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Only ignore inlined if conditions if pure. #2264

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Only ignore inlined if conditions if pure. #2264

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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/typer/Inliner.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -527,7 +527,7 @@ class Inliner(call: tpd.Tree, rhs: tpd.Tree)(implicit ctx: Context) {
cond1.tpe.widenTermRefExpr match {
case ConstantType(Constant(condVal: Boolean)) =>
val selected = typed(if (condVal) tree.thenp else tree.elsep, pt)
if (isIdempotentExpr(cond1)) selected
if (isPureExpr(cond1)) selected
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In fact it looks like all constant type conditions that reach this code are pure. Are they all supposed to be in this particular case? If not how could I construct a condition that has a constant type and is not pure.

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@DarkDimius DarkDimius Apr 15, 2017 •
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I think code should be transformed in a different way instead(That's what is done in linker):

if ($cond: true.type) { $themp } else { $elsep } 

==>> 
cond$; 
thenp$

Similar for false.type .

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In fact it looks like all constant type conditions that reach this code are pure. Are they all supposed to be in this particular case?

lazy val s: true = { println(1); true}

@inline def bla = 
  if (s) {...} else {...}

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That lazy val creates the idempotent condition with constant type. Just found another bug with lazy vals with constant type #2266.

else Block(cond1 :: Nil, selected)
case _ =>
val if1 = untpd.cpy.If(tree)(cond = untpd.TypedSplice(cond1))
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