PR# 19295 Incorrect report of code analysis rule CA020 violation

The Eiffel Inspector reports a CA020 violation (variable not read after assignment).  It is true that
the variable is not read after assignment, but the called function has a side effect so removing the
assignment would break the code.

Here is the assignment:

   cel := make_one_cell("\", 1, 1, false)

And the function is:

       make_one_cell(txt: STRING; row, col: INTEGER; hdr: BOOLEAN):
	                        HTML_TABLE_CELL
                -- row and col are MY_TABLE indices
	        -- txt is the text
	do  create Result.make(txt);
	    if hdr then Result.set_as_header end;
	    my_table.put(Result, row, col)
	end;

Note the call to my_table.put (side effect).

This is probably not a good way to write the code, but the inspector should not report a violation if the called
function has side effects.

Added test#code_analysis032.

Fixed in rev#102377 of EiffelStudio 18.11 intermediate release by reporting violation only when source expression is attached and an assignment

   target := source

can be replaced with

   source.do_nothing

Yes, I think suggesting a call to `do_nothing'  in the attached case would be fine.

Thank you for your report. Would it be reasonable to suggest replacing an assignment with a call to `do_nothing` if the return type is attached? (Unfortunately there is no good replacement yet for the case when the return type is detachable.)