Merge branch 'jk/suppress-clang-warning'

* jk/suppress-clang-warning:
  fix clang -Wunused-value warnings for error functions

cache.h

@@ -1147,7 +1147,7 @@ extern int check_repository_format_version(const char *var, const char *value, v
 extern int git_env_bool(const char *, int);
 extern int git_config_system(void);
 extern int config_error_nonbool(const char *);
-#ifdef __GNUC__
+#if defined(__GNUC__) && ! defined(__clang__)
 #define config_error_nonbool(s) (config_error_nonbool(s), -1)
 #endif
 extern const char *get_log_output_encoding(void);

git-compat-util.h

@@ -297,7 +297,7 @@ extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)))
  * behavior. But since we're only trying to help gcc, anyway, it's OK; other
  * compilers will fall back to using the function as usual.
  */
-#ifdef __GNUC__
+#if defined(__GNUC__) && ! defined(__clang__)
 #define error(fmt, ...) (error((fmt), ##__VA_ARGS__), -1)
 #endif
 

parse-options.h

@@ -177,7 +177,7 @@ extern NORETURN void usage_msg_opt(const char *msg,
 
 extern int optbug(const struct option *opt, const char *reason);
 extern int opterror(const struct option *opt, const char *reason, int flags);
-#ifdef __GNUC__
+#if defined(__GNUC__) && ! defined(clang)
 #define opterror(o,r,f) (opterror((o),(r),(f)), -1)
 #endif