How to fetch warnings from the dotnet build command

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Given a .Net C# project I want to check if the build contains warnings. When running the command

dotnet build -consoleloggerparameters:"Summary;Verbosity=normal" -m -p:"WarnLevel=5;EnforceCodeStyleInBuild=true" -t:"clean,build"

I get the expected output

Build succeeded.
    2 Warning(s)
    0 Error(s)

But the exit code is 0, so how do I know if that build contains warnings?

I created a shell script to play around

#!/bin/bash

dotnet build -consoleloggerparameters:"Summary;Verbosity=normal" -m -p:"WarnLevel=5;EnforceCodeStyleInBuild=true" -t:"clean,build"

if [ $? -eq 0 ]
then
  echo ">>> Success"
else
  echo ">>> Contains warnings or errors"
fi

read

but how can I extend the script to check for a successful build with warnings? The configured CI pipelines should pass but I want to mark them as unstable if warnings occured.

I would like to avoid Regex magic if possible.

Edit:

I don't want to add the flag -warnaserror because then CI pipelines will fail and you won't get to know if build errors occured or the code style is just bad.

exit-code shell .net c#
1 Answers

What you can do is simply add /WarnAsError to your dotnet build.

Example code:

using System;

namespace ConsoleApp1
{
   class Program
    {
        static void Main(string[] args)
        {
           Console.WriteLine("Hello World!");
           int x = 0;
        }
    }
}

Output of dotnet build:

dotnet build
Microsoft (R) Build Engine version 16.10.0+4242f381a for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  All projects are up-to-date for restore.
Program.cs(10,17): warning CS0219: The variable 'x' is assigned but its value is never used [ConsoleApp1.csproj]
  ConsoleApp1 -> ConsoleApp1.dll

Build succeeded.

\Program.cs(10,17): warning CS0219: The variable 'x' is assigned but its value is never used [ConsoleApp1.csproj]
    1 Warning(s)
    0 Error(s)

Time Elapsed 00:00:00.79

Output of dotnet build /WarnAsError:

dotnet build /WarnAsError
Microsoft (R) Build Engine version 16.10.0+4242f381a for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  Restored ConsoleApp1.csproj (in 60 ms).
Program.cs(10,17): error CS0219: The variable 'x' is assigned but its value is never used [ConsoleApp1.csproj]
  ConsoleApp1 -> ConsoleApp1.dll

Build FAILED.

Program.cs(10,17): error CS0219: The variable 'x' is assigned but its value is never used [ConsoleApp1.csproj]
    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:01.00

EDIT: OP requested to not fail the build upon warning.

Something you can try, is to have the warnings be written to a file and afterwards count the number of lines in that file.

Exmample:

I took the code above and added several variables:

int a = 0;
int b = 0;
int c = 0;
int d = 0;
int e = 0;

Now when I compile, I get 5 warnings. Now I added this to my dotnet build:

$warningsFile = "SomeFile.log"
dotnet build -fl1 "/flp1:logFile=$warningsFile;warningsonly"

Afterwards I can simply count the number of lines in that file. Using powershell:

gc $warningsFile | Measure-Object -Line

Results in:

Lines Words Characters Property
----- ----- ---------- --------
    5

I'm not sure whether this will work in all cases, but at least it will tell you whether you had warnings or not. Hope this helps you

user_67347620
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