[RFC PATCH v2 01/74] dtc-parser.y: Avoid an empty proplist

[Herve Codina]

In the dts parser grammar, a nodedef is defined by
  '{' proplist subnodes '}' ';'
with both proplist and subnodes that can be empty lists.

Having multiple possible empty list can lead to Bison warnings such as
  warning: 4 shift/reduce conflicts [-Wconflicts-sr]
  warning: 1 reduce/reduce conflict [-Wconflicts-rr]

This will happen as soon as a new list (which also could be empty) is
added in the nodedef definition.

The simpler way to remove those warning and thus have a robust parsing
is to avoid multiple empty lists.

Update the proplist definition and nodedef definition to avoid those
multiple empty lists. Instead of allowing a proplist to be an empty
list, force the list to be a non empty one and update the nodedef to
handle explicitly the absence of the proplist to support the case where
no properties are available, i.e. the case of a node composed only of
sub-nodes.

This doesn't change the functional behavior.

Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
---
 dtc-parser.y | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/dtc-parser.y b/dtc-parser.y
index 4d5eece5..e47f80d4 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -267,12 +267,16 @@ nodedef:
 		{
 			$$ = build_node($2, $3, &@$);
 		}
+	| '{' subnodes '}' ';'
+		{
+			$$ = build_node(NULL, $2, &@$);
+		}
 	;
 
 proplist:
-	  /* empty */
+	  propdef
 		{
-			$$ = NULL;
+			$$ = chain_property($1, NULL);
 		}
 	| proplist propdef
 		{
-- 
2.55.0