Merge branch 'jk/squelch-compiler-warning-from-funny-error-macro'

* jk/squelch-compiler-warning-from-funny-error-macro:
  let clang use the constant-return error() macro
  inline constant return from error() function

cache.h

@@ -1294,8 +1294,8 @@ 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 *);
-#if defined(__GNUC__) && ! defined(__clang__)
-#define config_error_nonbool(s) (config_error_nonbool(s), -1)
+#if defined(__GNUC__)
+#define config_error_nonbool(s) (config_error_nonbool(s), const_error())
 #endif
 extern const char *get_log_output_encoding(void);
 extern const char *get_commit_output_encoding(void);

git-compat-util.h

@@ -330,8 +330,12 @@ extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)))
  * trying to help gcc, anyway, it's OK; other compilers will fall back to
  * using the function as usual.
  */
-#if defined(__GNUC__) && ! defined(__clang__)
-#define error(...) (error(__VA_ARGS__), -1)
+#if defined(__GNUC__)
+static inline int const_error(void)
+{
+	return -1;
+}
+#define error(...) (error(__VA_ARGS__), const_error())
 #endif
 
 extern void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list params));

parse-options.h

@@ -176,8 +176,8 @@ 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);
-#if defined(__GNUC__) && ! defined(__clang__)
-#define opterror(o,r,f) (opterror((o),(r),(f)), -1)
+#if defined(__GNUC__)
+#define opterror(o,r,f) (opterror((o),(r),(f)), const_error())
 #endif
 
 /*----- incremental advanced APIs -----*/