Re: BUG #14800: substring produces different results with similar types

Tom:

On Wed, Sep 6, 2017 at 4:51 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Francisco Olarte <folarte(at)peoplecall(dot)com> writes:
>> Anyway, you may notice char() discards trailing blanks, varchar does not:
> More precisely, converting from char(n) to varchar or text discards
> trailing blanks. Since both substring() and the || operator take
> text argument types, an implicit coercion to text is happening in
> these examples ... and that's where the blanks went.

I was suspecting that, but
https://www.postgresql.org/docs/9.6/static/functions-string.html
documents them as "string || string", returns text, and
"substring(string {several variants})", returns text and trying to
look where the conversion to text happened ( i.e., in the arguments,
or after aplying overloaded variants ) seemed a bit extreme. Not
surprising, anyway, of the space chopping, having worked with punched
cards I'm used to it.