Fix #5107: disallow block as Apply.fun

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -69,8 +69,7 @@ class Compiler {
          new ExplicitOuter,          // Add accessors to outer classes from nested ones.
          new ExplicitSelf,           // Make references to non-trivial self types explicit as casts
          new StringInterpolatorOpt,  // Optimizes raw and s string interpolators by rewriting them to string concatentations
-         new CrossCastAnd,           // Normalize selections involving intersection types.
-         new Splitter) ::            // Expand selections involving union types into conditionals
+         new CrossCastAnd) ::        // Normalize selections involving intersection types.
     List(new PruneErasedDefs,        // Drop erased definitions from scopes and simplify erased expressions
          new VCInlineMethods,        // Inlines calls to value class methods
          new SeqLiterals,            // Express vararg arguments as arrays

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -40,11 +40,15 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   def Super(qual: Tree, mixName: TypeName, inConstrCall: Boolean, mixinClass: Symbol = NoSymbol)(implicit ctx: Context): Super =
     Super(qual, if (mixName.isEmpty) untpd.EmptyTypeIdent else untpd.Ident(mixName), inConstrCall, mixinClass)
 
-  def Apply(fn: Tree, args: List[Tree])(implicit ctx: Context): Apply =
+  def Apply(fn: Tree, args: List[Tree])(implicit ctx: Context): Apply = {
+    assert(fn.isInstanceOf[RefTree] || fn.isInstanceOf[GenericApply[_]])
     ta.assignType(untpd.Apply(fn, args), fn, args)
+  }
 
-  def TypeApply(fn: Tree, args: List[Tree])(implicit ctx: Context): TypeApply =
+  def TypeApply(fn: Tree, args: List[Tree])(implicit ctx: Context): TypeApply = {
+    assert(fn.isInstanceOf[RefTree] || fn.isInstanceOf[GenericApply[_]])
     ta.assignType(untpd.TypeApply(fn, args), fn, args)
+  }
 
   def Literal(const: Constant)(implicit ctx: Context): Literal =
     ta.assignType(untpd.Literal(const))
@@ -181,8 +185,10 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   def Alternative(trees: List[Tree])(implicit ctx: Context): Alternative =
     ta.assignType(untpd.Alternative(trees), trees)
 
-  def UnApply(fun: Tree, implicits: List[Tree], patterns: List[Tree], proto: Type)(implicit ctx: Context): UnApply =
+  def UnApply(fun: Tree, implicits: List[Tree], patterns: List[Tree], proto: Type)(implicit ctx: Context): UnApply = {
+    assert(fun.isInstanceOf[RefTree] || fun.isInstanceOf[GenericApply[_]])
     ta.assignType(untpd.UnApply(fun, implicits, patterns), proto)
+  }
 
   def ValDef(sym: TermSymbol, rhs: LazyTree = EmptyTree)(implicit ctx: Context): ValDef =
     ta.assignType(untpd.ValDef(sym.name, TypeTree(sym.info), rhs), sym)

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

@@ -36,9 +36,6 @@ class ElimByName extends TransformByNameApply with InfoTransformer {
 
   override def phaseName: String = ElimByName.name
 
-  override def runsAfterGroupsOf: Set[String] = Set(Splitter.name)
-    // I got errors running this phase in an earlier group, but I did not track them down.
-
   override def changesParents: Boolean = true // Only true for by-names
 
   /** Map `tree` to `tree.apply()` is `ftree` was of ExprType and becomes now a function */

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

@@ -34,7 +34,7 @@ class Erasure extends Phase with DenotTransformer {
   override def phaseName: String = Erasure.name
 
   /** List of names of phases that should precede this phase */
-  override def runsAfter: Set[String] = Set(InterceptedMethods.name, Splitter.name, ElimRepeated.name)
+  override def runsAfter: Set[String] = Set(InterceptedMethods.name, ElimRepeated.name)
 
   override def changesMembers: Boolean = true // the phase adds bridges
   override def changesParents: Boolean = true // the phase drops Any

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

@@ -2365,7 +2365,12 @@ class Typer extends Namer
             }
           } else issueErrors()
         }
-        else readaptSimplified(tpd.Apply(tree, args))
+        else tree match {
+          case tree: Block =>
+            readaptSimplified(tpd.Block(tree.stats, tpd.Apply(tree.expr, args)))
+          case _ =>
+            readaptSimplified(tpd.Apply(tree, args))
+        }
       }
       addImplicitArgs(argCtx(tree))
     }

compiler/test/dotty/tools/dotc/transform/PatmatExhaustivityTest.scala

@@ -17,7 +17,7 @@ import vulpix.TestConfiguration
 class PatmatExhaustivityTest {
   val testsDir = "tests/patmat"
   // stop-after: patmatexhaust-huge.scala crash compiler
-  val options = List("-color:never", "-Ystop-after:splitter", "-Ycheck-all-patmat", "-classpath", TestConfiguration.basicClasspath)
+  val options = List("-color:never", "-Ystop-after:crossCast", "-Ycheck-all-patmat", "-classpath", TestConfiguration.basicClasspath)
 
   private def compileFile(path: JPath) = {
     val stringBuffer = new StringWriter()

tests/pos/i5107.scala

@@ -0,0 +1,9 @@
+class Test {
+  inline def foo(x: Int = 5)(implicit y: Int): Int =
+    if (x > 0) y * y
+    else y + y
+
+  implicit val m: Int = 7
+
+  (new Test).foo()
+}