Merge pull request #10354 from dotty-staging/opaquify-assert

Make `assert` work as a plain inline function

Author: odersky

compiler/src/dotty/tools/dotc/transform/Erasure.scala

@@ -588,16 +588,17 @@ object Erasure {
       tree.withType(erasure(tree.tpe))
 
     /** This override is only needed to semi-erase type ascriptions */
-    override def typedTyped(tree: untpd.Typed, pt: Type)(using Context): Tree = {
+    override def typedTyped(tree: untpd.Typed, pt: Type)(using Context): Tree =
       val Typed(expr, tpt) = tree
-      val tpt1 = tpt match {
-        case Block(_, tpt) => tpt // erase type aliases (statements) from type block
-        case tpt => tpt
-      }
-      val tpt2 = typedType(tpt1)
-      val expr1 = typed(expr, tpt2.tpe)
-      assignType(untpd.cpy.Typed(tree)(expr1, tpt2), tpt2)
-    }
+      if tpt.typeOpt.typeSymbol == defn.UnitClass then
+        typed(expr, defn.UnitType)
+      else
+        val tpt1 = tpt match
+          case Block(_, tpt) => tpt // erase type aliases (statements) from type block
+          case tpt => tpt
+        val tpt2 = typedType(tpt1)
+        val expr1 = typed(expr, tpt2.tpe)
+        assignType(untpd.cpy.Typed(tree)(expr1, tpt2), tpt2)
 
     override def typedLiteral(tree: untpd.Literal)(using Context): Tree =
       if (tree.typeOpt.isRef(defn.UnitClass))

compiler/src/dotty/tools/dotc/typer/ReTyper.scala

@@ -12,6 +12,7 @@ import ast.{tpd, untpd, Trees}
 import Trees._
 import scala.util.control.NonFatal
 import util.Spans.Span
+import Nullables._
 
 /** A version of Typer that keeps all symbols defined and referenced in a
  *  previously typed tree.
@@ -53,13 +54,15 @@ class ReTyper extends Typer with ReChecking {
 
   override def typedTyped(tree: untpd.Typed, pt: Type)(using Context): Tree = {
     assertTyped(tree)
+
     val tpt1 = checkSimpleKinded(typedType(tree.tpt))
     val expr1 = tree.expr match {
       case id: untpd.Ident if (ctx.mode is Mode.Pattern) && untpd.isVarPattern(id) && (id.name == nme.WILDCARD || id.name == nme.WILDCARD_STAR) =>
         tree.expr.withType(tpt1.tpe)
       case _ => typed(tree.expr)
     }
-    untpd.cpy.Typed(tree)(expr1, tpt1).withType(tree.typeOpt)
+    val result = untpd.cpy.Typed(tree)(expr1, tpt1).withType(tree.typeOpt)
+    if ctx.mode.isExpr then result.withNotNullInfo(expr1.notNullInfo) else result
   }
 
   override def typedTypeTree(tree: untpd.TypeTree, pt: Type)(using Context): TypeTree =

library/src/dotty/DottyPredef.scala

@@ -3,15 +3,11 @@ package dotty
 object DottyPredef {
   import compiletime.summonFrom
 
-  inline final def assert(inline assertion: Boolean, inline message: => Any): Unit = {
-    if (!assertion)
-      scala.runtime.Scala3RunTime.assertFailed(message)
-  }
+  inline def assert(inline assertion: Boolean, inline message: => Any): Unit =
+    if !assertion then scala.runtime.Scala3RunTime.assertFailed(message)
 
-  transparent inline final def assert(inline assertion: Boolean): Unit = {
-    if (!assertion)
-      scala.runtime.Scala3RunTime.assertFailed()
-  }
+  inline def assert(inline assertion: Boolean): Unit =
+    if !assertion then scala.runtime.Scala3RunTime.assertFailed()
 
   /**
    * Retrieve the single value of a type with a unique inhabitant.