Add warning when compiler selects among multiple record type candidates, fslang-suggestion 1091 (#15256)

Author: dawedawe

src/Compiler/Checking/NameResolution.fs

@@ -2726,6 +2726,36 @@ let rec ResolveLongIdentInTypePrim (ncenv: NameResolver) nenv lookupKind (resInf
 
         let errorTextF s =
             match tryTcrefOfAppTy g ty with
+            | ValueSome tcref when tcref.IsRecordTycon ->
+                let alternative = nenv.eFieldLabels |> Map.tryFind nm
+                match alternative with
+                | Some fieldLabels ->
+                    let fieldsOfResolvedType = tcref.AllFieldsArray  |> Array.map (fun f -> f.LogicalName) |> Set.ofArray
+                    let fieldsOfAlternatives =
+                        fieldLabels
+                        |> Seq.collect (fun l -> l.Tycon.AllFieldsArray |> Array.map (fun f -> f.LogicalName))
+                        |> Set.ofSeq
+                    let intersect = Set.intersect fieldsOfAlternatives fieldsOfResolvedType
+
+                    if not intersect.IsEmpty then
+                        let resolvedTypeName = NicePrint.fqnOfEntityRef g tcref
+                        let namesOfAlternatives =
+                            fieldLabels
+                            |> List.map (fun l -> $"    %s{NicePrint.fqnOfEntityRef g l.TyconRef}")
+                            |> fun names -> $"    %s{resolvedTypeName}" :: names
+                        let candidates = System.String.Join("\n", namesOfAlternatives)
+                        let overlappingNames =
+                            intersect
+                            |> Set.toArray
+                            |> Array.sort
+                            |> Array.map (fun s -> $"    %s{s}")
+                            |> fun a -> System.String.Join("\n", a)
+                        if g.langVersion.SupportsFeature(LanguageFeature.WarningWhenMultipleRecdTypeChoice) then
+                            warning(Error(FSComp.SR.tcMultipleRecdTypeChoice(candidates, resolvedTypeName, overlappingNames), m))
+                        else
+                            informationalWarning(Error(FSComp.SR.tcMultipleRecdTypeChoice(candidates, resolvedTypeName, overlappingNames), m))
+                | _ -> ()
+                FSComp.SR.undefinedNameFieldConstructorOrMemberWhenTypeIsKnown(tcref.DisplayNameWithStaticParametersAndUnderscoreTypars, s)
             | ValueSome tcref ->
                 FSComp.SR.undefinedNameFieldConstructorOrMemberWhenTypeIsKnown(tcref.DisplayNameWithStaticParametersAndUnderscoreTypars, s)
             | _ ->

src/Compiler/Checking/NicePrint.fs

@@ -2615,6 +2615,8 @@ let stringOfFSAttrib denv x = x |> PrintTypes.layoutAttrib denv |> squareAngleL
 
 let stringOfILAttrib denv x = x |> PrintTypes.layoutILAttrib denv |> squareAngleL |> showL
 
+let fqnOfEntityRef g x = x |> layoutTyconRefImpl false (DisplayEnv.Empty g) |> showL
+
 let layoutImpliedSignatureOfModuleOrNamespace showHeader denv infoReader ad m contents =
     InferredSigPrinting.layoutImpliedSignatureOfModuleOrNamespace showHeader denv infoReader ad m contents 
 

src/Compiler/Checking/NicePrint.fsi

@@ -135,6 +135,8 @@ val stringOfFSAttrib: denv: DisplayEnv -> x: Attrib -> string
 
 val stringOfILAttrib: denv: DisplayEnv -> ILType * ILAttribElem list -> string
 
+val fqnOfEntityRef: g: TcGlobals -> x: EntityRef -> string
+
 val layoutImpliedSignatureOfModuleOrNamespace:
     showHeader: bool ->
     denv: DisplayEnv ->

src/Compiler/FSComp.txt

@@ -1572,6 +1572,7 @@ featureStaticMembersInInterfaces,"Static members in interfaces"
 featureNonInlineLiteralsAsPrintfFormat,"String values marked as literals and IL constants as printf format"
 featureNestedCopyAndUpdate,"Nested record field copy-and-update"
 featureExtendedStringInterpolation,"Extended string interpolation similar to C# raw string literals."
+featureWarningWhenMultipleRecdTypeChoice,"Raises warnings when multiple record type matches were found during name resolution because of overlapping field names."
 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."
@@ -1692,3 +1693,4 @@ featureEscapeBracesInFormattableString,"Escapes curly braces before calling Form
 3563,lexInvalidIdentifier,"This is not a valid identifier"
 3564,parsMissingUnionCaseName,"Missing union case name"
 3565,parsExpectingType,"Expecting type"
+3566,tcMultipleRecdTypeChoice,"Multiple type matches were found:\n%s\nThe type '%s' was used. Due to the overlapping field names\n%s\nconsider using type annotations or change the order of open statements."

src/Compiler/Facilities/LanguageFeatures.fs

@@ -67,6 +67,7 @@ type LanguageFeature =
     | NonInlineLiteralsAsPrintfFormat
     | NestedCopyAndUpdate
     | ExtendedStringInterpolation
+    | WarningWhenMultipleRecdTypeChoice
 
 /// LanguageVersion management
 type LanguageVersion(versionText) =
@@ -157,6 +158,7 @@ type LanguageVersion(versionText) =
                 LanguageFeature.NonInlineLiteralsAsPrintfFormat, previewVersion
                 LanguageFeature.NestedCopyAndUpdate, previewVersion
                 LanguageFeature.ExtendedStringInterpolation, previewVersion
+                LanguageFeature.WarningWhenMultipleRecdTypeChoice, previewVersion
 
             ]
 
@@ -279,6 +281,7 @@ type LanguageVersion(versionText) =
         | LanguageFeature.NonInlineLiteralsAsPrintfFormat -> FSComp.SR.featureNonInlineLiteralsAsPrintfFormat ()
         | LanguageFeature.NestedCopyAndUpdate -> FSComp.SR.featureNestedCopyAndUpdate ()
         | LanguageFeature.ExtendedStringInterpolation -> FSComp.SR.featureExtendedStringInterpolation ()
+        | LanguageFeature.WarningWhenMultipleRecdTypeChoice -> FSComp.SR.featureWarningWhenMultipleRecdTypeChoice ()
 
     /// Get a version string associated with the given feature.
     static member GetFeatureVersionString feature =

src/Compiler/Facilities/LanguageFeatures.fsi

@@ -57,6 +57,7 @@ type LanguageFeature =
     | NonInlineLiteralsAsPrintfFormat
     | NestedCopyAndUpdate
     | ExtendedStringInterpolation
+    | WarningWhenMultipleRecdTypeChoice
 
 /// LanguageVersion management
 type LanguageVersion =

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

@@ -422,6 +422,11 @@
         <target state="translated">Vyvolá upozornění, když se použije „let inline ... =“ společně s atributem [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. Funkce není vkládána.</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenMultipleRecdTypeChoice">
+        <source>Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</source>
+        <target state="new">Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWildCardInForLoop">
         <source>wild card in for loop</source>
         <target state="translated">zástupný znak ve smyčce for</target>
@@ -1077,6 +1082,11 @@
         <target state="translated">Je třeba inicializovat následující požadované vlastnosti:{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcMultipleRecdTypeChoice">
+        <source>Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</source>
+        <target state="new">Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcNoEagerConstraintApplicationAttribute">
         <source>Using methods with 'NoEagerConstraintApplicationAttribute' requires /langversion:6.0 or later</source>
         <target state="translated">Použití metod s atributem NoEagerConstraintApplicationAttribute vyžaduje /langversion:6.0 nebo novější.</target>

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

@@ -422,6 +422,11 @@
         <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>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenMultipleRecdTypeChoice">
+        <source>Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</source>
+        <target state="new">Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWildCardInForLoop">
         <source>wild card in for loop</source>
         <target state="translated">Platzhalter in for-Schleife</target>
@@ -1077,6 +1082,11 @@
         <target state="translated">Die folgenden erforderlichen Eigenschaften müssen initialisiert werden:{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcMultipleRecdTypeChoice">
+        <source>Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</source>
+        <target state="new">Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcNoEagerConstraintApplicationAttribute">
         <source>Using methods with 'NoEagerConstraintApplicationAttribute' requires /langversion:6.0 or later</source>
         <target state="translated">Die Verwendung von Methoden mit "NoEagerConstraintApplicationAttribute" erfordert /langversion:6.0 oder höher.</target>

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

@@ -422,6 +422,11 @@
         <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>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenMultipleRecdTypeChoice">
+        <source>Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</source>
+        <target state="new">Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWildCardInForLoop">
         <source>wild card in for loop</source>
         <target state="translated">carácter comodín en bucle for</target>
@@ -1077,6 +1082,11 @@
         <target state="translated">Se deben inicializar las siguientes propiedades necesarias:{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcMultipleRecdTypeChoice">
+        <source>Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</source>
+        <target state="new">Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcNoEagerConstraintApplicationAttribute">
         <source>Using methods with 'NoEagerConstraintApplicationAttribute' requires /langversion:6.0 or later</source>
         <target state="translated">El uso de métodos con "NoEagerConstraintApplicationAttribute" requiere /langversion:6.0 o posteriores</target>

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

@@ -422,6 +422,11 @@
         <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>
         <note />
       </trans-unit>
+      <trans-unit id="featureWarningWhenMultipleRecdTypeChoice">
+        <source>Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</source>
+        <target state="new">Raises warnings when multiple record type matches were found during name resolution because of overlapping field names.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureWildCardInForLoop">
         <source>wild card in for loop</source>
         <target state="translated">caractère générique dans une boucle for</target>
@@ -1077,6 +1082,11 @@
         <target state="translated">Les propriétés requises suivantes doivent être initialisées :{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcMultipleRecdTypeChoice">
+        <source>Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</source>
+        <target state="new">Multiple type matches were found:\n{0}\nThe type '{1}' was used. Due to the overlapping field names\n{2}\nconsider using type annotations or change the order of open statements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcNoEagerConstraintApplicationAttribute">
         <source>Using methods with 'NoEagerConstraintApplicationAttribute' requires /langversion:6.0 or later</source>
         <target state="translated">L’utilisation de méthodes avec « NoEagerConstraintApplicationAttribute » requiert/langversion:6.0 ou ultérieur</target>