Better error message for anon records with extra fields

src/Compiler/Checking/ConstraintSolver.fs

@@ -1090,7 +1090,12 @@ and SolveAnonInfoEqualsAnonInfo (csenv: ConstraintSolverEnv) m2 (anonInfo1: Anon
                     let missingFields = String.concat ", " missingFields
                     FSComp.SR.tcAnonRecdMultipleFieldsNameSubset(string missingFields)
             | Superset extraFields ->
-                FSComp.SR.tcAnonRecdFieldNameSuperset(string extraFields)
+                match extraFields with
+                | [extraField] ->
+                    FSComp.SR.tcAnonRecdSingleFieldNameSuperset(string extraField)
+                | _ ->
+                    let extraFields = String.concat ", " extraFields
+                    FSComp.SR.tcAnonRecdMultipleFieldsNameSuperset(string extraFields)
             | Overlap (missingFields, extraFields) ->
                 FSComp.SR.tcAnonRecdFieldNameMismatch(string missingFields, string extraFields)
             | CompletelyDifferent missingFields ->

src/Compiler/FSComp.txt

@@ -1397,7 +1397,8 @@ tcAnonRecdCcuMismatch,"Two anonymous record types are from different assemblies
 tcAnonRecdFieldNameMismatch,"This anonymous record does not exactly match the expected shape. Add the missing fields %s and remove the extra fields %s."
 tcAnonRecdSingleFieldNameSubset,"This anonymous record is missing field '%s'."
 tcAnonRecdMultipleFieldsNameSubset,"This anonymous record is missing fields '%s'."
-tcAnonRecdFieldNameSuperset,"This anonymous record has too many fields. Remove the extra fields %s."
+tcAnonRecdSingleFieldNameSuperset,"This anonymous record has an extra field. Remove field '%s'."
+tcAnonRecdMultipleFieldsNameSuperset,"This anonymous record has extra fields. Remove fields '%s'."
 tcAnonRecdFieldNameDifferent,"This is the wrong anonymous record. It should have the fields %s."
 keywordDescriptionAbstract,"Indicates a method that either has no implementation in the type in which it is declared or that is virtual and has a default implementation."
 keywordDescriptionAnd,"Used in mutually recursive bindings, in property declarations, and with multiple constraints on generic parameters."