System.Text.Json generator does not generate valid code for empty string default parameter constructors

[333fred]

Description

As the title says, when there is a get-only property with an empty string as the default parameter in the constructor, the generator generates invalid C# code.

Reproduction Steps

Attempt to compile the following code:

using System.Text.Json.Serialization;

public class Test
{
    public string Property { get; }

    public Test(string property = "") { Property = property; }
}

[JsonSerializable(typeof(Test))]
public partial class Context : JsonSerializerContext
{
}

Expected behavior

The code compiles.

Actual behavior

1>C:\temp\System.Text.Json.SourceGeneration\System.Text.Json.SourceGeneration.JsonSourceGenerator\Context.Test.g.cs(92,31,92,31): error CS1525: Invalid expression term '}'

It appears the generator is generating the following invalid object initializer:

        private static global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues[] TestCtorParamInit()
        {
            global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues[] parameters = new global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues[1];
            global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues info;
        
            info = new()
            {
                Name = "property",
                ParameterType = typeof(global::System.String),
                Position = 0,
                HasDefaultValue = true,
                DefaultValue = 
            };
            parameters[0] = info;
        
            return parameters;
        }

Regression?

No

Known Workarounds

Don't use empty strings as the default value.

Configuration

.NET 6.0.100.

Other information

No response

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Issue Details

---

Description

As the title says, when there is a get-only property with an empty string as the default parameter in the constructor, the generator generates invalid C# code.

Reproduction Steps

Attempt to compile the following code:

using System.Text.Json.Serialization;

public class Test
{
    public string Property { get; }

    public Test(string property = "") { Property = property; }
}


[JsonSerializable(typeof(Test))]
public partial class Context : JsonSerializerContext
{
    public static string Implicit => "World";
}

Expected behavior

The code compiles.

Actual behavior

1>C:\temp\System.Text.Json.SourceGeneration\System.Text.Json.SourceGeneration.JsonSourceGenerator\Context.Test.g.cs(92,31,92,31): error CS1525: Invalid expression term '}'

It appears the generator is generating the following invalid object initializer:

        private static global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues[] TestCtorParamInit()
        {
            global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues[] parameters = new global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues[1];
            global::System.Text.Json.Serialization.Metadata.JsonParameterInfoValues info;
        
            info = new()
            {
                Name = "property",
                ParameterType = typeof(global::System.String),
                Position = 0,
                HasDefaultValue = true,
                DefaultValue = 
            };
            parameters[0] = info;
        
            return parameters;
        }

Regression?

No

Known Workarounds

Don't use empty strings as the default value.

Configuration

.NET 6.0.100.

Other information

No response

Author:	333fred
Assignees:	-
Labels:	area-System.Text.Json, untriaged
Milestone:	-

[layomia]

I was able to repro.
6.0.x candidate as we are preventing successful compilation for a trivial/common scenario.

[layomia]

Re-opening for 6.0 consideration.