Report POSIX function or dot script name in error messages

An old annoyance of mine: when an error occurs in a ksh function,
the function name is reported in the error message, but the same is
not done for POSIX functions.

Since POSIX functions are treated as glorified dot scripts,
b_dot_cmd() needs an errorpush() call and an assignment to
error_info.id to make this happen for both POSIX functions and dot
scripts. This is the same thing that sh_funscope() does for ksh
functions. There is now no difference from ksh functions in how
these report errors.

Note that the sh_popcontext() macro includes an errorpop() call, so
that does not need to be added. See fault.h and error.h.

NEWS

@@ -8,6 +8,9 @@ Any uppercase BUG_* names are modernish shell bug IDs.
 - Fixed a bug where a reproducible $RANDOM sequence (after assigning a
   specific value to $RANDOM) was influenced by running any external command.
 
+- When an error occurs in a POSIX name() function or a dot script, the
+  function or script name is now reported in the error message.
+
 2022-07-14:
 
 - Fixed a bug that caused a spurious "Done" message on the interactive shell

src/cmd/ksh93/bltins/misc.c

@@ -305,6 +305,8 @@ int    b_dot_cmd(register int n,char *argv[],Shbltin_t *context)
 	if(np || argv[1])
 		argsave = sh_argnew(argv,&saveargfor);
 	sh_pushcontext(&buff,SH_JMPDOT);
+	errorpush(&buff.err,0);
+	error_info.id = argv[0];
 	jmpval = sigsetjmp(buff.buff,0);
 	if(jmpval == 0)
 	{