Extensions: FindReferences should link extension members and implementations by jcouv · Pull Request #81685 · dotnet/roslyn

jcouv · 2025-12-14T08:54:55Z

Addresses part of #81507

…tations

CyrusNajmabadi · 2025-12-14T10:25:26Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

+    {
+        // If the given symbol is an extension member, cascade to its implementation method
+        if (symbol.AssociatedExtensionImplementation is { } associatedExtensionImplementation)
+            result.Add(associatedExtensionImplementation);


can likely inline this method, and just replace it with result.AddIfNotNull(symbol.AssociatedExtensionImplementation) #Resolved

CyrusNajmabadi · 2025-12-14T10:26:36Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

+    private static void CascadeFromExtensionImplementation(IMethodSymbol symbol, ArrayBuilder<ISymbol> result)
+    {
+        // If the given symbol is an implementation method of an extension member, cascade to the extension member itself
+        var containingType = symbol.ContainingType;


since we're going from teh classic Foo(this whatever) method to the modern extension, can't you just check if the .MethodKind is Extension here instead of the MightContainExtensionMethods bit? #Resolved

The implementation method is not necessarily an extension method. It's only an extension method if the extension member is a non-static extension method.
If it's a static extension method or a property accessor, the implementation method is not an extension method.
So you can't do 42.get_P() for instance, you can only do E.get_P(42).

Can we at least check and only do this if the member is implicitly declared by the compiler? It feels weird to do this search for all members, including normal user ones.

CyrusNajmabadi · 2025-12-14T10:27:32Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

+        if (containingType is null || !containingType.MightContainExtensionMethods || !symbol.IsStatic)
+            return;
+
+        var implementationDefinition = symbol.OriginalDefinition;


i don't think you need to do .OriginalDefinition within the REfFinder code. Everything is OriginalDefs here. #Resolved

CyrusNajmabadi · 2025-12-14T10:28:40Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

+                    if (associated is null)
+                        continue;
+
+                    if (!object.ReferenceEquals(associated.OriginalDefinition, implementationDefinition))
+                        continue;


Suggested change

if (associated is null)

continue;

if (!object.ReferenceEquals(associated.OriginalDefinition, implementationDefinition))

continue;

if (!Equals(associated, implementationDefinition))

continue;

(we don't use RefEquals or == for symbols in IDE layer).
#Resolved

CyrusNajmabadi · 2025-12-14T10:29:21Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

+                    result.Add(method);
+                }
+            }
+        }


note: having this reverse mapping be available from the copielr would be nice (fi the methods are linked at that level). having to do the search like this feels not great. of course, if it's not available, this is fine. #Resolved

Such mapping isn't available (the compiler doesn't keep a map to easily expose a public API for this)

Filed tracking issue #81686 to collect usage scenarios where such an API would be useful

CyrusNajmabadi · 2025-12-14T10:29:59Z

...es/Core/Portable/FindSymbols/FindReferences/Finders/PropertyAccessorSymbolReferenceFinder.cs

+    {
+        // If the given symbol is an extension accessor, cascade to its implementation method
+        if (symbol.AssociatedExtensionImplementation is { } associatedExtensionImplementation)
+            result.Add(associatedExtensionImplementation);


like above. inline this and replace with:

result.AddIfNotNull(symbol.AssociatedExtensionImplementation); ``` #Resolved

CyrusNajmabadi

Signing off with feedback. Would love an actual compiler api to do some of the contorted stuff.

jcouv · 2025-12-15T21:11:20Z

@CyrusNajmabadi I'd missed operator scenarios. Added

CyrusNajmabadi · 2025-12-16T12:37:00Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

        // If the given symbol is an implementation method of an extension member, cascade to the extension member itself
        var containingType = symbol.ContainingType;
-        if (containingType is null || !containingType.MightContainExtensionMethods || !symbol.IsStatic)
+        if (containingType is null || !containingType.MightContainExtensionMethods || !symbol.IsStatic || !symbol.IsImplicitlyDeclared)


if (symbol is not { IsStatic: true, IsImplicitlyDeclared: true ContainingType.MightContainExtensionMethods: true }) return; ``` #Resolved

CyrusNajmabadi · 2025-12-16T12:37:47Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

+                    if (associated is null)
+                        continue;
+


Suggested change

if (associated is null)

continue;

``` #Resolved

CyrusNajmabadi · 2025-12-16T12:38:41Z

...es/Core/Portable/FindSymbols/FindReferences/Finders/PropertyAccessorSymbolReferenceFinder.cs

+        if (!options.AssociatePropertyReferencesWithSpecificAccessor && symbol.AssociatedSymbol != null)
+            result.Add(symbol.AssociatedSymbol);


if (!options.AssociatePropertyReferencesWithSpecificAccessor) result.AddIfNotNull(symbol.AssociatedSymbol) ``` #Resolved

CyrusNajmabadi · 2025-12-16T12:39:40Z

...es/Core/Portable/FindSymbols/FindReferences/Finders/PropertyAccessorSymbolReferenceFinder.cs

+            result.Add(symbol.AssociatedSymbol);
+
+        // If the given symbol is an extension accessor, cascade to its implementation method
+        result.AddIfNotNull(symbol.AssociatedExtensionImplementation);


what cascades abck from teh impl method to the extension accessor? #Resolved

That's handled by OrdinaryMethodReferenceFinder since the implementation method is an ordinary method. Then the iterative process of cascading should make the cascading transitive.

CyrusNajmabadi · 2025-12-16T12:40:19Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OrdinaryMethodReferenceFinder.cs

+
+            foreach (var member in nestedType.GetMembers())
+            {
+                if (member is IMethodSymbol method)


is this ok that we filtered down to just methods? couldn't an impl method for a property map back to an property?

or will it map back to the accessor? which then maps back to the property? #Resolved

The latter. From my understanding cascading is an iterative process (see DetermineInitialSearchSymbolsAsync)

ok great. thanks :)

CyrusNajmabadi · 2025-12-16T12:41:08Z

...Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/OperatorSymbolReferenceFinder.cs

+        if (symbol.AssociatedExtensionImplementation is { } associatedExtensionMethod)
+        {
+            // If given an extension operator `E.extension(...).operator+`, we cascade to the its implementation method `E.op_Addition(...)`
+            return new([associatedExtensionMethod]);
+        }
+
+        return new([]);


Suggested change

if (symbol.AssociatedExtensionImplementation is { } associatedExtensionMethod)

{

// If given an extension operator `E.extension(...).operator+`, we cascade to the its implementation method `E.op_Addition(...)`

return new([associatedExtensionMethod]);

}

return new([]);

// If given an extension operator `E.extension(...).operator+`, we cascade to the its implementation method `E.op_Addition(...)`

return symbol.AssociatedExtensionImplementation is { } associatedExtensionMethod)

? new([associatedExtensionMethod])

: new([]);

``` #Resolved

CyrusNajmabadi · 2025-12-16T12:44:35Z

minor cleanup feedback. overall looks great. thanks!

Extensions: FindReferences should link extension members and implemen…

a5879b0

…tations

jcouv self-assigned this Dec 14, 2025

jcouv added Area-IDE Feature - Extension Everything The extension everything feature labels Dec 14, 2025

dotnet-policy-service bot added the VSCode label Dec 14, 2025

jcouv mentioned this pull request Dec 14, 2025

Extension member and extension implementation are not tracked together by IDE #81507

Open

4 tasks

CyrusNajmabadi reviewed Dec 14, 2025

View reviewed changes

CyrusNajmabadi approved these changes Dec 14, 2025

View reviewed changes

Julien Couvreur added 2 commits December 14, 2025 08:04

Address feedback

a553bf9

Address feedback

28c0275

jcouv marked this pull request as ready for review December 14, 2025 16:48

jcouv requested a review from a team as a code owner December 14, 2025 16:48

Add support for operators

3e91853

Julien Couvreur added 2 commits December 15, 2025 23:12

Add multi-file tests

dd0b81a

Check IsImplicitlyDeclared

dd5a2f4

jcouv mentioned this pull request Dec 16, 2025

Consider adding a public API mapping implementation methods back to extension members #81686

Open

CyrusNajmabadi reviewed Dec 16, 2025

View reviewed changes

CyrusNajmabadi approved these changes Dec 16, 2025

View reviewed changes

Address feedback

3970d14

jcouv enabled auto-merge (squash) December 16, 2025 21:53

jcouv merged commit e69fc36 into dotnet:main Dec 16, 2025
25 of 26 checks passed

dotnet-policy-service bot added this to the Next milestone Dec 16, 2025

This was referenced Dec 17, 2025

The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

Open

[android-arm64] The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#6408

Open

This was referenced Dec 18, 2025

[release/10.0.2xx] Source code updates from dotnet/roslyn dotnet/dotnet#3936

Merged

[main] Source code updates from dotnet/roslyn dotnet/dotnet#3957

Merged

dotnet-bot mentioned this pull request Dec 19, 2025

[Automated] PRs inserted in VS build main-11318.64 #81761

Closed

davidwengier modified the milestones: Next, 18.3 Jan 6, 2026

davidwengier mentioned this pull request Jan 12, 2026

Update Razor and Roslyn dotnet/vscode-csharp#8877

Merged

		if (!options.AssociatePropertyReferencesWithSpecificAccessor && symbol.AssociatedSymbol != null)
		result.Add(symbol.AssociatedSymbol);

Comments

Conversation

jcouv commented Dec 14, 2025

Uh oh!

CyrusNajmabadi Dec 14, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 14, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

jcouv Dec 14, 2025

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 15, 2025

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 14, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 14, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 14, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

jcouv Dec 14, 2025

Choose a reason for hiding this comment

Uh oh!

jcouv Dec 14, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 14, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi left a comment

Choose a reason for hiding this comment

Uh oh!

jcouv commented Dec 15, 2025

Uh oh!

CyrusNajmabadi Dec 16, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 16, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 16, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 16, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

jcouv Dec 16, 2025

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 16, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

jcouv Dec 16, 2025

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 16, 2025

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi Dec 16, 2025 • edited by jcouv Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CyrusNajmabadi commented Dec 16, 2025

CyrusNajmabadi Dec 14, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 14, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 14, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 14, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 14, 2025 •

edited by jcouv

Loading

jcouv Dec 14, 2025 •

edited

Loading

CyrusNajmabadi Dec 14, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 16, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 16, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 16, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 16, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 16, 2025 •

edited by jcouv

Loading

CyrusNajmabadi Dec 16, 2025 •

edited by jcouv

Loading