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Nullness issue - Error shows on incorrect symbol when using |> #18013

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isaacabraham opened this issue Nov 16, 2024 · 0 comments
Open
1 of 7 tasks

Nullness issue - Error shows on incorrect symbol when using |> #18013

isaacabraham opened this issue Nov 16, 2024 · 0 comments
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Area-Nullness Issues related to handling of Nullable Reference Types Bug Impact-Low (Internal MS Team use only) Describes an issue with limited impact on existing code.
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@isaacabraham
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Issue description

When using the |> operator on a partially applied function, the compiler will show a red squiggle on the RHS rather than the LHS.

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

No response

Reproducible code snippet and actual behavior

Wrong (current behaviour):

let foo a b = "hello" + a + b
let bar : string | null = "test"
let result = bar |> foo "mr" // red squiggly shows incorrectly on 'foo mr'

Possible workarounds

Don't use |>

let foo a b = "hello" + a + b
let bar : string | null = "test"
let result = foo "mr" bar // red squiggly shows correctly on 'bar`
@isaacabraham isaacabraham added Area-Nullness Issues related to handling of Nullable Reference Types Bug Needs-Triage labels Nov 16, 2024
@github-actions github-actions bot added this to the Backlog milestone Nov 16, 2024
@T-Gro T-Gro removed their assignment Nov 18, 2024
@abonie abonie added Impact-Low (Internal MS Team use only) Describes an issue with limited impact on existing code. and removed Needs-Triage labels Nov 25, 2024
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Labels
Area-Nullness Issues related to handling of Nullable Reference Types Bug Impact-Low (Internal MS Team use only) Describes an issue with limited impact on existing code.
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