Fix pattern applying non-field to left side of assignment

3 files changed, 45 insertions, 3 deletions

diff --git a/src/main/kotlin/com/replaymod/gradle/remap/PsiPattern.kt b/src/main/kotlin/com/replaymod/gradle/remap/PsiPattern.kt
index 8573560..4e3a60a 100644
--- a/src/main/kotlin/com/replaymod/gradle/remap/PsiPattern.kt
+++ b/src/main/kotlin/com/replaymod/gradle/remap/PsiPattern.kt
@@ -10,7 +10,8 @@ internal class PsiPattern(
         private val parameters: Set<PsiParameter>,
         private val varArgs: Boolean,
         private val pattern: PsiStatement,
-        private val replacement: List<String>
+        private val replacement: List<String>,
+        private val replacementCanBeAssigned: Boolean,
 ) {
     private fun find(pattern: PsiElement, tree: PsiElement, result: MutableList<Matcher>) {
         tree.accept(object : JavaRecursiveElementVisitor() {
@@ -66,7 +67,13 @@ internal class PsiPattern(
             return changes.filterNot { it.first.isEmpty && it.second.isEmpty() }
         }
 
-        fun match(pattern: PsiElement): Boolean = match(pattern, root)
+        fun match(pattern: PsiElement): Boolean {
+            val parent = root.parent
+            if (parent is PsiAssignmentExpression && parent.lExpression == root && !replacementCanBeAssigned) {
+                return false
+            }
+            return match(pattern, root)
+        }
 
         private fun match(pattern: PsiElement?, expr: PsiElement?): Boolean = when (pattern) {
             null -> expr == null
diff --git a/src/main/kotlin/com/replaymod/gradle/remap/PsiPatterns.kt b/src/main/kotlin/com/replaymod/gradle/remap/PsiPatterns.kt
index fe6040c..ac5ea10 100644
--- a/src/main/kotlin/com/replaymod/gradle/remap/PsiPatterns.kt
+++ b/src/main/kotlin/com/replaymod/gradle/remap/PsiPatterns.kt
@@ -72,7 +72,9 @@ internal class PsiPatterns(private val annotationFQN: String) {
             replacement.push(replacementFile.slice(start until replacementExpression.endOffset))
         }
 
-        patterns.add(PsiPattern(parameters, varArgs, body.statements.last(), replacement))
+        val replacementCanBeAssigned = replacementExpression is PsiReferenceExpression
+
+        patterns.add(PsiPattern(parameters, varArgs, body.statements.last(), replacement, replacementCanBeAssigned))
     }
 
     fun find(block: PsiCodeBlock): MutableList<Matcher> {
diff --git a/src/test/kotlin/com/replaymod/gradle/remap/pattern/TestFieldReference.kt b/src/test/kotlin/com/replaymod/gradle/remap/pattern/TestFieldReference.kt
index a3a6efc..d24d2e6 100644
--- a/src/test/kotlin/com/replaymod/gradle/remap/pattern/TestFieldReference.kt
+++ b/src/test/kotlin/com/replaymod/gradle/remap/pattern/TestFieldReference.kt
@@ -37,4 +37,37 @@ class TestFieldReference {
             }
         """.trimIndent()
     }
+
+    @Test
+    fun `should not match final field on left side of assignment when replaced by non-field`() {
+        TestData.remap("test/Test.java", """
+            class Test {
+                Test field;
+                private void test() {
+                    field = field;
+                    this.field = this.field;
+                    this.field.field = this.field.field;
+                }
+            }
+        """.trimIndent(), """
+            @remap.Pattern
+            private test.Test pattern(test.Test obj) {
+                return obj.field;
+            }
+        """.trimIndent(), """
+            @remap.Pattern
+            private test.Test pattern(test.Test obj) {
+                return matched(obj);
+            }
+        """.trimIndent()) shouldBe """
+            class Test {
+                Test field;
+                private void test() {
+                    field = field;
+                    this.field = matched(this);
+                    matched(this).field = matched(matched(this));
+                }
+            }
+        """.trimIndent()
+    }
 }
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