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Merged
T-Gro merged 3 commits into from
Aug 13, 2026
+17 −9
Merged

Teach compiler driver to ignore unknown warning codes #20246

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2ebbb1b
Initial plan
Copilot Aug 11, 2026
25eb4d7
Ignore unknown warning diagnostic identifiers
Copilot Aug 11, 2026
4c967be
Add release note for warning code handling
baronfel Aug 11, 2026
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1 change: 1 addition & 0 deletions docs/release-notes/.FSharp.Compiler.Service/11.0.100.md
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Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,7 @@
* Direct delegate construction ([PR ##19993](https://github.com/dotnet/fsharp/pull/19993))

### Changed
* The `--warnaserror` option now ignores unrecognized diagnostic identifiers in warning lists while still applying recognized F# warning codes. ([PR #20246](https://github.com/dotnet/fsharp/pull/20246))

* Improvements in error and warning messages: new error FS3885 when `let!`/`use!` is the final expression in a computation expression; new warning FS3886 when a list literal contains a single tuple element (likely missing `;` separator); improved wording for FS0003, FS0025, FS0039, FS0072, FS0247, FS0597, FS0670, FS3082, and SRTP operator-not-in-scope hints. ([PR #19398](https://github.com/dotnet/fsharp/pull/19398))
* Exception field serialization (`GetObjectData` and field-restoring constructor) is now gated behind `langversion:11` (`LanguageFeature.ExceptionFieldSerializationSupport`). With langversion ≤10, exception codegen is unchanged from pre-#19342 behavior. ([PR #19746](https://github.com/dotnet/fsharp/pull/19746))
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17 changes: 8 additions & 9 deletions src/Compiler/Driver/CompilerOptions.fs
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Expand Up @@ -791,14 +791,6 @@ let inputFileFlagsFsi (tcConfigB: TcConfigBuilder) =
//---------------------------------

let errorsAndWarningsFlags (tcConfigB: TcConfigBuilder) =
let trimFS (s: string) =
if s.StartsWithOrdinal "FS" then s.Substring 2 else s

let trimFStoInt (s: string) =
match Int32.TryParse(trimFS s) with
| true, n -> Some n
| false, _ -> None

[
CompilerOption(
"warnaserror",
Expand All @@ -816,7 +808,14 @@ let errorsAndWarningsFlags (tcConfigB: TcConfigBuilder) =
"warnaserror",
tagWarnList,
OptionStringListSwitch(fun n switch ->
match trimFStoInt n with
match
GetWarningNumber(
rangeCmdArgs,
WarningDescription.String n,
tcConfigB.langVersion,
WarningNumberSource.CommandLineOption
)
with
| Some n ->
let options = tcConfigB.diagnosticsOptions

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8 changes: 8 additions & 0 deletions tests/FSharp.Compiler.ComponentTests/CompilerDirectives/NonStringArgs.fs
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Expand Up @@ -143,6 +143,14 @@ match None with None -> () // creates FS0025 - ignored due to flag
(Warning 988, Line 3, Col 3, Line 3, Col 3, "Main module of program is empty: nothing will happen when it is run")
]

[<Fact>]
let ``--warnaserror ignores unknown diagnostic identifiers`` () =
FSharp """ "" """
|> withOptions ["--warnaserror:NU1605;FS20"]
|> typecheck
|> shouldFail
|> withErrorCode 20


[<InlineData("8.0")>]
[<InlineData("9.0")>]
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