Draft: Add Pretty.zeroWidth{F,P}Text, use it in Cmm Ppr
This is ultimately so that we can drop the length field of FastString
.
The Cmm pretty printer doesn't look at the width anyway, so eagerly
computing it is redundant.
There are a multitude of occurrences of text
in compiler/GHC/Cmm
,
but they mostly rewrite to ptext
anyway, where computing the length
isn't particularly expensive, so I refrained from changing these
occurrences to zeroWidthText
for the time being.
From the three proposed approaches in
#17069 (comment 259689)
this one seemed like the simplest and least intrusive; plus, there is
already precedent with Pretty.zeroWidthText
.
Fixes #17069.