Cygwin fails to utilize Unicode replacement character

[Doug Henderson]

On Sat, 1 Sep 2018 at 10:13, Steven Penny  wrote:
...
> You get this result with Linux:
>
>     $ cat alfa.txt
>     �
...
> with Cygwin you get this:
>
>     $ cat alfa.txt
>     ▒
...
This is an issue with rendering the character in the terminal window.
In both the CMD/Conhost/bash and Mintty/bash terminals, I have
configure the font to be Lucinda Console. This font does not have a
glyph for U+FFFD: Replacement Character. (To check your character set,
open Charmap, and check Advanced View. Type "Replacement Character" on
the Search field, and search.) In the absence of that glyph, the
terminal program must choose a glyph to display. In a later reply,
Thomas Wolff, the maintainer of Mintty, indicates that Mintty displays
the glyph for U+2592: Medium Shade (or a similar one). Without
reference to the source, it is difficult to be certain, but Conhost
appears to use a similar glyph.

In Mintty, if you choose a font, such as DejaVu Sans Mono, which
contains a glyph for U+FFFD: Replacement Character, you could expect
to see that glyph, however that is determined by the terminal. As I
write this, both Mintty (2.9.0) and Conhost (Windows 10 Home,
10.0.17134 Build 17134, fully patched) display a glyph with the
appearance of U+2592 Medium Shade.

So, IMHO, to provide a similar visual, across all fonts and terminals,
these programs need to display a glyph common to all, such as the
Medium Shade.

HTH,
Doug

BTW, in my Debian 9.5 VM, the Replacement Character is displayed. The
Characters app shows that the default font contains the Replacement
Character, and that is what is displayed in the terminal.
-- 
Doug Henderson, Calgary, Alberta, Canada - from gmail.com

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