Terminal programs do not receive shortcuts led by the Shift modifier

[Rijnder Wever]

Expected behavior

If I type M-L (note the uppercase 'L') and, subsequently, M-l in gnome console (a terminal application), I get the following:

~> cat
^[L^[l

This is the expected and correct output — 'L' is being differentiated from 'l'. Unsurprisingly, the same goes for other letters as well.

Actual behavior

However, typing the same two shortcuts within emac's vterm results in no differentiation between shortcuts that are led by the shift modifier and those that aren't, that is, they are always interpreted as their lowercase variant:

~> cat
^[l^[l

This happens independent of shell program. Of course, the shift key is being recognized — I can type uppercase letters, just not use shift together with other modifier keys.

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Additional info

• Emacs version: GNU Emacs 29.1 (pgtk build, running under wayland)

• vterm version: 20240102.1640

• describe-key M-L in vterm-mode:

M-L runs the command vterm--self-insert-meta (found in
vterm-mode-map), which is an interactive native-compiled Lisp function
in ‘vterm.el’.

• describe-key M-l in vterm-mode:

M-l runs the command vterm--self-insert-meta (found in
vterm-mode-map), which is an interactive native-compiled Lisp function
in ‘vterm.el’.