Reserve an error message for "obj was inferred"

src/Compiler/Driver/CompilerDiagnostics.fs

@@ -380,6 +380,7 @@ type PhasedDiagnostic with
         | 3389 -> false // tcBuiltInImplicitConversionUsed - off by default
         | 3390 -> false // xmlDocBadlyFormed - off by default
         | 3395 -> false // tcImplicitConversionUsedForMethodArg - off by default
+        | 3559 -> false // typrelNeverRefinedAwayFromTop - off by default
         | _ ->
             (severity = FSharpDiagnosticSeverity.Info)
             || (severity = FSharpDiagnosticSeverity.Warning && level >= x.WarningLevel)

src/Compiler/FSComp.txt

@@ -1672,4 +1672,5 @@ featureEscapeBracesInFormattableString,"Escapes curly braces before calling Form
 3555,chkInstanceLetBindingOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Instance let bindings are not allowed."
 3556,chkImplementingInterfacesOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Implementing interfaces is not allowed."
 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."
+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'."

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

@@ -1137,6 +1137,11 @@
         <target state="translated">Rozhraní {0} nemůžete implementovat se dvěma instancemi {1} a {2}, protože by se mohly sjednotit.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">Typ {0} nedefinuje pole, konstruktor ani člen {1}.</target>

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

@@ -1137,6 +1137,11 @@
         <target state="translated">Sie können die Schnittstelle "{0}" mit den beiden Instanziierungen "{1}" und "{2}" nicht implementieren, weil sie möglicherweise zusammengeführt werden.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">Der Typ "{0}" definiert nicht das Feld, den Konstruktor oder den Member "{1}".</target>

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

@@ -1137,6 +1137,11 @@
         <target state="translated">No se puede implementar la interfaz "{0}" con ambas creaciones de instancias, "{1}" y "{2}", porque pueden unificarse.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">El tipo "{0}" no define el campo, constructor o miembro "{1}".</target>

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

@@ -1137,6 +1137,11 @@
         <target state="translated">Vous ne pouvez pas implémenter l'interface '{0}' avec les deux instanciations '{1}' et '{2}', car elles peuvent s'unifier.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">Le type '{0}' ne définit pas le champ, le constructeur ou le membre '{1}'.</target>

src/Compiler/xlf/FSComp.txt.it.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">Non è possibile implementare l'interfaccia '{0}' con le due creazioni di istanze '{1}' e '{2}' perché possono essere unificate.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">Il tipo '{0}' non definisce il campo, il costruttore o il membro '{1}'.</target>

src/Compiler/xlf/FSComp.txt.ja.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">統合している可能性があるため、'{1}' と '{2}' の 2 つのインスタンス化を含むインターフェイス '{0}' を実装することはできません。</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">型 '{0}' は、フィールド、コンストラクター、またはメンバー '{1}' を定義していません。</target>

src/Compiler/xlf/FSComp.txt.ko.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">'{1}' 및 '{2}' 인스턴스화가 포함된 '{0}' 인터페이스를 구현할 수 없습니다. 이 두 인스턴스화가 통합될 수 있기 때문입니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">'{0}' 형식은 '{1}' 필드, 생성자 또는 멤버를 정의하지 않습니다.</target>

src/Compiler/xlf/FSComp.txt.pl.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">Nie możesz zaimplementować interfejsu „{0}” przy użyciu dwóch wystąpień „{1}” i „{2}”, ponieważ mogą one się ujednolicić.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">Typ „{0}” nie definiuje pola, konstruktora lub składowej „{1}”.</target>

src/Compiler/xlf/FSComp.txt.pt-BR.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">Não é possível implementar a interface '{0}' com as duas instanciações '{1}' e '{2}' porque talvez elas sejam unificadas.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">O tipo '{0}' não define o campo, o construtor ou o membro '{1}'.</target>

src/Compiler/xlf/FSComp.txt.ru.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">Невозможно реализовать интерфейс "{0}" с двумя созданиями экземпляра "{1}" и "{2}", так как они могут быть объединены.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">Тип "{0}" не определяет поле, конструктор или член "{1}".</target>

src/Compiler/xlf/FSComp.txt.tr.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">'{1}' ve '{2}' örnek oluşturmaları birleşebileceğinden '{0}' arabirimini bunlarla birlikte uygulayamazsınız.</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">'{0}' türü; alanı, oluşturucuyu veya '{1}' üyesini tanımlamıyor.</target>

src/Compiler/xlf/FSComp.txt.zh-Hans.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">你无法实现具有两个实例化“{1}”和“{2}”的接口“{0}”，因为它们可能会统一。</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">类型“{0}”未定义字段、构造函数或成员“{1}”。</target>

src/Compiler/xlf/FSComp.txt.zh-Hant.xlf

@@ -1137,6 +1137,11 @@
         <target state="translated">因為 '{1}' 和 '{2}' 兩者的具現化可能整合，所以無法將其用於實作介面 '{0}'。</target>
         <note />
       </trans-unit>
+      <trans-unit id="typrelNeverRefinedAwayFromTop">
+        <source>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'.</source>
+        <target state="new">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'.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="undefinedNameFieldConstructorOrMemberWhenTypeIsKnown">
         <source>The type '{0}' does not define the field, constructor or member '{1}'.</source>
         <target state="translated">類型 '{0}' 未定義欄位、建構函式或成員 '{1}'。</target>

tests/FSharp.Test.Utilities/Compiler.fs

@@ -397,14 +397,14 @@ module rec Compiler =
 
     let withLangVersionPreview (cUnit: CompilationUnit) : CompilationUnit =
         withOptionsHelper [ "--langversion:preview" ] "withLangVersionPreview is only supported on F#" cUnit
-        
+
     let withLangVersion (version: string) (cUnit: CompilationUnit) : CompilationUnit =
         withOptionsHelper [ $"--langversion:{version}" ] "withLangVersion is only supported on F#" cUnit
 
     let withAssemblyVersion (version:string) (cUnit: CompilationUnit) : CompilationUnit =
         withOptionsHelper [ $"--version:{version}" ] "withAssemblyVersion is only supported on F#" cUnit
 
-    let withWarnOn  (cUnit: CompilationUnit) warning : CompilationUnit =
+    let withWarnOn (warning : int) (cUnit: CompilationUnit) : CompilationUnit =
         withOptionsHelper [ $"--warnon:{warning}" ] "withWarnOn is only supported for F#" cUnit
 
     let withNoWarn warning (cUnit: CompilationUnit) : CompilationUnit =
@@ -1088,7 +1088,7 @@ module rec Compiler =
                     failwith $"PDB file does not exists: {pdbPath}"
             | _ -> failwith "Output path is not set, please make sure compilation was successfull."
         match result with
-        | CompilationResult.Success r -> verifyPdbExists r 
+        | CompilationResult.Success r -> verifyPdbExists r
         | _ -> failwith "Result should be \"Success\" in order to verify PDB."
 
     let verifyNoPdb (result: CompilationResult): unit =
@@ -1100,7 +1100,7 @@ module rec Compiler =
                     failwith $"PDB file exists: {pdbPath}"
             | _ -> failwith "Output path is not set, please make sure compilation was successfull."
         match result with
-        | CompilationResult.Success r -> verifyPdbNotExists r 
+        | CompilationResult.Success r -> verifyPdbNotExists r
         | _ -> failwith "Result should be \"Success\" in order to verify PDB."
 
     [<AutoOpen>]
@@ -1369,6 +1369,6 @@ module rec Compiler =
             s.Replace("\r", "").Split('\n')
             |> Array.map (fun line -> line.TrimEnd())
             |> String.concat "\n"
-    
+
     let printSignatures cUnit = printSignaturesImpl None cUnit
     let printSignaturesWith pageWidth cUnit = printSignaturesImpl (Some pageWidth) cUnit