[NativeAOT] Add managed type sub-descriptor for cDAC - #127025

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@max-charlambmax-charlamb commented Apr 16, 2026

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This PR was created with assistance from GitHub Copilot.

Summary

Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).

Stacked on #127024 — review that PR first.

Changes

Attribute-based type discovery

Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:

  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)

ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.

Validation

The provider fails fast on misconfiguration:

  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names

Files

  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference

Validation

  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed

@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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, '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
[NativeAOT] Add managed type sub-descriptor for cDAC - #127025
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[NativeAOT] Add managed type sub-descriptor for cDAC#127025
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Apr 16, 2026

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This PR was created with assistance from GitHub Copilot.
Summary
Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).
Stacked on #127024 — review that PR first.
Changes
Attribute-based type discovery
Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:
  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)
ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.
Validation
The provider fails fast on misconfiguration:
  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names
Files
  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference
Validation
  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed
@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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, '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
[NativeAOT] Add managed type sub-descriptor for cDAC - #127025
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[NativeAOT] Add managed type sub-descriptor for cDAC#127025
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@max-charlambmax-charlamb
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Apr 16, 2026

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Note
This PR was created with assistance from GitHub Copilot.
Summary
Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).
Stacked on #127024 — review that PR first.
Changes
Attribute-based type discovery
Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:
  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)
ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.
Validation
The provider fails fast on misconfiguration:
  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names
Files
  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference
Validation
  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed
@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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, '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
[NativeAOT] Add managed type sub-descriptor for cDAC - #127025
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[NativeAOT] Add managed type sub-descriptor for cDAC#127025
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Note
This PR was created with assistance from GitHub Copilot.
Summary
Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).
Stacked on #127024 — review that PR first.
Changes
Attribute-based type discovery
Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:
  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)
ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.
Validation
The provider fails fast on misconfiguration:
  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names
Files
  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference
Validation
  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed
@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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, '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" + '

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[NativeAOT] Add managed type sub-descriptor for cDAC - #127025
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[NativeAOT] Add managed type sub-descriptor for cDAC#127025
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Note
This PR was created with assistance from GitHub Copilot.
Summary
Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).
Stacked on #127024 — review that PR first.
Changes
Attribute-based type discovery
Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:
  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)
ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.
Validation
The provider fails fast on misconfiguration:
  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names
Files
  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference
Validation
  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed
@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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, '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 = "*";
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[NativeAOT] Add managed type sub-descriptor for cDAC - #127025
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[NativeAOT] Add managed type sub-descriptor for cDAC#127025
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This PR was created with assistance from GitHub Copilot.
Summary
Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).
Stacked on #127024 — review that PR first.
Changes
Attribute-based type discovery
Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:
  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)
ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.
Validation
The provider fails fast on misconfiguration:
  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names
Files
  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference
Validation
  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed
@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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, '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");
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})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
[NativeAOT] Add managed type sub-descriptor for cDAC - #127025
Closed
max-charlamb wants to merge 1 commit into
dev/max-charlamb/nativeaot-datadescriptorfrom 
dev/max-charlamb/managed-type-descriptors
Closed
[NativeAOT] Add managed type sub-descriptor for cDAC#127025
max-charlamb wants to merge 1 commit into
dev/max-charlamb/nativeaot-datadescriptorfrom 
dev/max-charlamb/managed-type-descriptors
Conversation
@max-charlamb
@max-charlambmax-charlamb
commented
Apr 16, 2026

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Note
This PR was created with assistance from GitHub Copilot.
Summary
Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).
Stacked on #127024 — review that PR first.
Changes
Attribute-based type discovery
Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:
  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)
ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.
Validation
The provider fails fast on misconfiguration:
  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names
Files
  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference
Validation
  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed
@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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April 16, 2026 20:53
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, '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
[NativeAOT] Add managed type sub-descriptor for cDAC - #127025
Closed
max-charlamb wants to merge 1 commit into
dev/max-charlamb/nativeaot-datadescriptorfrom 
dev/max-charlamb/managed-type-descriptors
Closed
[NativeAOT] Add managed type sub-descriptor for cDAC#127025
max-charlamb wants to merge 1 commit into
dev/max-charlamb/nativeaot-datadescriptorfrom 
dev/max-charlamb/managed-type-descriptors
Conversation
@max-charlamb
@max-charlambmax-charlamb
commented
Apr 16, 2026

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Note
This PR was created with assistance from GitHub Copilot.
Summary
Adds ILC infrastructure to emit managed type field offsets as a cDAC sub-descriptor, enabling diagnostic tools to inspect managed type instances without runtime metadata (critical for NativeAOT where metadata may be stripped).
Stacked on #127024 — review that PR first.
Changes
Attribute-based type discovery
Instead of hardcoding BCL implementation details in the compiler (as flagged in #126972 review), types opt-in via internal attributes in NativeAOT CoreLib:
  • [CdacType(""ManagedThread"")] on the type — specifies the cDAC descriptor type name
  • [CdacField(""ManagedThreadId"")] on fields — specifies the cDAC field name (defaults to field name if omitted)
ILC discovers annotated types by scanning the system module metadata, following the same pattern as EagerStaticClassConstructionAttribute.
Validation
The provider fails fast on misconfiguration:
  • Empty/null descriptor names
  • Generic types (not supported — layout depends on instantiation)
  • Duplicate descriptor type or field names
Files
  • CdacTypeAttribute.cs / CdacFieldAttribute.cs — internal attributes
  • Thread.NativeAot.cs — annotated with ManagedThread descriptor
  • ManagedDataDescriptorNode.cs — emits ContractDescriptor with JSON layout
  • ManagedDataDescriptorProvider.cs — attribute scanning and registration
  • datadescriptor.h/.inc — managed sub-descriptor reference
Validation
  • Build: build.cmd clr.aot+libs -rc release — 0 errors, 0 warnings
  • cDAC reader tests: all passed
  • tools.cdac tests: all passed
@max-charlamb
[NativeAOT] Add managed type sub-descriptor for cDAC
f226bc3
Add ILC infrastructure to emit managed type field offsets as a cDAC
sub-descriptor, enabling diagnostic tools to inspect managed type
instances without runtime metadata.
Types opt-in via [CdacType] and [CdacField] attributes in CoreLib.
ILC discovers annotated types at compile time, computes field offsets,
and emits a ContractDescriptor (DotNetManagedContractDescriptor) that
the native runtime references as a sub-descriptor.
Includes:
- CdacTypeAttribute / CdacFieldAttribute in NativeAOT CoreLib
- ManagedDataDescriptorNode: emits ContractDescriptor with JSON layout
- ManagedDataDescriptorProvider: attribute-based type discovery with
validation (rejects generics, duplicates, empty names)
- Thread.NativeAot.cs annotated with ManagedThread descriptor fields
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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April 16, 2026 20:53
@max-charlamb
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