Add ExplicitThis recipe to make 'this.' prefix explicit. #791

motlin · 2025-11-25T13:35:05Z

What's changed?

Added a new ExplicitThis recipe that automatically adds the explicit this. prefix to instance field accesses and method invocations.

What's your motivation?

This recipe improves code clarity by making it immediately obvious when a field or method belongs to the current instance versus being a local variable, parameter, or static member.
The explicit this. prefix follows a common coding style preference in Java codebases.

Anything in particular you'd like reviewers to focus on?

I wound up writing quite a bit of code to determine whether we're looking at a non-static field that's not already prefixed with this. Is there a better way?

Should I register the recipe in any suite? Should I add the recipe to common-static-analysis.yml (commented out initially)?

Anyone you would like to review specifically?

Have you considered any alternatives or workarounds?

An alternative would be to make this configurable (e.g., only apply to fields, or only to methods), but starting with a simple "always add this." approach keeps the recipe straightforward.

Any additional context

Checklist

I've added unit tests to cover both positive and negative cases
I've read and applied the recipe conventions and best practices
I've used the IntelliJ IDEA auto-formatter on affected files

greg-at-moderne · 2025-11-25T15:41:34Z

Can you add a test with a typical setter implementation?
This is probably the most common example where of variable name shadowing. One being a field and another being a local.

github-actions · 2025-11-25T15:43:04Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+import org.openrewrite.marker.Markers;
+
+import java.time.Duration;
+import java.util.Collections;


Suggested change

import java.util.Collections;

import static java.util.Collections.emptyList;

github-actions · 2025-11-25T15:43:04Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext executionContext) {
+            boolean previousIsInsideFieldAccess = this.isInsideFieldAccess;
+            this.isInsideFieldAccess = true;
+


Suggested change

public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext executionContext) {

boolean previousIsInsideFieldAccess = this.isInsideFieldAccess;

this.isInsideFieldAccess = true;

public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext ctx) {

J result = super.visitFieldAccess(fieldAccess, ctx);

public J visitIdentifier(J.Identifier identifier, ExecutionContext ctx) {

J.Identifier id = (J.Identifier) super.visitIdentifier(identifier, ctx);

github-actions · 2025-11-25T15:43:05Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        public J visitBlock(J.Block block, ExecutionContext executionContext) {
+            if (!block.isStatic()) {
+                return super.visitBlock(block, executionContext);
+            }


Suggested change

public J visitBlock(J.Block block, ExecutionContext executionContext) {

if (!block.isStatic()) {

return super.visitBlock(block, executionContext);

}

public J visitBlock(J.Block block, ExecutionContext ctx) {

return super.visitBlock(block, ctx);

J.Block result = (J.Block) super.visitBlock(block, ctx);

public J visitMethodDeclaration(J.MethodDeclaration method, ExecutionContext ctx) {

github-actions · 2025-11-25T15:43:05Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+                this.isStatic = (methodType.getFlagsBitMap() & 0x0008L) != 0;
+            }
+
+            J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, executionContext);


Suggested change

J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, executionContext);

J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, ctx);

github-actions · 2025-11-25T15:43:05Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {
+            J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, executionContext);
+


Suggested change

public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {

J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, executionContext);

public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {

J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, ctx);

if ("super".equals(m.getName().getSimpleName()) || "this".equals(m.getName().getSimpleName())) {

github-actions · 2025-11-25T15:43:05Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+                String currentClassName = this.getSimpleClassName(currentClassType.getFullyQualifiedName());
+                boolean currentIsAnonymous = this.isAnonymousClassName(currentClassName);
+                return new ClassContext(currentClassType, currentIsAnonymous);
+            } else if (currentCursor.getValue() instanceof J.NewClass) {


Suggested change

} else if (currentCursor.getValue() instanceof J.NewClass) {

}

if (currentCursor.getValue() instanceof J.NewClass) {

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

github-actions · 2025-11-25T15:43:06Z

src/test/java/org/openrewrite/staticanalysis/ExplicitThisTest.java

+        spec.recipe(new ExplicitThis());
+    }
+
+    @Test


Suggested change

@Test

@Test

motlin · 2025-11-25T21:10:18Z

src/test/java/org/openrewrite/staticanalysis/ExplicitThisTest.java

+                  Test(String value) {
+                      super(value);
+                      // Shadowed parameter: looks like a bug but replacing would change semantics
+                      value = value;


Can you add a test with a typical setter implementation? This is probably the most common example where of variable name shadowing. One being a field and another being a local.

@greg-at-moderne I added tests for value = value in this constructor, and field = field in a setter. While these are "obvious" bugs - setting a parameter to itself - it was a deliberate choice not to replace these and the test shows they do not get replaced. The replacement would change semantics. It's not a bad idea to find and fix these but my preference is to separate recipes that may change semantics from recipes that perform pure refactorings and don't need much scrutiny. What do you think?

github-actions · 2025-11-25T21:16:40Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+import java.time.Duration;
+import java.util.Collections;


Suggested change

import java.time.Duration;

import java.util.Collections;

import java.time.Duration;

github-actions · 2025-11-25T21:16:40Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext executionContext) {
+            boolean previousIsInsideFieldAccess = this.isInsideFieldAccess;
+            this.isInsideFieldAccess = true;
+


Suggested change

public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext executionContext) {

boolean previousIsInsideFieldAccess = this.isInsideFieldAccess;

this.isInsideFieldAccess = true;

public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext ctx) {

J result = super.visitFieldAccess(fieldAccess, ctx);

public J visitIdentifier(J.Identifier identifier, ExecutionContext ctx) {

J.Identifier id = (J.Identifier) super.visitIdentifier(identifier, ctx);

github-actions · 2025-11-25T21:16:40Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        public J visitBlock(J.Block block, ExecutionContext executionContext) {
+            if (!block.isStatic()) {
+                return super.visitBlock(block, executionContext);
+            }


Suggested change

public J visitBlock(J.Block block, ExecutionContext executionContext) {

if (!block.isStatic()) {

return super.visitBlock(block, executionContext);

}

public J visitBlock(J.Block block, ExecutionContext ctx) {

return super.visitBlock(block, ctx);

J.Block result = (J.Block) super.visitBlock(block, ctx);

public J visitMethodDeclaration(J.MethodDeclaration method, ExecutionContext ctx) {

github-actions · 2025-11-25T21:16:40Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+                this.isStatic = (methodType.getFlagsBitMap() & 0x0008L) != 0;
+            }
+
+            J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, executionContext);


Suggested change

J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, executionContext);

J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, ctx);

github-actions · 2025-11-25T21:16:41Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {
+            J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, executionContext);
+


Suggested change

public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {

J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, executionContext);

public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {

J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, ctx);

if ("super".equals(m.getName().getSimpleName()) || "this".equals(m.getName().getSimpleName())) {

github-actions · 2025-11-25T21:16:41Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+                p instanceof J.ClassDeclaration ||
+                (p instanceof J.NewClass && ((J.NewClass) p).getBody() != null) ||
+                p == Cursor.ROOT_VALUE


Suggested change

p instanceof J.ClassDeclaration ||

(p instanceof J.NewClass && ((J.NewClass) p).getBody() != null) ||

p == Cursor.ROOT_VALUE

p instanceof J.ClassDeclaration ||

(p instanceof J.NewClass && ((J.NewClass) p).getBody() != null) ||

p == Cursor.ROOT_VALUE

github-actions · 2025-11-25T21:16:41Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+                String currentClassName = this.getSimpleClassName(currentClassType.getFullyQualifiedName());
+                boolean currentIsAnonymous = this.isAnonymousClassName(currentClassName);
+                return new ClassContext(currentClassType, currentIsAnonymous);
+            } else if (currentCursor.getValue() instanceof J.NewClass) {


Suggested change

} else if (currentCursor.getValue() instanceof J.NewClass) {

}

if (currentCursor.getValue() instanceof J.NewClass) {

github-actions · 2025-11-25T21:16:41Z

src/test/java/org/openrewrite/staticanalysis/ExplicitThisTest.java

+        spec.recipe(new ExplicitThis());
+    }
+
+    @Test


Suggested change

@Test

@Test

github-actions · 2025-11-26T14:18:59Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+                return m;
+            }
+
+            if (m.getName().getSimpleName().equals("super") || m.getName().getSimpleName().equals("this")) {


Suggested change

if (m.getName().getSimpleName().equals("super") || m.getName().getSimpleName().equals("this")) {

if ("super".equals(m.getName().getSimpleName()) || "this".equals(m.getName().getSimpleName())) {

github-actions · 2025-11-26T14:18:59Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        @Nullable
+        private ClassContext getCurrentClassContext() {
+            Cursor currentCursor = this.getCursor().dropParentUntil(p ->
+                p instanceof J.ClassDeclaration ||
+                (p instanceof J.NewClass && ((J.NewClass) p).getBody() != null) ||


Suggested change

@Nullable

private ClassContext getCurrentClassContext() {

Cursor currentCursor = this.getCursor().dropParentUntil(p ->

p instanceof J.ClassDeclaration ||

(p instanceof J.NewClass && ((J.NewClass) p).getBody() != null) ||

private @Nullable ClassContext getCurrentClassContext() {

p instanceof J.ClassDeclaration ||

(p instanceof J.NewClass && ((J.NewClass) p).getBody() != null) ||

p == Cursor.ROOT_VALUE

github-actions · 2025-11-26T14:18:59Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+                String currentClassName = this.getSimpleClassName(currentClassType.getFullyQualifiedName());
+                boolean currentIsAnonymous = this.isAnonymousClassName(currentClassName);
+                return new ClassContext(currentClassType, currentIsAnonymous);
+            } else if (currentCursor.getValue() instanceof J.NewClass) {


Suggested change

} else if (currentCursor.getValue() instanceof J.NewClass) {

}

if (currentCursor.getValue() instanceof J.NewClass) {

github-actions · 2025-11-26T14:18:59Z

src/main/java/org/openrewrite/staticanalysis/ExplicitThis.java

+        @Nullable
+        private Expression createQualifiedThisExpression(ClassContext currentContext, JavaType.FullyQualified targetType) {


Suggested change

@Nullable

private Expression createQualifiedThisExpression(ClassContext currentContext, JavaType.FullyQualified targetType) {

private @Nullable Expression createQualifiedThisExpression(ClassContext currentContext, JavaType.FullyQualified targetType) {

github-actions · 2025-11-26T14:18:59Z

src/test/java/org/openrewrite/staticanalysis/ExplicitThisTest.java

+        spec.recipe(new ExplicitThis());
+    }
+
+    @Test


Suggested change

@Test

@Test

moderne-meeseeks bot added this to OpenRewrite Nov 25, 2025

moderne-meeseeks bot assigned motlin Nov 25, 2025

github-project-automation bot moved this to In Progress in OpenRewrite Nov 25, 2025

github-actions bot reviewed Nov 25, 2025

View reviewed changes

motlin force-pushed the explicit-this branch from c485d95 to 1e30b0d Compare November 25, 2025 21:05

motlin commented Nov 25, 2025

View reviewed changes

github-actions bot reviewed Nov 25, 2025

View reviewed changes

motlin force-pushed the explicit-this branch from 1e30b0d to a556fe4 Compare November 25, 2025 22:28

Add ExplicitThis recipe to make 'this.' prefix explicit.

d379d75

motlin force-pushed the explicit-this branch from a556fe4 to d379d75 Compare November 26, 2025 14:09

github-actions bot reviewed Nov 26, 2025

View reviewed changes

	import java.util.Collections;

	import static java.util.Collections.emptyList;

-        public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext executionContext) {
-            boolean previousIsInsideFieldAccess = this.isInsideFieldAccess;
-            this.isInsideFieldAccess = true;
+        public J visitFieldAccess(FieldAccess fieldAccess, ExecutionContext ctx) {
+            J result = super.visitFieldAccess(fieldAccess, ctx);
+        public J visitIdentifier(J.Identifier identifier, ExecutionContext ctx) {
+            J.Identifier id = (J.Identifier) super.visitIdentifier(identifier, ctx);

-        public J visitBlock(J.Block block, ExecutionContext executionContext) {
-            if (!block.isStatic()) {
-                return super.visitBlock(block, executionContext);
-            }
+        public J visitBlock(J.Block block, ExecutionContext ctx) {
+                return super.visitBlock(block, ctx);
+            J.Block result = (J.Block) super.visitBlock(block, ctx);
+        public J visitMethodDeclaration(J.MethodDeclaration method, ExecutionContext ctx) {

	J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, executionContext);
	J.MethodDeclaration result = (J.MethodDeclaration) super.visitMethodDeclaration(method, ctx);

		public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {
		J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, executionContext);

-        public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {
-            J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, executionContext);
+        public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
+            J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, ctx);
+            if ("super".equals(m.getName().getSimpleName()) || "this".equals(m.getName().getSimpleName())) {

	} else if (currentCursor.getValue() instanceof J.NewClass) {
	}
	if (currentCursor.getValue() instanceof J.NewClass) {

	import java.time.Duration;
	import java.util.Collections;
	import java.time.Duration;

	if (m.getName().getSimpleName().equals("super") \|\| m.getName().getSimpleName().equals("this")) {
	if ("super".equals(m.getName().getSimpleName()) \|\| "this".equals(m.getName().getSimpleName())) {

		@Nullable
		private Expression createQualifiedThisExpression(ClassContext currentContext, JavaType.FullyQualified targetType) {

	@Nullable
	private Expression createQualifiedThisExpression(ClassContext currentContext, JavaType.FullyQualified targetType) {
	private @Nullable Expression createQualifiedThisExpression(ClassContext currentContext, JavaType.FullyQualified targetType) {

Add ExplicitThis recipe to make 'this.' prefix explicit. #791

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Add ExplicitThis recipe to make 'this.' prefix explicit. #791

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motlin commented Nov 25, 2025

What's changed?

What's your motivation?

Anything in particular you'd like reviewers to focus on?

Anyone you would like to review specifically?

Have you considered any alternatives or workarounds?

Any additional context

Checklist

Uh oh!

greg-at-moderne commented Nov 25, 2025

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