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Let inline val implement abstract inline def/val #8832

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Merged
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Apr 30, 2020
Merged

Let inline val implement abstract inline def/val #8832

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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/typer/RefChecks.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -398,7 +398,7 @@ object RefChecks {
overrideError("is an extension method, cannot override a normal method")
else if (other.isAllOf(ExtensionMethod) && !member.isAllOf(ExtensionMethod)) // (1.9.2)
overrideError("is a normal method, cannot override an extension method")
else if other.isInlineMethod && !member.isInlineMethod then // (1.10)
else if other.is(Inline) && !member.is(Inline) then // (1.10)
overrideError("is not inline, cannot implement an inline method")
else if (other.isScala2Macro && !member.isScala2Macro) // (1.11)
overrideError("cannot be used here - only Scala-2 macros can override Scala-2 macros")
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11 changes: 5 additions & 6 deletions compiler/src/dotty/tools/dotc/typer/Typer.scala
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Expand Up @@ -3082,18 +3082,17 @@ class Typer extends Namer
checkEqualityEvidence(tree, pt)
tree
}
else if (methPart(tree).symbol.isAllOf(Inline | Deferred) && !ctx.inInlineMethod) then
errorTree(tree, i"Deferred inline ${methPart(tree).symbol.showLocated} cannot be invoked")
else if (Inliner.isInlineable(tree) &&
!ctx.settings.YnoInline.value &&
!suppressInline) {
tree.tpe <:< wildApprox(pt)
val errorCount = ctx.reporter.errorCount
val meth = methPart(tree).symbol
if meth.is(Deferred) then
errorTree(tree, i"Deferred inline ${meth.showLocated} cannot be invoked")
else
val inlined = Inliner.inlineCall(tree)
if ((inlined ne tree) && errorCount == ctx.reporter.errorCount) readaptSimplified(inlined)
else inlined
val inlined = Inliner.inlineCall(tree)
if ((inlined ne tree) && errorCount == ctx.reporter.errorCount) readaptSimplified(inlined)
else inlined
}
else if (tree.symbol.isScala2Macro &&
// raw and s are eliminated by the StringInterpolatorOpt phase
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8 changes: 8 additions & 0 deletions tests/neg/abstract-inline-val.scala
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@@ -0,0 +1,8 @@
trait C:
inline def x: Int
inline val y: Int

def test: Unit =
val c: C = ???
c.x // error
c.y // error
11 changes: 11 additions & 0 deletions tests/pos/abstract-inline-val.scala
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@@ -0,0 +1,11 @@
trait C:
inline def x: Int
inline val y: Int

class C1 extends C:
inline val x = 1
inline val y = 2
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A side note: in inline val, we require the rhs to be a literal type, which is not really related to inline. Meanwhile, const-folding can be achieved by annotating the constant type explicitly.

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Actually, inline val requires a literal type result type and a pure body. This is a consequence of being marked as inline, as these are the only values that can be soundly inlined. We use constant folding to inline it because thee type already provides this functionality.

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It's more about semantics than soundness. There is an inconsistency between inline vals and inline parameters.


class C2 extends C:
inline def x = 3
inline val y = 4