Fix issue 5646

[lokax]

Fix #5646

[Mytherin]

Thanks for the PR! Looks good. Some comments below.

[Mytherin]

Could you fix the indentation here?

[Mytherin]

This seems to be a pattern that is repeated in several places here - could we perhaps extract it into a separate node (indirect_expr), and do something like this:

c_expr:
    ...
    | indirect_expr opt_indirection
    {
        if ($2) {
            PGAIndirection *n = makeNode(PGAIndirection);
            n->arg = (PGNode *) $1;
            n->indirection = check_indirection($2, yyscanner);
            $$ = (PGNode *) n;
        }
        else {
            $$ = (PGNode *) $1;
        }
    }
| ...

indirect_expr: 
    '?'
    {
        $$ = makeParamRef(0, @1);
    }
    | PARAM
    {
        PGParamRef *p = makeNode(PGParamRef);
        p->number = $1;
        p->location = @1;
         $$ = (PGNode *) n;
    }
    | ...    

[Mytherin]

Thanks for the fixes! LGTM