dotnet/roslyn

StackOverflowException during VB build with too many nested If/Then/Else statements

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#30,741 opened on Oct 24, 2018

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Description

I have a VB.net project that uses the v3.5\EdmGen.exe to generate a Model.Views.vb file. This generated file contians over 830 views.

Since the Visual Studio 2017 V15.8.1 update, trying to build the project containing the Model.Views.vb fails, just giving the following output.

C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\15.0\Bin\Roslyn\Microsoft.VisualBasic.Core.targets(41,5): error : Process is terminated due to StackOverflowException.

Worse still, this leaves Visual Studio in an unstable condition and trying to do more builds randomly locks the entire PC(Win 7 Pro machine) up requiring a power reset. This happens on multiple of our development machines.

I've managed to trace the problem down the the way the DotNet 3.5 EdmGen.exe program generates the Model.Views.vb file. It nests all the If/Then/Else statements for every new View and once the nested If statements reach approximately 824/825 levels deep, it causes the StackOverflowException.

If I manually remove the some of the nested If/Then/Else statements(and their View code), it builds OK. So there seems to be a limit on how many levels you can nest If/Then/Else statements.

I can also confirm that in VS2017 V15.7.3 we could build our current Model.Views.vb (with over 830 nested If/Then/Else statements), but since VS2017 V15.8.1 (up to 15.8.4) the same file fails with the StackOverflowException.

I am currently getting around the problem by using the v4.0.30319\EdmGen.exe which generates the Model.Views.vb WITHOUT all the nested If/Then/Else stetements.

This issue has been moved from https://developercommunity.visualstudio.com/content/problem/336992/stackoverflowexception-during-vb-build-with-too-ma.html VSTS ticketId: 685409 These are the original issue comments: (no comments) These are the original issue solutions: (no solutions)

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Tech stack
None
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
VB.NET languageRoslyn compiler architecturestack overflow debugging
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
10
Research direction
The issue is caused by excessively nested If/Then/Else statements in VB.NET code generated by EdmGen.exe. The Roslyn compiler's Visual Basic parser or binder likely uses recursion for nested statements, leading to a stack overflow. To fix, investigate the VB compiler's handling of nested conditionals, possibly introducing an iterative approach or increasing stack size. Key files to examine include the VB parser (SyntaxParser.vb) and binder (Binder.vb). There are no linked PRs or comments suggesting a solution. Maintainers should confirm whether this is a regression from a specific change between VS 15.7.3 and 15.8.1.