Auto merge of #6010 - ehuss:winsize, r=alexcrichton

Get window size on more Windows terminals.

This is an alternate approach to determining the window size that works on more Windows terminals.

Terminals with accurate width detection: Normal Windows console, cmder, ConEmu, VS Code, Hyper, etc.

mintty-based terminals will always be 60 characters wide. Cygwin in a command console is ok, but
running under x-windows will also always be 60.

Tested on Windows 8 and Windows 10.

Closes #5124.

src/cargo/core/shell.rs

@@ -359,18 +359,51 @@ mod imp {
     extern crate winapi;
 
     use std::mem;
+    use std::ptr;
+    use self::winapi::um::fileapi::*;
+    use self::winapi::um::handleapi::*;
     use self::winapi::um::processenv::*;
     use self::winapi::um::winbase::*;
     use self::winapi::um::wincon::*;
+    use self::winapi::um::winnt::*;
 
     pub fn stderr_width() -> Option<usize> {
         unsafe {
             let stdout = GetStdHandle(STD_ERROR_HANDLE);
             let mut csbi: CONSOLE_SCREEN_BUFFER_INFO = mem::zeroed();
-            if GetConsoleScreenBufferInfo(stdout, &mut csbi) == 0 {
+            if GetConsoleScreenBufferInfo(stdout, &mut csbi) != 0 {
+                return Some((csbi.srWindow.Right - csbi.srWindow.Left) as usize)
+            }
+
+            // On mintty/msys/cygwin based terminals, the above fails with
+            // INVALID_HANDLE_VALUE. Use an alternate method which works
+            // in that case as well.
+            let h = CreateFileA("CONOUT$\0".as_ptr() as *const CHAR,
+                GENERIC_READ | GENERIC_WRITE,
+                FILE_SHARE_READ | FILE_SHARE_WRITE,
+                ptr::null_mut(),
+                OPEN_EXISTING,
+                0,
+                ptr::null_mut()
+            );
+            if h == INVALID_HANDLE_VALUE {
                 return None;
             }
-            Some((csbi.srWindow.Right - csbi.srWindow.Left) as usize)
+
+            let mut csbi: CONSOLE_SCREEN_BUFFER_INFO = mem::zeroed();
+            let rc = GetConsoleScreenBufferInfo(h, &mut csbi);
+            CloseHandle(h);
+            if rc != 0 {
+                let width = (csbi.srWindow.Right - csbi.srWindow.Left) as usize;
+                // Some terminals, such as mintty, always return 79 instead of
+                // the actual width. In that case, use a conservative value.
+                if width == 79 {
+                    return Some(60);
+                } else {
+                    return Some(width);
+                }
+            }
+            return None;
         }
     }
 }