51945: assorted documentation improvements, bug fixes, and new test

1) Document the behavior of "typeset -n existing_var" (via Jun T. comment)
2) Prohibit "typeset -nm pattern" because, well, it's insane.  Add test.
3) Improve doc for ${(!)ref} including ${{t!)ref} (Jun T.)
4) Fix doc for how-to unset of a named ref (Jun T.)
5) Allow "typeset +r -n ref" and "typeset +r +n ref" (Jun T.)
6) Fix "typeset -r -n ref=param" to create readonly references
7) Avoid accidental removal of PM_UNSET flag (Jun T.) and update test
8) Fix "typeset -gn ref=value" and add a test for it
9) Add tests for read-only reference behavior
10) Fix infinite recursion when resolving scope of an unset local
named reference, add test.

1 files changed, 7 insertions, 1 deletions

diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo
index 7bc736470..f87832e75 100644
--- a/Doc/Zsh/expn.yo
+++ b/Doc/Zsh/expn.yo
@@ -987,6 +987,11 @@ means the same thing as the more readable `(tt(%%qqq))'.  The
 following flags are supported:
 
 startitem()
+item(tt(!))(
+When the parameter being expanded is a named reference, the reference
+itself is examined and thus is em(not) resolved to its referent.  In
+ksh emulation, the parens around this flag are optional.
+)
 item(tt(#))(
 Evaluate the resulting words as numeric expressions and interpret
 these as character codes.  Output the corresponding characters.  Note
@@ -1245,7 +1250,8 @@ item(tt(hideval))(
 for parameters with the `hideval' flag (tt(-H))
 )
 item(tt(nameref))(
-for named references having an empty value (tt(-n))
+for named references (tt(typeset -n)) either having an empty value or
+when combined with `tt(!)' as in `tt(${LPAR()!t)tt(RPAR()var(rname)})'
 )
 item(tt(special))(
 for special parameters defined by the shell