C++: Add support to __leave

[IdrissRio]

This PR adds support to the Microsoft-specific __leave statement.

[Copilot]

Pull Request Overview

Adds support for the Microsoft-specific __leave statement in the C++ QL libraries and tests.

• Introduces a new LeaveStmt class and maps it to a fresh statement kind.
• Updates the semmlecode schema, upgrade/downgrade scripts, and change notes.
• Adds library tests (leave.cpp, leave.ql, leave.expected) to verify detection and enclosing-try resolution.

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
cpp/ql/lib/semmlecode.cpp.dbscheme	Add 40 = @stmt_leave and extend @jump to include @stmt_leave
cpp/ql/lib/semmle/code/cpp/stmts/Stmt.qll	Define LeaveStmt class, implement getEnclosingTry recursive lookup
cpp/ql/lib/upgrades/3c45f8b9e71ec723bf50c40581e1f18f4f25e290/upgrade.properties	Declare upgrade metadata for __leave support
cpp/ql/lib/change-notes/2025-06-11-leave-stmt.md	Document feature addition of __leave statement
cpp/downgrades/a8c2176e9a5cf9be8d17053a4c8e7e56b5aced6d/upgrade.properties	Declare downgrade metadata for __leave support
cpp/downgrades/a8c2176e9a5cf9be8d17053a4c8e7e56b5aced6d/stmts.ql	Map legacy kinds, translating stmt_leave back to kind 4
cpp/ql/test/library-tests/stmt/leave/leave.ql	Add QL test query selecting LeaveStmt and its enclosing try
cpp/ql/test/library-tests/stmt/leave/leave.expected	Add expected results for leave.ql query
cpp/ql/test/library-tests/stmt/leave/leave.cpp	Add C++ source with __leave in both __finally and __except contexts

Comments suppressed due to low confidence (1)

cpp/ql/lib/upgrades/3c45f8b9e71ec723bf50c40581e1f18f4f25e290/upgrade.properties:2

• The upgrade properties do not include a stmts.rel: run stmts.qlo directive, so upgrade tests might not exercise the new __leave upgrade rules. Consider adding this to ensure the upgrade path is exercised.

compatibility: partial

[Copilot]

The recursive helper getEnclosingTry lacks a base case when no enclosing MicrosoftTryStmt exists, potentially leading to infinite recursion. Consider adding a guard that returns none() when reaching the root or a non-stmt parent.

Suggested change

	if s.getParent().getEnclosingStmt() instanceof MicrosoftTryStmt
	if s.getParent() = none() or s.getParent().getEnclosingStmt() = none()
	then result = none()
	else if s.getParent().getEnclosingStmt() instanceof MicrosoftTryStmt

[Copilot]

[nitpick] The new stmt_leave enum entry is added out of numeric order among existing cases, which can make future maintenance harder. Consider inserting it in sorted order or updating surrounding comments.

[jketema]

Two small comments, otherwise LGTM.

[jketema]

LGTM