-Yexplicit-nulls fails to detect null pointer dereference #21380
Description
-Yexplicit-nulls fails to detect method call on a variable holding null.
This might be regression, as scalac v3.3.3 detects the error as expected.
Compiler version
3.4.2
Minimized code
@main def test() = { var x: String | Null = null if (false) { x = "" } else { x = "" } try { x = "" throw new Exception() } catch { case e: Exception => { x = null } } x.replace("", "") }Output
The code compiles with -Yexplicit-nulls, but at runtime you get NPE
java.lang.NullPointerException at test$package$.test(test.scala:18) at test.main(test.scala:1) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at dotty.tools.runner.RichClassLoader$.run$extension$$anonfun$1(ScalaClassLoader.scala:36) at dotty.tools.runner.ScalaClassLoader$.asContext(ScalaClassLoader.scala:80) at dotty.tools.runner.RichClassLoader$.dotty$tools$runner$RichClassLoader$$$asContext$extension(ScalaClassLoader.scala:18) at dotty.tools.runner.RichClassLoader$.run$extension(ScalaClassLoader.scala:36) at dotty.tools.runner.CommonRunner.run(ObjectRunner.scala:23) at dotty.tools.runner.CommonRunner.run$(ObjectRunner.scala:13) at dotty.tools.runner.ObjectRunner$.run(ObjectRunner.scala:48) at dotty.tools.runner.CommonRunner.runAndCatch(ObjectRunner.scala:30) at dotty.tools.runner.CommonRunner.runAndCatch$(ObjectRunner.scala:13) at dotty.tools.runner.ObjectRunner$.runAndCatch(ObjectRunner.scala:48) at dotty.tools.MainGenericRunner$.run$1(MainGenericRunner.scala:215) at dotty.tools.MainGenericRunner$.process(MainGenericRunner.scala:270) at dotty.tools.MainGenericRunner$.main(MainGenericRunner.scala:281) at dotty.tools.MainGenericRunner.main(MainGenericRunner.scala)Expectation
The code should have been rejected with
-- [E008] Not Found Error: test.scala:18:4 ---------------------------------------------------------------------------------------------------------------------------------------------------- 18 | x.replace("", "") | ^^^^^^^^^ | value replace is not a member of String | Null. | Since explicit-nulls is enabled, the selection is rejected because | String | Null could be null at runtime. | If you want to select replace without checking for a null value, | insert a .nn before .replace or import scala.language.unsafeNulls. 1 error found