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Fix #9413: Fix test for user-defined equality #9414

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Merged
merged 2 commits into from
Jul 23, 2020
Merged

Fix #9413: Fix test for user-defined equality #9414

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ee9b034
Fix criterion when value classes have user defined equals methods
odersky Jul 23, 2020
b205858
Generalize NewWithArgs
odersky Jul 23, 2020
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6 changes: 5 additions & 1 deletion compiler/src/dotty/tools/dotc/transform/TreeExtractors.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -19,11 +19,15 @@ object TreeExtractors {
}
}

/** Match new C(args) and extract (C, args) */
/** Match new C(args) and extract (C, args).
* Also admit new C(args): T and {new C(args)}.
*/
object NewWithArgs {
def unapply(t: Tree)(using Context): Option[(Type, List[Tree])] = t match {
case Apply(Select(New(_), nme.CONSTRUCTOR), args) =>
Some((t.tpe, args))
case Typed(expr, _) => unapply(expr)
case Block(Nil, expr) => unapply(expr)
case _ =>
None
}
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16 changes: 11 additions & 5 deletions compiler/src/dotty/tools/dotc/transform/VCElideAllocations.scala
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Expand Up @@ -3,7 +3,7 @@ package transform

import ast.tpd
import core._
import Contexts._, Symbols._
import Contexts._, Symbols._, Types._, Flags._, Phases._
import DenotTransformers._, MegaPhase._
import TreeExtractors._, ValueClasses._

Expand All @@ -23,13 +23,19 @@ class VCElideAllocations extends MiniPhase with IdentityDenotTransformer {
override def runsAfter: Set[String] = Set(ElimErasedValueType.name)

override def transformApply(tree: Apply)(using Context): Tree =
def hasUserDefinedEquals(tp: Type): Boolean =
val eql = atPhase(erasurePhase) {
defn.Any_equals.matchingMember(tp.typeSymbol.thisType)
}
eql.owner != defn.AnyClass && !eql.is(Synthetic)

tree match {
// new V(u1) == new V(u2) => u1 == u2
// new V(u1) == new V(u2) => u1 == u2, unless V defines its own equals.
// (We don't handle != because it has been eliminated by InterceptedMethods)
case BinaryOp(NewWithArgs(tp1, List(u1)), op, NewWithArgs(tp2, List(u2)))
if (tp1 eq tp2) && (op eq defn.Any_==) &&
isDerivedValueClass(tp1.typeSymbol) &&
!defn.Any_equals.overridingSymbol(tp1.typeSymbol.asClass).exists =>
if (tp1 eq tp2) && (op eq defn.Any_==)
&& isDerivedValueClass(tp1.typeSymbol)
&& !hasUserDefinedEquals(tp1) =>
// == is overloaded in primitive classes
u1.equal(u2)

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41 changes: 41 additions & 0 deletions compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala
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Expand Up @@ -976,6 +976,47 @@ class TestBCode extends DottyBytecodeTest {
assert((getMethod(c, "x_$eq").access & Opcodes.ACC_DEPRECATED) != 0)
}
}

@Test def vcElideAllocations = {
val source =
s"""class ApproxState(val bits: Int) extends AnyVal
|class Foo {
| val FreshApprox: ApproxState = new ApproxState(4)
| var approx: ApproxState = FreshApprox
| def meth1: Boolean = approx == FreshApprox
| def meth2: Boolean = (new ApproxState(4): ApproxState) == FreshApprox
|}
""".stripMargin

checkBCode(source) { dir =>
val clsIn = dir.lookupName("Foo.class", directory = false).input
val clsNode = loadClassNode(clsIn)
val meth1 = getMethod(clsNode, "meth1")
val meth2 = getMethod(clsNode, "meth2")
val instructions1 = instructionsFromMethod(meth1)
val instructions2 = instructionsFromMethod(meth2)

val isFrameLine = (x: Instruction) => x.isInstanceOf[FrameEntry] || x.isInstanceOf[LineNumber]

// No allocations of ApproxState

assertSameCode(instructions1.filterNot(isFrameLine), List(
VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "Foo", "approx", "()I", false),
VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "Foo", "FreshApprox", "()I", false),
Jump(IF_ICMPNE, Label(7)), Op(ICONST_1),
Jump(GOTO, Label(10)),
Label(7), Op(ICONST_0),
Label(10), Op(IRETURN)))

assertSameCode(instructions2.filterNot(isFrameLine), List(
Op(ICONST_4),
VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "Foo", "FreshApprox", "()I", false),
Jump(IF_ICMPNE, Label(6)), Op(ICONST_1),
Jump(GOTO, Label(9)),
Label(6), Op(ICONST_0),
Label(9), Op(IRETURN)))
}
}
}

object invocationReceiversTestCode {
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