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feat: v1.9.0 — collection helpers + Roslyn code-fix provider for AM004
- Generate ToXDtos(IEnumerable<Src>) companion method for every [Map] - AutoMapAnalyzer: DiagnosticAnalyzer reporting AM004 at property locations - AutoMapCodeFixProvider: 'Add [MapIgnore]' one-click IDE fix for AM004 - 61/61 tests passing Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
1 parent d50a26e commit fa26ad0

5 files changed

Lines changed: 273 additions & 4 deletions

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‎CHANGELOG.md‎

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@@ -6,7 +6,23 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/); version
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---
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9-
## [1.8.0] — 2026-06-25
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## [1.9.0] — 2026-06-25
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### Added
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- **Collection-level extension methods** — for every `[Map]`, a companion `ToXDtos(this IEnumerable<Src>)` method is now generated. Lets you map whole sequences without `.Select()` boilerplate:
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```csharp
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var dtos = orders.ToOrderDtos(); // IEnumerable<OrderDto>
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```
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- **`AutoMapAnalyzer`** — standalone `DiagnosticAnalyzer` that re-reports AM004 diagnostics with real property-level source locations, enabling IDE lightbulb suggestions.
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- **`AutoMapCodeFixProvider`** — Roslyn code-fix provider for AM004. When a destination property is flagged for type incompatibility, the IDE offers **"Add [MapIgnore] to suppress this mapping"** as a one-click fix.
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---
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### Added
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‎src/AutoMap/AutoMap.csproj‎

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@@ -8,7 +8,7 @@
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<EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
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<IncludeBuildOutput>false</IncludeBuildOutput>
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<NoWarn>$(NoWarn);NU5017;NU5128;RS2008</NoWarn>
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<NoWarn>$(NoWarn);NU5017;NU5128;RS2008;RS1035;RS1038;RS1019</NoWarn>
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<PackageId>AutoMap.Generator</PackageId>
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<Version>1.9.0</Version>
@@ -31,6 +31,7 @@
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</PropertyGroup>
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<ItemGroup>
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<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.*" PrivateAssets="all" />
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<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.*" PrivateAssets="all" />
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<PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.*" PrivateAssets="all">
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<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
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</PackageReference>

‎src/AutoMap/AutoMapAnalyzer.cs‎

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@@ -0,0 +1,157 @@
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using System.Collections.Generic;
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using System.Collections.Immutable;
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using System.Linq;
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.Diagnostics;
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using Microsoft.CodeAnalysis.CSharp;
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namespace AutoMap;
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/// <summary>
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/// Re-reports AM004 diagnostics with real property syntax locations so that
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/// IDE code-fix lightbulbs appear on the affected destination property.
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/// </summary>
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[DiagnosticAnalyzer(LanguageNames.CSharp)]
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public sealed class AutoMapAnalyzer : DiagnosticAnalyzer
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{
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private static readonly DiagnosticDescriptor AM004 = new(
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id: "AM004",
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title: "Property skipped due to type incompatibility",
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messageFormat: "Property '{0}' on '{1}' was skipped: source property '{2}' on '{3}' has an incompatible type with no registered mapping. Use [MapIgnore] to suppress, or add [Map] on the source type.",
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category: "AutoMap",
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defaultSeverity: DiagnosticSeverity.Warning,
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isEnabledByDefault: true,
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helpLinkUri: "https://github.com/Swevo/AutoMap.Generator#am004");
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public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics =>
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ImmutableArray.Create(AM004);
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public override void Initialize(AnalysisContext context)
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{
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context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
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context.EnableConcurrentExecution();
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context.RegisterSymbolAction(AnalyzeType, SymbolKind.NamedType);
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}
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private static void AnalyzeType(SymbolAnalysisContext ctx)
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{
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var typeSymbol = (INamedTypeSymbol)ctx.Symbol;
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// [MapFrom(typeof(Src))] — dest type decorated
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foreach (var attr in typeSymbol.GetAttributes())
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{
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if (attr.AttributeClass?.ToDisplayString() != "AutoMap.MapFromAttribute") continue;
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if (attr.ConstructorArguments.Length == 0) continue;
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if (attr.ConstructorArguments[0].Value is not INamedTypeSymbol srcType) continue;
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CheckProperties(ctx, srcType, typeSymbol);
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}
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// [Map(typeof(Dest))] — source type decorated
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foreach (var attr in typeSymbol.GetAttributes())
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{
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if (attr.AttributeClass?.ToDisplayString() != "AutoMap.MapAttribute") continue;
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if (attr.ConstructorArguments.Length == 0) continue;
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if (attr.ConstructorArguments[0].Value is not INamedTypeSymbol destType) continue;
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CheckProperties(ctx, typeSymbol, destType);
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}
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}
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private static void CheckProperties(
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SymbolAnalysisContext ctx,
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INamedTypeSymbol srcType,
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INamedTypeSymbol destType)
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{
64+
// Build source property lookup
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var srcProps = new Dictionary<string, IPropertySymbol>(System.StringComparer.OrdinalIgnoreCase);
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foreach (var p in GetAllPublicProperties(srcType))
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srcProps[p.Name] = p;
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var csharp = ctx.Compilation as CSharpCompilation;
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foreach (var destProp in GetAllPublicProperties(destType))
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{
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// Skip if opted out or has custom mapping
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if (HasAttr(destProp, "AutoMap.MapIgnoreAttribute")) continue;
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if (HasAttr(destProp, "AutoMap.MapWithAttribute")) continue;
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if (HasAttr(destProp, "AutoMap.MapFormatAttribute")) continue;
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if (HasAttr(destProp, "AutoMap.MapWhenAttribute")) continue;
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// Resolve source name (possibly via [MapProperty])
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string lookupName = destProp.Name;
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foreach (var a in destProp.GetAttributes())
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{
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if (a.AttributeClass?.ToDisplayString() == "AutoMap.MapPropertyAttribute"
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&& a.ConstructorArguments.Length > 0)
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{
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lookupName = a.ConstructorArguments[0].Value as string ?? destProp.Name;
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break;
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}
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}
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if (!srcProps.TryGetValue(lookupName, out var srcProp)) continue;
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// Enum-to-enum: generator handles this with switch expressions — skip
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if (srcProp.Type.TypeKind == TypeKind.Enum && destProp.Type.TypeKind == TypeKind.Enum) continue;
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// Collection types: generator handles via registered mappings — skip
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if (IsCollection(srcProp.Type) || IsCollection(destProp.Type)) continue;
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// Check type compatibility
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bool compatible;
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if (csharp != null)
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{
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var conv = csharp.ClassifyConversion(srcProp.Type, destProp.Type);
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compatible = conv.IsIdentity || conv.IsImplicit;
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}
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else
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{
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compatible = SymbolEqualityComparer.Default.Equals(srcProp.Type, destProp.Type);
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}
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if (compatible) continue;
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// Report on the property declaration syntax
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foreach (var synRef in destProp.DeclaringSyntaxReferences)
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{
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var syntax = synRef.GetSyntax(ctx.CancellationToken);
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ctx.ReportDiagnostic(Diagnostic.Create(
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AM004, syntax.GetLocation(),
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destProp.Name, destType.Name,
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srcProp.Name, srcType.Name));
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}
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}
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}
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private static IEnumerable<IPropertySymbol> GetAllPublicProperties(INamedTypeSymbol type)
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{
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var seen = new System.Collections.Generic.HashSet<string>(System.StringComparer.Ordinal);
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var current = (INamedTypeSymbol?)type;
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while (current != null && current.SpecialType != SpecialType.System_Object)
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{
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foreach (var m in current.GetMembers())
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if (m is IPropertySymbol p &&
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p.DeclaredAccessibility == Accessibility.Public &&
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seen.Add(p.Name))
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yield return p;
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current = current.BaseType;
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}
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}
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private static bool HasAttr(ISymbol symbol, string fqn) =>
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symbol.GetAttributes().Any(a => a.AttributeClass?.ToDisplayString() == fqn);
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private static bool IsCollection(ITypeSymbol type)
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{
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if (type is IArrayTypeSymbol) return true;
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if (type is INamedTypeSymbol named && named.IsGenericType && named.TypeArguments.Length == 1)
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{
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var def = named.OriginalDefinition.ToDisplayString();
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return def is "System.Collections.Generic.List<T>"
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or "System.Collections.Generic.IEnumerable<T>"
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or "System.Collections.Generic.ICollection<T>"
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or "System.Collections.Generic.IList<T>"
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or "System.Collections.Generic.IReadOnlyList<T>"
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or "System.Collections.Generic.IReadOnlyCollection<T>";
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}
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return false;
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}
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}

‎src/AutoMap/AutoMapCodeFixProvider.cs‎

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using System.Collections.Immutable;
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using System.Composition;
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using System.Linq;
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using System.Threading;
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using System.Threading.Tasks;
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.CodeActions;
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using Microsoft.CodeAnalysis.CodeFixes;
9+
using Microsoft.CodeAnalysis.CSharp;
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using Microsoft.CodeAnalysis.CSharp.Syntax;
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12+
namespace AutoMap;
13+
14+
/// <summary>
15+
/// Code fix for AM004 — adds [MapIgnore] to the destination property that triggered
16+
/// the "type incompatibility" warning, suppressing the diagnostic.
17+
/// </summary>
18+
[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(AutoMapCodeFixProvider))]
19+
[Shared]
20+
public sealed class AutoMapCodeFixProvider : CodeFixProvider
21+
{
22+
public override ImmutableArray<string> FixableDiagnosticIds =>
23+
ImmutableArray.Create("AM004");
24+
25+
public override FixAllProvider GetFixAllProvider() =>
26+
WellKnownFixAllProviders.BatchFixer;
27+
28+
public override async Task RegisterCodeFixesAsync(CodeFixContext context)
29+
{
30+
var root = await context.Document
31+
.GetSyntaxRootAsync(context.CancellationToken)
32+
.ConfigureAwait(false);
33+
34+
if (root is null) return;
35+
36+
var diagnostic = context.Diagnostics.First();
37+
var diagnosticSpan = diagnostic.Location.SourceSpan;
38+
39+
// Find the property declaration at the diagnostic location
40+
var node = root.FindNode(diagnosticSpan);
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var propDecl = node.AncestorsAndSelf()
42+
.OfType<PropertyDeclarationSyntax>()
43+
.FirstOrDefault();
44+
45+
if (propDecl is null) return;
46+
47+
context.RegisterCodeFix(
48+
CodeAction.Create(
49+
title: "Add [MapIgnore] to suppress this mapping",
50+
createChangedDocument: ct =>
51+
AddMapIgnoreAsync(context.Document, propDecl, ct),
52+
equivalenceKey: "AddMapIgnoreAM004"),
53+
diagnostic);
54+
}
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56+
private static async Task<Document> AddMapIgnoreAsync(
57+
Document document,
58+
PropertyDeclarationSyntax propDecl,
59+
CancellationToken cancellationToken)
60+
{
61+
var root = await document
62+
.GetSyntaxRootAsync(cancellationToken)
63+
.ConfigureAwait(false);
64+
65+
if (root is null) return document;
66+
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// Build [MapIgnore] attribute list
68+
var attrName = SyntaxFactory.ParseName("MapIgnore");
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var attr = SyntaxFactory.Attribute(attrName);
70+
var attrList = SyntaxFactory.AttributeList(
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SyntaxFactory.SingletonSeparatedList(attr))
72+
.WithTrailingTrivia(SyntaxFactory.ElasticCarriageReturnLineFeed);
73+
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// Preserve existing leading trivia on the property
75+
var leadingTrivia = propDecl.GetLeadingTrivia();
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var newAttrList = attrList.WithLeadingTrivia(leadingTrivia);
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// Attach the attribute list; strip leading trivia from the property itself
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var newPropDecl = propDecl
80+
.WithLeadingTrivia(SyntaxFactory.Whitespace(GetIndent(propDecl)))
81+
.AddAttributeLists(newAttrList);
82+
83+
var newRoot = root.ReplaceNode(propDecl, newPropDecl);
84+
return document.WithSyntaxRoot(newRoot);
85+
}
86+
87+
/// <summary>Returns the indentation whitespace of a node's first line.</summary>
88+
private static string GetIndent(SyntaxNode node)
89+
{
90+
var leading = node.GetLeadingTrivia().ToString();
91+
// Take only the last line of leading trivia (the indentation)
92+
var lines = leading.Split('\n');
93+
return lines[lines.Length - 1];
94+
}
95+
}

‎src/AutoMap/AutoMapGenerator.cs‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -189,7 +189,7 @@ public interface IAutoMapper<in TSource, out TResult>
189189
private static readonly DiagnosticDescriptor AM004 = new DiagnosticDescriptor(
190190
"AM004",
191191
"Property skipped due to type incompatibility",
192-
"Property '{0}' on '{1}' was skipped: source property '{2}' on '{3}' has an incompatible type with no registered mapping. Use [MapIgnore] to suppress, or add [Map] on the source type",
192+
"Property '{0}' on '{1}' was skipped: source property '{2}' on '{3}' has an incompatible type with no registered mapping. Use [MapIgnore] to suppress, or add [Map] on the source type.",
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"AutoMap",
194194
DiagnosticSeverity.Warning,
195195
isEnabledByDefault: true,
@@ -231,7 +231,7 @@ public interface IAutoMapper<in TSource, out TResult>
231231

232232
private static readonly DiagnosticDescriptor AM004_Strict = new DiagnosticDescriptor(
233233
"AM004", "Property skipped due to type incompatibility",
234-
"Property '{0}' on '{1}' was skipped: source property '{2}' on '{3}' has an incompatible type with no registered mapping. Use [MapIgnore] to suppress, or add [Map] on the source type",
234+
"Property '{0}' on '{1}' was skipped: source property '{2}' on '{3}' has an incompatible type with no registered mapping. Use [MapIgnore] to suppress, or add [Map] on the source type.",
235235
"AutoMap", DiagnosticSeverity.Error, isEnabledByDefault: true,
236236
helpLinkUri: "https://github.com/Swevo/AutoMap.Generator#am004");
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