Export all variables assigned to while allexport is on (#431)

All variables that are assigned a value should be exported while
the allexport shell option is enabled. This works in most cases,
but variables assigned to with ${var:=foo} or $((var=123)) aren't
exported while allexport is on.

src/cmd/ksh93/sh/name.c:
- nv_putval(): This is the central assignment function; all forms
  of variable assignment end up here. So this is the best place
  to check for SH_ALLEXPORT and turn on the export attribute.
- nv_setlist(): Remove allexport handling, now redundant.

src/cmd/ksh93/bltins/read.c: sh_readline():
- Remove allexport handling, now redundant.

src/cmd/ksh93/sh/main.c: sh_main():
- nv_putval() is used to initialize PS4 and IFS using nv_putval();
  this is after an -a/--allexport specified on the ksh command
  line has been processed, so temporarily turn that off.

Co-authored-by: Martijn Dekker <martijn@inlv.org>

src/cmd/ksh93/tests/attributes.sh

@@ -2,7 +2,7 @@
 #                                                                      #
 #               This software is part of the ast package               #
 #          Copyright (c) 1982-2012 AT&T Intellectual Property          #
-#          Copyright (c) 2020-2021 Contributors to ksh 93u+m           #
+#          Copyright (c) 2020-2022 Contributors to ksh 93u+m           #
 #                      and is licensed under the                       #
 #                 Eclipse Public License, Version 1.0                  #
 #                    by AT&T Intellectual Property                     #
@@ -705,5 +705,30 @@ do
 	(( ${var:=1} == 0 )) || err_exit "\${var:=1} should yield 0 after typeset -$flag var=0 (got '$var')"
 done
 
+# ======
+# allexport tests
+# https://github.com/ksh93/ksh/pull/431
+set -o allexport
+unset bar
+: ${bar:=baz}
+exp='typeset -x bar=baz'
+got=$(typeset -p bar)
+[[ $got == "$exp" ]] || err_exit 'Variable ${bar} should be exported' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+# Set variable in arithmetic expressions
+unset bar
+((bar=1))
+exp='typeset -x bar=1'
+got=$(typeset -p bar)
+[[ $got == "$exp" ]] || err_exit 'Variable ${bar} should be exported' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+unset bar
+: $((bar=2))
+exp='typeset -x bar=2'
+got=$(typeset -p bar)
+[[ $got == "$exp" ]] || err_exit 'Variable ${bar} should be exported' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+set +o allexport
+
 # ======
 exit $((Errors<125?Errors:125))

src/cmd/ksh93/tests/namespace.sh

@@ -2,7 +2,7 @@
 #                                                                      #
 #               This software is part of the ast package               #
 #          Copyright (c) 1982-2012 AT&T Intellectual Property          #
-#          Copyright (c) 2020-2021 Contributors to ksh 93u+m           #
+#          Copyright (c) 2020-2022 Contributors to ksh 93u+m           #
 #                      and is licensed under the                       #
 #                 Eclipse Public License, Version 1.0                  #
 #                    by AT&T Intellectual Property                     #
@@ -98,4 +98,37 @@ false
 false
 [[ $(.x.runxrun) ==  'xfun local bar' ]] || err_exit 'namespace function on FPATH failed'
 
+# ======
+# Namespace variables should retain their exoprt attribute, even
+# though they are not actually exported outside the namespace block.
+set -o allexport
+namespace foo_nam
+{
+	typeset bar
+	typeset foo
+	typeset baz=baz
+	integer three
+}
+: ${.foo_nam.bar:=BAZ}
+exp='typeset -x .foo_nam.bar=BAZ'
+got=$(typeset -p .foo_nam.bar)
+[[ $got == "$exp" ]] || err_exit 'Variable ${.foo_nam.bar} did not retain -x attribute' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+.foo_nam.foo=FOO
+exp='typeset -x .foo_nam.foo=FOO'
+got=$(typeset -p .foo_nam.foo)
+[[ $got == "$exp" ]] || err_exit 'Variable ${.foo_nam.foo} did not retain -x attribute' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+exp='typeset -x .foo_nam.baz=baz'
+got=$(typeset -p .foo_nam.baz)
+[[ $got == "$exp" ]] || err_exit 'Variable ${.foo_nam.baz} did not retain -x attribute' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+((.foo_nam.three=3))
+exp='typeset -x -l -i .foo_nam.three=3'
+got=$(typeset -p .foo_nam.three)
+[[ $got == "$exp" ]] || err_exit 'Variable ${.foo_nam.three} did not retain -x attribute' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+set +o allexport
+
+# ======
 exit $((Errors<125?Errors:125))