unchecked error handling for empty or blocks used in string interpolation x := "${ f() or {} }"

[spytheman]

V doctor:

V full version: V 0.4.5 872bcbc.55cafa9
OS: linux, Ubuntu 20.04.6 LTS
Processor: 4 cpus, 64bit, little endian, Intel(R) Core(TM) i3-3225 CPU @ 3.30GHz

getwd: /space/v/oo
vexe: /space/v/oo/v
vexe mtime: 2024-04-03 14:54:06

vroot: OK, value: /space/v/oo
VMODULES: OK, value: /home/delian/.vmodules
VTMP: OK, value: /tmp/v_1000

Git version: git version 2.42.0
Git vroot status: weekly.2024.14-8-g55cafa9b-dirty
.git/config present: true

CC version: cc (Ubuntu 10.5.0-1ubuntu1~20.04) 10.5.0
thirdparty/tcc status: thirdparty-linux-amd64 40e5cbb5

What did you do?
v -g -o vdbg cmd/v && vdbg x.v

fn f() !string { return error('noo') }
value := 'value: "${f() or {}}" done'
println(value)

What did you expect to see?

a compiler error, similar to the one for assignment, requiring a non empty or block

What did you see instead?

value: "" done

Note that outside a string interpolation:

fn f() !string { return error('noo') }
value := f() or {}
println('value: "${value}"')

produces (as it should) an error:

x.v:2:14: error: assignment requires a non empty `or {}` block
    1 | fn f() !string { return error('noo') }
    2 | value := f() or {}
      |              ~~~~~
    3 | println('value: "${value}"')

The problem happens only inside string interpolations.

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[medvednikov]

I think to keep the language simple and readable, this simply should not be allowed.

[spytheman]

Yes, the checker should have caught it.

[felipensp]

This one is related to PR #17566

[Delta456]

Gives an error with the latest compilation of V.

file.v:2:25: error: assignment requires a non empty `or {}` block
    1 | fn f() !string { return error('noo') }
    2 | value := 'value: "${f() or {}}" done'
      |                         ~~~~~
    3 | println(value)