Fixes enums.fromInt failing at compile time on in range but invalid values #30156

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alexrp merged 1 commit from MasonRemaley/zig:enum-from-int-fix into master 2025-12-22 14:19:20 +01:00

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MasonRemaley commented 2025-12-09 02:38:50 +01:00

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std.enums.fromInt converts an int to an enum, or returns null if the int is not a valid value for the given enum.

However, the current implementation has a bug that results in it emitting a compiler error if the integer is in range but still invalid. The bug is here:

    for (values(E)) |value| {
        if (@intFromEnum(value) == integer) return @enumFromInt(integer);
    }

It's not legal to call @enumFromInt here when integer is not a valid value for the enum. Although it's wrapped in a conditional, that conditional is evaluated at runtime, so it still gets rejected. The fix is to return the value directly since we have it anyway, no conversion needed:

    for (values(E)) |value| {
        if (@intFromEnum(value) == integer) return value;
    }

This likely wasn't caught until now because this code is only run for invalid but in range values.

This PR fixes the bug, and adds a test to cover it.

`std.enums.fromInt` converts an int to an enum, or returns `null` if the int is not a valid value for the given enum. However, the current implementation has a bug that results in it emitting a compiler error if the integer is in range but still invalid. The bug is here: ```zig for (values(E)) |value| { if (@intFromEnum(value) == integer) return @enumFromInt(integer); } ``` It's not legal to call `@enumFromInt` here when integer is not a valid value for the enum. Although it's wrapped in a conditional, that conditional is evaluated at runtime, so it still gets rejected. The fix is to return the value directly since we have it anyway, no conversion needed: ```zig for (values(E)) |value| { if (@intFromEnum(value) == integer) return value; } ``` This likely wasn't caught until now because this code is only run for invalid but in range values. This PR fixes the bug, and adds a test to cover it.

MasonRemaley added 1 commit 2025-12-09 02:38:53 +01:00

Fixes enums.fromInt failing at compile time on in range but invalid values 455714a941

MasonRemaley force-pushed enum-from-int-fix from 455714a941 to 8f629465d2 2025-12-12 22:57:44 +01:00 Compare

MasonRemaley force-pushed enum-from-int-fix from 8f629465d2 to 7c49c78e51 2025-12-18 06:12:35 +01:00 Compare

alexrp merged commit 3af842f0e8 into master 2025-12-22 14:19:20 +01:00

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