dotnet/msbuild

Warn about WriteLinesToFile default behavior which is Append

Open

#11,927 opened on May 29, 2025

View on GitHub
 (6 comments) (0 reactions) (0 assignees)C# (5,062 stars) (1,364 forks)batch import
help wantedtriaged

Description

WriteLinesToFile appends by default unless you specify Overwrite. This is highly non-intuitive and probably almost never what the user intends.

Since we can't change the behavior, I propose to introduce a new optional parameter Append, that defaults to false, and if it's not specified and Overwrite is not specified, warn about it (that you should specify one or the other).

Not sure if a warning or a message, perhaps build check?

Contributor guide

Tech stack
csharp
Domain
build systemdeveloper experience
Issue type
feature
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.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C# programmingMSBuild task developmentUnderstanding of MSBuild XML syntax
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Examine the existing WriteLinesToFile task implementation in the MSBuild source code (likely in the 'src/Tasks' directory). Understand how task parameters are defined and how warnings are emitted. Propose adding an 'Append' parameter and implement a warning when neither 'Append' nor 'Overwrite' is set. Consider using the existing warning infrastructure such as the WarningTask or TaskLoggingHelper.