Fix statement exprs returning a local label

Like returned local variables also labels local to a statement expression
can be returned, and so their symbols must not be immediately freed
(though they need to be removed from the symbol table).

tcc.h

@@ -1234,7 +1234,7 @@ ST_INLN Sym *define_find(int v);
 ST_FUNC void free_defines(Sym *b);
 ST_FUNC Sym *label_find(int v);
 ST_FUNC Sym *label_push(Sym **ptop, int v, int flags);
-ST_FUNC void label_pop(Sym **ptop, Sym *slast);
+ST_FUNC void label_pop(Sym **ptop, Sym *slast, int keep);
 ST_FUNC void parse_define(void);
 ST_FUNC void preprocess(int is_bof);
 ST_FUNC void next_nomacro(void);

tccgen.c

@@ -5861,7 +5861,7 @@ static void block(int *bsym, int *csym, int is_expr)
             }
         }
         /* pop locally defined labels */
-        label_pop(&local_label_stack, llabel);
+        label_pop(&local_label_stack, llabel, is_expr);
         /* pop locally defined symbols */
         --local_scope;
 	/* In the is_expr case (a statement expression is finished here),
@@ -6948,7 +6948,7 @@ static void gen_function(Sym *sym)
     gsym(rsym);
     gfunc_epilog();
     cur_text_section->data_offset = ind;
-    label_pop(&global_label_stack, NULL);
+    label_pop(&global_label_stack, NULL, 0);
     /* reset local stack */
     local_scope = 0;
     sym_pop(&local_stack, NULL, 0);

tccpp.c

@@ -1376,7 +1376,7 @@ ST_FUNC Sym *label_push(Sym **ptop, int v, int flags)
 
 /* pop labels until element last is reached. Look if any labels are
    undefined. Define symbols if '&&label' was used. */
-ST_FUNC void label_pop(Sym **ptop, Sym *slast)
+ST_FUNC void label_pop(Sym **ptop, Sym *slast, int keep)
 {
     Sym *s, *s1;
     for(s = *ptop; s != slast; s = s1) {
@@ -1395,9 +1395,11 @@ ST_FUNC void label_pop(Sym **ptop, Sym *slast)
         }
         /* remove label */
         table_ident[s->v - TOK_IDENT]->sym_label = s->prev_tok;
-        sym_free(s);
+        if (!keep)
+            sym_free(s);
     }
-    *ptop = slast;
+    if (!keep)
+        *ptop = slast;
 }
 
 /* eval an expression for #if/#elif */

tests/tcctest.c

@@ -2899,6 +2899,11 @@ struct hlist_head {
     struct hlist_node *first, *last;
 };
 
+void consume_ulong (unsigned long i)
+{
+    i = 0;
+}
+
 void statement_expr_test(void)
 {
     int a, i;
@@ -2954,6 +2959,9 @@ void statement_expr_test(void)
 	   });
     printf ("stmtexpr: %d %d %d\n", t, b, c);
     printf ("stmtexpr: %ld %ld\n", (long)h.first, (long)h.last);
+
+    /* Test that we can give out addresses of local labels.  */
+    consume_ulong(({ __label__ __here; __here: (unsigned long)&&__here; }));
 }
 
 void local_label_test(void)