ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137

Closed
#93090
Closed
ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
#93090
Labels
area-Extensions-Configurationblocking-release
Milestone
8.0.0

Description

@ericstj
ericstj
opened on Sep 15, 2023

Description

When encountering an abstract type in an object graph the configuration generator tries to create it and throws.

This is inconsistent with the runtime binder, which will use an existing instance.

I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.

Reproduction Steps

Run attached repro project:
bindAbstract.zip

Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0

To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output

options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.

Expected behavior

Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.

Actual behavior

Warning emitted by the source generator:

C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

And exception thrown at runtime:

Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

Regression?

No response

Known Workarounds

Disable generator.

Configuration

No response

Other information

No response

Metadata

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Assignees

No one assigned

    Labels

    area-Extensions-Configurationblocking-release

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      Skip to content
      ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137
      Closed
      #93090
      Closed
      ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
      #93090
      Labels
      area-Extensions-Configurationblocking-release
      Milestone
      8.0.0
      Description
      @ericstj
      ericstj
      opened on Sep 15, 2023
      Description
      When encountering an abstract type in an object graph the configuration generator tries to create it and throws.
      This is inconsistent with the runtime binder, which will use an existing instance.
      I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.
      Reproduction Steps
      Run attached repro project:
      bindAbstract.zip
      Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0
      To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output
      options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

      Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.
      Expected behavior
      Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.
      Actual behavior
      Warning emitted by the source generator:
      C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

      And exception thrown at runtime:
      Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

      Regression?
      No response
      Known Workarounds
      Disable generator.
      Configuration
      No response
      Other information
      No response
      Metadata
      Metadata
      Assignees
      No one assigned
        Labels
        area-Extensions-Configurationblocking-release
        Type
        No type
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          None yet
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          No branches or pull requests
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          Skip to content
          ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137
          Closed
          #93090
          Closed
          ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
          #93090
          Labels
          area-Extensions-Configurationblocking-release
          Milestone
          8.0.0
          Description
          @ericstj
          ericstj
          opened on Sep 15, 2023
          Description
          When encountering an abstract type in an object graph the configuration generator tries to create it and throws.
          This is inconsistent with the runtime binder, which will use an existing instance.
          I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.
          Reproduction Steps
          Run attached repro project:
          bindAbstract.zip
          Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0
          To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output
          options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

          Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.
          Expected behavior
          Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.
          Actual behavior
          Warning emitted by the source generator:
          C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

          And exception thrown at runtime:
          Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

          Regression?
          No response
          Known Workarounds
          Disable generator.
          Configuration
          No response
          Other information
          No response
          Metadata
          Metadata
          Assignees
          No one assigned
            Labels
            area-Extensions-Configurationblocking-release
            Type
            No type
            Projects
            No projects
              Milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
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(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

              Skip to content
              ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137
              Closed
              #93090
              Closed
              ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
              #93090
              Labels
              area-Extensions-Configurationblocking-release
              Milestone
              8.0.0
              Description
              @ericstj
              ericstj
              opened on Sep 15, 2023
              Description
              When encountering an abstract type in an object graph the configuration generator tries to create it and throws.
              This is inconsistent with the runtime binder, which will use an existing instance.
              I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.
              Reproduction Steps
              Run attached repro project:
              bindAbstract.zip
              Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0
              To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output
              options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

              Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.
              Expected behavior
              Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.
              Actual behavior
              Warning emitted by the source generator:
              C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

              And exception thrown at runtime:
              Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

              Regression?
              No response
              Known Workarounds
              Disable generator.
              Configuration
              No response
              Other information
              No response
              Metadata
              Metadata
              Assignees
              No one assigned
                Labels
                area-Extensions-Configurationblocking-release
                Type
                No type
                Projects
                No projects
                  Milestone
                  Relationships
                  None yet
                  Development
                  No branches or pull requests
                  Issue actions
                  
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})();
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try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

                  Skip to content
                  ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137
                  Closed
                  #93090
                  Closed
                  ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
                  #93090
                  Labels
                  area-Extensions-Configurationblocking-release
                  Milestone
                  8.0.0
                  Description
                  @ericstj
                  ericstj
                  opened on Sep 15, 2023
                  Description
                  When encountering an abstract type in an object graph the configuration generator tries to create it and throws.
                  This is inconsistent with the runtime binder, which will use an existing instance.
                  I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.
                  Reproduction Steps
                  Run attached repro project:
                  bindAbstract.zip
                  Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0
                  To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output
                  options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

                  Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.
                  Expected behavior
                  Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.
                  Actual behavior
                  Warning emitted by the source generator:
                  C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

                  And exception thrown at runtime:
                  Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

                  Regression?
                  No response
                  Known Workarounds
                  Disable generator.
                  Configuration
                  No response
                  Other information
                  No response
                  Metadata
                  Metadata
                  Assignees
                  No one assigned
                    Labels
                    area-Extensions-Configurationblocking-release
                    Type
                    No type
                    Projects
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                      Milestone
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                      None yet
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                      No branches or pull requests
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(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

                      Skip to content
                      ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137
                      Closed
                      #93090
                      Closed
                      ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
                      #93090
                      Labels
                      area-Extensions-Configurationblocking-release
                      Milestone
                      8.0.0
                      Description
                      @ericstj
                      ericstj
                      opened on Sep 15, 2023
                      Description
                      When encountering an abstract type in an object graph the configuration generator tries to create it and throws.
                      This is inconsistent with the runtime binder, which will use an existing instance.
                      I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.
                      Reproduction Steps
                      Run attached repro project:
                      bindAbstract.zip
                      Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0
                      To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output
                      options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

                      Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.
                      Expected behavior
                      Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.
                      Actual behavior
                      Warning emitted by the source generator:
                      C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

                      And exception thrown at runtime:
                      Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

                      Regression?
                      No response
                      Known Workarounds
                      Disable generator.
                      Configuration
                      No response
                      Other information
                      No response
                      Metadata
                      Metadata
                      Assignees
                      No one assigned
                        Labels
                        area-Extensions-Configurationblocking-release
                        Type
                        No type
                        Projects
                        No projects
                          Milestone
                          Relationships
                          None yet
                          Development
                          No branches or pull requests
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                          Skip to content
                          ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137
                          Closed
                          #93090
                          Closed
                          ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
                          #93090
                          Labels
                          area-Extensions-Configurationblocking-release
                          Milestone
                          8.0.0
                          Description
                          @ericstj
                          ericstj
                          opened on Sep 15, 2023
                          Description
                          When encountering an abstract type in an object graph the configuration generator tries to create it and throws.
                          This is inconsistent with the runtime binder, which will use an existing instance.
                          I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.
                          Reproduction Steps
                          Run attached repro project:
                          bindAbstract.zip
                          Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0
                          To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output
                          options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

                          Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.
                          Expected behavior
                          Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.
                          Actual behavior
                          Warning emitted by the source generator:
                          C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

                          And exception thrown at runtime:
                          Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

                          Regression?
                          No response
                          Known Workarounds
                          Disable generator.
                          Configuration
                          No response
                          Other information
                          No response
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filter: invert(1) hue-rotate(180deg) !important;
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})();
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} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

                              Skip to content
                              ConfigurationBinder source generator throws on an abstract member rather than binding to existing value #92137
                              Closed
                              #93090
                              Closed
                              ConfigurationBinder source generator throws on an abstract member rather than binding to existing value#92137
                              #93090
                              Labels
                              area-Extensions-Configurationblocking-release
                              Milestone
                              8.0.0
                              Description
                              @ericstj
                              ericstj
                              opened on Sep 15, 2023
                              Description
                              When encountering an abstract type in an object graph the configuration generator tries to create it and throws.
                              This is inconsistent with the runtime binder, which will use an existing instance.
                              I wonder if we should warn on this or not. Definitely if the abstract type is the root and we're generating Get calls that's a problem. Anywhere else it could be supported if the member is already initialized - since we won't need to create one in the binder.
                              Reproduction Steps
                              Run attached repro project:
                              bindAbstract.zip
                              Also shown here: https://gist.github.com/ericstj/121fe52f9a1b5115b246c08605c685c0
                              To see expected behavior remove EnableConfigurationBindingGenerator. You'll see the output
                              options.Abstract.GetHashCode() before bind: 55915408
options.Abstract.GetHashCode() after bind: 55915408
John Doe

                              Note that the runtime binder didn't rely on seeing the derived type and creating a new one -- this is apparent by seeing that the object is the same before and after then bind.
                              Expected behavior
                              Repro runs successfully and sets the members on the existing instance of the derived type. Not creating a new instance nor throwing.
                              Actual behavior
                              Warning emitted by the source generator:
                              C:\scratch\bindAbstract\Program.cs(11,1): warning SYSLIB1100: Cannot create instance of type 'MyAbstractClass' because
it is missing a public instance constructor. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib
1100.md)

                              And exception thrown at runtime:
                              Unhandled exception. System.InvalidOperationException: Cannot create instance of type '<global namespace>.MyAbstractClass' because it is missing a public instance constructor.
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.BindCore(IConfiguration configuration, MyOptions& instance, Boolean defaultValueIfNotFound, BinderOptions binderOptions) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 144
at Microsoft.Extensions.Configuration.Binder.SourceGeneration.<BindingExtensions_g>FC276FD7C89D1ED0B2B3E96BAC8F157FABB86A642EAABC54639B357A857C01D08__BindingExtensions.Bind_MyOptions(IConfiguration configuration, Object instance) in C:\scratch\bindAbstract\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs:line 48
at Program.<Main>$(String[] args) in C:\scratch\bindAbstract\Program.cs:line 11

                              Regression?
                              No response
                              Known Workarounds
                              Disable generator.
                              Configuration
                              No response
                              Other information
                              No response
                              Metadata
                              Metadata
                              Assignees
                              No one assigned
                                Labels
                                area-Extensions-Configurationblocking-release
                                Type
                                No type
                                Projects
                                No projects
                                  Milestone
                                  Relationships
                                  None yet
                                  Development
                                  No branches or pull requests
                                  Issue actions