dotnet/runtime

ILVerify fails to verify some catch-to-try leave instructions

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#48,250 opened on Feb 12, 2021

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Priority:3area-Tools-ILVerificationhelp wanted

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Description

Description

To reproduce: Run ILVerify on the Foo.dll assembly in this zip file. The following output should be produced:

[IL]: Error [LeaveIntoTry]: [...\Foo.dll : .A::m2(int32)][offset 0x00000014] Leave into try block.
1 Error(s) Verifying ...\Foo.dll

If the assembly is executed on .NET 5 (by invoking its Main method), it produces the expected output without any errors.

The assembly contains two static methods A.m1 and A.m2. Both contain leave instructions that jump from a catch block to its associated try block, which is legal according to ECMA-335, section I.12.4.2.8.2.8.

ILVerify correctly verifies the leave in A.m1. In A.m2, the catch block and the try block to which it jumps to are nested in another try block which has a finally block, which triggers the bug.

Configuration

ILVerify version: 5.0.0-rtm.20519.4+cf258a14b70ad9069470a108f13765e0e5988f51

Contributor guide

Research direction
Investigate the ILVerify source code to understand why leave instructions from catch to try are incorrectly rejected when nested inside another try block with a finally handler. Compare the cases of methods m1 and m2.
Tech stack
csharp
Domain
compilerstooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C#basic understanding of IL
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40