MSB4086: A numeric comparison was attempted

msbuild

Solution

Ok, daftness.

<CompareVersions LeftHandSide="3.7" RightHandSide="3.6">
  <Output ItemName="ComparisonResult" TaskParameter="Result"/>
</CompareVersions>

should be this:

<CompareVersions LeftHandSide="3.7" RightHandSide="3.6">
  <Output PropertyName="ComparisonResult" TaskParameter="Result"/>
</CompareVersions>

PropertyName instead of ItemName

Problem

My msbuild needs to take conditional action if one version number is greater than another. I've tried to code it like the following, but find I get an error (also below). Where have I gone wrong? ``` <?xml version="1.0" encoding="utf-8"?> <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTargets="Main" ToolsVersion="4.0"> <UsingTask TaskName="CompareVersions" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll"> <ParameterGroup> <LeftHandSide Required="true"/> <RightHandSide Required="true"/> <Result ParameterType="System.Int32" Output="true"/> </ParameterGroup> <Task> <Code Type="Fragment" Language="cs"> Version a = Version.Parse( LeftHandSide ); Version b = Version.Parse( RightHandSide ); Result = a.CompareTo(b); </Code> </Task> </UsingTask> <Target Name="Main"> <CompareVersions LeftHandSide="3.7" RightHandSide="3.6"> <Output ItemName="ComparisonResult" TaskParameter="Result"/> </CompareVersions> <Message Text="ComparisonResult=$(ComparisonResult)"></Message> <PropertyGroup> <Setting Condition="$(ComparisonResult) < 0">true</Setting> </PropertyGroup> <Message Text="Setting=$(Setting)"></Message> </Target> </Project> ``` ``` S:\>msbuild test.proj Microsoft (R) Build Engine version 4.0.30319.18408 [Microsoft .NET Framework, version 4.0.30319.18408] Copyright (C) Microsoft Corporation. All rights reserved. Build started 04/12/2013 15:26:38. Project "S:\test.proj" on node 1 (default targets). Main: ComparisonResult= S:\test.proj(28,16): error MSB4086: A numeric comparison was attempted on "$(ComparisonResult)" that evaluates to "" instead of a number, in conditio n "$(ComparisonResult) < 0". Done Building Project "S:\test.proj" (default targets) -- FAILED. Build FAILED. "S:\test.proj" (default target) (1) -> (Main target) -> S:\test.proj(28,16): error MSB4086: A numeric comparison was attempted on "$(ComparisonResult)" that evaluates to "" instead of a number, in condit ion "$(ComparisonResult) < 0". 0 Warning(s) 1 Error(s) Time Elapsed 00:00:00.09 S:\> ```

Original source