical_${kind}$(val) result(new)
+        elemental module function new_string_from_logical_${kind}$(val) result(new)
             logical(${kind}$), intent(in) :: val
             type(string_type) :: new
         end function new_string_from_logical_${kind}$
@@ -678,7 +678,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_string_string(from, to)
+    elemental subroutine move_string_string(from, to)
         type(string_type), intent(inout) :: from
         type(string_type), intent(out) :: to
 
@@ -688,7 +688,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_string_char(from, to)
+    pure subroutine move_string_char(from, to)
         type(string_type), intent(inout) :: from
         character(len=:), intent(out), allocatable :: to
 
@@ -698,7 +698,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_char_string(from, to)
+    pure subroutine move_char_string(from, to)
         character(len=:), intent(inout), allocatable :: from
         type(string_type), intent(out) :: to
 
@@ -708,7 +708,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_char_char(from, to)
+    pure subroutine move_char_char(from, to)
         character(len=:), intent(inout), allocatable :: from
         character(len=:), intent(out), allocatable :: to
 

src/tests/string/test_string_intrinsic.f90

@@ -667,9 +667,11 @@ subroutine test_move(error)
         !> Error handling
         type(error_type), allocatable, intent(out) :: error
         type(string_type) :: from_string, to_string
+        type(string_type) :: from_strings(2), to_strings(2)
         character(len=:), allocatable :: from_char, to_char
 
         from_string = "Move This String"
+        from_strings = "Move This String"
         from_char = "Move This Char"
         call check(error, from_string == "Move This String" .and. to_string == "" .and. &
             & from_char == "Move This Char" .and. .not. allocated(to_char), &
@@ -713,7 +715,11 @@ subroutine test_move(error)
         ! string_type (allocated) --> string_type (allocated)
         call move(from_string, from_string)
         call check(error, from_string == "", "move: test_case 8")
-
+        if (allocated(error)) return
+
+        ! elemental: string_type (allocated) --> string_type (not allocated)
+        call move(from_strings, to_strings)
+        call check(error, all(from_strings(:) == "") .and. all(to_strings(:) == "Move This String"), "move: test_case 9")
     end subroutine test_move
 
 end module test_string_intrinsic