c# - Check if IPropertySymbol has a backing field -

i started playing roslyn few days ago , trying write extension method tells if ipropertysymbol has backing field, thought property has backing field if , if following not apply(as far concerned):

• if abstract
• if extern
• if readonlyproperty
• if getter or setter has no body or empty body

so came with

public static bool hasbackingfield(this ipropertysymbol property)         {             return !(property.isabstract || property.isextern || property.isreadonly);         } 

my questions are

• did miss condition?
• how check last condition? found getmethod , setmethodproperties in ipropertysymbol don't know check if have body

example start with

                var code =                  @"class xyz                    {                       public int x => 4;                                  //hasbacking field : false isreadonly                        public int m { { return 0;}}                    //hasbacking field : false isreadonly                             public int y { get; set; }                          //hasbacking field : false null body setter or getter                        public int z { { return 0; } set { } }          //hasbacking field : false empty body setter or getter                        private int _g;                       public int g                                        //hasbacking field : true getter , setter has no empty bodies                        {                            { return _g; }                            set { _g = value; }                        }                   }";              var syntaxtree = csharpsyntaxtree.parsetext(code);             var compilation = csharpcompilation.create("xxx").addsyntaxtrees(syntaxtree);             var classsymbol = compilation.gettypebymetadataname("xyz");             var propsymbols = classsymbol.getmembers().oftype<ipropertysymbol>();             var results = propsymbols.select(ps => ps.hasbackingfield()); //should [false false false false true] 

i decided @ syntax representation rather actual symbol -- syntax @ lower level symbol , contains raw information we're interested in: looking @ individual statements.

this seems you're interested in:

internal static bool hasbackingfield(this propertydeclarationsyntax property) {     var getter = property.accessorlist?.accessors.firstordefault(x => x.iskind(syntaxkind.getaccessordeclaration));     var setter = property.accessorlist?.accessors.firstordefault(x => x.iskind(syntaxkind.setaccessordeclaration));      if (setter?.body == null || getter?.body == null)     {         return false;     }      bool setterhasbodystatements = setter.body.statements.any();     bool getterhasbodystatements = getter.body.statements.any();      return setterhasbodystatements && getterhasbodystatements; } 

note i'm not convinced reliable enough conclude there backing field available, follows idea had checking if there body or not.

i haven't added other checks had in mind these can trivially added (either use symbol or through propertydeclarationsyntax modifiers/attributes).

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full code test out yourself:

public static void execute() {     var code = @"class xyz {   public int x => 4;                                  //hasbacking field : false isreadonly    public int m { { return 0;}}                    //hasbacking field : false isreadonly         public int y { get; set; }                          //hasbacking field : false null body setter or getter    public int z { { return 0; } set { } }          //hasbacking field : false empty body setter or getter    private int _g;   public int g                                        //hasbacking field : true getter , setter has no empty bodies    {        { return _g; }        set { _g = value; }    } }";      var tree = csharpsyntaxtree.parsetext(code);     var root = tree.getroot();      foreach (var prop in root.descendantnodes().oftype<propertydeclarationsyntax>())     {         console.writeline(prop.hasbackingfield());     } }     }  internal static class extensions {     internal static bool hasbackingfield(this propertydeclarationsyntax property)     {         var getter = property.accessorlist?.accessors.firstordefault(x => x.iskind(syntaxkind.getaccessordeclaration));         var setter = property.accessorlist?.accessors.firstordefault(x => x.iskind(syntaxkind.setaccessordeclaration));          if (setter?.body == null || getter?.body == null)         {             return false;         }          bool setterhasbodystatements = setter.body.statements.any();         bool getterhasbodystatements = getter.body.statements.any();          return setterhasbodystatements && getterhasbodystatements;     } }