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SI-7185 Avoid NPE in TreeInfo.isExprSafeToInline

We got there typechecking code with a redundant
layer of Block.

We can't express that in source code, so we test
this with manual tree construction and with XML
literals, which as reported produce such trees.
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retronym committed Feb 26, 2013
1 parent 88b2915 commit 387fbf459efe5bb89f3d7a76c819f72b8f8fd58f
@@ -98,7 +98,8 @@ abstract class TreeInfo {
// However, before typing, applications of nullary functional values are also
// Apply(function, Nil) trees. To prevent them from being treated as pure,
// we check that the callee is a method.
- fn.symbol.isMethod && !fn.symbol.isLazy && isExprSafeToInline(fn)
+ // The callee might also be a Block, which has a null symbol, so we guard against that (SI-7185)
+ fn.symbol != null && fn.symbol.isMethod && !fn.symbol.isLazy && isExprSafeToInline(fn)
case Typed(expr, _) =>
isExprSafeToInline(expr)
case Block(stats, expr) =>
@@ -0,0 +1,7 @@
+t7185.scala:2: error: overloaded method value apply with alternatives:
+ (f: scala.xml.Node => Boolean)scala.xml.NodeSeq <and>
+ (i: Int)scala.xml.Node
+ cannot be applied to ()
+ <e></e>()
+ ^
+one error found
@@ -0,0 +1,3 @@
+object Test {
+ <e></e>()
+}
View
@@ -0,0 +1,34 @@
+Type in expressions to have them evaluated.
+Type :help for more information.
+
+scala>
+
+scala> import scala.tools.reflect.ToolBox
+import scala.tools.reflect.ToolBox
+
+scala> import scala.reflect.runtime.universe._
+import scala.reflect.runtime.universe._
+
+scala> object O { def apply() = 0 }
+defined module O
+
+scala> val ORef = reify { O }.tree
+ORef: reflect.runtime.universe.Tree = $read.O
+
+scala> val tree = Apply(Block(Nil, Block(Nil, ORef)), Nil)
+tree: reflect.runtime.universe.Apply =
+{
+ {
+ $read.O
+ }
+}()
+
+scala> {val tb = reflect.runtime.currentMirror.mkToolBox(); tb.typeCheck(tree): Any}
+res0: Any =
+{
+ {
+ $read.O.apply()
+ }
+}
+
+scala>
View
@@ -0,0 +1,12 @@
+import scala.tools.partest.ReplTest
+
+object Test extends ReplTest {
+ override def code = """
+import scala.tools.reflect.ToolBox
+import scala.reflect.runtime.universe._
+object O { def apply() = 0 }
+val ORef = reify { O }.tree
+val tree = Apply(Block(Nil, Block(Nil, ORef)), Nil)
+{val tb = reflect.runtime.currentMirror.mkToolBox(); tb.typeCheck(tree): Any}
+"""
+}

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