From b43f69364b683dd9f437fd3fed6ff5f56d0778d0 Mon Sep 17 00:00:00 2001
From: Dmitriy Novozhilov <dmitriy.novozhilov@jetbrains.com>
Date: Tue, 5 Mar 2024 13:10:56 +0200
Subject: [PATCH] [IR] Forcefully collect mapping of f/o for all source classes

```kotlin
// FILE: AB.kt
interface A {
    val x: Int = 1
}

interface B : A {
    // f/o val x: Int
    //    overrides: A.x
}

// FILE: C.java
public interface C extends B {
    // f/o val x: Int
    //    overrides: (B, A.x)
}

// FILE: D.java
public interface D extends C {
    // f/o val x: Int
    //    overrides: (C, A.x)
}

// FILE: usage.kt
fun test(d: D) {
    d.x
}
```

In such test backend will ask for overriddens of lazy property C.x only
  after property lowering, which removes property `B.x` and replaces it
  with getter `B.<get-x>`. That fact that there is no property anymore
  really confuses `SpecialFakeOverrideSymbolsResolver` during computation
  of overriddens of `C.x`.
So, to prevent this situation, we can process all source kotlin classes
  beforehand, so when any lazy function/property will start computation
  of its overriddens, there won't be the need to calculate mapping of
  f/o for classes

This problem was found during work on KT-66341, after total signature
  computation removal from fir2ir. Previously those fake-overrides just
  matched by signature in symbol table
---
 .../kotlin/fir/pipeline/convertToIr.kt        |  7 ++++++-
 .../SpecialFakeOverrideSymbolsResolver.kt     | 19 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/pipeline/convertToIr.kt b/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/pipeline/convertToIr.kt
index f9027085356..ab514554b50 100644
--- a/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/pipeline/convertToIr.kt
+++ b/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/pipeline/convertToIr.kt
@@ -36,6 +36,7 @@ import org.jetbrains.kotlin.ir.util.KotlinMangler
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
+import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
 data class FirResult(val outputs: List<ModuleCompilerAnalyzedOutput>)
 
@@ -123,14 +124,18 @@ fun FirResult.convertToIrAndActualize(
         components.fakeOverrideBuilder.buildForAll(allIrModules, temporaryResolver)
     }
     val expectActualMap = irActualizer?.actualizeCallablesAndMergeModules() ?: emptyMap()
-    if (!components.configuration.useFirBasedFakeOverrideGenerator) {
+    val fakeOverrideResolver = runIf(!components.configuration.useFirBasedFakeOverrideGenerator) {
         val fakeOverrideResolver = SpecialFakeOverrideSymbolsResolver(expectActualMap)
         irModuleFragment.acceptVoid(SpecialFakeOverrideSymbolsResolverVisitor(fakeOverrideResolver))
         @OptIn(Fir2IrSymbolsMappingForLazyClasses.SymbolRemapperInternals::class)
         components.symbolsMappingForLazyClasses.initializeSymbolMap(fakeOverrideResolver)
+        fakeOverrideResolver
     }
     Fir2IrConverter.evaluateConstants(irModuleFragment, components)
     val actualizationResult = irActualizer?.runChecksAndFinalize(expectActualMap)
+
+    fakeOverrideResolver?.cacheFakeOverridesOfAllClasses(irModuleFragment)
+
     pluginContext.applyIrGenerationExtensions(irModuleFragment, irGeneratorExtensions)
     return Fir2IrActualizedResult(irModuleFragment, components, pluginContext, actualizationResult)
 }
diff --git a/compiler/ir/ir.actualization/src/main/kotlin/org/jetbrains/kotlin/backend/common/actualizer/SpecialFakeOverrideSymbolsResolver.kt b/compiler/ir/ir.actualization/src/main/kotlin/org/jetbrains/kotlin/backend/common/actualizer/SpecialFakeOverrideSymbolsResolver.kt
index 49c97290d38..4f05073519e 100644
--- a/compiler/ir/ir.actualization/src/main/kotlin/org/jetbrains/kotlin/backend/common/actualizer/SpecialFakeOverrideSymbolsResolver.kt
+++ b/compiler/ir/ir.actualization/src/main/kotlin/org/jetbrains/kotlin/backend/common/actualizer/SpecialFakeOverrideSymbolsResolver.kt
@@ -21,7 +21,6 @@ import org.jetbrains.kotlin.ir.util.SymbolRemapper
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
-import org.jetbrains.kotlin.utils.addToStdlib.shouldNotBeCalled
 
 /**
  * This class provides utility to resolve [org.jetbrains.kotlin.ir.symbols.impl.IrFunctionFakeOverrideSymbol]
@@ -112,6 +111,24 @@ class SpecialFakeOverrideSymbolsResolver(private val expectActualMap: Map<IrSymb
             }
         }
     }
+
+    fun cacheFakeOverridesOfAllClasses(irModuleFragment: IrModuleFragment) {
+        val visitor = object : IrElementVisitorVoid {
+            override fun visitElement(element: IrElement) {}
+
+            override fun visitFile(declaration: IrFile) {
+                declaration.acceptChildrenVoid(this)
+            }
+
+            override fun visitClass(declaration: IrClass) {
+                if (!declaration.isExpect) {
+                    processClass(declaration)
+                }
+                declaration.acceptChildrenVoid(this)
+            }
+        }
+        irModuleFragment.acceptChildrenVoid(visitor)
+    }
 }