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Description
Issue description
When trying to pass a string option
value to a null-agnostic method taking string
using Option.toObj
, the input type gets inferred as string | null option
.
Choose one or more from the following categories of impact
- Unexpected nullness warning (false positive in nullness checking, code uses --checknulls and langversion:preview).
- Missing nullness warning in a case which can produce nulls (false negative, code uses --checknulls and langversion:preview).
- Breaking change related to older
null
constructs in code not using the checknulls switch. - Breaking change related to generic code and explicit type constraints (
null
,not null
). - Type inference issue (i.e. code worked without type annotations before, and applying the --checknulls enforces type annotations).
- C#/F# interop issue related to nullness metadata.
- Other (none of the categories above apply).
Operating System
Windows (Default)
What .NET runtime/SDK kind are you seeing the issue on
.NET SDK (.NET Core, .NET 5+)
.NET Runtime/SDK version
9.0.100-rc.1.24452.12
Reproducible code snippet and actual behavior
// assembly A, null-agnostic
let work (x: string) = ()
// assembly B, null-aware
let whatever x =
work (Option.toObj x)
The type of whatever
is inferred to be string | null option -> unit
, but string option -> unit
seems more reasonable.
Possible workarounds
let whatever (x: string option) =
work (Option.toObj x)
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