From e67914ae40b2a6143adbcda527370fab25666ff5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 27 Jan 2026 01:12:30 +0000
Subject: [PATCH 1/6] Initial plan


From 87161f504e7b5d5a03616ca8f340bd963004a907 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 27 Jan 2026 01:16:10 +0000
Subject: [PATCH 2/6] Document thread-safety concerns for
 NullabilityInfoContext

Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>
---
 xml/System.Reflection/NullabilityInfoContext.xml | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/xml/System.Reflection/NullabilityInfoContext.xml b/xml/System.Reflection/NullabilityInfoContext.xml
index 2abcb3f555a..fd85bab6211 100644
--- a/xml/System.Reflection/NullabilityInfoContext.xml
+++ b/xml/System.Reflection/NullabilityInfoContext.xml
@@ -26,6 +26,7 @@
   <Docs>
     <summary>Provides APIs for populating nullability information and context from reflection members: <see cref="T:System.Reflection.ParameterInfo" />, <see cref="T:System.Reflection.FieldInfo" />, <see cref="T:System.Reflection.PropertyInfo" />, and <see cref="T:System.Reflection.EventInfo" />.</summary>
     <remarks>To be added.</remarks>
+    <threadsafe>This type is not thread-safe. The <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.EventInfo)" />, <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.FieldInfo)" />, <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.ParameterInfo)" />, and <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.PropertyInfo)" /> methods can't be called concurrently from multiple threads, as they use a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />. If you need to use <see cref="T:System.Reflection.NullabilityInfoContext" /> from multiple threads, create a separate instance for each thread or use external synchronization.</threadsafe>
   </Docs>
   <Members>
     <Member MemberName=".ctor">
@@ -75,7 +76,7 @@
         <param name="eventInfo">The event for which to populate nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.EventInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="eventInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -106,7 +107,7 @@
         <param name="fieldInfo">The field for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.FieldInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="fieldInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -137,7 +138,7 @@
         <param name="parameterInfo">The parameter for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.ParameterInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="parameterInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -168,7 +169,7 @@
         <param name="propertyInfo">The property for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.PropertyInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="propertyInfo" /> is <see langword="null" />.</exception>
       </Docs>

From f4705b84fbec565485e4c1f7a048dbb9225feaf1 Mon Sep 17 00:00:00 2001
From: Genevieve Warren <24882762+gewarren@users.noreply.github.com>
Date: Mon, 26 Jan 2026 19:31:16 -0800
Subject: [PATCH 3/6] Update xml/System.Reflection/NullabilityInfoContext.xml

---
 xml/System.Reflection/NullabilityInfoContext.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xml/System.Reflection/NullabilityInfoContext.xml b/xml/System.Reflection/NullabilityInfoContext.xml
index fd85bab6211..e943713a361 100644
--- a/xml/System.Reflection/NullabilityInfoContext.xml
+++ b/xml/System.Reflection/NullabilityInfoContext.xml
@@ -26,7 +26,7 @@
   <Docs>
     <summary>Provides APIs for populating nullability information and context from reflection members: <see cref="T:System.Reflection.ParameterInfo" />, <see cref="T:System.Reflection.FieldInfo" />, <see cref="T:System.Reflection.PropertyInfo" />, and <see cref="T:System.Reflection.EventInfo" />.</summary>
     <remarks>To be added.</remarks>
-    <threadsafe>This type is not thread-safe. The <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.EventInfo)" />, <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.FieldInfo)" />, <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.ParameterInfo)" />, and <see cref="M:System.Reflection.NullabilityInfoContext.Create(System.Reflection.PropertyInfo)" /> methods can't be called concurrently from multiple threads, as they use a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />. If you need to use <see cref="T:System.Reflection.NullabilityInfoContext" /> from multiple threads, create a separate instance for each thread or use external synchronization.</threadsafe>
+    <threadsafe>This type is not thread-safe. The <see cref="Overload:System.Reflection.NullabilityInfoContext.Create" /> methods can't be called concurrently from multiple threads, as they use a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />. If you need to use <see cref="T:System.Reflection.NullabilityInfoContext" /> from multiple threads, create a separate instance for each thread or use external synchronization.</threadsafe>
   </Docs>
   <Members>
     <Member MemberName=".ctor">

From d103db79188b919309449a90c3e49a5d296fe597 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 27 Jan 2026 08:45:08 +0000
Subject: [PATCH 4/6] Update thread-safety documentation per review feedback

Co-authored-by: eiriktsarpalis <2813363+eiriktsarpalis@users.noreply.github.com>
---
 xml/System.Reflection/NullabilityInfoContext.xml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/xml/System.Reflection/NullabilityInfoContext.xml b/xml/System.Reflection/NullabilityInfoContext.xml
index e943713a361..753271049b5 100644
--- a/xml/System.Reflection/NullabilityInfoContext.xml
+++ b/xml/System.Reflection/NullabilityInfoContext.xml
@@ -26,7 +26,7 @@
   <Docs>
     <summary>Provides APIs for populating nullability information and context from reflection members: <see cref="T:System.Reflection.ParameterInfo" />, <see cref="T:System.Reflection.FieldInfo" />, <see cref="T:System.Reflection.PropertyInfo" />, and <see cref="T:System.Reflection.EventInfo" />.</summary>
     <remarks>To be added.</remarks>
-    <threadsafe>This type is not thread-safe. The <see cref="Overload:System.Reflection.NullabilityInfoContext.Create" /> methods can't be called concurrently from multiple threads, as they use a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />. If you need to use <see cref="T:System.Reflection.NullabilityInfoContext" /> from multiple threads, create a separate instance for each thread or use external synchronization.</threadsafe>
+    <threadsafe>This type is not thread safe. The <see cref="Overload:System.Reflection.NullabilityInfoContext.Create" /> methods can't be called concurrently from multiple threads, as they use a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />. If you need to use <see cref="T:System.Reflection.NullabilityInfoContext" /> from multiple threads, use external synchronization.</threadsafe>
   </Docs>
   <Members>
     <Member MemberName=".ctor">
@@ -76,7 +76,7 @@
         <param name="eventInfo">The event for which to populate nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.EventInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="eventInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -107,7 +107,7 @@
         <param name="fieldInfo">The field for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.FieldInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="fieldInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -138,7 +138,7 @@
         <param name="parameterInfo">The parameter for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.ParameterInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="parameterInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -169,7 +169,7 @@
         <param name="propertyInfo">The property for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.PropertyInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread-safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="propertyInfo" /> is <see langword="null" />.</exception>
       </Docs>

From 14fc0d7ee21672ca3473aa2a892f5b85dfe0119d Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 27 Jan 2026 17:59:31 +0000
Subject: [PATCH 5/6] Remove thread-safety remarks from individual methods

Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>
---
 xml/System.Reflection/NullabilityInfoContext.xml | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/xml/System.Reflection/NullabilityInfoContext.xml b/xml/System.Reflection/NullabilityInfoContext.xml
index 753271049b5..fddd9a361b6 100644
--- a/xml/System.Reflection/NullabilityInfoContext.xml
+++ b/xml/System.Reflection/NullabilityInfoContext.xml
@@ -76,7 +76,7 @@
         <param name="eventInfo">The event for which to populate nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.EventInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="eventInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -107,7 +107,7 @@
         <param name="fieldInfo">The field for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.FieldInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="fieldInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -138,7 +138,7 @@
         <param name="parameterInfo">The parameter for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.ParameterInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="parameterInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -169,7 +169,7 @@
         <param name="propertyInfo">The property for which to populate the nullability information.</param>
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.PropertyInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
-        <remarks>This method is not thread safe. Don't call it concurrently from multiple threads, as it uses a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />.</remarks>
+        <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="propertyInfo" /> is <see langword="null" />.</exception>
       </Docs>

From 961c4b6035f7bb877dfd24df65d84fca8e21d625 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 27 Jan 2026 22:17:42 +0000
Subject: [PATCH 6/6] Add threadsafe sections to Create methods

Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>
---
 xml/System.Reflection/NullabilityInfoContext.xml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xml/System.Reflection/NullabilityInfoContext.xml b/xml/System.Reflection/NullabilityInfoContext.xml
index fddd9a361b6..03d05b526bd 100644
--- a/xml/System.Reflection/NullabilityInfoContext.xml
+++ b/xml/System.Reflection/NullabilityInfoContext.xml
@@ -77,6 +77,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.EventInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="eventInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -108,6 +109,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.FieldInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="fieldInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -139,6 +141,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.ParameterInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="parameterInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -170,6 +173,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.PropertyInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="propertyInfo" /> is <see langword="null" />.</exception>
       </Docs>