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[release/10.0] Don't warn if we can't find the backing field in trim tools #119857

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Merged
merged 7 commits into from
Sep 19, 2025
+59 −79
Merged

[release/10.0] Don't warn if we can't find the backing field in trim tools #119857

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bb293b1
Don't warn if we can't find the backing field
jtschuster Sep 17, 2025
3e1a2d0
Re-add warning for mismatched backing fields found in get vs set
jtschuster Sep 17, 2025
942cb06
Don't warn for mismatching backing fields
jtschuster Sep 17, 2025
5f86950
Apply suggestion from @Copilot
jtschuster Sep 17, 2025
dc02a3d
Apply suggestion from @Copilot
jtschuster Sep 17, 2025
22efb83
PR Feedback: only check for existing backing field annotation when th…
jtschuster Sep 18, 2025
6c6c999
Fix analyzer tests
jtschuster Sep 18, 2025
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34 changes: 8 additions & 26 deletions src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/Dataflow/FlowAnnotations.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -592,39 +592,21 @@ protected override TypeAnnotations CreateValueFromKey(TypeDesc key)
}
}

if (IsAutoProperty(property))
FieldDesc? backingField = backingFieldFromSetter ?? backingFieldFromGetter;
if (backingField is not null)
{
FieldDesc? backingField = null;
if ((property.SetMethod is not null
&& property.SetMethod.HasCustomAttribute("System.Runtime.CompilerServices", "CompilerGeneratedAttribute")
&& backingFieldFromSetter is null)
|| (property.GetMethod is not null
&& property.GetMethod.HasCustomAttribute("System.Runtime.CompilerServices", "CompilerGeneratedAttribute")
&& backingFieldFromGetter is null))
bool validBackingFieldFound = backingFieldFromGetter is null
|| backingFieldFromSetter is null
|| backingFieldFromGetter == backingFieldFromSetter;
if (validBackingFieldFound)
{
// We failed to find the backing field of an auto-property accessor
_logger.LogWarning(property, DiagnosticId.DynamicallyAccessedMembersCouldNotFindBackingField, property.GetDisplayName());
}
else if (backingFieldFromGetter is not null && backingFieldFromSetter is not null
&& backingFieldFromSetter != backingFieldFromGetter)
{
// We found two different backing fields for the getter and the setter
_logger.LogWarning(property, DiagnosticId.DynamicallyAccessedMembersCouldNotFindBackingField, property.GetDisplayName());
}
else
{
// We either have a single auto-property accessor or both accessors point to the same backing field
backingField = backingFieldFromSetter ?? backingFieldFromGetter;
}

if (backingField != null)
{
if (annotatedFields.Any(a => a.Field == backingField))
if (annotatedFields.Any(a => a.Field == backingField && a.Annotation != annotation))
{
_logger.LogWarning(backingField, DiagnosticId.DynamicallyAccessedMembersOnPropertyConflictsWithBackingField, property.GetDisplayName(), backingField.GetDisplayName());
}
else
{
// Unique backing field with no conflicts with property or existing field
annotatedFields.Add(new FieldAnnotation(backingField, annotation));
}
}
Expand Down
6 changes: 3 additions & 3 deletions src/tools/illink/src/ILLink.RoslynAnalyzer/TrimAnalysis/FlowAnnotations.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -117,11 +117,11 @@ internal static DynamicallyAccessedMemberTypes GetFieldAnnotation(IFieldSymbol f
if (!field.OriginalDefinition.Type.IsTypeInterestingForDataflow(isByRef: field.RefKind is not RefKind.None))
return DynamicallyAccessedMemberTypes.None;

if (field.AssociatedSymbol is IPropertySymbol property)
if (field.AssociatedSymbol is IPropertySymbol property
&& property.IsAutoProperty())
{
// If this is an auto property, we get the property annotation
if (property.IsAutoProperty())
return property.GetDynamicallyAccessedMemberTypes();
return property.GetDynamicallyAccessedMemberTypes();
}

return field.GetDynamicallyAccessedMemberTypes();
Expand Down
2 changes: 1 addition & 1 deletion src/tools/illink/src/ILLink.Shared/DiagnosticId.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -101,7 +101,7 @@ public enum DiagnosticId
XmlInvalidValueForAttributeActionForResource = 2039,
XmlCouldNotFindResourceToRemoveInAssembly = 2040,
DynamicallyAccessedMembersIsNotAllowedOnMethods = 2041,
DynamicallyAccessedMembersCouldNotFindBackingField = 2042,
unused_DynamicallyAccessedMembersCouldNotFindBackingField = 2042,
DynamicallyAccessedMembersConflictsBetweenPropertyAndAccessor = 2043,
XmlCouldNotFindAnyTypeInNamespace = 2044,
AttributeIsReferencedButTrimmerRemoveAllInstances = 2045,
Expand Down
35 changes: 9 additions & 26 deletions src/tools/illink/src/linker/Linker.Dataflow/FlowAnnotations.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -417,39 +417,22 @@ TypeAnnotations BuildTypeAnnotations(TypeDefinition type)
}
}

if (IsAutoProperty(property))

FieldDefinition? backingField = backingFieldFromSetter ?? backingFieldFromGetter;
if (backingField is not null)
{
FieldDefinition? backingField = null;
// If it's an annotated auto-prop, we should be able to find the compiler generated field
if ((property.SetMethod is not null
&& property.SetMethod.IsCompilerGenerated()
&& backingFieldFromSetter is null)
|| (property.GetMethod is not null
&& property.GetMethod.IsCompilerGenerated()
&& backingFieldFromGetter is null))
{
// We failed to find the backing field of an auto-property accessor
_context.LogWarning(property, DiagnosticId.DynamicallyAccessedMembersCouldNotFindBackingField, property.GetDisplayName());
}
else if (backingFieldFromGetter is not null && backingFieldFromSetter is not null
&& backingFieldFromSetter != backingFieldFromGetter)
{
// We found two different backing fields for the getter and the setter
_context.LogWarning(property, DiagnosticId.DynamicallyAccessedMembersCouldNotFindBackingField, property.GetDisplayName());
}
else
{
// We either have a single auto-property accessor or both accessors point to the same backing field
backingField = backingFieldFromSetter ?? backingFieldFromGetter;
}
if (backingField != null)
bool validBackingFieldFound = backingFieldFromGetter is null
|| backingFieldFromSetter is null
|| backingFieldFromGetter == backingFieldFromSetter;
if (validBackingFieldFound)
{
if (annotatedFields.Any(a => a.Field == backingField))
if (annotatedFields.Any(a => a.Field == backingField && a.Annotation != annotation))
{
_context.LogWarning(backingField, DiagnosticId.DynamicallyAccessedMembersOnPropertyConflictsWithBackingField, property.GetDisplayName(), backingField.GetDisplayName());
}
else
{
// Unique backing field with no conflicts with property or existing field
annotatedFields.Add(new FieldAnnotation(backingField, annotation));
}
}
Expand Down
61 changes: 38 additions & 23 deletions src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/PropertyDataFlow.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -288,8 +288,6 @@ public void TestPropertyWithDifferentBackingFields()
private Type PropertyWithDifferentBackingFields_SetterField;

// Analyzer doesn't try to detect backing fields of properties: https://github.com/dotnet/linker/issues/2273
[ExpectedWarning("IL2042",
"Mono.Linker.Tests.Cases.DataFlow.PropertyDataFlow.TestAutomaticPropagationType.PropertyWithDifferentBackingFields", Tool.Trimmer | Tool.NativeAot, "Requires IL")]
[ExpectedWarning("IL2078",
nameof(TestAutomaticPropagationType) + "." + nameof(PropertyWithDifferentBackingFields) + ".get",
"Type", Tool.Analyzer, "")]
Expand All @@ -313,32 +311,57 @@ Type PropertyWithDifferentBackingFields

public void TestPropertyWithExistingAttributes()
{
_ = PropertyWithExistingAttributes;
PropertyWithExistingAttributes = null;
_ = PropertyWithExistingMatchingAttributes;
PropertyWithExistingMatchingAttributes = null;
_ = PropertyWithExistingMismatchedAttributes;
PropertyWithExistingMismatchedAttributes = null;
}

// Analyzer doesn't try to detect backing fields of properties: https://github.com/dotnet/linker/issues/2273
[ExpectedWarning("IL2056", "PropertyWithExistingAttributes", "PropertyWithExistingAttributes_Field", Tool.Trimmer | Tool.NativeAot, "")]
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[CompilerGenerated]
Type PropertyWithExistingAttributes_Field;
Type PropertyWithExistingMatchingAttributes_Field;

[ExpectedWarning("IL2043", ["PropertyWithExistingAttributes", "PropertyWithExistingAttributes.get"], Tool.Analyzer, "")]
[ExpectedWarning("IL2043", ["PropertyWithExistingAttributes", "PropertyWithExistingAttributes.set"], Tool.Analyzer, "")]
[ExpectedWarning("IL2043", ["PropertyWithExistingMatchingAttributes", "PropertyWithExistingMatchingAttributes.get"], Tool.Analyzer, "")]
[ExpectedWarning("IL2043", ["PropertyWithExistingMatchingAttributes", "PropertyWithExistingMatchingAttributes.set"], Tool.Analyzer, "")]
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
Type PropertyWithExistingAttributes
Type PropertyWithExistingMatchingAttributes
{
// On property/accessor mismatch, ILLink warns on accessor and analyzer warns on property https://github.com/dotnet/linker/issues/2654
[ExpectedWarning("IL2043", "PropertyWithExistingAttributes", "PropertyWithExistingAttributes.get", Tool.Trimmer | Tool.NativeAot, "")]
[ExpectedWarning("IL2043", ["PropertyWithExistingMatchingAttributes", "PropertyWithExistingMatchingAttributes.get"], Tool.Trimmer | Tool.NativeAot, "")]
[return: DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[CompilerGenerated]
get { return PropertyWithExistingAttributes_Field; }
get { return PropertyWithExistingMatchingAttributes_Field; }

// On property/accessor mismatch, ILLink warns on accessor and analyzer warns on property https://github.com/dotnet/linker/issues/2654
[ExpectedWarning("IL2043", "PropertyWithExistingAttributes", "PropertyWithExistingAttributes.set", Tool.Trimmer | Tool.NativeAot, "")]
[ExpectedWarning("IL2043", ["PropertyWithExistingMatchingAttributes", "PropertyWithExistingMatchingAttributes.set"], Tool.Trimmer | Tool.NativeAot, "")]
[param: DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[CompilerGenerated]
set { PropertyWithExistingAttributes_Field = value; }
set { PropertyWithExistingMatchingAttributes_Field = value; }
}

// Analyzer doesn't try to detect backing fields of properties: https://github.com/dotnet/linker/issues/2273
[ExpectedWarning("IL2056", "PropertyWithExistingMismatchedAttributes", "PropertyWithExistingMismatchedAttributes_Field", Tool.Trimmer | Tool.NativeAot, "")]
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)]
[CompilerGenerated]
Type PropertyWithExistingMismatchedAttributes_Field;

[ExpectedWarning("IL2043", ["PropertyWithExistingMismatchedAttributes", "PropertyWithExistingMismatchedAttributes.get"], Tool.Analyzer, "")]
[ExpectedWarning("IL2043", ["PropertyWithExistingMismatchedAttributes", "PropertyWithExistingMismatchedAttributes.set"], Tool.Analyzer, "")]
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)]
Type PropertyWithExistingMismatchedAttributes
{
// On property/accessor mismatch, ILLink warns on accessor and analyzer warns on property https://github.com/dotnet/linker/issues/2654
[ExpectedWarning("IL2043", "PropertyWithExistingMismatchedAttributes", "PropertyWithExistingMismatchedAttributes.get", Tool.Trimmer | Tool.NativeAot, "")]
[ExpectedWarning("IL2078", "return value", "PropertyWithExistingMismatchedAttributes_Field")]
[return: DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)]
[CompilerGenerated]
get { return PropertyWithExistingMismatchedAttributes_Field; }

// On property/accessor mismatch, ILLink warns on accessor and analyzer warns on property https://github.com/dotnet/linker/issues/2654
[ExpectedWarning("IL2043", "PropertyWithExistingMismatchedAttributes", "PropertyWithExistingMismatchedAttributes.set", Tool.Trimmer | Tool.NativeAot, "")]
[ExpectedWarning("IL2069", "PropertyWithExistingMismatchedAttributes_Field", "parameter 'value'")]
[param: DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)]
[CompilerGenerated]
set { PropertyWithExistingMismatchedAttributes_Field = value; }
}

// When the property annotation conflicts with the getter/setter annotation,
Expand Down Expand Up @@ -959,7 +982,6 @@ class AutoPropertyUnrecognizedField
private Type Property_BackingField;

[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[ExpectedWarning("IL2042", Tool.NativeAot | Tool.Trimmer, "Requires IL")] // Can't find backing field
public Type Property
{
[CompilerGenerated]
Expand All @@ -980,7 +1002,6 @@ public Type Property
}

[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[ExpectedWarning("IL2042", Tool.NativeAot | Tool.Trimmer, "Requires IL")] // Can't find backing field
public Type PropertyAutoSet
{
[CompilerGenerated]
Expand All @@ -995,10 +1016,8 @@ public Type PropertyAutoSet
}

[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[ExpectedWarning("IL2042", Tool.NativeAot | Tool.Trimmer, "Requires IL")] // Can't find backing field
public Type PropertyAutoGet
{
[ExpectedWarning("IL2078", ["return value", nameof(PropertyAutoGet), "BackingField"], producedBy: Tool.NativeAot | Tool.Trimmer, "Requires IL")]
get;
[CompilerGenerated]
set
Expand All @@ -1010,7 +1029,6 @@ public Type PropertyAutoGet
}

[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[ExpectedWarning("IL2042", Tool.NativeAot | Tool.Trimmer, "Requires IL")] // Can't find backing field
public Type PropertyManualSet
{
[CompilerGenerated]
Expand All @@ -1025,7 +1043,6 @@ public Type PropertyManualSet
}

[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[ExpectedWarning("IL2042", Tool.NativeAot | Tool.Trimmer, "Requires IL")] // Can't find backing field
public Type PropertyManualGet
{
[ExpectedWarning("IL2078", "return value", nameof(Property_BackingField))]
Expand All @@ -1040,7 +1057,6 @@ public Type PropertyManualGet
}

[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[ExpectedWarning("IL2042", Tool.NativeAot | Tool.Trimmer, "Requires IL")] // Can't find backing field
public Type PropertyOnlyGet
{
[CompilerGenerated]
Expand All @@ -1054,7 +1070,6 @@ public Type PropertyOnlyGet
}

[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
[ExpectedWarning("IL2042", nameof(PropertyOnlySet), Tool.NativeAot | Tool.Trimmer, "Requires IL")] // Can't find backing field
public Type PropertyOnlySet
{
[CompilerGenerated]
Expand Down
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