From 263f1b35de01cb04a6c2cbc635ae0258f8401a3f Mon Sep 17 00:00:00 2001
From: Johannes Altmanninger <aclopte@gmail.com>
Date: Sat, 28 Sep 2024 09:14:20 +0200
Subject: [PATCH] Reapply "Clear to eol before outputting line in multi-line
 prompt"

In case a terminal resize[1] causes us
to repaint a multi-line prompt that changes width like

    function fish_prompt
        for i in 1 2 3
            random choice 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaa' 'bbbbbbbbbbb'
        end
    end

we add a clr_eol after each line[2] , to make sure
that a "b" line does not have leftover "a" letters
(80aaae5b7 (Clear to end of each line in left prompt, 2020-10-25)).

Unfortunately, if a prompt line takes up all the columns, clr_eol will
wrongly clear the last column. Reproduce with

    function fish_prompt
        string repeat $COLUMNS -
        echo "$PWD> "
    end

and observe that the last "-" is missing.

Previous (reverted) attempt d3ceba107 (Clear to eol before outputting line
in multi-line prompt, 2021-05-17) found the right fix but had an off-by-one
error which reintroduced the leftover "a" letters in the "random choice"
prompt above.

Given prompt string "aa\nbb\ncc", it wrongly printed

    clr_eol "aa" clr_eol "\nbb" "\ncc"

Observe that the first line is cleared twice, while the second line is
never cleared. Fix that.

[1]: or an async "commandline -f repaint" triggered by a uvar change /
     async prompt update
[2]: except after the last line where we probably already emit clr_eol
     elsewhere..

Alternative fix: emit both clr_eol and clr_bol *before* drawing the current
line. However, if fish and the terminal disagree on character width, that
approach might erase too much.

Closes #8164
---
 src/screen.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/screen.rs b/src/screen.rs
index a532e528c..ff4f923c3 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -824,11 +824,11 @@ impl Screen {
             zelf.write_bytes(b"\x1b]133;A;special_key=1\x07");
             let mut start = 0;
             for line_break in left_prompt_layout.line_breaks {
-                zelf.write_str(&left_prompt[start..line_break]);
                 zelf.outp
                     .borrow_mut()
                     .tputs_if_some(&term.and_then(|term| term.clr_eol.as_ref()));
-                start = line_break;
+                zelf.write_str(&left_prompt[start..=line_break]);
+                start = line_break + 1;
             }
             zelf.write_str(&left_prompt[start..]);
             zelf.actual_left_prompt = left_prompt.to_owned();