Better error message when using wrong anon record

src/Compiler/Checking/ConstraintSolver.fs

@@ -1078,7 +1078,9 @@ and SolveAnonInfoEqualsAnonInfo (csenv: ConstraintSolverEnv) m2 (anonInfo1: Anon
             elif Set.intersect first second <> Set.empty then
                 Overlap(firstOnly, secondOnly)
             else
-                CompletelyDifferent(Seq.toList first)
+                let first = Set.toList first
+                let second = Set.toList second
+                CompletelyDifferent(first, second)
 
         let message =
             match anonInfo1.SortedNames, anonInfo2.SortedNames with
@@ -1087,19 +1089,39 @@ and SolveAnonInfoEqualsAnonInfo (csenv: ConstraintSolverEnv) m2 (anonInfo1: Anon
                 | [missingField] ->
                     FSComp.SR.tcAnonRecdSingleFieldNameSubset(string missingField)
                 | _ ->
+                    let missingFields = missingFields |> List.map(sprintf "'%s'")
                     let missingFields = String.concat ", " missingFields
                     FSComp.SR.tcAnonRecdMultipleFieldsNameSubset(string missingFields)
             | Superset extraFields ->
                 match extraFields with
                 | [extraField] ->
                     FSComp.SR.tcAnonRecdSingleFieldNameSuperset(string extraField)
                 | _ ->
+                    let extraFields = extraFields |> List.map(sprintf "'%s'")
                     let extraFields = String.concat ", " extraFields
                     FSComp.SR.tcAnonRecdMultipleFieldsNameSuperset(string extraFields)
             | Overlap (missingFields, extraFields) ->
                 FSComp.SR.tcAnonRecdFieldNameMismatch(string missingFields, string extraFields)
             | CompletelyDifferent missingFields ->
-                FSComp.SR.tcAnonRecdFieldNameDifferent(string missingFields)
+                let missingFields, usedFields = missingFields
+                match missingFields, usedFields with
+                | [ missingField ], [ usedField ] ->
+                    FSComp.SR.tcAnonRecdSingleFieldNameSingleDifferent(missingField, usedField)
+                | [ missingField ], usedFields ->
+                    let usedFields = usedFields |> List.map(sprintf "'%s'")
+                    let usedFields = String.concat ", " usedFields
+                    FSComp.SR.tcAnonRecdSingleFieldNameMultipleDifferent(missingField, usedFields)
+                | missingFields, [ usedField ] ->
+                    let missingFields = missingFields |> List.map(sprintf "'%s'")
+                    let missingFields = String.concat ", " missingFields
+                    FSComp.SR.tcAnonRecdMultipleFieldNameSingleDifferent(missingFields, usedField)
+
+                | missingFields, usedFields ->
+                    let missingFields = missingFields |> List.map(sprintf "'%s'")
+                    let missingFields = String.concat ", " missingFields
+                    let usedFields = usedFields |> List.map(sprintf "'%s'")
+                    let usedFields = String.concat ", " usedFields
+                    FSComp.SR.tcAnonRecdMultipleFieldNameMultipleDifferent(missingFields, usedFields)
 
         ErrorD (ConstraintSolverError(message, csenv.m,m2)) 
     else 

src/Compiler/FSComp.txt

@@ -1396,10 +1396,13 @@ tcAnonRecdInvalid,"Invalid Anonymous Record type declaration."
 tcAnonRecdCcuMismatch,"Two anonymous record types are from different assemblies '%s' and '%s'"
 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'."
+tcAnonRecdMultipleFieldsNameSubset,"This anonymous record is missing 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."
+tcAnonRecdMultipleFieldsNameSuperset,"This anonymous record has extra fields. Remove fields %s."
+tcAnonRecdSingleFieldNameSingleDifferent,"This anonymous record should have field '%s' but here has field '%s'."
+tcAnonRecdSingleFieldNameMultipleDifferent,"This anonymous record should have field '%s' but here has fields %s."
+tcAnonRecdMultipleFieldNameSingleDifferent,"This anonymous record should have fields %s; but here has field '%s'."
+tcAnonRecdMultipleFieldNameMultipleDifferent,"This anonymous record should have fields %s; but here has 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."
 keywordDescriptionAs,"Used to give the current class object an object name. Also used to give a name to a whole pattern within a pattern match."