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[generator] Don't avoid blittable types for fields - #1353

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jonathanpeppers merged 2 commits into
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jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
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[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean

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Fixes: dotnet/android#10404

Context: 57f7bc8

Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:

  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.

The problem is that this hit a codepath which was not "for native callback methods": field bindings.

Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:

package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:

namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.

The following code fragment:

var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:

F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.

The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:

namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).

@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
CopilotAI reviewed Aug 12, 2025
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Pull Request Overview

This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.

  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests

Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
jonathanpeppers enabled auto-merge (squash) August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers merged commit 90ac202 into dotnet:mainAug 12, 2025
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@jonathanpeppersjonathanpeppers mentioned this pull request Aug 18, 2025
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+2 more reviewers
@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
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JNI DETECTED ERROR IN APPLICATION around accessing boolean fields

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@jonpryor@grendello@jonathanpeppers
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content

This repository was archived by the owner on Aug 27, 2026. It is now read-only.

[generator] Don't avoid blittable types for fields - #1353
Merged
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
Merged
[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Conversation
@jonpryor
@jonpryorjonpryor
commented
Aug 12, 2025

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Contributor
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:
  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was not "for native callback methods": field bindings.
Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.
The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).
@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
CopilotAI
reviewed
Aug 12, 2025
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left a comment


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Pull Request Overview
This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.
  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests
Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
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enabled auto-merge (squash)
August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers
merged commit 90ac202
into
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@jonathanpeppersjonathanpeppers
mentioned this pull request
Aug 18, 2025

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Applies to this pull request for everyone.Learn more about Copilot code review.
Copilot left review comments

+2 more reviewers

@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
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Successfully merging this pull request may close these issues.

JNI DETECTED ERROR IN APPLICATION around accessing boolean fields


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@jonpryor@grendello@jonathanpeppers

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content

This repository was archived by the owner on Aug 27, 2026. It is now read-only.

[generator] Don't avoid blittable types for fields - #1353
Merged
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
Merged
[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Conversation
@jonpryor
@jonpryorjonpryor
commented
Aug 12, 2025

Copy link


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Contributor
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:
  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was not "for native callback methods": field bindings.
Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.
The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).
@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
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Pull Request Overview
This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.
  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests
Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
jonathanpeppers
enabled auto-merge (squash)
August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers
merged commit 90ac202
into
dotnet:mainAug 12, 2025

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mentioned this pull request
Aug 18, 2025

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@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
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JNI DETECTED ERROR IN APPLICATION around accessing boolean fields


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@jonpryor@grendello@jonathanpeppers

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content

This repository was archived by the owner on Aug 27, 2026. It is now read-only.

[generator] Don't avoid blittable types for fields - #1353
Merged
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
Merged
[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
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@jonpryor
@jonpryorjonpryor
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Aug 12, 2025

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Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:
  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was not "for native callback methods": field bindings.
Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.
The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).
@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
CopilotAI
reviewed
Aug 12, 2025
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left a comment


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Pull Request Overview
This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.
  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests
Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
jonathanpeppers
enabled auto-merge (squash)
August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers
merged commit 90ac202
into
dotnet:mainAug 12, 2025

2 checks passed

@jonathanpeppersjonathanpeppers
mentioned this pull request
Aug 18, 2025

Closed

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Applies to this pull request for everyone.Learn more about Copilot code review.
Copilot left review comments

+2 more reviewers

@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
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Successfully merging this pull request may close these issues.

JNI DETECTED ERROR IN APPLICATION around accessing boolean fields


4 participants

@jonpryor@grendello@jonathanpeppers

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content

This repository was archived by the owner on Aug 27, 2026. It is now read-only.

[generator] Don't avoid blittable types for fields - #1353
Merged
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
Merged
[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Conversation
@jonpryor
@jonpryorjonpryor
commented
Aug 12, 2025

Copy link


Copy Markdown

Contributor
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:
  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was not "for native callback methods": field bindings.
Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.
The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).
@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
CopilotAI
reviewed
Aug 12, 2025
View reviewed changes
CopilotAI
left a comment


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Copy Markdown

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Pull Request Overview
This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.
  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests
Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
jonathanpeppers
enabled auto-merge (squash)
August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers
merged commit 90ac202
into
dotnet:mainAug 12, 2025

2 checks passed

@jonathanpeppersjonathanpeppers
mentioned this pull request
Aug 18, 2025

Closed

@github-actionsgithub-actionsBot
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Sep 12, 2025
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Copilot code reviewCopilot
Copilot review effort, defaults to Lite
Applies to this pull request for everyone.Learn more about Copilot code review.
Copilot left review comments

+2 more reviewers

@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
Reviewers whose approvals may not affect merge requirements

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Successfully merging this pull request may close these issues.

JNI DETECTED ERROR IN APPLICATION around accessing boolean fields


4 participants

@jonpryor@grendello@jonathanpeppers

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content

This repository was archived by the owner on Aug 27, 2026. It is now read-only.

[generator] Don't avoid blittable types for fields - #1353
Merged
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
Merged
[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
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@jonpryorjonpryor
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Aug 12, 2025

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Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:
  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was not "for native callback methods": field bindings.
Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.
The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).
@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
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Pull Request Overview
This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.
  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests
Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
jonathanpeppers
enabled auto-merge (squash)
August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers
merged commit 90ac202
into
dotnet:mainAug 12, 2025

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mentioned this pull request
Aug 18, 2025

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@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
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JNI DETECTED ERROR IN APPLICATION around accessing boolean fields


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@jonpryor@grendello@jonathanpeppers

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content

This repository was archived by the owner on Aug 27, 2026. It is now read-only.

[generator] Don't avoid blittable types for fields - #1353
Merged
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
Merged
[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Conversation
@jonpryor
@jonpryorjonpryor
commented
Aug 12, 2025

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Contributor
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:
  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was not "for native callback methods": field bindings.
Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.
The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).
@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
CopilotAI
reviewed
Aug 12, 2025
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left a comment


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Pull Request Overview
This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.
  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests
Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
jonathanpeppers
enabled auto-merge (squash)
August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers
merged commit 90ac202
into
dotnet:mainAug 12, 2025

2 checks passed

@jonathanpeppersjonathanpeppers
mentioned this pull request
Aug 18, 2025

Closed

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+2 more reviewers

@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
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JNI DETECTED ERROR IN APPLICATION around accessing boolean fields


4 participants

@jonpryor@grendello@jonathanpeppers

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

Skip to content

This repository was archived by the owner on Aug 27, 2026. It is now read-only.

[generator] Don't avoid blittable types for fields - #1353
Merged
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Aug 12, 2025
Merged
[generator] Don't avoid blittable types for fields#1353
jonathanpeppers merged 2 commits into
dotnet:mainfrom 
jonpryor:dev/jonpryor/jonp-field-SetValue-boolean
Conversation
@jonpryor
@jonpryorjonpryor
commented
Aug 12, 2025

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Contributor
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated generator to "avoid non-blittable types" in native callback methods, for which there were two non-blittables:
  • System.Boolean, which should be marshaled as a System.SByte, and
  • System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was not "for native callback methods": field bindings.
Consider android.widget.RelativeLayout.LayoutParams.alignWithParent:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}

which is bound as RelativeLayout.LayoutParams.AlignWithParent:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}

The problem is the property setter, which calls
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte). Before 57f7bc8, it would instead call
Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool), but with 57f7bc8 there are now runtime crashes when boolean fields are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};

crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)

Fix this by updating generator so that BoundFieldAsProperty.cs uses the parameter as-is when ISymbol.OnlyFormatOnMarshal=true.
The binding for RelativeLayout.LayoutParams.AlignWithParent becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}

i.e. calling JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool).
@jonpryor
[generator] Don't avoid blittable types for fields
45c4381
Fixes: dotnet/android#10404
Context: 57f7bc8
Commit 57f7bc8 updated `generator` to "avoid non-blittable types"
in native callback methods, for which there were two non-blittables:
* System.Boolean, which should be marshaled as a System.SByte, and
* System.Char, which should be marshaled as a System.UInt16.
The problem is that this hit a codepath which was *not*
"for native callback methods": field bindings.
Consider [`android.widget.RelativeLayout.LayoutParams.alignWithParent`][0]:
package android.widget;
public /* partial */ class RelativeLayout {
public /* partial */ class LayoutParams {
public boolean alignWithParent;
}
}
which is bound as [`RelativeLayout.LayoutParams.AlignWithParent`][1]:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value ? (sbyte)1 : (sbyte)0);
}
}
}
}
The problem is the property setter, which calls
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, sbyte)`.
Before 57f7bc8, it would instead call
`Java.Interop.JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`,
but with 57f7bc8 there are now runtime crashes when boolean fields
are accessed, starting in .NET 10 Preview 2.
The following code fragment:
var p = new RelativeLayout.LayoutParams (1, 2) {
AlignWithParent = true,
};
crashes with:
F droid_boolfiel: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: attempt to access field boolean android.widget.RelativeLayout$LayoutParams.alignWithParent of type boolean with the wrong type byte: 0x709385d8
F droid_boolfiel: java_vm_ext.cc:542] in call to SetByteField
F droid_boolfiel: java_vm_ext.cc:542] from void crc6463d68d2626be2acb.MainActivity.n_onCreate(android.os.Bundle)
Fix this by updating `generator` so that `BoundFieldAsProperty.cs`
uses the parameter as-is when `ISymbol.OnlyFormatOnMarshal`=true.
The binding for `RelativeLayout.LayoutParams.AlignWithParent` becomes:
namespace Android.Widget;
public partial class RelativeLayout {
public new partial class LayoutParams {
[Register]
public bool AlignWithParent {
get => _members.InstanceFields.GetBooleanValue ("alignWithParent.Z", this);
set {
_members.InstanceFields.SetValue("alignWithParent.Z", this, value);
}
}
}
}
i.e. calling `JniPeerMembers.JniInstanceFields.SetValue(string, IJavaPeerable, bool)`.
[0]: https://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams#alignWithParent
[1]: https://learn.microsoft.com/en-us/dotnet/api/android.widget.relativelayout.layoutparams.alignwithparent?view=net-android-34.0
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Pull Request Overview
This PR fixes a runtime crash in .NET 10 Preview 2 where boolean field setters were calling the wrong JNI method due to an unintended side effect of commit 57f7bc8. The issue occurred when the generator's "avoid non-blittable types" logic, intended for native callback methods, was incorrectly applied to field bindings.
  • Fixes field property setters to use the correct parameter type instead of converting to native types
  • Restores proper boolean field handling by preserving the original parameter when OnlyFormatOnMarshal is true
  • Adds test coverage for boolean and char field bindings to prevent regression
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
tools/generator/SourceWriters/BoundFieldAsProperty.csCore fix - conditionally preserve parameter type for field setters when OnlyFormatOnMarshal is true
tests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.csTest output showing corrected static boolean/char field property generation
tests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.csTest output showing corrected instance boolean/char field property generation
tests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected static field generation
tests/generator-Tests/expected.ji/StaticFields/StaticField.xmlTest metadata defining boolean and char fields for static field tests
tests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.csTest output for Java.Interop target showing corrected instance field generation
tests/generator-Tests/expected.ji/NonStaticFields/NonStaticField.xmlTest metadata defining boolean and char fields for instance field tests
Comment threadtests/generator-Tests/expected.xaji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.xaji/NonStaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/StaticFields/Xamarin.Test.SomeObject.cs
Comment threadtests/generator-Tests/expected.ji/NonStaticFields/Xamarin.Test.SomeObject.cs
@jonathanpeppers
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August 12, 2025 18:44
@jonathanpeppers
jonathanpeppers
merged commit 90ac202
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dotnet:mainAug 12, 2025

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Aug 18, 2025

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@grendellogrendellogrendello approved these changes
@jonathanpeppersjonathanpeppersjonathanpeppers approved these changes
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JNI DETECTED ERROR IN APPLICATION around accessing boolean fields


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