Add LocalRewritingValidator check for BoundUnconvertedObjectCreationExpression #80724

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Merged

jcouv merged 2 commits into main from copilot/modify-local-rewriting-validator

Oct 15, 2025

Merged

Add LocalRewritingValidator check for BoundUnconvertedObjectCreationExpression #80724

jcouv merged 2 commits into main from copilot/modify-local-rewriting-validator

Oct 15, 2025

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@Copilot Copilot AI commented Oct 14, 2025 •

edited by jcouv

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Fixes #57179

This PR adds a validation check in LocalRewritingValidator to enforce that BoundUnconvertedObjectCreationExpression nodes do not survive past local rewriting.

Background

BoundUnconvertedObjectCreationExpression represents target-typed new() expressions before they are converted to their actual target type during binding. These nodes should be fully converted during the binding phase and should never reach the local rewriting phase.

The main LocalRewriter class already has a VisitUnconvertedObjectCreationExpression method that throws ExceptionUtilities.Unreachable(), indicating these nodes are unexpected during local rewriting. However, there was no corresponding DEBUG-time validation to catch cases where such nodes might inadvertently survive into the local rewriting phase.

Changes

Added a VisitUnconvertedObjectCreationExpression method to the LocalRewritingValidator class that:

Calls Fail(node) to trigger a debug assertion if an unconverted object creation expression is encountered
Follows the same pattern as existing validator methods like VisitDefaultLiteral, VisitUsingStatement, etc.
Only executes in DEBUG builds (the entire LocalRewritingValidator class is #if DEBUG)

This provides an additional safety net to catch potential bugs during development where unconverted object creation expressions might leak into the local rewriting phase.

Testing

All existing tests pass, including:
- 163 ImplicitObjectCreationTests (target-typed new() expressions)
- 94 TargetTyped tests
- Full Compilers.slnf solution builds successfully

The change is minimal (6 lines) and follows established patterns in the codebase.

Originally requested by @jcouv in #57091 (comment)

Co-authored-by: jcouv 12466233+jcouv@users.noreply.github.com

Original prompt

This section details on the original issue you should resolve

<issue_title>Can we modify LocalRewritingValidator to enforce that BoundUnconvertedObjectCreation does not survive past local rewriting?</issue_title>
<issue_description>Can we modify LocalRewritingValidator to enforce that BoundUnconvertedObjectCreation does not survive past local rewriting?

Originally posted by @jcouv in #57091 (comment) </issue_description>

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

Fixes #57179

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 Initial plan

440f013

@Copilot Copilot AI assigned Copilot and jcouv

Oct 14, 2025

Copilot started work on behalf of jcouv

October 14, 2025 21:09

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@Copilot @jcouv


 Add LocalRewritingValidator check for BoundUnconvertedObjectCreationE...

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Co-authored-by: jcouv <12466233+jcouv@users.noreply.github.com>

@Copilot Copilot AI changed the title ~~(削除) [WIP] Modify LocalRewritingValidator to restrict BoundUnconvertedObjectCreation (削除ここまで)~~ (追記) Add LocalRewritingValidator check for BoundUnconvertedObjectCreationExpression (追記ここまで)

Oct 14, 2025

@Copilot Copilot AI requested a review from jcouv

October 14, 2025 21:28

Copilot finished work on behalf of jcouv

October 14, 2025 21:28

jcouv

jcouv approved these changes

Oct 14, 2025

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