Allow configuration binding to set-only properties

[cincuranet]

The configuration binder previously skipped all properties without a getter. This change enables binding to true set-only properties (those with a setter but no getter at all) in both the reflection-based binder and the source generator.

Fixes #63508.

[Copilot]

Pull request overview

This PR updates the Microsoft.Extensions.Configuration binder to allow binding to true set-only properties (setter present, no getter) in both the reflection-based binder and the source-generated binder, aligning behavior with documented expectations (Fixes #63508).

Changes:

• Reflection binder: allow binding set-only properties by handling the “no getter” case in BindProperty.
• Source generator: distinguish “no getter at all” vs “non-public getter” and generate binding code for true set-only properties.
• Tests: update/extend coverage for set-only binding (including complex types and type conversion) and adjust an existing virtual-property assertion.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Enables reflection binder binding for true set-only properties by adjusting getter/setter checks and binding point initialization.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Adds HasAnyGetter to distinguish true set-only from “non-public getter” properties in generator metadata.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Implements HasAnyGetter for properties based on presence of any getter (regardless of accessibility).
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates generated binding logic to support set-only properties and avoid emitting getter-dependent code paths.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs	Updates existing test and adds new tests validating set-only binding scenarios (simple, conversion, complex).
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.TestClasses.cs	Expands test POCOs to track which setters were invoked and adds new POCOs for complex/type-conversion scenarios.

Comments suppressed due to low confidence (1)

src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs:992

• The source-generator path skips the empty-string -> empty-array fallback when the bound member is set-only (no getter), but the reflection binder will still assign an empty array in that case (because the binding point’s initial value is null). To keep parity, emit a set-only-specific fallback that assigns Array.Empty() when the config value is "" without reading the member value (since it has no getter).

                            // The current configuration section doesn't have any children, let's check if we are binding to an array and the configuration value is empty string.
                            // In this case, we will assign an empty array to the member. Otherwise, we will skip the binding logic.
                            // The null check on the member requires a getter, so skip this fallback for set-only properties.
                            if ((complexType is ArraySpec || complexType.IsExactIEnumerableOfT) && canSet && canGet)
                            {
                                // Either we have an array or we have an IEnumerable<T> both these types can be assigned an empty array when having empty string configuration value.
                                Debug.Assert(complexType is ArraySpec || complexType is EnumerableSpec);
                                string valueIdentifier = GetIncrementalIdentifier(Identifier.value);
                                EmitStartBlock($@"if ({memberAccessExpr} is null && {Identifier.TryGetConfigurationValue}({configSection}, {Identifier.key}: null, out string? {valueIdentifier}) && {valueIdentifier} == string.Empty)");
                                _writer.WriteLine($"{memberAccessExpr} = global::System.{Identifier.Array}.Empty<{((CollectionSpec)complexType).ElementTypeRef.FullyQualifiedName}>();");
                                EmitEndBlock();

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[Copilot]

Pull request overview

This PR updates Microsoft.Extensions.Configuration.Binder to bind true set-only properties (setter present, no getter at all) in both the reflection-based binder and the configuration binding source generator, addressing the documented behavior gap from #63508.

Changes:

• Reflection binder: allow binding of set-only properties by handling PropertyInfo.GetMethod == null and using a BindingPoint without a getter-backed initial value.
• Source generator: add HasAnyGetter to distinguish true set-only properties from properties with non-public getters, and update emission logic to support set-only binding.
• Tests: update/extend coverage to validate set-only binding, including type conversion and complex object binding; update virtual set-only property binding expectation.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs	Updates existing test and adds new tests covering set-only binding scenarios (including complex and type conversion) and virtual set-only property binding.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.TestClasses.cs	Updates SetOnlyPoco test helper and adds new POCOs used by set-only binding tests.
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Implements reflection binder support for set-only properties by adjusting property filtering and binding point initialization.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Adds HasAnyGetter to capture “getter exists at any accessibility” for generated binding decisions.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Introduces HasAnyGetter contract (defaulting to CanGet) to distinguish true set-only properties vs. non-public getters.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates generated binding logic to allow set-only properties while trying to preserve parity with reflection binder behavior.

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[Copilot]

Pull request overview

This PR updates Microsoft.Extensions.Configuration.Binder to bind true set-only properties (properties with a setter and no getter at all) in both the reflection-based binder and the source-generated binder, aligning behavior more closely with the documented expectations.

Changes:

• Reflection binder: allow binding to set-only properties by treating them as writable binding targets even without an initial value getter.
• Source generator: distinguish “true set-only” (no getter) from “non-public getter” to enable the former while continuing to skip the latter.
• Tests: update existing coverage and add new cases for set-only binding (including complex and type-converted scenarios).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Enables reflection-based binding for set-only properties by changing property eligibility checks and binding-point initialization.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates generated binding logic to allow true set-only properties and handle getterless complex members via temp variables.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Introduces HasAnyGetter abstraction to differentiate “no getter” vs “non-public getter”.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Implements HasAnyGetter for properties (getter exists at any accessibility).
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs	Renames/updates existing test and adds new tests validating set-only binding scenarios.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.TestClasses.cs	Adds new POCOs used by the new/updated set-only binding tests.

Comments suppressed due to low confidence (1)

src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs:1386

• New behavior adds support for set-only properties, including honoring BindNonPublicProperties for non-public setters in the reflection binder. There’s no test exercising a true set-only property with a non-public setter (and no getter) that only becomes bindable when BindNonPublicProperties = true, which would help prevent regressions in the new accessibility checks.

        public void BindsSetOnlyProperties()
        {
            var dic = new Dictionary<string, string>
            {
                {"SetOnly", "42"},
                {"PrivateGetter", "42"},
                {"InitOnly", "42"},
            };

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[Copilot]

Pull request overview

Enables Microsoft.Extensions.Configuration.Binder to bind configuration values to true set-only properties (setter present, no getter) in both the reflection-based binder and the configuration binding source generator, aligning behavior with the documented expectations.

Changes:

• Update reflection binder property binding to support set-only properties while continuing to skip properties that only have non-public getters (unless opted in via BindNonPublicProperties).
• Extend source generator member modeling and emitted binding logic to support true set-only properties (including complex types and empty-string → empty-array behavior).
• Add/adjust tests to validate binding set-only properties (simple, type conversion, and complex object binding), plus update expectations for virtual set-only property binding.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Updates reflection binder to bind set-only properties by adjusting property eligibility checks and binding-point initialization.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Adds HasAnyGetter to distinguish true set-only properties from properties with non-public getters.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Implements HasAnyGetter based on Roslyn symbol getter presence.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates generated binding logic to allow true set-only properties and avoid emitting getter-dependent code paths when no getter exists.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs	Renames/updates existing test and adds new tests for set-only binding scenarios; updates virtual set-only property expectation.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.TestClasses.cs	Expands/adjusts test POCOs to track per-property invocation and introduces new set-only test types.

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[Copilot]

Pull request overview

This PR updates Microsoft.Extensions.Configuration.Binder to allow configuration binding to true set-only properties (public setter with no getter at all) in both the reflection-based binder and the source generator, aligning behavior more closely with documented expectations.

Changes:

• Reflection binder: allow binding to properties with no getter, when an accessible setter exists.
• Source generator: distinguish “no getter at all” vs “non-public getter” and bind only the former (when settable).
• Tests: add coverage for set-only binding scenarios (including type conversion and complex objects) and update virtual set-only property expectations.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Enables reflection binder to bind true set-only properties and adjusts binding point initialization accordingly.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates source-gen emission rules to support true set-only properties while continuing to skip non-public getters for parity.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Introduces HasAnyGetter to distinguish true set-only properties from non-public getter properties.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Implements HasAnyGetter based on presence of any getter on the symbol.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests*.cs	Adds/updates tests validating set-only binding behavior (string, conversion, complex) and virtual set-only binding.

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[Copilot]

Pull request overview

This PR updates Microsoft.Extensions.Configuration.Binder to allow binding to true set-only properties (properties with a setter but no getter) in both the reflection-based binder and the source-generated binder, aligning behavior with documented expectations.

Changes:

• Reflection binder: allow binding to set-only properties while still skipping indexers and respecting BindNonPublicProperties for accessor visibility.
• Source generator: add a HasAnyGetter distinction so true set-only properties can be bound, while properties with non-public getters are still skipped to match reflection behavior.
• Tests: expand coverage to validate binding of set-only properties, including type conversion and complex object binding; update an existing virtual-property test to reflect the new behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs	Adds/updates tests to validate binding to set-only properties (including conversion/complex types) and updates the virtual set-only property expectation.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.TestClasses.cs	Updates/introduces test POCOs for set-only scenarios (simple, complex, and conversion-driven).
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Enables reflection-based binding for true set-only properties while maintaining indexer/non-public filtering rules.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Tracks presence of any getter (HasAnyGetter) to differentiate true set-only vs non-public getters for generator decisions.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Introduces HasAnyGetter to support generator logic distinctions around getter presence.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates emitted binding logic to handle true set-only properties without reading current values.

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[Copilot]

Pull request overview

This PR updates Microsoft.Extensions.Configuration.Binder to support binding to true set-only properties (properties with a setter but no getter) in both the reflection-based binder and the source generator, aligning behavior with documented expectations (Issue #63508).

Changes:

• Reflection binder: allow binding to set-only properties by validating accessibility via the setter when no getter exists.
• Source generator: distinguish true set-only properties (no getter at all) from properties with non-public getters, and emit binding code accordingly.
• Tests: expand coverage for set-only property binding (including type conversion and complex types) and update a virtual set-only property test expectation.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs	Updates/expands tests to validate binding to set-only properties and adjusts an existing virtual-property assertion.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.TestClasses.cs	Refactors/extends test POCOs to track which set-only properties were invoked; adds new set-only test types.
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Enables reflection-based binding for true set-only properties and adjusts setter-invocation conditions.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Adds HasAnyGetter metadata for distinguishing true set-only vs non-public getter cases.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Introduces HasAnyGetter (virtual) to support source-gen decisions around set-only properties.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates emitted binding logic to support true set-only properties while continuing to skip properties with non-public getters.

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[Copilot]

Pull request overview

Enables Microsoft.Extensions.Configuration.Binder to bind to true set-only properties (setter present, no getter at all) in both the reflection-based binder and the source generator, aligning behavior with documented expectations.

Changes:

• Update reflection binder property-binding logic to allow set-only properties while preserving indexer/non-public accessor rules.
• Extend source generator specs/emitter to distinguish true set-only properties from properties with non-public getters and emit appropriate binding code.
• Add/adjust unit tests covering set-only binding scenarios (including type conversion and complex/struct properties).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs	Adds/updates tests for set-only binding; currently contains a compile-breaking type declaration placement.
src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.TestClasses.cs	Updates existing test POCO and adds new POCOs used by the new set-only tests.
src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs	Allows binding set-only properties in reflection binder and refines setter invocation conditions.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/PropertySpec.cs	Adds HasAnyGetter tracking to distinguish true set-only properties in generator.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Specs/Members/MemberSpec.cs	Introduces HasAnyGetter abstraction and documentation for generator logic.
src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Emitter/CoreBindingHelpers.cs	Updates generator emission logic to bind true set-only properties while skipping non-public getters.

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