Merge pull request #12235 from dotty-staging/fix-#12196

Support inline val references in top level splices

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/Splicer.scala

@@ -161,7 +161,7 @@ object Splicer {
         case SeqLiteral(elems, _) =>
           elems.foreach(checkIfValidArgument)
 
-        case tree: Ident if summon[Env].contains(tree.symbol) =>
+        case tree: Ident if summon[Env].contains(tree.symbol) || tree.symbol.is(Inline, butNot = Method) =>
           // OK
 
         case _ =>
@@ -172,6 +172,7 @@ object Splicer {
               |Parameters may only be:
               | * Quoted parameters or fields
               | * Literal values of primitive types
+              | * References to `inline val`s
               |""".stripMargin, tree.srcPos)
       }
 
@@ -242,6 +243,11 @@ object Splicer {
       case Literal(Constant(value)) =>
         interpretLiteral(value)
 
+      case tree: Ident if tree.symbol.is(Inline, butNot = Method) =>
+        tree.tpe.widenTermRefExpr match
+          case ConstantType(c) => c.value.asInstanceOf[Object]
+          case _ => throw new StopInterpretation(em"${tree.symbol} could not be inlined", tree.srcPos)
+
       // TODO disallow interpreted method calls as arguments
       case Call(fn, args) =>
         if (fn.symbol.isConstructor && fn.symbol.owner.owner.is(Package))

tests/neg-macros/i7839.check

@@ -6,3 +6,4 @@
   |                  Parameters may only be:
   |                   * Quoted parameters or fields
   |                   * Literal values of primitive types
+  |                   * References to `inline val`s

tests/neg/i12196.scala

@@ -0,0 +1,10 @@
+import scala.quoted.*
+
+def qqq(s: String)(using Quotes): Expr[Unit] = '{()}
+
+inline val InlineVal = "i"
+inline def InlineDef = "i"
+
+inline def withInlineVal = ${ qqq(InlineVal) }
+inline def withInlineDef = ${ qqq(InlineDef) } // error
+inline def withString    = ${ qqq("i") }

tests/neg/i12196b.scala

@@ -0,0 +1,10 @@
+import scala.quoted.*
+
+def qqq(s: String)(using Quotes): Expr[Unit] = '{()}
+
+abstract class Foo:
+  inline val InlineVal: String
+
+val foo: Foo = ???
+
+inline def withInlineVal = ${ qqq(foo.InlineVal) } // error

tests/pos-macros/i12196/Macros_1.scala

@@ -0,0 +1,8 @@
+
+import scala.quoted.*
+
+inline val InlineStringVal = "abc"
+
+inline def withInlineVal = ${ qqq(InlineStringVal) }
+
+def qqq(s: String)(using Quotes): Expr[String] = Expr(s)

tests/pos-macros/i12196/Test_2.scala

@@ -0,0 +1 @@
+def test = withInlineVal