compiler panic: string.repeat: count is negative: -1

[pd-giz-dave]

Describe the bug

Compile this code:

module main

struct Blob {
	label int
}

// this breaks the compiler - comment it out and everything runs OK
// with it in get:
// V panic: string.repeat: count is negative: -1
// v hash: ac2dcc2
//                                                        | 0x561fbf1fa1a3 | /usr/lib/vlang/v(+0x1681a3)
//                                                        | 0x561fbf1fd7c3 | /usr/lib/vlang/v(+0x16b7c3)
//                                                        | 0x561fbf306e23 | /usr/lib/vlang/v(+0x274e23)
//                                                        | 0x561fbf2a0737 | /usr/lib/vlang/v(+0x20e737)
//                                                        | 0x561fbf2a3879 | /usr/lib/vlang/v(+0x211879)
//                                                        | 0x561fbf2a68b0 | /usr/lib/vlang/v(+0x2148b0)
//                                                        | 0x561fbf09571a | /usr/lib/vlang/v(+0x371a)
//                                                        | 0x7f83ce258cd0 | /usr/lib/libc.so.6(+0x27cd0)
//                                                        | 0x7f83ce258d8a | /usr/lib/libc.so.6(__libc_start_main+0x8a)
//                                                        | 0x561fbf095755 | /usr/lib/vlang/v(+0x3755)
// remove the mut and it works, put it in and get the error above
fn (mut b Blob) str() string {
	return ''
}

struct Labels {
	blobs map[int]Blob
}

fn break_it() Labels {
	mut a := Labels{}
	return a
}

fn main() {
	mut a := break_it()
	println(a)
}

Reproduction Steps

Just attempt to compile the above code

Expected Behavior

Compiles OK

Current Behavior

Compiler reports:

V panic: string.repeat: count is negative: -1
v hash: ac2dcc2
                                                        | 0x64f0576211a3 | /usr/lib/vlang/v(+0x1681a3) 
                                                        | 0x64f0576247c3 | /usr/lib/vlang/v(+0x16b7c3) 
                                                        | 0x64f05772de23 | /usr/lib/vlang/v(+0x274e23) 
                                                        | 0x64f0576c7737 | /usr/lib/vlang/v(+0x20e737) 
                                                        | 0x64f0576ca879 | /usr/lib/vlang/v(+0x211879) 
                                                        | 0x64f0576cd8b0 | /usr/lib/vlang/v(+0x2148b0) 
                                                        | 0x64f0574bc71a | /usr/lib/vlang/v(+0x371a) 
                                                        | 0x70499631dcd0 | /usr/lib/libc.so.6(+0x27cd0) 
                                                        | 0x70499631dd8a | /usr/lib/libc.so.6(__libc_start_main+0x8a) 
                                                        | 0x64f0574bc755 | /usr/lib/vlang/v(+0x3755) 

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.4 ac2dcc2

Environment details (OS name and version, etc.)

EndeavourOS

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[pd-giz-dave]

After doing a v up to "V 0.4.4 a374d25, timestamp: 2024-02-05 17:14:27 +0200" stack trace slightly more informative:

V panic: string.repeat: count is negative: -1
v hash: a374d25
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:21494: at _v_panic: Backtrace
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:25928: by string_repeat
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:29478: by v__gen__c__Gen_gen_str_for_map
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:28841: by v__gen__c__Gen_final_gen_str
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:30571: by v__gen__c__gen
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:53223: by v__builder__cbuilder__gen_c
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:53192: by v__builder__cbuilder__build_c
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:53182: by v__builder__cbuilder__compile_c
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:53088: by v__builder__Builder_rebuild
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:52193: by v__builder__compile
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:53523: by main__rebuild
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:53471: by main__main
/tmp/v_1000/v2.01HNWY079Z5K8D4Z9M7VDKMQ8R.tmp.c:54180: by main

[viniciusfdasilva]

To contribute with this issue, I executed several tests and managed to find a solution by passing & to reference Blob and successfully executed with mut in the str() function. The problem lies in using mut with the value of a map being of type Blob (struct) as in the code below:

module main

struct Blob {
	label int
}

// remove the mut and it works, put it in and get the error above
module main

struct Blob {
	label int
}

// remove the mut and it works, put it in and get the error above
fn (mut b Blob) str() string {
	return 'blob'
}

fn main() {

	// Works
	mut a1 := map[int]&Blob
	a1[1] = &Blob{label: 4}
	println('First execution ${a1}')


	// Not works
	//mut a2 := map[int]Blob
	//a2[1] = Blob{label: 4}
	//println('Second execution ${a2}')

	
}

[pd-giz-dave]

Thanks for your solution. But it would be nice if the compiler reported an error rather than panic.

…

On Tue, 6 Feb 2024 at 00:43, Vinicius Silva ***@***.***> wrote: To contribute with this issue, I executed several tests and managed to find a solution by passing & to reference Blob and successfully executed with mut in the str() function. The problem lies in using mut with the value of a map being of type Blob (struct) as in the code below: module main struct Blob { label int } // remove the mut and it works, put it in and get the error abovemodule main struct Blob { label int } // remove the mut and it works, put it in and get the error abovefn (mut b Blob) str() string { return 'blob' } fn main() { // Works mut a1 := map[int]&Blob a1[1] = &Blob{label: 4} println('First execution ${a1}') // Not works //mut a2 := map[int]Blob //a2[1] = Blob{label: 4} //println('Second execution ${a2}') } — Reply to this email directly, view it on GitHub <#20734 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AEEESAE56LCWQZVRKIQ22ETYSF4EJAVCNFSM6AAAAABC2I7AMOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSMRYGU3TEMJSGM> . You are receiving this because you authored the thread.Message ID: ***@***.***>