match: C error with explicit enum values

[caseman]

Describe the bug

If you explicitly reference enum values as match cases you will get a C error error: duplicate case value once you exceed 4 cases with an else or you will receive error: match must be exhaustive without an else even if your cases are exhaustive.

Note this works properly if you use the shortcut .enum_value notation, but I didn't realize that existed until I ran into this.

Reproduction Steps

pub enum TokenType {
	null
	word
	get_word
	set_word
	lit_word
	int_value
	dec_value
	bin_value
	str_value
	block_start
	block_end
	expr_start
	expr_end
	comment
}

t := TokenType.word
s := match t {
	(TokenType.null) { "" }
	(TokenType.word) { "a" }
	(TokenType.get_word) { "b" }
	(TokenType.set_word) { "c" }
	(TokenType.lit_word) { "d" }
	else { "other" }
}
println(s)

Expected Behavior

Should simply print "a", and it will if you remove the case (TokenType.lit_word) { "d" }

Current Behavior

On V playground:

Running code...
Can't run code. The server returned an error:
/box/code.v:27: error: duplicate case value
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .
Exited with error status 1
Please try again.

Possible Solution

These examples work properly:

t := TokenType.word
s := match t {
	(TokenType.null) { "" }
	(TokenType.word) { "a" }
	(TokenType.get_word) { "b" }
	(TokenType.set_word) { "c" }
	else { "other" }
}
println(s)

t := TokenType.word
s := match t {
	.null { "" }
	.word { "a" }
	.get_word { "b" }
	.set_word { "c" }
	.lit_word { "d" }
	else { "other" }
}
println(s)

Additional Information/Context

V version

0.4.12

Environment details (OS name and version, etc.)

|V full version      |V 0.4.12 55436caa9ae9c179639a4b238fc358ee7d768645
|:-------------------|:-------------------
|OS                  |windows, Microsoft Windows 11 Pro 26200 64-bit
|Processor           |28 cpus, 64bit, little endian, 13th Gen Intel(R) Core(TM) i7-13850HX
|Memory              |16.39GB/31.61GB
|                    |
|V executable        |C:\Program Files\v_windows\v\v.exe
|V last modified time|2025-12-06 21:31:43
|                    |
|V home dir          |contains spaces, value: C:\Program Files\v_windows\v
|VMODULES            |contains spaces, value: C:\Users\Casey Duncan\.vmodules
|VTMP                |contains spaces, value: C:\Users\Casey Duncan\AppData\Local\Temp\v_0
|Current working dir |contains spaces, value: C:\Users\Casey Duncan\projects\vebol
|                    |
|Git version         |git version 2.52.0.windows.1
|V git status        |N/A
|.git/config present |false
|                    |
|cc version          |N/A
|gcc version         |N/A
|clang version       |N/A
|msvc version        |N/A
|tcc version         |tcc version 0.9.27 (x86_64 Windows)
|tcc git status      |N/A
|emcc version        |N/A
|glibc version       |ldd (cygwin) 3.6.5

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[kbkpbot]

And I think, the checker should issue an error message about extra prefix for enum type usage. Or we need to fix parser to support such syntax.

[JalonSolov]

The reason it doesn't expect it now is because it already knows the type of the variable, so there is no need to keep re-typing the prefix.

However, the error: duplicate case value does need to be fixed.

[spytheman]

Very good find, thank you @caseman .