awk: allow empty fuinctions with no arguments, disallow function redefinitions

function                                             old     new   delta
.rodata                                           103681  103700     +19
parse_program                                        303     307      +4
evaluate                                            3145    3141      -4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 23/-4)              Total: 19 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 17 insertions, 4 deletions

diff --git a/editors/awk.c b/editors/awk.c
index 1115085da..c05d5d651 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -139,6 +139,7 @@ typedef struct chain_s {
 /* Function */
 typedef struct func_s {
         unsigned nargs;
+        smallint defined;
         struct chain_s body;
 } func;
 
@@ -1662,9 +1663,11 @@ static void parse_program(char *p)
                         debug_printf_parse("%s: TC_FUNCDECL\n", __func__);
                         next_token(TC_FUNCTION);
                         f = newfunc(t_string);
-//FIXME: dup check: functions can't be redefined, this is not ok: awk 'func f(){}; func f(){}'
-                        f->body.first = NULL;
-                        f->nargs = 0;
+                        if (f->defined)
+                                syntax_error("Duplicate function");
+                        f->defined = 1;
+                        //f->body.first = NULL; - already is
+                        //f->nargs = 0; - already is
                         /* func arg list: comma sep list of args, and a close paren */
                         for (;;) {
                                 if (next_token(TC_VARIABLE | TC_RPAREN) == TC_RPAREN) {
@@ -2912,7 +2915,7 @@ static var *evaluate(node *op, var *res)
 
                         debug_printf_eval("FUNC\n");
 
-                        if (op->r.f->nargs == 0 && !op->r.f->body.first)
+                        if (!op->r.f->defined)
                                 syntax_error(EMSG_UNDEF_FUNC);
 
                         /* The body might be empty, still has to eval the args */
diff --git a/testsuite/awk.tests b/testsuite/awk.tests
index 6e35d33dd..873cc3680 100755
--- a/testsuite/awk.tests
+++ b/testsuite/awk.tests
@@ -45,6 +45,16 @@ testing "awk handles empty function f(arg){}" \
         "" ""
 
 prg='
+function empty_fun(){}
+END {empty_fun()
+  print "Ok"
+}'
+testing "awk handles empty function f(){}" \
+        "awk '$prg'" \
+        "Ok\n" \
+        "" ""
+
+prg='
 function outer_fun() {
   return 1
 }