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/tests-common/tests/org/jetbrains/kotlin/codegen/SMAPTestUtil.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.codegen.inline.GENERATE_SMAP
 import org.jetbrains.kotlin.test.KotlinBaseTest
 import org.jetbrains.kotlin.test.util.JUnit4Assertions
 import org.junit.Assert
+import java.io.File
 import java.io.StringReader
 
 object SMAPTestUtil {
@@ -62,7 +63,7 @@ object SMAPTestUtil {
         }.associateBy { it.sourceFile }
 
         for (source in sourceData) {
-            val ktFileName = "/" + source.sourceFile
+            val ktFileName = "/" + File(source.sourceFile).name
                 .replace(".smap-nonseparate-compilation", ".kt")
                 .replace(".smap-separate-compilation", ".kt")
                 .replace(".smap", ".kt")

compiler/tests-common/tests/org/jetbrains/kotlin/fir/AbstractFirBaseDiagnosticsTest.kt

@@ -11,6 +11,7 @@ import com.intellij.openapi.vfs.VirtualFileManager
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiElementFinder
 import com.intellij.psi.search.GlobalSearchScope
+import org.jetbrains.kotlin.KtInMemoryTextSourceFile
 import org.jetbrains.kotlin.analyzer.ModuleInfo
 import org.jetbrains.kotlin.asJava.finder.JavaElementFinder
 import org.jetbrains.kotlin.checkers.BaseDiagnosticsTest
@@ -46,6 +47,7 @@ import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.resolve.AnalyzingUtils
 import org.jetbrains.kotlin.resolve.PlatformDependentAnalyzerServices
 import org.jetbrains.kotlin.resolve.jvm.platform.JvmPlatformAnalyzerServices
+import org.jetbrains.kotlin.toSourceLinesMapping
 import java.io.File
 
 abstract class AbstractFirBaseDiagnosticsTest : BaseDiagnosticsTest() {
@@ -133,7 +135,12 @@ abstract class AbstractFirBaseDiagnosticsTest : BaseDiagnosticsTest() {
         if (useLightTree) {
             val lightTreeBuilder = LightTree2Fir(session, firProvider.kotlinScopeProvider)
             ktFiles.mapTo(firFiles) {
-                val firFile = lightTreeBuilder.buildFirFile(it.text, it.name, it.virtualFilePath)
+                val firFile =
+                    lightTreeBuilder.buildFirFile(
+                        it.text,
+                        KtInMemoryTextSourceFile(it.name, it.virtualFilePath, it.text),
+                        it.text.toSourceLinesMapping()
+                    )
                 (session.firProvider as FirProviderImpl).recordFile(firFile)
                 firFile
             }

compiler/tests-common/tests/org/jetbrains/kotlin/fir/FirResolveBench.kt

@@ -9,6 +9,7 @@ import com.intellij.openapi.util.io.FileUtil
 import com.intellij.openapi.util.text.StringUtil
 import com.intellij.openapi.vfs.CharsetToolkit
 import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.KtIoFileSourceFile
 import org.jetbrains.kotlin.fir.builder.RawFirBuilder
 import org.jetbrains.kotlin.fir.declarations.FirFile
 import org.jetbrains.kotlin.fir.diagnostics.ConeStubDiagnostic
@@ -26,6 +27,7 @@ import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.FirDefaultVisitorVoid
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
+import org.jetbrains.kotlin.readSourceFileWithMapping
 import org.jetbrains.kotlin.utils.addToStdlib.sumByLong
 import java.io.File
 import java.io.PrintStream
@@ -139,16 +141,18 @@ class FirResolveBench(val withProgress: Boolean, val listener: BenchListener? =
         return files.map { file ->
             val before = vmStateSnapshot()
             val firFile: FirFile
-            val code: String
             val time = measureNanoTime {
-                code = FileUtil.loadFile(file, CharsetToolkit.UTF8, true).trim()
-                firFile = builder.buildFirFile(code, file.name, file.path)
+                val sourceFile = KtIoFileSourceFile(file)
+                val (code, linesMapping) = with(file.inputStream().reader(Charsets.UTF_8)) {
+                    this.readSourceFileWithMapping()
+                }
+                totalLines += linesMapping.linesCount
+                firFile = builder.buildFirFile(code, sourceFile, linesMapping)
                 (builder.session.firProvider as FirProviderImpl).recordFile(firFile)
             }
             val after = vmStateSnapshot()
             val diff = after - before
             recordTime(builder::class, diff, time)
-            totalLines += StringUtil.countNewLines(code)
             firFile
         }.also {
             listener?.after(builder::class)