$env assignment silently runs wrong command

[amtoine]

Describe the bug

related to #9589

i was playing with variable assignment with the new #9589 feature and i think i noticed a pretty bad silent bug 🤔

1. this is fine because Let with pipeline #9589 did not address assignment

> $env.foo = ls | where type == file

Error: nu::shell::only_supports_this_input_type

  × Input type not supported.
   ╭─[entry #29:1:1]
 1 │ $env.foo = ls | where type == file
   · ──┬─            ──┬──
   ·   │               ╰── only list, binary, raw data or range input data is supported
   ·   ╰── input type: nothing
   ╰────

the error is a bit unhelpful but it's easily fixed by adding parentheses: $env.foo = (ls | where type == file)

2. this fails because we do not support the syntax as it might be ambiguous inside a record

> export-env { load-env { $env.FOO: ls | where type == file } }

Error: nu::parser::parse_mismatch

  × Parse mismatch during operation.
   ╭─[entry #31:1:1]
 1 │ export-env { load-env { $env.FOO: ls | where type == file } }
   ·                       ──────────────────┬──────────────────
   ·                                         ╰── expected record
   ╰────

3. however, the following does work in the sense in does not throw an error... but i think it does not make any sense here to have $env.FOO being equal to the "ls" string, without any error

> export-env { $env.FOO = ls | where type == file }; $env.FOO

ls

How to reproduce

1. run export-env { $env.FOO = ls | where type == file }; $env.FOO
2. see that it gives ls

Expected behavior

i expected export-env { $env.FOO = ls | where type == file } to either

• give an error just as $env.FOO = ls | where type == file does
• give the result of ls | where type == file inside $env.FOO

Screenshots

No response

Configuration

key	value
version	0.82.1
branch	main
commit_hash	2bb0c1c
build_os	linux-x86_64
build_target	x86_64-unknown-linux-gnu
rust_version	rustc 1.68.2 (9eb3afe9e 2023-03-27)
rust_channel	1.68.2-x86_64-unknown-linux-gnu
cargo_version	cargo 1.68.2 (6feb7c9cf 2023-03-26)
build_time	2023-07-03 18:32:11 +02:00
build_rust_channel	release
allocator	standard
features	default, sqlite, trash, which, zip
installed_plugins	hist, plot

Additional context

No response

[WindSoilder]

Actually I think it's better to wrap the ls | where type == file with () to make it more readable.

[amtoine]

Actually I think it's better to wrap the ls | where type == file with () to make it more readable.

mm i dunno.
the syntax has been relaxed in #9589 and i think it's great not being forced to use parentheses for such simple pipes 😋

and because the syntax has been relaxed in that area, i think this behaviour above is a bug and a pretty nasty one 🤔

[amtoine]

i mean if we allow writing things like something = foo | bar | baz it should always mean that something, either through let or $env., will be able to foo | bar | baz not the string "foo" 🤔

[sholderbach]

This is basically #9698 rearing its head by returning nothing.

[sholderbach]

Closing in favor of #12956 as we collected more cases there.