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Fix null conditional rewrite generating invalid member access on nullable value types#169

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PhenX merged 2 commits intomasterfrom
copilot/fix-null-conditional-rewrite-value-types
Mar 6, 2026
Merged

Fix null conditional rewrite generating invalid member access on nullable value types#169
PhenX merged 2 commits intomasterfrom
copilot/fix-null-conditional-rewrite-value-types

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Copilot AI commented Mar 6, 2026

When NullConditionalRewriteSupport.Rewrite rewrites A?.B where A is a Nullable<T> struct, it was emitting A.B in the true branch — which doesn't compile. The correct form is A.Value.B.

Changes

  • ExpressionSyntaxRewriter.cs: Changed _conditionalAccessExpressionsStack from Stack<ExpressionSyntax> to Stack<(ExpressionSyntax, ITypeSymbol?)> to carry type information through the visitor.
  • ExpressionSyntaxRewriter.NullConditionalRewrite.cs:
    • Captures the semantic type of the target when pushing to the stack.
    • VisitMemberBindingExpression and VisitElementBindingExpression now insert a .Value accessor when the target is Nullable<T>, applied for both Rewrite and Ignore modes.
    • Extracted IsNullableValueType(ITypeSymbol?) helper.

Example

public struct Point { public double X { get; set; } }

[Projectable(NullConditionalRewriteSupport = NullConditionalRewriteSupport.Rewrite)]
public static double? GetX(this Point? point) => point?.X;

Before (invalid):

(point != null ? (point.X) : (double?)null)

After (correct):

(point != null ? (point.Value.X) : (double?)null)

Tests

Added three snapshot tests in NullableTests covering member access on a nullable struct with Rewrite, Ignore, and null-coalescing patterns.

Original prompt

This section details on the original issue you should resolve

<issue_title>Null Conditional Rewrite doesn't work with value types</issue_title>
<issue_description>When applying [Projectable(NullConditionalRewriteSupport = NullConditionalRewriteSupport.Rewrite)] to a method that accesses a value type (like e.g. NpgsqlPoint), the generated code does not insert the needed .Value access, leading to compile time errors.</issue_description>

<agent_instructions>Investigate on the issue and add tests on common value types, nullable or not, when accessed in various ways</agent_instructions>

Comments on the Issue (you are @copilot in this section)


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Co-authored-by: PhenX <42170+PhenX@users.noreply.github.com>
Copilot AI changed the title [WIP] Fix null conditional rewrite for value types Fix null conditional rewrite generating invalid member access on nullable value types Mar 6, 2026
Copilot finished work on behalf of PhenX March 6, 2026 22:14
@PhenX PhenX requested a review from Copilot March 6, 2026 22:33
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Pull request overview

Fixes the source generator’s null-conditional rewrite for nullable value types (Nullable<T>), ensuring generated member/element access compiles by using .Value when needed.

Changes:

  • Track both the rewritten conditional-access target expression and its semantic type through the rewrite visitor.
  • Insert .Value before member/element access when the conditional-access target is Nullable<T> (for both Rewrite and Ignore modes).
  • Add snapshot tests covering nullable struct member access across Rewrite, Ignore, and ?? coalescing patterns.

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/EntityFrameworkCore.Projectables.Generator/ExpressionSyntaxRewriter.cs Extends the conditional-access stack to carry semantic type info alongside the expression.
src/EntityFrameworkCore.Projectables.Generator/ExpressionSyntaxRewriter.NullConditionalRewrite.cs Uses semantic type info to add .Value for Nullable<T> targets during member/element binding rewrites.
tests/EntityFrameworkCore.Projectables.Generator.Tests/NullableTests.cs Adds new generator tests validating nullable struct null-conditional rewriting behavior.
tests/EntityFrameworkCore.Projectables.Generator.Tests/NullableTests.NullableValueType_MemberAccess_WithRewriteSupport_IsBeingRewritten.verified.txt Snapshot verifying .Value is emitted in rewritten conditional branch.
tests/EntityFrameworkCore.Projectables.Generator.Tests/NullableTests.NullableValueType_MemberAccess_WithIgnoreSupport_IsBeingRewritten.verified.txt Snapshot verifying .Value is emitted when ignoring ?. on nullable structs.
tests/EntityFrameworkCore.Projectables.Generator.Tests/NullableTests.NullableValueType_MemberAccessWithCoalesce_WithRewriteSupport_IsBeingRewritten.verified.txt Snapshot verifying .Value is emitted and integrates correctly with ?? coalescing.

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@PhenX PhenX marked this pull request as ready for review March 6, 2026 22:43
@PhenX PhenX merged commit 9f32281 into master Mar 6, 2026
8 checks passed
@PhenX PhenX deleted the copilot/fix-null-conditional-rewrite-value-types branch March 8, 2026 08:48
@PhenX PhenX added this to the v6.0.0 milestone Mar 8, 2026
github-merge-queue bot pushed a commit to DFE-Digital/teaching-record-system that referenced this pull request Mar 27, 2026
Updated
[EntityFrameworkCore.Projectables](https://github.com/EFNext/EntityFrameworkCore.Projectables)
from 5.0.2 to 6.0.0.

<details>
<summary>Release notes</summary>

_Sourced from [EntityFrameworkCore.Projectables's
releases](https://github.com/EFNext/EntityFrameworkCore.Projectables/releases)._

## 6.0.0

## What's Changed

### Major changes

* Add support for projectable method overloads by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#143
* Add C#​14 extension members by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#148
* Support explicitly implemented interface members and default interface
properties by @​rhodon-jargon in
EFNext/EntityFrameworkCore.Projectables#135
* Support block-bodied members with [Projectable] attribute by @​Copilot
in EFNext/EntityFrameworkCore.Projectables#152
* Add ExpandEnumMethods to expand enum extension calls into ternary
expressions by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#150
* Add support for pattern matching in various cases by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#158
* Add support for projectable constructors by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#161
* AOT-compatible static projection registry + SyntaxFactory-based
emission by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#166
* Improve UseMemberBody and add new diagnostics by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#174
* Add code fixes for EFP0001, EFP0002 and EFP0008, with tests by @​PhenX
in EFNext/EntityFrameworkCore.Projectables#181
* Add a code fixer and a code refactorer to transform factory methods
into constructors by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#183
* Improve source generator and analyzer responsiveness by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#171
* Docs website by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#194
* Implement global MSBuild defaults for [Projectable] options by
@​koenbeuk in
EFNext/EntityFrameworkCore.Projectables#191

### Other changes

* Check source generator output compilation by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#156
* Fix GetImplementingProperty issue when using interfaces by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#144
* Full qualification not needed anymore by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#157
* Split generator tests in different classes by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#162
* Refactor ExpressionSyntaxRewriter into focused partial class files by
@​Copilot in
EFNext/EntityFrameworkCore.Projectables#163
* Update readme and add new test for constructors by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#165
* Remove obsolete code by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#167
* Add source generator self-benchmark covering all expression
transformers by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#168
* Fix null conditional rewrite generating invalid member access on
nullable value types by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#169
* Improve generator benchmark with more realistic scenario by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#170
* Fix stale incremental generator cache when referenced types change in
other source files by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#172
* Add tests for properties with a getter and setter by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#173
* UseMemberBody more strict with expressions by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#175
* Add custom Copilot instructions by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#177
* Reorganize generator project by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#178
* Add closure resolution benchmark by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#179
* Feature/optimize closures by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#180
* Feature/optimize resolver by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#182
* Update github project urls by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#184
* Update deps by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#185
* Remove obsolete verified files and name net8 files correctly by
@​PhenX in
EFNext/EntityFrameworkCore.Projectables#186
* Remove all allocations when resolving and make it even faster by
@​PhenX in
EFNext/EntityFrameworkCore.Projectables#189
* Add devcontainer configuration for C# (.NET) development by @​koenbeuk
in EFNext/EntityFrameworkCore.Projectables#190

**Full Changelog**:
EFNext/EntityFrameworkCore.Projectables@v5.0.2...v6.0.0

Commits viewable in [compare
view](EFNext/EntityFrameworkCore.Projectables@v5.0.2...v6.0.0).
</details>

[![Dependabot compatibility
score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=EntityFrameworkCore.Projectables&package-manager=nuget&previous-version=5.0.2&new-version=6.0.0)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

Dependabot will resolve any conflicts with this PR as long as you don't
alter it yourself. You can also trigger a rebase manually by commenting
`@dependabot rebase`.

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[//]: # (dependabot-automerge-end)

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</details>

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: James Gunn <james@gunn.io>
gunndabad added a commit to DFE-Digital/teaching-record-system that referenced this pull request Mar 27, 2026
Updated
[EntityFrameworkCore.Projectables](https://github.com/EFNext/EntityFrameworkCore.Projectables)
from 5.0.2 to 6.0.0.

<details>
<summary>Release notes</summary>

_Sourced from [EntityFrameworkCore.Projectables's
releases](https://github.com/EFNext/EntityFrameworkCore.Projectables/releases)._

## 6.0.0

## What's Changed

### Major changes

* Add support for projectable method overloads by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#143
* Add C#​14 extension members by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#148
* Support explicitly implemented interface members and default interface
properties by @​rhodon-jargon in
EFNext/EntityFrameworkCore.Projectables#135
* Support block-bodied members with [Projectable] attribute by @​Copilot
in EFNext/EntityFrameworkCore.Projectables#152
* Add ExpandEnumMethods to expand enum extension calls into ternary
expressions by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#150
* Add support for pattern matching in various cases by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#158
* Add support for projectable constructors by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#161
* AOT-compatible static projection registry + SyntaxFactory-based
emission by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#166
* Improve UseMemberBody and add new diagnostics by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#174
* Add code fixes for EFP0001, EFP0002 and EFP0008, with tests by @​PhenX
in EFNext/EntityFrameworkCore.Projectables#181
* Add a code fixer and a code refactorer to transform factory methods
into constructors by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#183
* Improve source generator and analyzer responsiveness by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#171
* Docs website by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#194
* Implement global MSBuild defaults for [Projectable] options by
@​koenbeuk in
EFNext/EntityFrameworkCore.Projectables#191

### Other changes

* Check source generator output compilation by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#156
* Fix GetImplementingProperty issue when using interfaces by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#144
* Full qualification not needed anymore by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#157
* Split generator tests in different classes by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#162
* Refactor ExpressionSyntaxRewriter into focused partial class files by
@​Copilot in
EFNext/EntityFrameworkCore.Projectables#163
* Update readme and add new test for constructors by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#165
* Remove obsolete code by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#167
* Add source generator self-benchmark covering all expression
transformers by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#168
* Fix null conditional rewrite generating invalid member access on
nullable value types by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#169
* Improve generator benchmark with more realistic scenario by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#170
* Fix stale incremental generator cache when referenced types change in
other source files by @​Copilot in
EFNext/EntityFrameworkCore.Projectables#172
* Add tests for properties with a getter and setter by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#173
* UseMemberBody more strict with expressions by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#175
* Add custom Copilot instructions by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#177
* Reorganize generator project by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#178
* Add closure resolution benchmark by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#179
* Feature/optimize closures by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#180
* Feature/optimize resolver by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#182
* Update github project urls by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#184
* Update deps by @​PhenX in
EFNext/EntityFrameworkCore.Projectables#185
* Remove obsolete verified files and name net8 files correctly by
@​PhenX in
EFNext/EntityFrameworkCore.Projectables#186
* Remove all allocations when resolving and make it even faster by
@​PhenX in
EFNext/EntityFrameworkCore.Projectables#189
* Add devcontainer configuration for C# (.NET) development by @​koenbeuk
in EFNext/EntityFrameworkCore.Projectables#190

**Full Changelog**:
EFNext/EntityFrameworkCore.Projectables@v5.0.2...v6.0.0

Commits viewable in [compare
view](EFNext/EntityFrameworkCore.Projectables@v5.0.2...v6.0.0).
</details>

[![Dependabot compatibility
score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=EntityFrameworkCore.Projectables&package-manager=nuget&previous-version=5.0.2&new-version=6.0.0)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

Dependabot will resolve any conflicts with this PR as long as you don't
alter it yourself. You can also trigger a rebase manually by commenting
`@dependabot rebase`.

[//]: # (dependabot-automerge-start)
[//]: # (dependabot-automerge-end)

---

<details>
<summary>Dependabot commands and options</summary>
<br />

You can trigger Dependabot actions by commenting on this PR:
- `@dependabot rebase` will rebase this PR
- `@dependabot recreate` will recreate this PR, overwriting any edits
that have been made to it
- `@dependabot show <dependency name> ignore conditions` will show all
of the ignore conditions of the specified dependency
- `@dependabot ignore this major version` will close this PR and stop
Dependabot creating any more for this major version (unless you reopen
the PR or upgrade to it yourself)
- `@dependabot ignore this minor version` will close this PR and stop
Dependabot creating any more for this minor version (unless you reopen
the PR or upgrade to it yourself)
- `@dependabot ignore this dependency` will close this PR and stop
Dependabot creating any more for this dependency (unless you reopen the
PR or upgrade to it yourself)


</details>

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: James Gunn <james@gunn.io>
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Null Conditional Rewrite doesn't work with value types

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