[KLIB Resolver] Deprecate Logger.fatal()

Invocation of Logger.fatal() may cause severe side effects such as
throwing an exception or even terminating the current JVM process
(check various implementations of this function for details).

The code that uses Logger.fatal() sometimes expects a particular kind
of side effect. This is totally a design flaw. And it's definitely not
a responsibility of Logger to influence the execution flow of
the program.

compiler/util-klib/src/org/jetbrains/kotlin/library/SearchPathResolver.kt

@@ -268,7 +268,18 @@ abstract class KotlinLibrarySearchPathResolver<L : KotlinLibrary>(
 
     override fun resolve(unresolved: RequiredUnresolvedLibrary, isDefaultLink: Boolean): L {
         return resolveOrNull(unresolved, isDefaultLink)
-            ?: logger.fatal("KLIB resolver: Could not find \"${unresolved.path}\" in ${searchRoots.map { it.searchRootPath.absolutePath }}")
+            ?: run {
+                // It does not make sense to replace logger.fatal() by logger.error() here, because:
+                // 1. We don't know which exactly side effect (throwing an exception, exiting JVM process, etc) is performed
+                //    by logger.fatal() as we don't know the concrete Logger class. So, we can't use logger.error()
+                //    and emulate the proper side effect here.
+                // 2. The contract of resolve(RequiredUnresolvedLibrary, Boolean) has a design flaw: It assumes that either
+                //    the library is resolved or the side effect takes place. The latter (side effect) affects the execution
+                //    flow of the program and should not be a responsibility of SearchPathResolver.
+                // 3. Finally, we are going to drop SearchPathResolver which is a part of KLIB resolver.
+                @Suppress("DEPRECATION")
+                logger.fatal("KLIB resolver: Could not find \"${unresolved.path}\" in ${searchRoots.map { it.searchRootPath.absolutePath }}")
+            }
     }
 
     override fun libraryMatch(candidate: L, unresolved: UnresolvedLibrary): Boolean = true

compiler/util-klib/src/org/jetbrains/kotlin/library/impl/KotlinLibraryImpl.kt

@@ -371,6 +371,8 @@ fun isKotlinLibrary(libraryFile: File): Boolean = try {
             override fun log(message: String) = Unit // don't log
             override fun error(message: String) = Unit // don't log
             override fun warning(message: String) = Unit // don't log
+
+            @Deprecated(Logger.FATAL_DEPRECATION_MESSAGE, ReplaceWith(Logger.FATAL_REPLACEMENT))
             override fun fatal(message: String): Nothing = kotlin.error("This function should not be called")
         },
         knownIrProviders = emptyList()