avoid shifting signed integers 31 bits

We sometimes use 32-bit unsigned integers as bit-fields.
It's fine to access the MSB, because it's unsigned. However,
doing so as "1 << 31" is wrong, because the constant "1" is
a signed int, and we shift into the sign bit, causing
undefined behavior.

We can fix this by using "1U" as the constant.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index e6b93d0..e35ed40 100644 (file)
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -1597,7 +1597,7 @@ static void prepare_shallow_update(struct command *commands,
                                continue;
                        si->need_reachability_test[i]++;
                        for (k = 0; k < 32; k++)
-                               if (si->used_shallow[i][j] & (1 << k))
+                               if (si->used_shallow[i][j] & (1U << k))
                                        si->shallow_ref[j * 32 + k]++;
                }
 

diff --git a/cache.h b/cache.h
index 6f53962..9088843 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -214,7 +214,7 @@ struct cache_entry {
 #define CE_INTENT_TO_ADD     (1 << 29)
 #define CE_SKIP_WORKTREE     (1 << 30)
 /* CE_EXTENDED2 is for future extension */
-#define CE_EXTENDED2         (1 << 31)
+#define CE_EXTENDED2         (1U << 31)
 
 #define CE_EXTENDED_FLAGS (CE_INTENT_TO_ADD | CE_SKIP_WORKTREE)
 

diff --git a/diff.h b/diff.h
index f7208ad..893f446 100644 (file)
--- a/diff.h
+++ b/diff.h
@@ -91,7 +91,7 @@ typedef struct strbuf *(*diff_prefix_fn_t)(struct diff_options *opt, void *data)
 #define DIFF_OPT_DIRSTAT_BY_LINE     (1 << 28)
 #define DIFF_OPT_FUNCCONTEXT         (1 << 29)
 #define DIFF_OPT_PICKAXE_IGNORE_CASE (1 << 30)
-#define DIFF_OPT_DEFAULT_FOLLOW_RENAMES (1 << 31)
+#define DIFF_OPT_DEFAULT_FOLLOW_RENAMES (1U << 31)
 
 #define DIFF_OPT_TST(opts, flag)    ((opts)->flags & DIFF_OPT_##flag)
 #define DIFF_OPT_TOUCHED(opts, flag)    ((opts)->touched_flags & DIFF_OPT_##flag)