FIR LT: Introduce source file abstraction, carry it from parsing to IR

along with source lines mapping, allows to "emulate" usage of the
PSI files which allows to extract source file and line mapping info
on every stage from source element.
It makes sense to use this mapping for the error reporting too.

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/Utils.kt

@@ -18,14 +18,9 @@ package org.jetbrains.kotlin.backend.common
 
 import org.jetbrains.kotlin.AbstractKtSourceElement
 import org.jetbrains.kotlin.KtOffsetsOnlySourceElement
-import org.jetbrains.kotlin.KtRealPsiSourceElement
-import org.jetbrains.kotlin.KtSourceElement
-import org.jetbrains.kotlin.backend.common.psi.PsiSourceManager
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
-import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.util.render
 
 fun CommonBackendContext.reportWarning(message: String, irFile: IrFile?, irElement: IrElement) {
     report(irElement, irFile, message, false)
@@ -37,12 +32,6 @@ fun <E> MutableList<E>.pop() = this.removeAt(size - 1)
 
 fun <E> MutableList<E>.peek(): E? = if (size == 0) null else this[size - 1]
 
-fun findKtSourceElement(irElement: IrElement, irDeclaration: IrDeclaration): KtSourceElement {
-    val psiElement = PsiSourceManager.findPsiElement(irElement, irDeclaration)
-        ?: throw AssertionError("No PsiElement found for '${irElement.render()}'")
-    return KtRealPsiSourceElement(psiElement)
-}
-
 fun IrElement.sourceElement(): AbstractKtSourceElement? =
     if (startOffset != UNDEFINED_OFFSET) KtOffsetsOnlySourceElement(this.startOffset, this.endOffset)
     else null

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrUtils.kt

@@ -285,7 +285,7 @@ fun IrFile.getKtFile(): KtFile? =
 fun IrFile.getIoFile(): File? =
     when (val fe = fileEntry) {
         is PsiIrFileEntry -> fe.psiFile.virtualFile?.path?.let(::File)
-        else -> File(fe.name).takeIf { it.exists() }
+        else -> File(fe.name)
     }
 
 inline fun IrElement.hasChild(crossinline block: (IrElement) -> Boolean): Boolean {

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/AdditionalIrUtils.kt

@@ -186,7 +186,8 @@ val IrFileEntry.lineStartOffsets: IntArray
 
 class NaiveSourceBasedFileEntryImpl(
     override val name: String,
-    private val lineStartOffsets: IntArray = intArrayOf()
+    private val lineStartOffsets: IntArray = intArrayOf(),
+    override val maxOffset: Int = UNDEFINED_OFFSET
 ) : IrFileEntry {
     val lineStartOffsetsAreEmpty: Boolean
         get() = lineStartOffsets.isEmpty()
@@ -215,15 +216,19 @@ class NaiveSourceBasedFileEntryImpl(
         if (offset == SYNTHETIC_OFFSET) return 0
         if (offset < 0) return -1
         val lineNumber = getLineNumber(offset)
-        return offset - lineStartOffsets[lineNumber]
+        return if (lineNumber < 0) -1 else offset - lineStartOffsets[lineNumber]
     }
 
-    override val maxOffset: Int
-        get() = UNDEFINED_OFFSET
-
-    override fun getSourceRangeInfo(beginOffset: Int, endOffset: Int): SourceRangeInfo {
-        return SourceRangeInfo(name, beginOffset, -1, -1, endOffset, -1, -1)
-    }
+    override fun getSourceRangeInfo(beginOffset: Int, endOffset: Int): SourceRangeInfo =
+        SourceRangeInfo(
+            filePath = name,
+            startOffset = beginOffset,
+            startLineNumber = getLineNumber(beginOffset),
+            startColumnNumber = getColumnNumber(beginOffset),
+            endOffset = endOffset,
+            endLineNumber = getLineNumber(endOffset),
+            endColumnNumber = getColumnNumber(endOffset)
+        )
 }
 
 private fun IrClass.getPropertyDeclaration(name: String): IrProperty? {