Merge pull request #12334 from dotty-staging/fix-#10552

Check transparent inline type argument bounds

Author: odersky

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

@@ -125,6 +125,14 @@ object Inliner {
       case Apply(fn, args) =>
         cpy.Apply(tree)(liftBindings(fn, liftPos), args)
       case TypeApply(fn, args) =>
+        fn.tpe.widenTermRefExpr match
+          case tp: PolyType =>
+            val targBounds = tp.instantiateParamInfos(args.map(_.tpe))
+            for (arg, bounds: TypeBounds) <- args.zip(targBounds) if !bounds.contains(arg.tpe) do
+              val boundsStr =
+                if bounds == TypeBounds.empty then " <: Any. Note that this type is higher-kinded."
+                else bounds.show
+              report.error(em"${arg.tpe} does not conform to bound$boundsStr", arg)
         cpy.TypeApply(tree)(liftBindings(fn, liftPos), args)
       case Select(qual, name) =>
         cpy.Select(tree)(liftBindings(qual, liftPos), name)

tests/neg/i10552a.scala

@@ -0,0 +1,4 @@
+transparent inline def foo[T]: Int = 10
+
+def test =
+  foo[List] // error

tests/neg/i10552b.check

@@ -0,0 +1,24 @@
+-- Error: tests/neg/i10552b.scala:10:17 --------------------------------------------------------------------------------
+10 |    println(foo1["hi"]) // error
+   |                 ^^^^
+   |                 ("hi" : String) does not conform to bound <: Int
+-- Error: tests/neg/i10552b.scala:11:17 --------------------------------------------------------------------------------
+11 |    println(foo1[String]) // error
+   |                 ^^^^^^
+   |                 String does not conform to bound <: Int
+-- Error: tests/neg/i10552b.scala:12:17 --------------------------------------------------------------------------------
+12 |    println(foo1[Any]) // error
+   |                 ^^^
+   |                 Any does not conform to bound <: Int
+-- Error: tests/neg/i10552b.scala:13:17 --------------------------------------------------------------------------------
+13 |    println(foo1[AnyKind]) // error
+   |                 ^^^^^^^
+   |                 AnyKind does not conform to bound <: Int
+-- Error: tests/neg/i10552b.scala:15:17 --------------------------------------------------------------------------------
+15 |    println(foo2["hi"]) // error
+   |                 ^^^^
+   |                 ("hi" : String) does not conform to bound >: Int <: Int
+-- Error: tests/neg/i10552b.scala:17:17 --------------------------------------------------------------------------------
+17 |    println(foo3[X]) // error
+   |                 ^
+   |                 Foo.this.X does not conform to bound <: Any. Note that this type is higher-kinded.

tests/neg/i10552b.scala

@@ -0,0 +1,17 @@
+class Foo:
+  transparent inline def foo1[A <: Int]: Int = valueOf[A]
+  transparent inline def foo2[A >: Int <: Int]: Int = valueOf[A]
+  transparent inline def foo3[A]: Int = ???
+
+  type X >: AnyKind <: AnyKind
+
+  def run =
+    println(foo1[Int])
+    println(foo1["hi"]) // error
+    println(foo1[String]) // error
+    println(foo1[Any]) // error
+    println(foo1[AnyKind]) // error
+
+    println(foo2["hi"]) // error
+
+    println(foo3[X]) // error

tests/run-macros/from-type.check

@@ -1,7 +1,5 @@
 Some(true)
 Some(false)
-Some(1)
-Some(2)
 Some(3)
 Some(4)
 Some(5)

tests/run-macros/from-type/Test_2.scala

@@ -2,8 +2,9 @@
 @main def Test: Unit =
   testValueOfType[true]
   testValueOfType[false]
-  testValueOfByte[1]
-  testValueOfShort[2]
+  // TODO support Byte and short literal types
+  // testValueOfType[1b]
+  // testValueOfType[2s]
   testValueOfType[3]
   testValueOfType[4]
   testValueOfType[5L]
@@ -29,6 +30,3 @@
   testValueOfType[Null]
   testValueOfType[Any]
   testValueOfType[Some[1]]
-
-transparent inline def testValueOfByte[B <: Byte] = testValueOfType[B]
-transparent inline def testValueOfShort[S <: Short] = testValueOfType[S]