Fix #2939: Avoid duplicating symbols in default arguments #3839
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odersky
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Something fails with the CI. |
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I can reproduce the failure locally, the added run test compiles correctly but generates invalid bytecode which is detected at runtime: > run tests/run/i2939.scala
[info] Running dotty.tools.dotc.Main -classpath /home/smarter/opt/dotty/library/target/scala-2.12/dotty-library_2.12-0.7.0-bin-SNAPSHOT-nonbootstrapped.jar tests/run/i2939.scala
[success] Total time: 4 s, completed 21 janv. 2018 18:57:56
> dotr Test
Exception in thread "main" java.lang.VerifyError: Bad local variable type
Exception Details:
Location:
Test$.x$1$1()I @0: aload_1
Reason:
Type top (current frame, locals[1]) is not assignable to reference type
Current Frame:
bci: @0
flags: { }
locals: { 'Test$' }
stack: { }
Bytecode:
0x0000000: 2bbe ac
at Test.main(i2939.scala) |
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Actually, compilation also fails with Ycheck: > run -Ycheck:all tests/run/i2939.scala
exception while typing def x$2: Int = args.length of class class dotty.tools.dotc.ast.Trees$DefDef # 584
...
Exception in thread "main" java.lang.AssertionError: assertion failed: wrong type, expect a method type for Test$._$x$2, but found: Int
at scala.Predef$.assert(Predef.scala:219)
at dotty.tools.dotc.transform.TreeChecker$Checker.$anonfun$typedDefDef$2(TreeChecker.scala:405)
at dotty.tools.dotc.transform.TreeChecker$Checker.withDefinedSyms(TreeChecker.scala:180)
at dotty.tools.dotc.transform.TreeChecker$Checker.$anonfun$typedDefDef$1(TreeChecker.scala:393)
at dotty.tools.dotc.transform.TreeChecker$Checker.withDefinedSyms(TreeChecker.scala:180)
at dotty.tools.dotc.transform.TreeChecker$Checker.typedDefDef(TreeChecker.scala:392)
at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:1708)
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Previously a method argument could be duplicated because it was passed to the method as well as to its default argument methods. This was fatal if the argument contained local definitions or was a closure. We now unconditionally lift such arguments if the method has default parameters.
smarter
reviewed
Feb 1, 2018
| @@ -345,7 +346,7 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] => | |||
| | Super(_, _) | |||
| | Literal(_) | |||
| | Closure(_, _, _) => | |||
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How come a Closure is considered a PurePath? It can contain local definitions.
smarter
approved these changes
Feb 2, 2018
| /** Test indicating `expr` does not need lifting */ | ||
| def noLift(expr: Tree)(implicit ctx: Context): Boolean | ||
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| /** The corresponding lifter for paam-by-name arguments */ |
| * @return pure if expression has no side effects | ||
| * idempotent if running the expression a second time has no side effects | ||
| * impure otherwise | ||
| * @return PurePath if expression has no side effects and cannot contain local definitions |
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Not sure if PurePath is the best name for this since not every PurePath expression is a valid path. Maybe NoDefPure? Or SimplePure/ComplexPure considering that later on we talk about "complex expressions" ?
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Previously a method argument could be duplicated because it was passed
to the method as well as to its default argument methods. This was fatal
if the argument contained local definitions or was a closure.
We now unconditionally lift such arguments if the method has default
parameters.