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Fix #4815: Illegal modifier on local def #4850

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Merged
merged 1 commit into from
Jul 27, 2018
Merged

Fix #4815: Illegal modifier on local def #4850

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7 changes: 6 additions & 1 deletion compiler/src/dotty/tools/dotc/parsing/Parsers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -2545,7 +2545,12 @@ object Parsers {
def localDef(start: Int, implicitMods: Modifiers = EmptyModifiers): Tree = {
var mods = defAnnotsMods(localModifierTokens)
for (imod <- implicitMods.mods) mods = addMod(mods, imod)
defOrDcl(start, mods)
if (mods.is(Final)) {
// A final modifier means the local definition is "class-like".
tmplDef(start, mods)
} else {
defOrDcl(start, mods)
}
}

/** BlockStatSeq ::= { BlockStat semi } [ResultExpr]
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4 changes: 2 additions & 2 deletions language-server/src/dotty/tools/languageserver/Memory.scala
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Expand Up @@ -37,11 +37,11 @@ object Memory {
}

def stats(): String = {
final val M = 2 << 20
val M = 2 << 20
val runtime = Runtime.getRuntime
def total = runtime.totalMemory / M
def maximal = runtime.maxMemory / M
def free = runtime.freeMemory / M
s"total used memory: $total MB, free: $free MB, maximal available = $maximal MB"
}
}
}
26 changes: 26 additions & 0 deletions tests/neg/t4815.scala
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@@ -0,0 +1,26 @@
class Test {
def foo = {
final def bar = 1 // error: local def may not be final
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scalac rejects this. I think we should reject it as well

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I'm not sure I understand. We do reject this. This is what this PR does.

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Sorry, it was meant for the line below (i.e. final val v = 42)

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Ah, I see. There's at least one test that uses this feature (constant value expression):

A constant value definition is of the form

final val x = e

where e is a constant expression. The final modifier must be present and no type annotation may be given. References to the constant value x are themselves treated as constant expressions; in the generated code they are replaced by the definition's right-hand side e.

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This part of the spec only specifies what a constant value is, not where it is allowed. Looking at the syntax part of the spec, it doesn't seems to be allowed

  BlockStat         ::=  Import
                      |  {Annotation} [‘implicit’ | ‘lazy’] Def
                      |  {Annotation} {LocalModifier} TmplDef
                      |  Expr1
  Def               ::=  PatVarDef
                      |  ‘def’ FunDef
                      |  ‘type’ {nl} TypeDef
                      |  TmplDef
  PatVarDef         ::=  ‘val’ PatDef
                      |  ‘var’ VarDef

final val v = 42 // error: local val may not be final
final var v2 = 100 // error: local var may not be final
final type T = Int // error: local type def may not be final
}

{
final def foo(x: Int) = x // error: local def may not be final
}

final def foo2(x: Int) = x // ok: final allowed in class field

object Foo {
final def foo(x: Int) = x // ok, but redundant
}

abstract class Bar {
def foo: Int
}

val x = new Bar {
override final def foo = 42 // ok: def is a field
}
}
3 changes: 2 additions & 1 deletion tests/run/tasty-eval/quoted_2.scala
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Expand Up @@ -2,10 +2,11 @@
import Macros._

object Test {
final val y = 5

def main(args: Array[String]): Unit = {
println(foo(1)) // "Some(1)"
println(foo(1 + 7)) // "Some(8)"
final val y = 5
println(foo(y)) // "Some(5)"
println(foo(y + 1))
val x = 4
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