Fall back from uv tty instances more aggressively

It appears that uv's support for interacting with a stdio stream as a tty when
it's actually a pipe is pretty problematic. To get around this, promote a check
to see if the stream is a tty to the top of the tty constructor, and bail out
quickly if it's not identified as a tty.

Closes #10237

2 files changed, 2 insertions, 5 deletions

diff --git a/src/libstd/rt/io/stdio.rs b/src/libstd/rt/io/stdio.rs
index d33821a34b1..674b34639bc 100644
--- a/src/libstd/rt/io/stdio.rs
+++ b/src/libstd/rt/io/stdio.rs
@@ -277,12 +277,10 @@ impl StdWriter {
         }
     }
 
-    /// Returns whether this tream is attached to a TTY instance or not.
-    ///
-    /// This is similar to libc's isatty() function
+    /// Returns whether this stream is attached to a TTY instance or not.
     pub fn isatty(&self) -> bool {
         match self.inner {
-            TTY(ref tty) => tty.isatty(),
+            TTY(*) => true,
             File(*) => false,
         }
     }
diff --git a/src/libstd/rt/rtio.rs b/src/libstd/rt/rtio.rs
index 1e12da8645c..d623914cdad 100644
--- a/src/libstd/rt/rtio.rs
+++ b/src/libstd/rt/rtio.rs
@@ -222,7 +222,6 @@ pub trait RtioTTY {
     fn write(&mut self, buf: &[u8]) -> Result<(), IoError>;
     fn set_raw(&mut self, raw: bool) -> Result<(), IoError>;
     fn get_winsize(&mut self) -> Result<(int, int), IoError>;
-    fn isatty(&self) -> bool;
 }
 
 pub trait PausibleIdleCallback {