add debug log level macros.

Signed-off-by: Jason Volk <jason@zemos.net>

src/utils/debug.rs

+/// Log message at the ERROR level in debug-mode (when debug-assertions are
+/// enabled). In release mode it becomes DEBUG level, and possibly subject to
+/// elision.
+#[macro_export]
+macro_rules! debug_error {
+	( $($x:tt)+ ) => {
+		if cfg!(debug_assertions) {
+			error!( $($x)+ );
+		} else {
+			debug!( $($x)+ );
+		}
+	}
+}
+
+/// Log message at the WARN level in debug-mode (when debug-assertions are
+/// enabled). In release mode it becomes DEBUG level, and possibly subject to
+/// elision.
+#[macro_export]
+macro_rules! debug_warn {
+	( $($x:tt)+ ) => {
+		if cfg!(debug_assertions) {
+			warn!( $($x)+ );
+		} else {
+			debug!( $($x)+ );
+		}
+	}
+}
+
+/// Log message at the INFO level in debug-mode (when debug-assertions are
+/// enabled). In release mode it becomes DEBUG level, and possibly subject to
+/// elision.
+#[macro_export]
+macro_rules! debug_info {
+	( $($x:tt)+ ) => {
+		if cfg!(debug_assertions) {
+			info!( $($x)+ );
+		} else {
+			debug!( $($x)+ );
+		}
+	}
+}

src/utils/mod.rs

+pub(crate) mod debug;
 pub(crate) mod error;
 
 use std::{