[Header Mode] Elide property initializers

compiler/fir/analysis-tests/testData/resolve/headerMode/constructorDeclaration.fir.txt

@@ -4,10 +4,10 @@ FILE: constructorDeclaration.kt
             super<R|kotlin/Any|>()
         }
 
-        public final val a: R|kotlin/String| = R|<local>/a|
+        public final val a: R|kotlin/String|
             public get(): R|kotlin/String|
 
-        public final val b: R|kotlin/Int| = R|<local>/b|
+        public final val b: R|kotlin/Int|
             public get(): R|kotlin/Int|
 
         public constructor(e: R|kotlin/String|): R|A| {
@@ -24,10 +24,10 @@ FILE: constructorDeclaration.kt
             super<R|kotlin/Any|>()
         }
 
-        public final val a: R|kotlin/String| = R|<local>/a|
+        public final val a: R|kotlin/String|
             public get(): R|kotlin/String|
 
-        public final val b: R|kotlin/Int| = R|<local>/b|
+        public final val b: R|kotlin/Int|
             public get(): R|kotlin/Int|
 
         public constructor(e: R|kotlin/String|): R|B| {

compiler/fir/analysis-tests/testData/resolve/headerMode/dataClassDeclaration.fir.txt

@@ -4,10 +4,10 @@ FILE: dataClassDeclaration.kt
             super<R|kotlin/Any|>()
         }
 
-        public final val name: R|kotlin/String| = R|<local>/name|
+        public final val name: R|kotlin/String|
             public get(): R|kotlin/String|
 
-        public final val age: R|kotlin/Int| = R|<local>/age|
+        public final val age: R|kotlin/Int|
             public get(): R|kotlin/Int|
 
         public final operator fun component1(): R|kotlin/String|

compiler/fir/analysis-tests/testData/resolve/headerMode/propertyDeclaration.fir.txt

@@ -1,8 +1,40 @@
 FILE: propertyDeclaration.kt
-    public final val a: R|kotlin/String| = String(A)
+    public final val a: R|kotlin/String|
         public get(): R|kotlin/String|
-    public final val b: R|kotlin/String| = String(B)
+    public final val b: R|kotlin/String|
         public get(): R|kotlin/String|
     public final fun foo(): R|kotlin/String|
     public final val c: R|kotlin/String|
         public get(): R|kotlin/String|
+    public final val d: R|kotlin/Boolean|
+        public get(): R|kotlin/Boolean|
+    public final val e: R|kotlin/String|
+        public get(): R|kotlin/String|
+    public final var f: R|kotlin/Int|
+        public get(): R|kotlin/Int|
+        public set(value: R|kotlin/Int|): R|kotlin/Unit|
+    public final val g: R|kotlin/Int|
+        public get(): R|kotlin/Int|
+    public final val h: R|kotlin/String|by R|kotlin/lazy|<R|kotlin/String|>(<L> = lazy@fun <anonymous>(): R|kotlin/String| <inline=NoInline>  {
+        ^ String(H)
+    }
+    )
+        public get(): R|kotlin/String|
+    public final const val i: R|kotlin/Int| = Int(123)
+        public get(): R|kotlin/Int|
+    public final val j: R|kotlin/Any| = object : R|kotlin/Any| {
+        private constructor(): R|<anonymous>| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final fun foo(): R|kotlin/String| {
+            ^foo String(foo)
+        }
+
+        public final fun bar(): R|kotlin/String| {
+            ^bar String(bar)
+        }
+
+    }
+
+        public get(): R|kotlin/Any|

compiler/fir/analysis-tests/testData/resolve/headerMode/propertyDeclaration.kt

@@ -1,3 +1,4 @@
+// WITH_STDLIB
 // RUN_PIPELINE_TILL: BACKEND
 // FIR_DUMP
 // Public property with explicit type
@@ -7,5 +8,29 @@ val b = "B"
 // Property with overriden getter and implicit type.
 fun foo() = "C"
 val c get() = foo()
-
+// Property initializer with control statement.
+val d = true
+val e = if(d) "True" else "False"
+// Property with backing field use in setter.
+var f: Int
+        set(value) {
+            if (value >= 0) {
+                // 'field' references the actual backing storage
+                field = value
+            }
+        }
+// Property with backing field use in getter.
+val g: Int
+    get() {
+        return g + 1
+    }
+// Delegated property with implicit type.
+val h by lazy {
+    "H"
+}
+const val i = 123
+val j = object {
+    fun foo() = "foo"
+    fun bar(): String = "bar"
+}
 /* GENERATED_FIR_TAGS: propertyDeclaration, stringLiteral */

compiler/fir/raw-fir/light-tree2fir/src/org/jetbrains/kotlin/fir/lightTree/converter/LightTreeRawFirDeclarationBuilder.kt

@@ -1426,9 +1426,13 @@ class LightTreeRawFirDeclarationBuilder(
                     BACKING_FIELD -> fieldDeclaration = it
                     else -> if (it.isExpression()) {
                         context.calleeNamesForLambda += null
-                        propertyInitializer = withForcedLocalContext {
-                            expressionConverter.getAsFirExpression(it, "Should have initializer")
-                        }
+                        propertyInitializer =
+                            if (!headerMode ||
+                                context.forceKeepingTheBodyInHeaderMode ||
+                                !isReturnType ||
+                                modifiers?.isConst() == true) withForcedLocalContext {
+                                expressionConverter.getAsFirExpression(it, "Should have initializer")
+                            } else null
                         context.calleeNamesForLambda.removeLast()
                     }
                 }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirDeclarationsResolveTransformer.kt

@@ -178,6 +178,11 @@ open class FirDeclarationsResolveTransformer(
 
         val cannotHaveDeepImplicitTypeRefs = property.backingField?.returnTypeRef !is FirImplicitTypeRef
         if (!property.isConst && implicitTypeOnly && property.returnTypeRef !is FirImplicitTypeRef && cannotHaveDeepImplicitTypeRefs) {
+            if (session.languageVersionSettings.getFlag(AnalysisFlags.headerMode) &&
+                property.initializer !is FirAnonymousObjectExpression
+            ) {
+                property.replaceInitializer(null)
+            }
             return property
         }
 
@@ -188,6 +193,14 @@ open class FirDeclarationsResolveTransformer(
             if (!initializerIsAlreadyResolved) {
                 dataFlowAnalyzer.enterProperty(property)
             }
+            else if (
+                session.languageVersionSettings.getFlag(AnalysisFlags.headerMode) &&
+                !property.isConst &&
+                property.returnTypeRef !is FirImplicitTypeRef &&
+                property.initializer !is FirAnonymousObjectExpression
+            ) {
+                property.replaceInitializer(null)
+            }
 
             var backingFieldIsAlreadyResolved = false
             context.withProperty(property) {
@@ -295,6 +308,13 @@ open class FirDeclarationsResolveTransformer(
                     property.replaceControlFlowGraphReference(FirControlFlowGraphReferenceImpl(it))
                 }
             }
+            if (session.languageVersionSettings.getFlag(AnalysisFlags.headerMode) &&
+                !property.isConst &&
+                property.returnTypeRef !is FirImplicitTypeRef &&
+                property.initializer !is FirAnonymousObjectExpression
+            ) {
+                property.replaceInitializer(null)
+            }
 
             property
         }