Define Predef.assert overwrite directly in Scala 2 library TASTy

Define `assert` in `scala.Predef` instead `scala.runtime.stdLibPatches.Predef`.
We assume that all patches to `scala.Predef` are inline methods, therefore
if we see an inline method in `scala.Predef` we do not patch it with the
method in `scala.runtime.stdLibPatches.Predef`.

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1436,11 +1436,14 @@ class Definitions {
           )
 
       if patchCls.exists then
+        val patchedInSource = mutable.Set.empty[Symbol] // example: symbol patched in scala2-library-bootstrapped/src/scala/Predef.scala
         val patches = patchCls.info.decls.filter(patch =>
           !patch.isConstructor && !patch.isOneOf(PrivateOrSynthetic))
         for patch <- patches if !recurse(patch) do
           val e = scope.lookupEntry(patch.name)
-          if e != null then scope.unlink(e)
+          if e != null then
+            if e.sym.isInlineMethod then patchedInSource += patch
+            else scope.unlink(e)
         for patch <- patches do
           patch.ensureCompleted()
           if !recurse(patch) then
@@ -1451,8 +1454,9 @@ class Definitions {
               case _ =>
                 makeNonClassSymbol(patch)
               end match
-            sym.annotations = patch.annotations
-            scope.enter(sym)
+            if !patchedInSource(sym) then
+              sym.annotations = patch.annotations
+              scope.enter(sym)
           if patch.isClass then
             patch2(scope.lookup(patch.name).asClass, patch)
 

project/MiMaFilters.scala

@@ -22,6 +22,9 @@ object MiMaFilters {
   val StdlibBootstrappedBackwards: Map[String, Seq[ProblemFilter]] = Map(
     Build.stdlibBootstrappedVersion -> {
       Seq(
+        // Methods overwritten in `scala.Predef` instead of `scala.runtime.stdLibPatches`
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.Predef.assert"), // `assert` is `inline` and therefore is not emitted in the bytecode
+
         // Files that are not compiled in the bootstrapped library
         ProblemFilters.exclude[MissingClassProblem]("scala.AnyVal"),
 

scala2-library-bootstrapped/src/scala/Predef.scala

@@ -259,9 +259,9 @@ object Predef extends LowPriorityImplicits {
    *  @group assertions
    */
   @elidable(ASSERTION)
-  def assert(assertion: Boolean): Unit = {
+  transparent inline def assert(inline assertion: Boolean): Unit = {
     if (!assertion)
-      throw new java.lang.AssertionError("assertion failed")
+      scala.runtime.Scala3RunTime.assertFailed()
   }
 
   /** Tests an expression, throwing an `AssertionError` if false.
@@ -274,9 +274,9 @@ object Predef extends LowPriorityImplicits {
    *  @group assertions
    */
   @elidable(ASSERTION) @inline
-  final def assert(assertion: Boolean, message: => Any): Unit = {
+  transparent inline def assert(inline assertion: Boolean, inline message: => Any): Unit = {
     if (!assertion)
-      throw new java.lang.AssertionError("assertion failed: "+ message)
+      scala.runtime.Scala3RunTime.assertFailed(message)
   }
 
   /** Tests an expression, throwing an `AssertionError` if false.