How to debug with gdbtui and utf-8 source files?

["Dedeco Balaco Baco via gdb" <gdb at sourceware dot org>]

I have:

- a terminal set to UTF-8 in an OS where UTF-8 locales are installed: Mate Terminal 1.12.1 (does not matter, as long as its character encoding is utf-8)

- a C source file which contains (both) utf-8 comments and utf-8 strings

- gdbtui:

  $  gdbtui --version
    GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1

The program compiles and works flawlessly, with its output being correctly shown in the terminal.

gdbtui, on the other hand, does not show the comments correctly, making them hard to read and also braking the size and making a few lines occupy two screenlines. This makes strange things happen when we step-by-step through these lines.

For example, instead of showing:

"// Não temos nenhum nó, garante não ter um falso ponteiro"

in the source window, gdbtui shows:

"// NM-CM-#o temos nenhum nM-CM-3, garante nM-CM-#o ter um falso ponteiro"

The environment is correctly set:

  $  set | grep -e 'LANG|LC_ALL'
    LANG=pt_BR.UTF-8
    LANGUAGE=pt_BR.UTF-8:en_GB:en
    LC_ALL=pt_BR.UTF-8

How can I make gdbtui work correctly? If no answer exist for this question, I may help filling a bug report about it. I will need a bit of help with that, please offer, if that is possible.