From 0fb64d65cc9897d7f53fe42580d538d15d8d8c96 Mon Sep 17 00:00:00 2001
From: Julien Lebosquain <julien@lebosquain.net>
Date: Wed, 21 Jan 2026 08:16:46 +0000
Subject: [PATCH] Enable warnings as errors (#20504)

---
 .editorconfig                                 | 57 +++++++++----------
 Avalonia.sln                                  |  1 -
 Directory.Build.props                         | 23 ++++----
 build/NullableEnable.props                    |  8 +--
 build/TrimmingEnable.props                    | 18 +-----
 build/WarnAsErrors.props                      | 23 --------
 .../Avalonia.HarfBuzz.csproj                  |  2 -
 src/Skia/Avalonia.Skia/Avalonia.Skia.csproj   |  2 -
 8 files changed, 43 insertions(+), 91 deletions(-)
 delete mode 100644 build/WarnAsErrors.props

diff --git a/.editorconfig b/.editorconfig
index 7051372383..bfeab8c84f 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -138,30 +138,25 @@ space_within_single_line_array_initializer_braces = true
 #Net Analyzer
 dotnet_analyzer_diagnostic.category-Performance.severity = none #error - Uncomment when all violations are fixed.
 
-# CS0649: Field 'field' is never assigned to, and will always have its default value 'value'
-dotnet_diagnostic.CS0649.severity = error
-
-# CS0162: Remove unreachable code
-dotnet_diagnostic.CS0162.severity = error
 # CA1018: Mark attributes with AttributeUsageAttribute
-dotnet_diagnostic.CA1018.severity = error
+dotnet_diagnostic.CA1018.severity = warning
 # CA1304: Specify CultureInfo
 dotnet_diagnostic.CA1304.severity = warning
 # CA1802: Use literals where appropriate
 dotnet_diagnostic.CA1802.severity = warning
 # CA1813: Avoid unsealed attributes
-dotnet_diagnostic.CA1813.severity = error
+dotnet_diagnostic.CA1813.severity = warning
 # CA1815: Override equals and operator equals on value types
 dotnet_diagnostic.CA1815.severity = warning
 # CA1820: Test for empty strings using string length
 dotnet_diagnostic.CA1820.severity = warning
 # CA1821: Remove empty finalizers
-dotnet_diagnostic.CA1821.severity = error
+dotnet_diagnostic.CA1821.severity = warning
 # CA1822: Mark members as static
 dotnet_diagnostic.CA1822.severity = suggestion
 dotnet_code_quality.CA1822.api_surface = private, internal
 # CA1823: Avoid unused private fields
-dotnet_diagnostic.CA1823.severity = error
+dotnet_diagnostic.CA1823.severity = warning
 # CA1825: Avoid zero-length array allocations
 dotnet_diagnostic.CA1825.severity = warning
 # CA1826: Use property instead of Linq Enumerable method
@@ -179,48 +174,48 @@ dotnet_diagnostic.CA1851.severity = warning
 #CA1854: Prefer the IDictionary.TryGetValue(TKey, out TValue) method
 dotnet_diagnostic.CA1854.severity = warning
 #CA2211:Non-constant fields should not be visible
-dotnet_diagnostic.CA2211.severity = error
+dotnet_diagnostic.CA2211.severity = warning
 
 # Wrapping preferences
 csharp_wrap_before_ternary_opsigns = false
 
 # Avalonia DevAnalyzer preferences
-dotnet_diagnostic.AVADEV2001.severity = error
+dotnet_diagnostic.AVADEV2001.severity = warning
 
 # Avalonia PublicAnalyzer preferences
-dotnet_diagnostic.AVP1000.severity = error
-dotnet_diagnostic.AVP1001.severity = error
-dotnet_diagnostic.AVP1002.severity = error
-dotnet_diagnostic.AVP1010.severity = error
-dotnet_diagnostic.AVP1011.severity = error
+dotnet_diagnostic.AVP1000.severity = warning
+dotnet_diagnostic.AVP1001.severity = warning
+dotnet_diagnostic.AVP1002.severity = warning
+dotnet_diagnostic.AVP1010.severity = warning
+dotnet_diagnostic.AVP1011.severity = warning
 dotnet_diagnostic.AVP1012.severity = warning
-dotnet_diagnostic.AVP1013.severity = error
-dotnet_diagnostic.AVP1020.severity = error
-dotnet_diagnostic.AVP1021.severity = error
-dotnet_diagnostic.AVP1022.severity = error
-dotnet_diagnostic.AVP1030.severity = error
-dotnet_diagnostic.AVP1031.severity = error
-dotnet_diagnostic.AVP1032.severity = error
-dotnet_diagnostic.AVP1040.severity = error
-dotnet_diagnostic.AVA2001.severity = error
+dotnet_diagnostic.AVP1013.severity = warning
+dotnet_diagnostic.AVP1020.severity = warning
+dotnet_diagnostic.AVP1021.severity = warning
+dotnet_diagnostic.AVP1022.severity = warning
+dotnet_diagnostic.AVP1030.severity = warning
+dotnet_diagnostic.AVP1031.severity = warning
+dotnet_diagnostic.AVP1032.severity = warning
+dotnet_diagnostic.AVP1040.severity = warning
+dotnet_diagnostic.AVA2001.severity = warning
 
 # Xaml files
 [*.{xaml,axaml}]
 indent_size = 2
 # DuplicateSetterError
-avalonia_xaml_diagnostic.AVLN2203.severity = error
+avalonia_xaml_diagnostic.AVLN2203.severity = warning
 # StyleInMergedDictionaries
-avalonia_xaml_diagnostic.AVLN2204.severity = error
+avalonia_xaml_diagnostic.AVLN2204.severity = warning
 # RequiredTemplatePartMissing
-avalonia_xaml_diagnostic.AVLN2205.severity = error
+avalonia_xaml_diagnostic.AVLN2205.severity = warning
 # OptionalTemplatePartMissing
 avalonia_xaml_diagnostic.AVLN2206.severity = info
 # TemplatePartWrongType
-avalonia_xaml_diagnostic.AVLN2207.severity = error
+avalonia_xaml_diagnostic.AVLN2207.severity = warning
 # ItemContainerInsideTemplate
-avalonia_xaml_diagnostic.AVLN2208.severity = error
+avalonia_xaml_diagnostic.AVLN2208.severity = warning
 # Obsolete
-avalonia_xaml_diagnostic.AVLN5001.severity = error
+avalonia_xaml_diagnostic.AVLN5001.severity = warning
 
 # Xml project files
 [*.{csproj,vcxproj,vcxproj.filters,proj,nativeproj,locproj}]
diff --git a/Avalonia.sln b/Avalonia.sln
index 1083462dcc..06c3e051ac 100644
--- a/Avalonia.sln
+++ b/Avalonia.sln
@@ -106,7 +106,6 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Props", "Props", "{F3AC8BC1
 		build\TargetFrameworks.props = build\TargetFrameworks.props
 		build\TrimmingEnable.props = build\TrimmingEnable.props
 		build\UnitTests.NetFX.props = build\UnitTests.NetFX.props
-		build\WarnAsErrors.props = build\WarnAsErrors.props
 		build\XUnit.props = build\XUnit.props
 	EndProjectSection
 EndProject
diff --git a/Directory.Build.props b/Directory.Build.props
index 4498f87dab..400198daf9 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -1,17 +1,18 @@
 <Project>
   <Import Project="$(MSBuildThisFileDirectory)/build/AvaloniaPublicKey.props"/>
   <Import Project="$(MSBuildThisFileDirectory)/build/TargetFrameworks.props"/>
-  <Import Project="$(MSBuildThisFileDirectory)/build/WarnAsErrors.props" />
   <PropertyGroup>
-      <PackageOutputPath Condition="'$(PackageOutputPath)' == ''">$(MSBuildThisFileDirectory)build-intermediate/nuget</PackageOutputPath>
-      <AvaloniaPreviewerNetCoreToolPath>$(MSBuildThisFileDirectory)\src\tools\Avalonia.Designer.HostApp\bin\$(Configuration)\$(AvsCurrentTargetFramework)\Avalonia.Designer.HostApp.dll</AvaloniaPreviewerNetCoreToolPath>
-      <!-- https://github.com/dotnet/msbuild/issues/2661 -->
-      <AddSyntheticProjectReferencesForSolutionDependencies>false</AddSyntheticProjectReferencesForSolutionDependencies>
-      <RunApiCompat>False</RunApiCompat>
-      <LangVersion>14.0</LangVersion>
-      <CreateHardLinksForCopyAdditionalFilesIfPossible>true</CreateHardLinksForCopyAdditionalFilesIfPossible>
-      <CreateHardLinksForCopyFilesToOutputDirectoryIfPossible>true</CreateHardLinksForCopyFilesToOutputDirectoryIfPossible>
-      <CreateHardLinksForCopyLocalIfPossible>true</CreateHardLinksForCopyLocalIfPossible>
-      <CreateHardLinksForPublishFilesIfPossible>true</CreateHardLinksForPublishFilesIfPossible>
+    <PackageOutputPath Condition="'$(PackageOutputPath)' == ''">$(MSBuildThisFileDirectory)build-intermediate/nuget</PackageOutputPath>
+    <AvaloniaPreviewerNetCoreToolPath>$(MSBuildThisFileDirectory)\src\tools\Avalonia.Designer.HostApp\bin\$(Configuration)\$(AvsCurrentTargetFramework)\Avalonia.Designer.HostApp.dll</AvaloniaPreviewerNetCoreToolPath>
+    <!-- https://github.com/dotnet/msbuild/issues/2661 -->
+    <AddSyntheticProjectReferencesForSolutionDependencies>false</AddSyntheticProjectReferencesForSolutionDependencies>
+    <RunApiCompat>False</RunApiCompat>
+    <LangVersion>14.0</LangVersion>
+    <TreatWarningsAsErrors Condition="'$(TreatWarningsAsErrors)' == ''">$(AvnTreatWarningsAsErrors)</TreatWarningsAsErrors>
+    <TreatWarningsAsErrors Condition="'$(TreatWarningsAsErrors)' == '' And '$(Configuration)' == 'Release'">true</TreatWarningsAsErrors>
+    <CreateHardLinksForCopyAdditionalFilesIfPossible>true</CreateHardLinksForCopyAdditionalFilesIfPossible>
+    <CreateHardLinksForCopyFilesToOutputDirectoryIfPossible>true</CreateHardLinksForCopyFilesToOutputDirectoryIfPossible>
+    <CreateHardLinksForCopyLocalIfPossible>true</CreateHardLinksForCopyLocalIfPossible>
+    <CreateHardLinksForPublishFilesIfPossible>true</CreateHardLinksForPublishFilesIfPossible>
   </PropertyGroup>
 </Project>
diff --git a/build/NullableEnable.props b/build/NullableEnable.props
index ef62ecc50c..60b91b85a3 100644
--- a/build/NullableEnable.props
+++ b/build/NullableEnable.props
@@ -1,11 +1,7 @@
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <!-- 
-    The Nullable annotations on netstandard2.0 are incomplete and incorrect in places. Ignore
-    nullable warnings before .NET 6 and make them errors on later target frameworks.
-  -->
   <PropertyGroup>
     <Nullable>enable</Nullable>
-    <WarningsAsErrors Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net6.0'))">$(WarningsAsErrors);nullable</WarningsAsErrors>
-    <NoWarn Condition="!$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net6.0'))">$(NoWarn);nullable</NoWarn>
+    <!-- The nullable annotations on netstandard2.0 are incomplete and incorrect in places. Ignore them. -->
+    <NoWarn Condition="'$(TargetFramework)' == 'netstandard2.0'">$(NoWarn);nullable</NoWarn>
   </PropertyGroup>
 </Project>
diff --git a/build/TrimmingEnable.props b/build/TrimmingEnable.props
index 34b3e232b6..cf84ae67b4 100644
--- a/build/TrimmingEnable.props
+++ b/build/TrimmingEnable.props
@@ -1,28 +1,16 @@
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
 
-  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net6.0'))">
+  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
     <SuppressTrimAnalysisWarnings>false</SuppressTrimAnalysisWarnings>
     <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
     <TrimmerSingleWarn>false</TrimmerSingleWarn>
     <IsTrimmable>true</IsTrimmable>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
     <IsAotCompatible Condition="'$(IsAotCompatible)' == ''">true</IsAotCompatible>
+    <ILLinkTreatWarningsAsErrors>$(TreatWarningsAsErrors)</ILLinkTreatWarningsAsErrors>
   </PropertyGroup>
 
-  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net6.0'))">
-    <ILLinkTreatWarningsAsErrors>true</ILLinkTreatWarningsAsErrors>
-    <!-- Trim warnings -->
-    <WarningsAsErrors>$(WarningsAsErrors);IL2000;IL2001;IL2002;IL2003;IL2004;IL2005;IL2006;IL2007;IL2008;IL2009;IL2010;IL2011;IL2012;IL2013;IL2014;IL2015;IL2016;IL2017;IL2018;IL2019;IL2020;IL2021;IL2022;IL2023;IL2024;IL2025;IL2026;IL2027;IL2028;IL2029;IL2030;IL2031;IL2032;IL2033;IL2034;IL2035;IL2036;IL2037;IL2038;IL2039;IL2040;IL2041;IL2042;IL2043;IL2044;IL2045;IL2046;IL2047;IL2048;IL2049;IL2050;IL2051;IL2052;IL2053;IL2054;IL2055;IL2056;IL2057;IL2058;IL2059;IL2060;IL2061;IL2062;IL2063;IL2064;IL2065;IL2066;IL2067;IL2068;IL2069;IL2070;IL2071;IL2072;IL2073;IL2074;IL2075;IL2076;IL2077;IL2078;IL2079;IL2080;IL2081;IL2082;IL2083;IL2084;IL2085;IL2086;IL2087;IL2088;IL2089;IL2090;IL2091;IL2092;IL2093;IL2094;IL2095;IL2096;IL2097;IL2098;IL2099;IL2100;IL2101;IL2102;IL2103;IL2104;IL2105;IL2106;IL2107;IL2108;IL2109;IL2110;IL2111;IL2112;IL2113;IL2114;IL2115;IL2116;IL2117;IL2118;IL2119;IL2120;IL2121;IL2122;IL2123;IL2124;IL2125;IL2126;IL2127;IL2128;IL2129;IL2130;IL2131;IL2132;IL2133;IL2134;IL2135;IL2136;IL2137;IL2138;IL2139;IL2140;IL2141;IL2142;IL2143;IL2144;IL2145;IL2146;IL2147;IL2148;IL2149;IL2150;IL2151;IL2152;IL2153;IL2154;IL2155;IL2156;IL2157</WarningsAsErrors>
-    <!-- NativeAOT warnings -->
-    <WarningsAsErrors Condition="'$(IsAotCompatible)' == 'true'">$(WarningsAsErrors);IL3050;IL3051;IL3052;IL3053;IL3054;IL3055;IL3056</WarningsAsErrors>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0')) AND '$(EnableRuntimeMarshalling)' != 'true'">
-    <WarningsAsErrors>$(WarningsAsErrors);CA1420;CA1421</WarningsAsErrors>
-  </PropertyGroup>
   <ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0')) AND '$(EnableRuntimeMarshalling)' != 'true'">
     <AssemblyAttribute Include="System.Runtime.CompilerServices.DisableRuntimeMarshallingAttribute" />
   </ItemGroup>
+
 </Project>
diff --git a/build/WarnAsErrors.props b/build/WarnAsErrors.props
deleted file mode 100644
index eaab7bd00c..0000000000
--- a/build/WarnAsErrors.props
+++ /dev/null
@@ -1,23 +0,0 @@
-<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <!-- Keep in sync with .editorconfig -->
-  <PropertyGroup Condition="'$(AvsEnableDevWarningsNotAsErrors)' == 'true'">
-    <!-- CS0649: Field 'field' is never assigned to, and will always have its default value 'value' -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);CS0649</WarningsNotAsErrors>
-    <!-- CS0162: Remove unreachable code -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);CS0162</WarningsNotAsErrors>
-    <!-- CA2211:Non-constant fields should not be visible -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);CA2211</WarningsNotAsErrors>
-    <!-- CA1821: Remove empty finalizers -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);CA1821</WarningsNotAsErrors>
-    <!-- CA1823: Avoid unused private fields -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);CA1823</WarningsNotAsErrors>
-    <!-- AVLN2203: DuplicateSetterError -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);AVLN2203</WarningsNotAsErrors>
-    <!-- AVLN2205: RequiredTemplatePartMissing -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);AVLN2205</WarningsNotAsErrors>
-    <!-- AVLN2207: TemplatePartWrongType -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);AVLN2207</WarningsNotAsErrors>
-    <!-- AVLN2208: ItemContainerInsideTemplate -->
-    <WarningsNotAsErrors>$(WarningsNotAsErrors);AVLN2208</WarningsNotAsErrors>
-  </PropertyGroup>
-</Project>
diff --git a/src/HarfBuzz/Avalonia.HarfBuzz/Avalonia.HarfBuzz.csproj b/src/HarfBuzz/Avalonia.HarfBuzz/Avalonia.HarfBuzz.csproj
index a528326db9..788886f3a9 100644
--- a/src/HarfBuzz/Avalonia.HarfBuzz/Avalonia.HarfBuzz.csproj
+++ b/src/HarfBuzz/Avalonia.HarfBuzz/Avalonia.HarfBuzz.csproj
@@ -4,8 +4,6 @@
         <IncludeLinuxSkia>true</IncludeLinuxSkia>
         <IncludeWasmSkia>true</IncludeWasmSkia>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-        <!-- No obsolete code usage -->
-        <WarningsAsErrors>$(WarningsAsErrors);CS0618</WarningsAsErrors>
     </PropertyGroup>
     <ItemGroup>
         <ProjectReference Include="..\..\..\packages\Avalonia\Avalonia.csproj" />
diff --git a/src/Skia/Avalonia.Skia/Avalonia.Skia.csproj b/src/Skia/Avalonia.Skia/Avalonia.Skia.csproj
index 9c4c4f62fb..d5f541a014 100644
--- a/src/Skia/Avalonia.Skia/Avalonia.Skia.csproj
+++ b/src/Skia/Avalonia.Skia/Avalonia.Skia.csproj
@@ -4,8 +4,6 @@
     <IncludeLinuxSkia>true</IncludeLinuxSkia>
     <IncludeWasmSkia>true</IncludeWasmSkia>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <!-- No obsolete code usage -->
-    <WarningsAsErrors>$(WarningsAsErrors);CS0618</WarningsAsErrors>
   </PropertyGroup>
   <ItemGroup>
     <EmbeddedResource Include="Assets\NoiseAsset_256X256_PNG.png" />