From 7424844df5496d90a6bad94a1ff5570a185ae1c1 Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Thu, 1 Oct 2020 16:49:10 +0200
Subject: [PATCH] Remove SH_SUBSHELL option vestiges

Mildly interesting: apparently there was once an idea to implement
shared-state command substitutions as a shell option like 'set -o
subshare'. They were implemented using a new ${ syntax; } instead,
but there is a vestigial SH_SUBSHARE option ID in shell.h plus a
check for it in subshell.c that would cause backtick-style command
substitutions (comsub==1) to share their state. That option isn't
defined in data/options.c so it's impossible for a user to set it.

src/cmd/ksh93/include/shell.h,
src/cmd/ksh93/sh/subshell.c:
- Remove SH_SUBSHELL option vestiges.

src/cmd/ksh93/include/defs.h:
- Correct my comment on 'comsub' flag; I was wrong about what the
  values meant. 2 is for a shared-state comsub. (re: 4ce486a7)
---
 src/cmd/ksh93/include/defs.h  | 4 ++--
 src/cmd/ksh93/include/shell.h | 1 -
 src/cmd/ksh93/sh/subshell.c   | 2 +-
 3 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/cmd/ksh93/include/defs.h b/src/cmd/ksh93/include/defs.h
index 8eab62100..e4ea7d34b 100644
--- a/src/cmd/ksh93/include/defs.h
+++ b/src/cmd/ksh93/include/defs.h
@@ -211,8 +211,8 @@ struct shared
 	unsigned char	ignsig;		/* ignored signal in subshell */ \
 	unsigned char	lastsig;	/* last signal received */ \
 	char		pathinit;	/* pathinit called from subshell */ \
-	char		comsub;		/* set to 1 when in `` comsub, 2 when in $() comsub */ \
-	char		subshare;	/* set when in ${..} comsub */ \
+	char		comsub;		/* set to 1 when in `...`, 2 when in ${ ...; }, 3 when in $(...) */ \
+	char		subshare;	/* set when comsub==2 (shared-state ${ ...; } command substitution) */ \
 	char		toomany;	/* set when out of fd's */ \
 	char		instance;	/* in set_instance */ \
 	char		decomma;	/* decimal_point=',' */ \
diff --git a/src/cmd/ksh93/include/shell.h b/src/cmd/ksh93/include/shell.h
index 77d908dd0..15f32059d 100644
--- a/src/cmd/ksh93/include/shell.h
+++ b/src/cmd/ksh93/include/shell.h
@@ -86,7 +86,6 @@ typedef union Shnode_u Shnode_t;
 #define SH_GMACS	24
 #define SH_EMACS	25
 #define SH_PRIVILEGED	26
-#define SH_SUBSHARE	27	/* subshell shares state with parent */
 #define SH_NOLOG	28
 #define SH_NOTIFY	29
 #define SH_DICTIONARY	30
diff --git a/src/cmd/ksh93/sh/subshell.c b/src/cmd/ksh93/sh/subshell.c
index cd98deb04..51bc5aa16 100644
--- a/src/cmd/ksh93/sh/subshell.c
+++ b/src/cmd/ksh93/sh/subshell.c
@@ -523,7 +523,7 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
 		job.curpgid = 0;
 	sp->subshare = shp->subshare;
 	sp->comsub = shp->comsub;
-	shp->subshare = comsub==2 ||  (comsub==1 && sh_isoption(SH_SUBSHARE));
+	shp->subshare = comsub==2;
 	if(comsub)
 	{
 		shp->comsub = comsub;