Merge pull request #8832 from dotty-staging/let-inline-vals-implement-abstract-inline-def-or-val

Let inline val implement abstract inline def/val

Author: nicolasstucki

compiler/src/dotty/tools/dotc/typer/RefChecks.scala

@@ -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")

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -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

tests/neg/abstract-inline-val.scala

@@ -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

tests/pos/abstract-inline-val.scala

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