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Source Generator Configuration Model

This document describes the unified configuration model used by XamlToCSharpGenerator.

Sources and precedence

Configuration is merged from these sources:

1. Built-in defaults.
2. File source (xaml-sourcegen.config.json in project root, and explicit AdditionalFiles with the same file name).
3. MSBuild source (build_property.* options).
4. Code source ([assembly: AssemblyMetadata(...)]).

Default precedence values:

Source	Default precedence
Project-default config file	90
Explicit config file AdditionalFiles	100
MSBuild	200
Code	300

Higher precedence wins when multiple sources set the same value.

Overriding source precedence

Set XamlSourceGenConfigurationPrecedence (or compatibility alias AvaloniaSourceGenConfigurationPrecedence) in MSBuild:

<PropertyGroup>
  <XamlSourceGenConfigurationPrecedence>ProjectDefaultFile=90;File=100;MsBuild=200;Code=300</XamlSourceGenConfigurationPrecedence>
</PropertyGroup>

Supported keys:

• ProjectDefaultFile
• File
• MsBuild
• Code

Aliases for ProjectDefaultFile are also accepted: ProjectDefault, DefaultFile.

Invalid segments produce warning AXSG0933.

Canonical file

File name:

• xaml-sourcegen.config.json

The parser accepts JSON comments and trailing commas.

schemaVersion is optional; when specified it must currently be 1 (otherwise warning AXSG0917).

Top-level schema

Top-level sections:

• build
• parser
• semanticContract
• binding
• emitter
• transform
• diagnostics
• frameworkExtras

Unknown keys are ignored. Known keys with invalid value shape produce AXSG0918-AXSG0927 warnings.

Section reference

build

Key	Type
isEnabled	bool
backend	string
strictMode	bool
hotReloadEnabled	bool
hotReloadErrorResilienceEnabled	bool
ideHotReloadEnabled	bool
hotDesignEnabled	bool
iosHotReloadEnabled	bool
iosHotReloadUseInterpreter	bool
dotNetWatchBuild	bool
buildingInsideVisualStudio	bool
buildingByReSharper	bool
additionalProperties	object<string,string>

parser

Key	Type
allowImplicitXmlnsDeclaration	bool
implicitStandardXmlnsPrefixesEnabled	bool
implicitDefaultXmlns	string
inferClassFromPath	bool
implicitProjectNamespacesEnabled	bool
globalXmlnsPrefixes	object<string,string>
additionalProperties	object<string,string>

semanticContract

Key	Type
typeContracts	object<string,string>
propertyContracts	object<string,string>
eventContracts	object<string,string>
additionalProperties	object<string,string>

binding

Key	Type
useCompiledBindingsByDefault	bool
cSharpExpressionsEnabled	bool
implicitCSharpExpressionsEnabled	bool
markupParserLegacyInvalidNamedArgumentFallbackEnabled	bool
typeResolutionCompatibilityFallbackEnabled	bool
additionalProperties	object<string,string>

emitter

Key	Type
createSourceInfo	bool
tracePasses	bool
metricsEnabled	bool
metricsDetailed	bool
additionalProperties	object<string,string>

transform

Key	Type
rawTransformDocuments	object<string,string>
additionalProperties	object<string,string>

diagnostics

Key	Type
treatWarningsAsErrors	bool
severityOverrides	object<string,Info\|Warning\|Error|null>
additionalProperties	object<string,string>

frameworkExtras

Key	Type
sections	object<sectionName, object<string,string>>
additionalProperties	object<string,string>

File example

{
  "schemaVersion": 1,
  "build": {
    "isEnabled": true,
    "backend": "SourceGen",
    "strictMode": true
  },
  "parser": {
    "allowImplicitXmlnsDeclaration": true,
    "implicitDefaultXmlns": "https://github.com/avaloniaui",
    "globalXmlnsPrefixes": {
      "vm": "using:Demo.ViewModels"
    }
  },
  "binding": {
    "useCompiledBindingsByDefault": true
  },
  "diagnostics": {
    "severityOverrides": {
      "AXSG0113": "Info"
    }
  }
}

Code-based configuration

Use assembly metadata keys with prefix XamlSourceGen.:

using System.Reflection;

[assembly: AssemblyMetadata("XamlSourceGen.Build.Backend", "SourceGen")]
[assembly: AssemblyMetadata("XamlSourceGen.Build.IsEnabled", "true")]
[assembly: AssemblyMetadata("XamlSourceGen.Binding.UseCompiledBindingsByDefault", "true")]
[assembly: AssemblyMetadata("XamlSourceGen.Parser.GlobalXmlnsPrefixes.vm", "using:Demo.ViewModels")]

Section/key names are case-insensitive. Invalid keys/values produce warnings AXSG0930-AXSG0932.