FIR: Use Any? expect type to the argument list of ==

^KT-47409 Related

compiler/fir/analysis-tests/legacy-fir-tests/tests-gen/org/jetbrains/kotlin/fir/LazyBodyIsNotTouchedTilContractsPhaseTestGenerated.java

@@ -2421,6 +2421,11 @@ public class LazyBodyIsNotTouchedTilContractsPhaseTestGenerated extends Abstract
             runTest("compiler/fir/analysis-tests/testData/resolve/inference/elvisAndUnit.kt");
         }
 
+        @TestMetadata("equals.kt")
+        public void testEquals() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/inference/equals.kt");
+        }
+
         @TestMetadata("extensionCallableReferences.kt")
         public void testExtensionCallableReferences() throws Exception {
             runTest("compiler/fir/analysis-tests/testData/resolve/inference/extensionCallableReferences.kt");

compiler/fir/analysis-tests/testData/resolve/inference/equals.fir.txt

@@ -0,0 +1,18 @@
+FILE: equals.kt
+    public final fun <T> materialize(): R|T| {
+        ^materialize R|kotlin/TODO|()
+    }
+    public final fun main(): R|kotlin/Unit| {
+        when () {
+            ==(String(), R|/materialize|<R|kotlin/Any?|>()) ->  {
+                ^main Unit
+            }
+        }
+
+        when () {
+            ==(R|/materialize|<R|kotlin/Any?|>(), String()) ->  {
+                ^main Unit
+            }
+        }
+
+    }

compiler/fir/analysis-tests/testData/resolve/inference/equals.kt

@@ -0,0 +1,6 @@
+fun <T> materialize(): T = TODO()
+
+fun main() {
+    if ("" == materialize()) return // FE1.0: OK, type argument inferred to Any?
+    if (materialize() == "") return // FE1.0: Error, uninferred type argument for `T`
+}

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticTestGenerated.java

@@ -2751,6 +2751,12 @@ public class FirDiagnosticTestGenerated extends AbstractFirDiagnosticTest {
                 runTest("compiler/fir/analysis-tests/testData/resolve/inference/elvisAndUnit.kt");
             }
 
+            @Test
+            @TestMetadata("equals.kt")
+            public void testEquals() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolve/inference/equals.kt");
+            }
+
             @Test
             @TestMetadata("extensionCallableReferences.kt")
             public void testExtensionCallableReferences() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticsWithLightTreeTestGenerated.java

@@ -2751,6 +2751,12 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
                 runTest("compiler/fir/analysis-tests/testData/resolve/inference/elvisAndUnit.kt");
             }
 
+            @Test
+            @TestMetadata("equals.kt")
+            public void testEquals() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolve/inference/equals.kt");
+            }
+
             @Test
             @TestMetadata("extensionCallableReferences.kt")
             public void testExtensionCallableReferences() throws Exception {