sh_deparse(): braces ignored in and/or lists

[McDutchie]

(note: this bug does not apply to the 1.0.* releases)

Background info: f21ace5

Reproducer:

f() { true || { false && echo WRONG; }; }
typeset -f f
eval "$(typeset -f f)"
f

Actual output:

f()
{	true || false && echo WRONG
}
WRONG

Expected output: something like

f()
{       true || {
                false && echo WRONG
        }
}

The braces should be preserved in the generated typeset -f output as not having them changes the meaning of the code, and WRONG is printed.

I have no idea where or how to solve this issue. The problem is here somewhere:

ksh/src/cmd/ksh93/sh/deparse.c

Lines 210 to 254 in 0975086

	case TAND:
	cp = "&&";
	goto andor;
	case TORF:
	cp = "||";
	goto andor;
	case TFIL:
	cp = "|";
	andor:
	{
	int bracket = 0;
	if(t->tre.tretyp&TTEST)
	{
	tflags |= NO_NEWLINE;
	if(!(tflags&NO_BRACKET))
	{
	p_keyword("[[",BEGIN|NOTAB);
	tflags |= NO_BRACKET;
	bracket=1;
	}
	}
	p_tree(t->lst.lstlef,NEED_BRACE|NO_NEWLINE|(tflags&NO_BRACKET));
	begin_line = 0;
	if(tflags&FALTPIPE)
	{
	Shnode_t *tt = t->lst.lstrit;
	if(tt->tre.tretyp!=TFIL || !(tt->lst.lstlef->tre.tretyp&FALTPIPE))
	{
	sfputc(outfile,'\n');
	return;
	}
	}
	sfputr(outfile,cp,here_doc?'\n':' ');
	if(here_doc)
	{
	here_body(here_doc);
	here_doc = 0;
	}
	level++;
	p_tree(t->lst.lstrit,tflags|NEED_BRACE);
	if(bracket)
	p_keyword("]]",END);
	level--;
	break;
	}

A naïve patch could reuse code like this:

ksh/src/cmd/ksh93/sh/deparse.c

Lines 199 to 200 in 0975086

	if(needbrace)
	p_keyword("{",BEGIN);

ksh/src/cmd/ksh93/sh/deparse.c

Lines 205 to 206 in 0975086

	if(needbrace)
	p_keyword("}",END);

– but if that is copied over to the &&/|| code, we end up with far too many braces. The braces should be reproduced only if they were in the original code, but I have no idea how the deparser can determine that. Any ideas appreciated.