[PATCH 2/3] git-compat: introduce BUG_ON(condition, fmt, ...) macro

From

Stefan Beller <sbeller@google.com>

Date

Nov 22, 2017, 22:38 UTC

Message-ID

<20171122223827.26773-3-sbeller@google.com>

In-Reply-To

<20171122223827.26773-1-sbeller@google.com>

A lot of BUG() invocations are in the form of
    if (condition)
        BUG()
so moving the condition into the same line as the macro will result in
more readable code.  The conversion to use this MACRO will happen in a
later patch.

This macro in name and spirit is borrowed from linux, which defines it as

    #define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 git-compat-util.h |  4 ++++
 usage.c           | 12 +++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/git-compat-util.h b/git-compat-util.h
index cedad4d581..4fec462e30 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1092,9 +1092,13 @@ static inline int regexec_buf(const regex_t *preg, const char *buf, size_t size,
 __attribute__((format (printf, 3, 4))) NORETURN
 void BUG_fl(const char *file, int line, const char *fmt, ...);
 #define BUG(...) BUG_fl(__FILE__, __LINE__, __VA_ARGS__)
+#define BUG_ON(condition, ...) do { if (condition) BUG(__VA_ARGS__); } while (0)
 #else
 __attribute__((format (printf, 1, 2))) NORETURN
 void BUG(const char *fmt, ...);
+
+__attribute__((format (printf, 2, 3)))
+void BUG_ON(int condition, const char *fmt, ...);
 #endif
 
 /*
diff --git a/usage.c b/usage.c
index cdd534c9df..3aed669181 100644
--- a/usage.c
+++ b/usage.c
@@ -240,7 +240,17 @@ NORETURN void BUG(const char *fmt, ...)
 	BUG_vfl(NULL, 0, fmt, ap);
 	va_end(ap);
 }
-#endif
+
+void BUG_ON(int condition, const char *fmt, ...)
+{
+	if (condition) {
+		va_list ap;
+		va_start(ap, fmt);
+		BUG_vfl(NULL, 0, fmt, ap);
+		va_end(ap);
+	}
+}
+#endif /* HAVE_VARIADIC_MACROS */
 
 #ifdef SUPPRESS_ANNOTATED_LEAKS
 void unleak_memory(const void *ptr, size_t len)

-- 
2.15.0.448.gf294e3d99a-goog