compat: fall back on __va_copy if available

diff --git a/builtin/diff.c b/builtin/diff.c
index a43d3263638daf083c52f37f3bd0872327d7459b..42822cd5374dbcf0e63c17078a55284c432ddc77 100644 (file)
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -22,7 +22,7 @@ struct blobinfo {
 };
 
 static const char builtin_diff_usage[] =
-"git diff <options> <rev>{0,2} -- <path>*";
+"git diff [<options>] [<commit> [<commit>]] [--] [<path>...]";
 
 static void stuff_change(struct diff_options *opt,
                         unsigned old_mode, unsigned new_mode,
@@ -330,8 +330,11 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
                        else if (!strcmp(arg, "--cached") ||
                                 !strcmp(arg, "--staged")) {
                                add_head_to_pending(&rev);
-                               if (!rev.pending.nr)
-                                       die("No HEAD commit to compare with (yet)");
+                               if (!rev.pending.nr) {
+                                       struct tree *tree;
+                                       tree = lookup_tree((const unsigned char*)EMPTY_TREE_SHA1_BIN);
+                                       add_pending_object(&rev, &tree->object, "HEAD");
+                               }
                                break;
                        }
                }