Is it possible to interpret C-like escape characters stored in postgresql table's column?

Question

Based on https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-ESCAPE , I can do it:

SELECT E'Test:\t\u00e1\u00e4\u00e9' as col;
-- Result (\t is interpreted tab character without problem, unicodes too):
     col
-------------
 Test:   áäé

but I'd like to do something different and I can't solve it:

SELECT do_something_with_text(col)
FROM (SELECT 'Test:\t\u00e1\u00e4\u00e9' as col) as t;

where do_something_with_text(text) function will interpret escape Unicode and well-known codes and returns exactly the same result as first one.

Is it possible in easy way? I don't want to replace all escaping characters by E'' versions.

Regards

Answer 1

Per the Caution block at the link String Constants with C-Style Escapes you provided:

show standard_conforming_strings ;
 standard_conforming_strings 
-----------------------------
 on

show escape_string_warning ;
 escape_string_warning 
-----------------------
 on

set standard_conforming_strings = off;

set escape_string_warning = off;

SELECT 'Test:\t\u00e1\u00e4\u00e9' as col;
     col     
-------------
 Test:   áäé

This used to be the default behavior in Postgres 9.1-. I would read the Caution and the contents of the links within in it to get a idea of what rolling back to previous behavior means.