Better error message when using wrong anon record

src/Compiler/Checking/ConstraintSolver.fs

@@ -1099,7 +1099,12 @@ and SolveAnonInfoEqualsAnonInfo (csenv: ConstraintSolverEnv) m2 (anonInfo1: Anon
             | Overlap (missingFields, extraFields) ->
                 FSComp.SR.tcAnonRecdFieldNameMismatch(string missingFields, string extraFields)
             | CompletelyDifferent missingFields ->
-                FSComp.SR.tcAnonRecdFieldNameDifferent(string missingFields)
+                match missingFields with
+                | [missingField] ->
+                    FSComp.SR.tcAnonRecdSingleFieldNameDifferent(missingField)
+                | _ ->
+                    let missingFields = String.concat ", " missingFields
+                    FSComp.SR.tcAnonRecdMultipleFieldNameDifferent(missingFields)
 
         ErrorD (ConstraintSolverError(message, csenv.m,m2)) 
     else 

src/Compiler/FSComp.txt

@@ -1399,7 +1399,8 @@ tcAnonRecdSingleFieldNameSubset,"This anonymous record is missing field '%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."
+tcAnonRecdSingleFieldNameDifferent,"This anonymous record should have field '%s'."
+tcAnonRecdMultipleFieldNameDifferent,"This anonymous record should have 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."