feat: make is_terminal replaceable with std via cfg

Cargo.toml

@@ -30,7 +30,6 @@ evcxr = []
 win_crlf = []
 # This feature is inentionally opt-out (enabled by default) not to break older clients,
 # although it may become no-op with a MSRV bummp (which is considered a minor change) and removed with a major update
-# TODO: make this feature no-op once MSRV is at least `1.70`
 legacy-is-terminal = ["is-terminal"]
 
 [[bin]]
@@ -45,6 +44,9 @@ name = "prettytable"
 unicode-width = "0.1"
 term = "0.7"
 lazy_static = "1.4"
-is-terminal = { version = "0.4", optional = true }
 encode_unicode = "1.0"
 csv = { version = "1.1", optional = true }
+
+# TODO: remove it once MSRV is at least `1.70`
+[target.'cfg(not(prettytable_is_terminal_implementation = "std"))'.dependencies]
+is-terminal = { version = "0.4", optional = true }

src/lib.rs

@@ -194,9 +194,9 @@ impl<'a> TableSlice<'a> {
     /// # Returns
     /// A `Result` holding the number of lines printed, or an `io::Error` if any failure happens
     pub fn print_tty(&self, force_colorize: bool) -> Result<usize, Error> {
-        #[cfg(not(feature = "legacy-is-terminal"))]
+        #[cfg(prettytable_is_terminal_implementation = "std")]
         use std::io::IsTerminal;
-        #[cfg(feature = "legacy-is-terminal")]
+        #[cfg(not(prettytable_is_terminal_implementation = "std"))]
         use is_terminal::IsTerminal;
 
         match (stdout(), io::stdout().is_terminal() || force_colorize) {