using roslyn, how to get a type of 'var'?

Question

I want to get the type represented by var.

var localDeclaration = methodDeclaration.DescendantNodes().OfType<LocalDeclarationStatementSyntax>().First();
var identifierName = localDeclaration.DescendantNodes().OfType<IdentifierNameSyntax>().First();
var symbolInfo = semanticModel.GetSymbolInfo(identifierName);
var typeSymbol = semanticModel.GetTypeInfo(identifierName).Type;

I tried GetSymbolInfo() and GetTypeInfo(), the first one returns null, the second one returns {?}.

Get Type of 'var' with Roslyn The method it provides does not work either. The debugging information is attached in the figure below. You can see that these values are all null or {?}.

My code looks like this

public class Start
{

    static void Main(string[] args)
    {
        InitEnvironment();
        Run();
        Console.ReadLine();
    }

    private static void InitEnvironment()
    {
        GlobalVariable.MySolution = MSBuildWorkspace.Create().OpenSolutionAsync(ConstVariable.SolutionPath).Result;
        GlobalVariable.MyProject = GlobalVariable.MySolution.Projects.First(x => x.Name == "GamePlay");
        GlobalVariable.CompilationByAll = GlobalVariable.MyProject.GetCompilationAsync().Result;
    }

    private static void Run()
    {
        var tree = SyntaxTreeProcessor.GetSyntaxTreeByFileName(ConstVariable.SystemPath + @"\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs");
        var semanticModel = GlobalVariable.CompilationByAll.GetSemanticModel(tree);
        var methodDeclarations = tree.GetRoot().DescendantNodes().OfType<MethodDeclarationSyntax>().ToList();
        foreach(var methodDeclaration in methodDeclarations)
        {
            Console.WriteLine($"methodDeclaration:{methodDeclaration.Identifier.ValueText}");
            var localDeclaration = methodDeclaration.DescendantNodes().OfType<LocalDeclarationStatementSyntax>().First();
            var identifierName = localDeclaration.DescendantNodes().OfType<IdentifierNameSyntax>().First();
            foreach (var varibale in localDeclaration.Declaration.Variables)
            {
                Console.WriteLine($"varibale.Identifier:{varibale.Identifier}");
                Console.WriteLine($"varibale.Initializer:{varibale.Initializer}");
            }
            var variableType = semanticModel.GetSymbolInfo(localDeclaration.Declaration.Type).Symbol;
            var typeSymbol = semanticModel.GetTypeInfo(identifierName).Type;
            var symbolInfo = semanticModel.GetSymbolInfo(identifierName);
        }
        Console.WriteLine(tree.FilePath);
    }
}

I tried the Syntax Visualizer tool in visual studio 2019 and it showed the correct type.

The result of GetDiagnostic() is as follows:

COUNT:  32
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (0,6)-(0,12)未能找到类型或命名空间名“System”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (1,6)-(1,12)未能找到类型或命名空间名“System”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (2,6)-(2,12)未能找到类型或命名空间名“System”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (3,6)-(3,12)未能找到类型或命名空间名“System”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (6,6)-(6,13)未能找到类型或命名空间名“Entitas”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (10,111)-(10,128)未能找到类型或命名空间名“IInitializeSystem”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (14,15)-(14,19)预定义类型“System.Void”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (20,54)-(20,60)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (20,54)-(20,60)未能找到类型或命名空间名“Entity”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (20,79)-(20,97)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (20,27)-(20,31)预定义类型“System.Void”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (12,16)-(12,41)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (16,24)-(16,32)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (16,24)-(16,32)当前上下文中不存在名称“GetWorld”
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (17,60)-(17,85)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (22,24)-(22,32)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (22,24)-(22,32)当前上下文中不存在名称“GetWorld”
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (23,12)-(23,42)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (23,53)-(23,83)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (23,53)-(23,83)预定义类型“System.Void”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (24,65)-(24,95)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (24,97)-(24,101)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (24,97)-(24,101)未能找到类型或命名空间名“Game”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (26,45)-(26,75)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (26,77)-(26,81)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (26,77)-(26,81)未能找到类型或命名空间名“Game”(是否缺少 using 指令或程序集引用?)
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (32,12)-(32,30)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (34,16)-(34,107)预定义类型“System.Boolean”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (38,16)-(38,30)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (38,31)-(38,40)预定义类型“System.Object”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (38,16)-(38,47)预定义类型“System.Boolean”未定义或导入
I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs: (40,20)-(40,111)预定义类型“System.Boolean”未定义或导入
methodDeclaration:Initialize
varibale.Identifier:world
varibale.Initializer:= GetWorld()

methodDeclaration:HandleReliableRequest
varibale.Identifier:world
varibale.Initializer:= GetWorld()

I:\gameplay\Test\GamePlay\System\GameModeSystems\JokerMode\JokerProcessPlayerStatisSystems.cs

Does this answer your question? [Get Type of 'var' with Roslyn?](https://stackoverflow.com/questions/23878120/get-type-of-var-with-roslyn) — GSerg, Nov 01 '21 at 07:02
If you mean "in the question": nothing wrong I can see, except maybe replace that image with code (images are the absolute worst way to share code); interesting question, and the post GSerg links to may help - it sound like you e already tried GetSymbolInfo(), though — Marc Gravell, Nov 01 '21 at 07:15
Yes, I tried my best to search for similar problems and try to solve them. But until now, I still don't know how to solve it. I have added relevant debugging information and relatively complete code. — eden, Nov 01 '21 at 07:29
What does GlobalVariable.CompilationByAll().GetDiagnostics() return? — Jason Malinowski, Nov 01 '21 at 18:54
Judging from the result of GetDiagnostic(), the relevant definition is missing. These definitions exist in common.dll, how should I introduce it into my compilation? — eden, Nov 02 '21 at 02:56

score 0 · Answer 1 · answered Nov 02 '21 at 04:11

I seem to have found a solution. I put it here for people with the same confusion. If you have a better way, you are welcome to write it down below. thanks.

        private static void InitEnvironment()
        {
            GlobalVariable.MySolution = MSBuildWorkspace.Create().OpenSolutionAsync(ConstVariable.SolutionPath).Result;

            var metadataReferenceCustomDlls = Directory.GetFiles(@"I:\gameplay\Library\", "*.dll");
            var metadataReferences = metadataReferenceCustomDlls.Select(f => MetadataReference.CreateFromFile(f)).ToList();
            var metadataReferenceNetStandardDlls = Directory.GetFiles(@"C:\Users\user\.nuget\packages\netstandard.library\2.0.3\build\netstandard2.0\ref\", "*.dll");
            var metadataReferencesB = metadataReferenceNetStandardDlls.Select(f => MetadataReference.CreateFromFile(f)).ToList();
            metadataReferences = metadataReferences.Concat(metadataReferencesB).ToList();
            foreach (var projectId in GlobalVariable.MySolution.ProjectIds.ToArray())
            {
                GlobalVariable.MySolution = GlobalVariable.MySolution.AddMetadataReferences(projectId, metadataReferences);
            }

            GlobalVariable.MyProject = GlobalVariable.MySolution.Projects.First(x => x.Name == "GamePlay");
            GlobalVariable.CompilationByAll = GlobalVariable.MyProject.GetCompilationAsync().Result;
        }

I added some code in InitEnvironment().In general, the corresponding reference is added.

using roslyn, how to get a type of 'var'?

1 Answers1