cannot call function wrapped in a parexpr

[zeozeozeo]

V doctor:

V full version: V 0.4.8 5c65e58.a454f06
OS: windows, Microsoft Windows 10 Pro v19045 64-bit
Processor: 10 cpus, 64bit, little endian, 

getwd: C:\Users\user\Downloads
vexe: C:\Users\user\Desktop\Code\v\v.exe
vexe mtime: 2024-10-25 17:08:19

vroot: OK, value: C:\Users\user\Desktop\Code\v
VMODULES: OK, value: C:\Users\user\.vmodules
VTMP: OK, value: C:\Users\user\AppData\Local\Temp\v_0

Git version: git version 2.42.0.windows.1
Git vroot status: weekly.2024.41-127-ga454f064
.git/config present: true

CC version: Error: 'cc' is not recognized as an internal or external command,

operable program or batch file.


thirdparty/tcc status: thirdparty-windows-amd64 b425ac82

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

fn add(a int, b int) int {
	return a + b
}

fn main() {
	res := (add)(2, 4)
	println("2 + 4 = ${res}")
}

What did you expect to see?

2 + 4 = 6 printed to stdout or a better error message

What did you see instead?

test.v:6:16: error: unexpected token `,`, expecting `)`
    4 | 
    5 | fn main() {
    6 |     res := (add)(2, 4)
      |                   ^
    7 |     println("2 + 4 = ${res}")
    8 | }

Additional information

The following works, meaning that add can be used as an expression:

fn add(a int, b int) int {
    return a + b
}

fn main() {
    ptr := add
    res := ptr(2, 4)
    println("2 + 4 = ${res}")
}

As for other languages, this prints 2 + 4 = 6 in Go and in Rust:

package main

import "fmt"

func add(a, b int) int {
	return a + b
}

func main() {
	res := (add)(2, 4)
	fmt.Println("2 + 4 =", res)
}

fn add(a: i32, b: i32) -> i32 {
    return a + b;
}

fn main() {
    let res = (add)(2, 4);
    println!("2 + 4 = {res}");
}

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_{Huly®: V_0.6-21101}

[JalonSolov]

I am against this change. I see zero utility for something that can be confusing... is (add) supposed to mean to call add, or is it a cast, or is it something else?

Yes, I do know what it is meant to do, I simply don't know why the syntax should allow it... it just adds unnecessary complexity with no discernible benefit.

As far as other languages allowing it... V is not those other languages. It doesn't have to do what they do, with the same syntax.

The conclusion above, "The following works, meaning that add can be used as an expression:" is also incorrect. add is not being used as an expression in that example, the code is simply creating a function pointer and calling add through that pointer. That has nothing to do with an expression. It may appear as though it is being used as an expression, if you assume the syntax of other languages.

ptr := add in the example case is virtually the same as doing ptr := fn(a int, b int) int { return a + b } - an anonymous function pointer.

ptr := fn(a int, b int) int { return a + b }
res := ptr(2, 4)
println('2 + 4 = ${res}')

output is, as expected,

2 + 4 = 6

[Delta456]

I don't believe we need a better error message for this