Playground @LOCATION and @FILE_LINE interpolation problems

[jorgeluismireles]

Describe the bug

When you println interpolated values @LOCATION or @FILE_LINE the compiler fails under two conditions:

• The values are the first thing to print
• Only in the playground

Reproduction Steps

Run in playground this https://play.vlang.io/p/1c01efec08 :

fn main() {
	ok()
	workaround()
	fail_1()
	fail_2()
}

fn ok() {
	println('${@VROOT}')
	println('${@VMODROOT}')
	println('${@VEXEROOT}')
	println('${@FN}')
	println('${@METHOD}')
	println('${@MOD}')
	println('${@STRUCT}')
	println('${@VEXE}')
	println('${@FILE}')
	println('${@LINE}')
	println('${@COLUMN}')
	println('${@VHASH}')
	println('${@VCURRENTHASH}')
	println('${@BUILD_DATE}')
	println('${@BUILD_TIME}')
	println('${@BUILD_TIMESTAMP}')
}

fn workaround() {
	println('X ${@LOCATION}')
	println('X ${@FILE_LINE}')
}

fn fail_1() {
	println('${@LOCATION}')
}

fn fail_2() {
	println('${@FILE_LINE}')
}

Explanation

• ok function works ok for all the variables within starting in every interpolation.
• workaround function works because I started with an X before @LOCATION and @FILE_LINE, only this way worked.
• fail_1 and fail_2 functions fail, anyone.

Expected Behavior

Some boring list with values (all the recommended by the compiler...)

Current Behavior

OK (0.298 sec real, 0.298 sec wall)
Can't run code. t[3] is undefined
Please try again.

Possible Solution

Workaround is to comment both fail_1 and fail_2 calls in main, even is not necessary to comment the functions.

fn main() {
	ok()
	workaround()
	//fail_1()
	//fail_2()
}

Or in other words, do what workaround function don't start the print interpolation with the values.

Additional Information/Context

Found while inspecting this issue: #23550

V version

V 0.4.9 6b0c272

Environment details (OS name and version, etc.)

Playground only.

For me only failed in playground. I ran the code in ubuntu and worked for gcc, clang and tcc so maybe the problem is specific to the plaground platform.

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[huly-for-github]

Connected to Huly®: V_0.6-21982

[spytheman]

That is a problem with the JS frontend of the playground, not a compiler one:
The compiler and the program ran successfully, but later, the returned response failed to be processed:

[spytheman]

A simpler reproduction is with just:
println('code.v:2')

which also causes:

[spytheman]

I think that the JS frontend of the playground treats code.v: at the start of a line, as a pattern for errors, and tries to retrieve the error value after that, which fails, because the line ends.

[spytheman]

@LOCATION and @FILE_LINE are involved only indirectly, because they also produce code.v: (the name of the file on the playground, that is compiled on each click of the Run button).

[jorgeluismireles]

println('code.v:2')

At least as println('code.v:') fails, though dump('code.v:') works.