Add polyfills for `Interlocked.And` and `Interlocked.Or` by Copilot · Pull Request #80 · Tyrrrz/PolyShim

Copilot · 2026-02-17T20:38:17Z

Adds polyfills for non-generic Interlocked.And and Interlocked.Or methods (for int, uint, long, ulong types) introduced in .NET 5.0, enabling their use on all .NET Standard, .NET Framework, and .NET Core 1.0-4.x versions.

Implementation

Polyfills (PolyShim/Net50/Interlocked.cs):

Non-generic overloads for int, uint, long, ulong (introduced in .NET 5.0)
Implemented using CompareExchange loops (no dependencies)
uint/ulong overloads use unsafe pointers for type conversion (gated by ALLOW_UNSAFE_BLOCKS)
Method signatures match .NET 5.0+ API exactly (not marked unsafe)
Returns the original value before the operation (consistent with .NET 5.0+ behavior)
Active on all .NET Standard, .NET Framework, and .NET Core 1.0-4.x versions
Uses standard Net50 conditional compilation pattern: (NETCOREAPP && !NET5_0_OR_GREATER) || (NETFRAMEWORK) || (NETSTANDARD)

Tests (PolyShim.Tests/Net50/InterlockedTests.cs):

2 focused test methods covering all supported integer types (int, uint, long, ulong)

Usage

// Works on all framework versions instead of requiring .NET 5.0+
int value = 0xFF;
int original = Interlocked.And(ref value, 0x0F);  // Now available via polyfill
// original: 0xFF, value: 0x0F

long flags = 0x1;
Interlocked.Or(ref flags, 0x4);  // Now available via polyfill
// flags: 0x5

Technical Details

int/long methods: Use CompareExchange loops for atomic bitwise operations (no dependencies)
uint/ulong methods: Use unsafe pointers with internal unsafe blocks to delegate to int/long implementations (no dependencies)
Framework coverage: All .NET Standard versions, all .NET Framework versions, and .NET Core 1.0-4.x

The implementation provides maximum framework support with zero external dependencies by using CompareExchange loops and unsafe pointers for type conversions. The polyfill signatures exactly match the actual .NET 5.0+ API surface - methods are not marked as unsafe even though they use unsafe code internally, ensuring perfect binary compatibility.

Note

Generic overloads like Interlocked.And<T> and Interlocked.Or<T> do not exist in .NET - only Interlocked.Exchange<T> and Interlocked.CompareExchange<T> have generic versions.

Original prompt

Let's add polyfills for recently introduced Interlocked methods and overloads

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Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

…data types Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Tyrrrz

@copilot

Tyrrrz · 2026-02-17T21:05:35Z

PolyShim.Tests/Net100/InterlockedTests.cs

+    [Theory]
+    [InlineData((byte)0b00001111, (byte)0b11110000, (byte)0b00000000)]


Don't do theories. Just make one test that verifies a bunch of overloads at the same time.

Done in 6c9a45b - replaced Theory tests with single Fact tests that verify multiple overloads.

Tyrrrz · 2026-02-17T21:06:21Z

PolyShim/Net100/Interlocked.cs

@@ -0,0 +1,197 @@
+#if (NETCOREAPP) || (NETFRAMEWORK) || (NETSTANDARD)


Aren't these added in .NET 10?

These generic methods (Interlocked.Or<T> and Interlocked.And<T>) were actually added in .NET 11 according to the API proposal (dotnet/runtime#114568). The non-generic overloads for int/uint/long/ulong exist in .NET 9, but the generic versions are .NET 11. Since NET11_0_OR_GREATER doesn't exist yet in the SDK, the polyfills remain active for now and will automatically be disabled once .NET 11 is released.

Tyrrrz · 2026-02-17T21:06:32Z

PolyShim/Net100/Interlocked.cs

+#if (NETCOREAPP) || (NETFRAMEWORK) || (NETSTANDARD)
+// NOTE: These polyfills will be automatically disabled when NET11_0_OR_GREATER is defined.
+// Until then, they provide the generic And<T>/Or<T> methods for .NET 9 and 10.
+#if NET9_0_OR_GREATER


Removed in 6c9a45b - the comment was unnecessary.

Tyrrrz · 2026-02-17T21:06:49Z

PolyShim/Net100/Interlocked.cs

+[ExcludeFromCodeCoverage]
+internal static class MemberPolyfills_Net100_Interlocked
+{
+    extension(global::System.Threading.Interlocked)


Why global::

Removed in 6c9a45b - changed to just System.Threading.Interlocked without the global:: prefix to match project style.

Tyrrrz · 2026-02-17T21:07:29Z

PolyShim/Net100/Interlocked.cs

+            where T : struct
+        {
+            // Only integer primitive types and enum types backed by integer types are supported.
+            // Floating-point types and floating-point backed enums are not supported.


Are floating point enums even a thing?

You're right, they don't exist in C#. Removed that check in 6c9a45b - now only checking for float/double primitive types.

Tyrrrz · 2026-02-17T21:08:18Z

PolyShim/Net100/Interlocked.cs

+    }
+}
+#endif
+#endif


What about the generic Interlocked.Exchange?

Generic Interlocked.Exchange<T> already exists in .NET Core 2.0+ (according to MS docs), so it doesn't need a polyfill for the frameworks targeted by Net100.

…x conditionals Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot · 2026-02-17T21:19:20Z

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

example.com
- Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/PolyShim/PolyShim/PolyShim.Tests/bin/Release/net10.0/PolyShim.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/PolyShim/PolyShim/PolyShim.Tests/bin/Release/net10.0/PolyShim.Tests.deps.json /home/REDACTED/work/PolyShim/PolyShim/PolyShim.Tests/bin/Release/net10.0/testhost.dll --port 38063 --endpoint 127.0.0.1:038063 --role client --parentprocessid 6805 --telemetryoptedin false emblyInfo.cs nfig/composer/ve--noprofile grep (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Tyrrrz

@copilot

Tyrrrz · 2026-02-17T21:23:15Z

PolyShim/Net100/Interlocked.cs

+[ExcludeFromCodeCoverage]
+internal static class MemberPolyfills_Net100_Interlocked
+{
+    extension(System.Threading.Interlocked)


Why fully qualified name?

Removed in 3c26340 - changed from System.Threading.Interlocked to just Interlocked to match the pattern in other Net100 files.

Tyrrrz · 2026-02-17T21:27:54Z

PolyShim/Net100/Interlocked.cs

+    extension(System.Threading.Interlocked)
+    {
+        // https://learn.microsoft.com/dotnet/api/system.threading.interlocked.and#system-threading-interlocked-and-1(-0@-0)
+        public static T And<T>(ref T location1, T value)


Can we have an overload for every type and have the generic overload delegate to what's appropriate? Same with Or

Done in 3c26340 - added specific overloads for int, uint, long, and ulong. The generic methods now check the type and delegate to the appropriate specific overload when possible, falling back to size-based dispatch for enums.

…ification Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot · 2026-02-17T21:37:24Z

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

example.com
- Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/PolyShim/PolyShim/PolyShim.Tests/bin/Release/net10.0/PolyShim.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/PolyShim/PolyShim/PolyShim.Tests/bin/Release/net10.0/PolyShim.Tests.deps.json /home/REDACTED/work/PolyShim/PolyShim/PolyShim.Tests/bin/Release/net10.0/testhost.dll --port 35581 --endpoint 127.0.0.1:035581 --role client --parentprocessid 7132 --telemetryoptedin false (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Tyrrrz · 2026-02-18T07:08:48Z

Any way to polyfill these below net 5? @copilot

Copilot · 2026-02-18T07:10:17Z

Any way to polyfill these below net 5? @copilot

The current implementation requires .NET 5.0+ due to the Unsafe class usage. However, the fundamental constraint is that the non-generic Interlocked.And/Or methods (for int/uint/long/ulong) were only added in .NET 9.0, and these polyfills depend on those base methods.

We could potentially lower the requirement from NET5_0 to include older frameworks like .NET Core 2.0+ and .NET Framework 4.6.1+ since those have Unsafe available through the System.Memory package (which is already referenced in the project). However, this would only work if the target runtime is .NET 9.0+, which defeats the purpose since at that point the base And/Or methods would already be available.

To truly polyfill below .NET 9, we would need to implement the non-generic And/Or methods first (using CompareExchange loops), but that seems outside the scope of Net100 polyfills.

Tyrrrz · 2026-02-18T07:15:15Z

How hard would it be to polyfill these APIs without Unsafe? @copilot

Copilot · 2026-02-18T07:16:24Z

How hard would it be to polyfill these APIs without Unsafe? @copilot

It's feasible but with trade-offs:

Non-generic overloads for uint/ulong: Could use unsafe pointers instead of Unsafe.As:

unsafe { return *(uint*)&Interlocked.And(ref *(int*)&location1, *(int*)&value); }

This would work on .NET Framework 4.5+ and other older frameworks.

Generic overload: Much harder. Without Unsafe.As<T, TResult>() and Unsafe.SizeOf<T>(), we'd need workarounds that sacrifice either:

Type safety (IL emit, reflection)
Performance (boxing/unboxing)
Atomicity (non-atomic read-modify-write)

The cleanest approach would be to split the implementation:

Non-generic overloads: Use unsafe pointers (available on older frameworks)
Generic overload: Keep Unsafe requirement OR only support known types (int/uint/long/ulong) without size-based fallback for enums

Would you like me to implement the unsafe pointer approach to remove the System.Memory dependency?

…ocks instead Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot · 2026-02-19T12:18:11Z

@copilot can you review the latest comments and evaluate whether you can address them?

Done in b6389a2 - removed the unsafe modifier from all uint/ulong method signatures and moved it to internal unsafe blocks. The polyfill signatures now exactly match the .NET 5.0+ API surface.

Copilot

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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Tyrrrz · 2026-02-19T12:26:02Z

@copilot can you fix merge conflicts by following these steps:

Reset Signatures.md to its original version.
Merge master into your branch.
Regenerate Signatures.md by running the build.
Commit & push

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot · 2026-02-19T12:28:30Z

@copilot can you fix merge conflicts by following these steps:

Reset Signatures.md to its original version.
...

Done in commits f3c6f0e (reset), then merged master, and db95a53 (regenerated signatures). The merge conflicts are resolved and Signatures.md now correctly includes both the Interlocked methods and the TimeProvider/ITimer methods from master. Total: 372 signatures.

codecov · 2026-02-19T12:49:59Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (328ab8f) to head (db95a53).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@     Coverage Diff      @@
##   master   #80   +/-   ##
============================
============================

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Initial plan

480df01

Copilot AI assigned Copilot and Tyrrrz Feb 17, 2026

Copilot started work on behalf of Tyrrrz February 17, 2026 20:38 View session

Copilot AI and others added 3 commits February 17, 2026 20:55

Add Interlocked.Or<T> and Interlocked.And<T> polyfills with tests

95241dd

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Fix Interlocked polyfills - use generic CompareExchange and fix test …

e9341cf

…data types Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Add comment about NET11 conditional compilation

ebd527c

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add polyfills for new Interlocked methods and overloads~~ Add polyfills for Interlocked.Or<T> and Interlocked.And<T> Feb 17, 2026

Copilot AI requested a review from Tyrrrz February 17, 2026 21:04

Copilot finished work on behalf of Tyrrrz February 17, 2026 21:04

Tyrrrz added the enhancement New feature or request label Feb 17, 2026

Tyrrrz reviewed Feb 17, 2026

View reviewed changes

Copilot started work on behalf of Tyrrrz February 17, 2026 21:08 View session

Address PR feedback: simplify implementation, remove Theory tests, fi…

6c9a45b

…x conditionals Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot AI requested a review from Tyrrrz February 17, 2026 21:19

Copilot finished work on behalf of Tyrrrz February 17, 2026 21:19

Tyrrrz reviewed Feb 17, 2026

View reviewed changes

Copilot started work on behalf of Tyrrrz February 17, 2026 21:28 View session

Add specific overloads for int/uint/long/ulong, remove namespace qual…

3c26340

…ification Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot AI requested a review from Tyrrrz February 17, 2026 21:37

Copilot finished work on behalf of Tyrrrz February 17, 2026 21:37

Copilot started work on behalf of Tyrrrz February 18, 2026 07:09 View session

Copilot finished work on behalf of Tyrrrz February 18, 2026 07:10

Copilot started work on behalf of Tyrrrz February 18, 2026 07:15 View session

Copilot started work on behalf of Tyrrrz February 19, 2026 12:15 View session

Remove unsafe modifier from method signatures, use internal unsafe bl…

b6389a2

…ocks instead Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Tyrrrz requested a review from Copilot February 19, 2026 12:18

Copilot AI requested a review from Tyrrrz February 19, 2026 12:18

Copilot finished work on behalf of Tyrrrz February 19, 2026 12:18

Copilot started reviewing on behalf of Tyrrrz February 19, 2026 12:18 View session

Copilot AI reviewed Feb 19, 2026

View reviewed changes

Copilot started work on behalf of Tyrrrz February 19, 2026 12:26 View session

Copilot AI and others added 3 commits February 19, 2026 12:27

Reset Signatures.md to original version before merge

f3c6f0e

Merge master into copilot/add-interlocked-polyfills

f7ee9e5

Regenerate Signatures.md after merging master

db95a53

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

Copilot finished work on behalf of Tyrrrz February 19, 2026 12:30

Tyrrrz approved these changes Feb 19, 2026

View reviewed changes

Tyrrrz changed the title ~~Add polyfills for Interlocked.And and Interlocked.Or~~ Add polyfills for Interlocked.And and Interlocked.Or Feb 19, 2026

Tyrrrz merged commit 9bb9128 into master Feb 19, 2026
5 checks passed

Tyrrrz deleted the copilot/add-interlocked-polyfills branch February 19, 2026 12:49

		[Theory]
		[InlineData((byte)0b00001111, (byte)0b11110000, (byte)0b00000000)]

		@@ -0,0 +1,197 @@
		#if (NETCOREAPP) \|\| (NETFRAMEWORK) \|\| (NETSTANDARD)

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