Output line with ANSI escape code disappears #5528
Description
Expected Behavior
Consider this OCaml file (repro/test2.ml) using ANSI escape codes:
type color = Normal | Cyan
let int_of_color = function
| Normal -> 0
| Cyan -> 6
let in_color c pp out x =
let n = int_of_color c in
Printf.fprintf out "\x1b[3%dm" n;
pp out x;
Printf.fprintf out "\x1b[0m"
let reset_line = "\x1b[2K\r"
;;
Printf.printf "%sVery Secret!\n%!" reset_line;
Printf.printf "%s\n%!" (String.make 15 '-');
Printf.printf "%a\n%!" (in_color Cyan output_string) "Can you see it?";and a corresponding repro/dune file:
(test
(name test2)
(modules test2))
When executed with dune exec the first line is displayed - and the last line is displayed in cyan:
$ dune exec repro/test2.exe
Very Secret!
---------------
Can you see it?
I also get this behaviour when running the executable _build/default/repro/test2.exe directly (outside dune).
However if I run the above through dune with dune runtest the first line is not visible (the last line is still in cyan).
Actual Behavior
$ dune runtest repro -f
---------------
Can you see it?
Reproduction
To reproduce
save repro/test2.mlandrepro/dune- run
dune exec repro/test2.exe - run
dune runtest repro -f
Specifications
- Version of
dune(output ofdune --version): 3.0.3 - Version of
ocaml(output ofocamlc --version): 4.13.1 - Operating system (distribution and version): Linux Mint, running 5.4.0-105-generic
Additional information
Digging some more I learned about the script command useful to study the produced output.
Compare the following:
$ script log -qc ' _build/default/repro/test2.exe' && hexdump -C log
Very Secret!
---------------
Can you see it?
00000000 53 63 72 69 70 74 20 73 74 61 72 74 65 64 20 6f |Script started o|
00000010 6e 20 32 30 32 32 2d 30 33 2d 32 33 20 31 37 3a |n 2022-03-23 17:|
00000020 34 32 3a 33 31 2b 30 31 3a 30 30 20 5b 54 45 52 |42:31+01:00 [TER|
00000030 4d 3d 22 78 74 65 72 6d 2d 32 35 36 63 6f 6c 6f |M="xterm-256colo|
00000040 72 22 20 54 54 59 3d 22 2f 64 65 76 2f 70 74 73 |r" TTY="/dev/pts|
00000050 2f 32 22 20 43 4f 4c 55 4d 4e 53 3d 22 31 34 32 |/2" COLUMNS="142|
00000060 22 20 4c 49 4e 45 53 3d 22 34 36 22 5d 0a 1b 5b |" LINES="46"]..[|
00000070 32 4b 0d 56 65 72 79 20 53 65 63 72 65 74 21 0d |2K.Very Secret!.|
00000080 0a 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |.---------------|
00000090 0d 0a 1b 5b 33 36 6d 43 61 6e 20 79 6f 75 20 73 |...[36mCan you s|
000000a0 65 65 20 69 74 3f 1b 5b 30 6d 0d 0a 0a 53 63 72 |ee it?.[0m...Scr|
000000b0 69 70 74 20 64 6f 6e 65 20 6f 6e 20 32 30 32 32 |ipt done on 2022|
000000c0 2d 30 33 2d 32 33 20 31 37 3a 34 32 3a 33 31 2b |-03-23 17:42:31+|
000000d0 30 31 3a 30 30 20 5b 43 4f 4d 4d 41 4e 44 5f 45 |01:00 [COMMAND_E|
000000e0 58 49 54 5f 43 4f 44 45 3d 22 30 22 5d 0a |XIT_CODE="0"].|
000000ee
I get the same log when running script log -qc 'dune exec repro/test2.exe -f --display=quiet' && hexdump -C log
When run with dune runtest it seems the first line is swallowed:
$ script log -qc 'dune runtest repro -f --display=quiet' && hexdump -C log
---------------
Can you see it?
00000000 53 63 72 69 70 74 20 73 74 61 72 74 65 64 20 6f |Script started o|
00000010 6e 20 32 30 32 32 2d 30 33 2d 32 33 20 31 37 3a |n 2022-03-23 17:|
00000020 34 33 3a 34 35 2b 30 31 3a 30 30 20 5b 54 45 52 |43:45+01:00 [TER|
00000030 4d 3d 22 78 74 65 72 6d 2d 32 35 36 63 6f 6c 6f |M="xterm-256colo|
00000040 72 22 20 54 54 59 3d 22 2f 64 65 76 2f 70 74 73 |r" TTY="/dev/pts|
00000050 2f 32 22 20 43 4f 4c 55 4d 4e 53 3d 22 31 34 32 |/2" COLUMNS="142|
00000060 22 20 4c 49 4e 45 53 3d 22 34 36 22 5d 0a 0d 0a |" LINES="46"]...|
00000070 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0d |---------------.|
00000080 0a 1b 5b 33 36 6d 43 61 6e 20 79 6f 75 20 73 65 |..[36mCan you se|
00000090 65 20 69 74 3f 1b 5b 30 6d 0d 0a 0a 53 63 72 69 |e it?.[0m...Scri|
000000a0 70 74 20 64 6f 6e 65 20 6f 6e 20 32 30 32 32 2d |pt done on 2022-|
000000b0 30 33 2d 32 33 20 31 37 3a 34 33 3a 34 35 2b 30 |03-23 17:43:45+0|
000000c0 31 3a 30 30 20 5b 43 4f 4d 4d 41 4e 44 5f 45 58 |1:00 [COMMAND_EX|
000000d0 49 54 5f 43 4f 44 45 3d 22 30 22 5d 0a |IT_CODE="0"].|
000000dd
I believe this is related to #2664 and #3160 and the escape code parsing in https://github.com/ocaml/dune/blob/main/otherlibs/stdune/ansi_color.ml
The test case is a reduced version based on c-cube/qcheck#227