From 4f9456d69f66c2d93c752b119ac322a0e61870c5 Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Thu, 9 Jun 2022 21:50:26 +0100
Subject: [PATCH] posix: re-allow preset aliases on interactive (re: ddaa145b)

The POSIX standard in fact contains a sentence that specifically
allows preset aliases: "Implementations also may provide predefined
valid aliases that are in effect when the shell is invoked."
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_03_01

I had missed that back then. It's still a terrible idea for scripts
(particularly the way 93u+ implemented them), but for interactive
POSIX shells it makes a lot more sense and does not violate POSIX.

src/cmd/ksh93/sh/main.c: sh_main():
- Preset aliases for interactive shell regardless of SH_POSIX.
---
 NEWS                    |  3 +++
 src/cmd/ksh93/sh.1      | 11 +++--------
 src/cmd/ksh93/sh/main.c |  9 +++------
 3 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/NEWS b/NEWS
index b6d7f7a8c..7223a2e66 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,9 @@ Any uppercase BUG_* names are modernish shell bug IDs.
   <##pattern redirection operators will not work and the -n option to the
   read built-in will not return early when reading from a slow device.)
 
+- An interactive shell initialized in POSIX mode now once again has the
+  preset aliases defined. This amends a change made on 2020-09-11.
+
 2022-06-08:
 
 - If -B/--braceexpand is turned on in --posix mode, it now only allows brace
diff --git a/src/cmd/ksh93/sh.1 b/src/cmd/ksh93/sh.1
index 7557a9481..361308e49 100644
--- a/src/cmd/ksh93/sh.1
+++ b/src/cmd/ksh93/sh.1
@@ -811,11 +811,7 @@ definition command has to be executed before
 the command which references the alias is read.
 .PP
 The following aliases are automatically preset
-when the shell is invoked as an interactive shell,
-unless invoked in POSIX compliance mode
-(see
-.I Invocation\^
-below).
+when the shell is invoked as an interactive shell.
 Preset aliases can be unset or redefined.
 .RS 20
 .PD 0
@@ -7700,9 +7696,8 @@ is automatically turned on upon invocation if the shell is invoked as \fBsh\fR
 or \fBrsh\fR, or if \fB\-o posix\fR or \fB\-\-posix\fR is specified on the
 shell invocation command line, or when executing scripts without a \fB#!\fR path
 with this option active in the invoking shell. In that case, the invoked shell
-will not set the preset aliases even if interactive, and will not import type
-attributes for variables (such as integer or left/right justify)
-from the environment.
+will not import type attributes for variables (such as integer or left/right
+justify) from the environment.
 .RS 8
 .PP
 In addition, while on, the \fBposix\fR option
diff --git a/src/cmd/ksh93/sh/main.c b/src/cmd/ksh93/sh/main.c
index 5d2c20e0b..065f6d85c 100644
--- a/src/cmd/ksh93/sh/main.c
+++ b/src/cmd/ksh93/sh/main.c
@@ -166,12 +166,9 @@ int sh_main(int ac, char *av[], Shinit_f userinit)
 		{
 			sh_onoption(SH_BGNICE);
 			sh_onoption(SH_RC);
-			if(!sh_isoption(SH_POSIX))
-			{
-				/* preset aliases for interactive non-POSIX ksh */
-				dtclose(sh.alias_tree);
-				sh.alias_tree = sh_inittree(shtab_aliases);
-			}
+			/* preset aliases for interactive ksh/sh */
+			dtclose(sh.alias_tree);
+			sh.alias_tree = sh_inittree(shtab_aliases);
 		}
 #if SHOPT_REMOTE
 		/*