Warn when record update expression changes all fields

src/Compiler/Checking/CheckExpressions.fs

@@ -6565,8 +6565,14 @@ and TcRecordConstruction (cenv: cenv) (overallTy: TType) env tpenv withExprInfoO
     let ns1 = NameSet.ofList (List.map fst fldsList)
     let ns2 = NameSet.ofList (List.map (fun x -> x.rfield_id.idText) fspecs)
 
-    if withExprInfoOpt.IsNone && not (Zset.subset ns2 ns1) then
-        error (MissingFields(Zset.elements (Zset.diff ns2 ns1), m))
+    match withExprInfoOpt with
+    | None ->
+        if not (Zset.subset ns2 ns1) then
+            error(MissingFields(Zset.elements (Zset.diff ns2 ns1), m))
+    | _ ->
+        if oldFldsList.IsEmpty then
+            let enabledByLangFeature = g.langVersion.SupportsFeature LanguageFeature.WarningWhenCopyAndUpdateRecordChangesAllFields
+            warning(ErrorEnabledWithLanguageFeature(FSComp.SR.tcCopyAndUpdateRecordChangesAllFields(fullDisplayTextOfTyconRef tcref), m, enabledByLangFeature))
 
     if not (Zset.subset ns1 ns2) then
         error (Error(FSComp.SR.tcExtraneousFieldsGivenValues(), m))

src/Compiler/Driver/CompilerDiagnostics.fs

@@ -128,6 +128,7 @@ type Exception with
         | LetRecEvaluatedOutOfOrder (_, _, _, m)
         | DiagnosticWithText (_, _, m)
         | DiagnosticWithSuggestions (_, _, m, _, _)
+        | DiagnosticEnabledWithLanguageFeature (_, _, m, _)
         | SyntaxError (_, m)
         | InternalError (_, m)
         | InterfaceNotRevealed (_, _, m)
@@ -330,6 +331,7 @@ type Exception with
         | WrappedError (e, _) -> e.DiagnosticNumber
         | DiagnosticWithText (n, _, _) -> n
         | DiagnosticWithSuggestions (n, _, _, _, _) -> n
+        | DiagnosticEnabledWithLanguageFeature (n, _, _, _) -> n
         | Failure _ -> 192
         | IllegalFileNameChar (fileName, invalidChar) -> fst (FSComp.SR.buildUnexpectedFileNameCharacter (fileName, string invalidChar))
 #if !NO_TYPEPROVIDERS
@@ -353,6 +355,7 @@ type PhasedDiagnostic with
         | DefensiveCopyWarning _ -> 5
 
         | DiagnosticWithText (n, _, _)
+        | DiagnosticEnabledWithLanguageFeature (n, _, _, _)
         | DiagnosticWithSuggestions (n, _, _, _, _) ->
             // 1178, tcNoComparisonNeeded1, "The struct, record or union type '%s' is not structurally comparable because the type parameter %s does not satisfy the 'comparison' constraint..."
             // 1178, tcNoComparisonNeeded2, "The struct, record or union type '%s' is not structurally comparable because the type '%s' does not satisfy the 'comparison' constraint...."
@@ -382,8 +385,11 @@ type PhasedDiagnostic with
         | 3395 -> false // tcImplicitConversionUsedForMethodArg - off by default
         | 3559 -> false // typrelNeverRefinedAwayFromTop - off by default
         | _ ->
-            (severity = FSharpDiagnosticSeverity.Info)
-            || (severity = FSharpDiagnosticSeverity.Warning && level >= x.WarningLevel)
+            match x.Exception with
+            | DiagnosticEnabledWithLanguageFeature (_, _, _, enabled) -> enabled
+            | _ ->
+                (severity = FSharpDiagnosticSeverity.Info)
+                || (severity = FSharpDiagnosticSeverity.Warning && level >= x.WarningLevel)
 
     /// Indicates if a diagnostic should be reported as an informational
     member x.ReportAsInfo(options, severity) =
@@ -1655,7 +1661,8 @@ type Exception with
 
             os.AppendString(NonUniqueInferredAbstractSlot4E().Format)
 
-        | DiagnosticWithText (_, s, _) -> os.AppendString s
+        | DiagnosticWithText (_, s, _)
+        | DiagnosticEnabledWithLanguageFeature (_, s, _, _) -> os.AppendString s
 
         | DiagnosticWithSuggestions (_, s, _, idText, suggestionF) ->
             os.AppendString(ConvertValLogicalNameToDisplayNameCore s)

src/Compiler/FSComp.txt

@@ -1561,6 +1561,7 @@ featureErrorForNonVirtualMembersOverrides,"Raises errors for non-virtual members
 featureWarningWhenInliningMethodImplNoInlineMarkedFunction,"Raises warnings when 'let inline ... =' is used together with [<MethodImpl(MethodImplOptions.NoInlining)>] attribute. Function is not getting inlined."
 featureArithmeticInLiterals,"Allow arithmetic and logical operations in literals"
 featureErrorReportingOnStaticClasses,"Error reporting on static classes"
+featureWarningWhenCopyAndUpdateRecordChangesAllFields,"Raises warnings when an copy-and-update record expression changes all fields of a record."
 3353,fsiInvalidDirective,"Invalid directive '#%s %s'"
 3354,tcNotAFunctionButIndexerNamedIndexingNotYetEnabled,"This value supports indexing, e.g. '%s.[index]'. The syntax '%s[index]' requires /langversion:preview. See https://aka.ms/fsharp-index-notation."
 3354,tcNotAFunctionButIndexerIndexingNotYetEnabled,"This expression supports indexing, e.g. 'expr.[index]'. The syntax 'expr[index]' requires /langversion:preview. See https://aka.ms/fsharp-index-notation."
@@ -1674,3 +1675,4 @@ featureEscapeBracesInFormattableString,"Escapes curly braces before calling Form
 3557,chkAbstractMembersDeclarationsOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Abstract member declarations are not allowed."
 3558,chkExplicitFieldsDeclarationsOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Explicit field declarations are not allowed."
 3559,typrelNeverRefinedAwayFromTop,"A type has been implicitly inferred as 'obj', which may be unintended. Consider adding explicit type annotations. You can disable this warning by using '#nowarn \"3559\"' or '--nowarn:3559'."
+3560,tcCopyAndUpdateRecordChangesAllFields,"This copy-and-update record expression changes all fields of record type '%s'. Consider using the record construction syntax instead."

src/Compiler/Facilities/DiagnosticsLogger.fs

@@ -113,6 +113,9 @@ exception DiagnosticWithSuggestions of number: int * message: string * range: ra
         | DiagnosticWithSuggestions (_, msg, _, _, _) -> msg
         | _ -> "impossible"
 
+/// A diagnostic that is raised when enabled manually, or by default with a language feature
+exception DiagnosticEnabledWithLanguageFeature of number: int * message: string * range: range * enabledByLangFeature: bool
+
 /// The F# compiler code currently uses 'Error(...)' in many places to create
 /// an DiagnosticWithText as an exception even if it's a warning.
 ///
@@ -126,6 +129,9 @@ let Error ((n, text), m) = DiagnosticWithText(n, text, m)
 let ErrorWithSuggestions ((n, message), m, id, suggestions) =
     DiagnosticWithSuggestions(n, message, m, id, suggestions)
 
+let ErrorEnabledWithLanguageFeature ((n, message), m, enabledByLangFeature) =
+    DiagnosticEnabledWithLanguageFeature (n, message, m, enabledByLangFeature)
+
 let inline protectAssemblyExploration dflt f =
     try
         f ()

src/Compiler/Facilities/DiagnosticsLogger.fsi

@@ -44,6 +44,13 @@ val StopProcessing<'T> : exn
 /// Represents a diagnostic exeption whose text comes via SR.*
 exception DiagnosticWithText of number: int * message: string * range: range
 
+/// A diagnostic that is raised when enabled manually, or by default with a language feature
+exception DiagnosticEnabledWithLanguageFeature of
+    number: int *
+    message: string *
+    range: range *
+    enabledByLangFeature: bool
+
 /// Creates a diagnostic exeption whose text comes via SR.*
 val Error: (int * string) * range -> exn
 
@@ -77,6 +84,9 @@ exception DiagnosticWithSuggestions of
 /// Creates a DiagnosticWithSuggestions whose text comes via SR.*
 val ErrorWithSuggestions: (int * string) * range * string * Suggestions -> exn
 
+/// Creates a DiagnosticEnabledWithLanguageFeature whose text comes via SR.*
+val ErrorEnabledWithLanguageFeature: (int * string) * range * bool -> exn
+
 val inline protectAssemblyExploration: dflt: 'T -> f: (unit -> 'T) -> 'T
 
 val inline protectAssemblyExplorationF: dflt: (string * string -> 'T) -> f: (unit -> 'T) -> 'T

src/Compiler/Facilities/LanguageFeatures.fs

@@ -61,6 +61,7 @@ type LanguageFeature =
     | EscapeDotnetFormattableStrings
     | ArithmeticInLiterals
     | ErrorReportingOnStaticClasses
+    | WarningWhenCopyAndUpdateRecordChangesAllFields
 
 /// LanguageVersion management
 type LanguageVersion(versionText) =
@@ -138,6 +139,7 @@ type LanguageVersion(versionText) =
                 LanguageFeature.EscapeDotnetFormattableStrings, previewVersion
                 LanguageFeature.ArithmeticInLiterals, previewVersion
                 LanguageFeature.ErrorReportingOnStaticClasses, previewVersion
+                LanguageFeature.WarningWhenCopyAndUpdateRecordChangesAllFields, previewVersion
 
             ]
 
@@ -252,6 +254,7 @@ type LanguageVersion(versionText) =
         | LanguageFeature.EscapeDotnetFormattableStrings -> FSComp.SR.featureEscapeBracesInFormattableString ()
         | LanguageFeature.ArithmeticInLiterals -> FSComp.SR.featureArithmeticInLiterals ()
         | LanguageFeature.ErrorReportingOnStaticClasses -> FSComp.SR.featureErrorReportingOnStaticClasses ()
+        | LanguageFeature.WarningWhenCopyAndUpdateRecordChangesAllFields -> FSComp.SR.featureWarningWhenCopyAndUpdateRecordChangesAllFields ()
 
     /// Get a version string associated with the given feature.
     static member GetFeatureVersionString feature =

src/Compiler/Facilities/LanguageFeatures.fsi

@@ -51,6 +51,7 @@ type LanguageFeature =
     | EscapeDotnetFormattableStrings
     | ArithmeticInLiterals
     | ErrorReportingOnStaticClasses
+    | WarningWhenCopyAndUpdateRecordChangesAllFields
 
 /// LanguageVersion management
 type LanguageVersion =

src/Compiler/TypedTree/TypedTreeOps.fs

@@ -5983,14 +5983,14 @@ and remapUnionCases ctxt tmenv (x: TyconUnionData) =
     x.UnionCasesAsList |> List.map (remapUnionCase ctxt tmenv) |> Construct.MakeUnionCases 
 
 and remapFsObjData ctxt tmenv x = 
-    { x with 
-          fsobjmodel_kind = 
-             (match x.fsobjmodel_kind with 
-              | TFSharpDelegate slotsig -> TFSharpDelegate (remapSlotSig (remapAttribs ctxt tmenv) tmenv slotsig)
-              | TFSharpClass | TFSharpInterface | TFSharpStruct | TFSharpEnum -> x.fsobjmodel_kind)
-          fsobjmodel_vslots = x.fsobjmodel_vslots |> List.map (remapValRef tmenv)
-          fsobjmodel_rfields = x.fsobjmodel_rfields |> remapRecdFields ctxt tmenv } 
-
+    { 
+        fsobjmodel_kind = 
+            match x.fsobjmodel_kind with 
+            | TFSharpDelegate slotsig -> TFSharpDelegate (remapSlotSig (remapAttribs ctxt tmenv) tmenv slotsig)
+            | TFSharpClass | TFSharpInterface | TFSharpStruct | TFSharpEnum -> x.fsobjmodel_kind
+        fsobjmodel_vslots = x.fsobjmodel_vslots |> List.map (remapValRef tmenv)
+        fsobjmodel_rfields = x.fsobjmodel_rfields |> remapRecdFields ctxt tmenv
+    } 
 
 and remapTyconRepr ctxt tmenv repr = 
     match repr with 

src/Compiler/xlf/FSComp.txt.cs.xlf

@@ -382,6 +382,11 @@
         <target state="translated">reprezentace struktury aktivních vzorů</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
+        <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
+        <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Vyvolá upozornění, když se použije „let inline ... =“ společně s atributem [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. Funkce není vkládána.</target>
@@ -872,6 +877,11 @@
         <target state="translated">Atributy nejde použít pro rozšíření typů.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcCopyAndUpdateRecordChangesAllFields">
+        <source>This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</source>
+        <target state="new">This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcHighPrecedenceFunctionApplicationToListDeprecated">
         <source>The syntax 'expr1[expr2]' is used for indexing. Consider adding a type annotation to enable indexing, or if calling a function add a space, e.g. 'expr1 [expr2]'.</source>
         <target state="translated">Syntaxe expr1[expr2] se používá pro indexování. Pokud chcete povolit indexování, zvažte možnost přidat anotaci typu, nebo pokud voláte funkci, přidejte mezeru, třeba expr1 [expr2].</target>

src/Compiler/xlf/FSComp.txt.de.xlf

@@ -382,6 +382,11 @@
         <target state="translated">Strukturdarstellung für aktive Muster</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
+        <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
+        <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Löst Warnungen aus, wenn „let inline ... =“ zusammen mit dem Attribut [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] verwendet wird. Die Funktion wird nicht inline gesetzt.</target>
@@ -872,6 +877,11 @@
         <target state="translated">Attribute können nicht auf Typerweiterungen angewendet werden.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcCopyAndUpdateRecordChangesAllFields">
+        <source>This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</source>
+        <target state="new">This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcHighPrecedenceFunctionApplicationToListDeprecated">
         <source>The syntax 'expr1[expr2]' is used for indexing. Consider adding a type annotation to enable indexing, or if calling a function add a space, e.g. 'expr1 [expr2]'.</source>
         <target state="translated">Die Syntax "expr1[expr2]" wird für die Indizierung verwendet. Fügen Sie ggf. eine Typanmerkung hinzu, um die Indizierung zu aktivieren, oder fügen Sie beim Aufrufen einer Funktion ein Leerzeichen hinzu, z. B. "expr1 [expr2]".</target>

src/Compiler/xlf/FSComp.txt.es.xlf

@@ -382,6 +382,11 @@
         <target state="translated">representación de struct para modelos activos</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
+        <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
+        <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Genera advertencias cuando se usa "let inline ... =" junto con el atributo [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. La función no se está insertando.</target>
@@ -872,6 +877,11 @@
         <target state="translated">Los atributos no se pueden aplicar a las extensiones de tipo.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcCopyAndUpdateRecordChangesAllFields">
+        <source>This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</source>
+        <target state="new">This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcHighPrecedenceFunctionApplicationToListDeprecated">
         <source>The syntax 'expr1[expr2]' is used for indexing. Consider adding a type annotation to enable indexing, or if calling a function add a space, e.g. 'expr1 [expr2]'.</source>
         <target state="translated">La sintaxis "expr1[expr2]" se usa para la indexación. Considere la posibilidad de agregar una anotación de tipo para habilitar la indexación, si se llama a una función, agregue un espacio, por ejemplo, "expr1 [expr2]".</target>

src/Compiler/xlf/FSComp.txt.fr.xlf

@@ -382,6 +382,11 @@
         <target state="translated">représentation de structure pour les modèles actifs</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
+        <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
+        <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Génère des avertissements lorsque « let inline ... = » est utilisé avec l’attribut [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. La fonction n’est pas inlined.</target>
@@ -872,6 +877,11 @@
         <target state="translated">Impossible d'appliquer des attributs aux extensions de type.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcCopyAndUpdateRecordChangesAllFields">
+        <source>This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</source>
+        <target state="new">This copy-and-update record expression changes all fields of record type '{0}'. Consider using the record construction syntax instead.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcHighPrecedenceFunctionApplicationToListDeprecated">
         <source>The syntax 'expr1[expr2]' is used for indexing. Consider adding a type annotation to enable indexing, or if calling a function add a space, e.g. 'expr1 [expr2]'.</source>
         <target state="translated">La syntaxe « expr1[expr2] » est utilisée pour l’indexation. Envisagez d’ajouter une annotation de type pour activer l’indexation, ou si vous appelez une fonction, ajoutez un espace, par exemple « expr1 [expr2] ».</target>