[PATCH v2 4/5] commit-graph: invert negated conditional, extract to function

[Taylor Blau <me@ttaylorr.com>]

Now that we're using `commit_graph_generation_from_graph()` (which can
return a zero value) and we have a pure if/else instead of an else-if,
let's swap the arms of the if-statement.

This avoids an "if (!x) { foo(); } else { bar(); }" and replaces it with
the more readable "if (x) { bar(); } else { foo(); }".

Let's also move this code to verify mixed zero/non-zero generation
numbers out to its own function, and have it modify the
`generation_zero` variable through a pointer.

There is no functionality change in this patch, but note that there are
a couple of textual differences. First, the wrapping is adjusted on both
`graph_report()` calls to avoid overly-long lines. Second, we use the
OID from `graph_commit` instead of passing in `cur_oid`, since these are
verified to be the same by `verify_one_commit_graph()`.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 commit-graph.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/commit-graph.c b/commit-graph.c
index acca753ce8..f7d9b31546 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -2568,6 +2568,27 @@ static int commit_graph_checksum_valid(struct commit_graph *g)
 	return hashfile_checksum_valid(g->data, g->data_len);
 }
 
+static void verify_mixed_generation_numbers(struct commit_graph *g,
+					    struct commit *graph_commit,
+					    int *generation_zero)
+{
+	if (commit_graph_generation_from_graph(graph_commit)) {
+		if (*generation_zero == GENERATION_ZERO_EXISTS)
+			graph_report(_("commit-graph has non-zero generation "
+				       "number for commit %s, but zero "
+				       "elsewhere"),
+				     oid_to_hex(&graph_commit->object.oid));
+		*generation_zero = GENERATION_NUMBER_EXISTS;
+	} else {
+		if (*generation_zero == GENERATION_NUMBER_EXISTS)
+			graph_report(_("commit-graph has generation number "
+				       "zero for commit %s, but non-zero "
+				       "elsewhere"),
+				     oid_to_hex(&graph_commit->object.oid));
+		*generation_zero = GENERATION_ZERO_EXISTS;
+	}
+}
+
 static int verify_one_commit_graph(struct repository *r,
 				   struct commit_graph *g,
 				   struct progress *progress,
@@ -2681,17 +2702,8 @@ static int verify_one_commit_graph(struct repository *r,
 			graph_report(_("commit-graph parent list for commit %s terminates early"),
 				     oid_to_hex(&cur_oid));
 
-		if (!commit_graph_generation_from_graph(graph_commit)) {
-			if (generation_zero == GENERATION_NUMBER_EXISTS)
-				graph_report(_("commit-graph has generation number zero for commit %s, but non-zero elsewhere"),
-					     oid_to_hex(&cur_oid));
-			generation_zero = GENERATION_ZERO_EXISTS;
-		} else {
-			if (generation_zero == GENERATION_ZERO_EXISTS)
-				graph_report(_("commit-graph has non-zero generation number for commit %s, but zero elsewhere"),
-					     oid_to_hex(&cur_oid));
-			generation_zero = GENERATION_NUMBER_EXISTS;
-		}
+		verify_mixed_generation_numbers(g, graph_commit,
+						&generation_zero);
 
 		if (generation_zero == GENERATION_ZERO_EXISTS)
 			continue;
-- 
2.42.0.rc0.30.gb82b15ebc8