Fix missing inlining in checkCompiles

Author: nicolasstucki

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

@@ -283,11 +283,16 @@ object Inliner {
       assert(tree.symbol == defn.CompiletimeTesting_typeChecks || tree.symbol == defn.CompiletimeTesting_typeCheckErrors)
       def stripTyped(t: Tree): Tree = t match {
         case Typed(t2, _) => stripTyped(t2)
+        case Inlined(_, Nil, t2) => stripTyped(t2)
         case _ => t
       }
 
       val Apply(_, codeArg :: Nil) = tree
-      val underlyingCodeArg = stripTyped(codeArg.underlying)
+      val underlyingCodeArg =
+        val codeArg1 = stripTyped(codeArg.underlying)
+        if Inliner.isInlineable(codeArg1) then stripTyped(Inliner.inlineCall(codeArg1))
+        else codeArg1
+
       ConstFold(underlyingCodeArg).tpe.widenTermRefExpr match {
         case ConstantType(Constant(code: String)) =>
           val source2 = SourceFile.virtual("tasty-reflect", code)
@@ -303,7 +308,7 @@ object Inliner {
             res ++= typerErrors.map(e => ErrorKind.Typer -> e)
           res.toList
         case t =>
-          report.error(em"argument to compileError must be a statically known String but was: $tree", underlyingCodeArg.srcPos)
+          report.error(em"argument to ${tree.symbol} must be a statically known String but was: $codeArg", codeArg.srcPos)
           Nil
       }
 

library/src/scala/compiletime/testing/package.scala

@@ -9,7 +9,7 @@ package testing
  *
  *  The code should be a sequence of expressions or statements that may appear in a block.
  */
-inline def typeChecks(inline code: String): Boolean =
+transparent inline def typeChecks(inline code: String): Boolean =
   // implemented in package dotty.tools.dotc.typer.Inliner.Intrinsics
   error("Compiler bug: `typeChecks` was not checked by the compiler")
 
@@ -26,6 +26,6 @@ inline def typeChecks(inline code: String): Boolean =
  *
  *  The code should be a sequence of expressions or statements that may appear in a block.
  */
-inline def typeCheckErrors(inline code: String): List[Error] =
+transparent inline def typeCheckErrors(inline code: String): List[Error] =
   // implemented in package dotty.tools.dotc.typer.Inliner.Intrinsics
   error("Compiler bug: `typeCheckErrors` was not checked by the compiler")

tests/pos-macros/forced-inline-typeChecks.scala

@@ -0,0 +1,8 @@
+class Test:
+  def test: Unit =
+    assert2(scala.compiletime.testing.typeChecks(stripMargin("|1 + 1")))
+
+  inline def stripMargin(inline x: String): String = x
+
+  transparent inline def assert2(inline assertion: Boolean): Unit =
+    if !assertion then scala.runtime.Scala3RunTime.assertFailed()

tests/run-macros/reflect-inline/test_2.scala

@@ -2,7 +2,7 @@ import api._
 
 object Test {
   def main(args: Array[String]): Unit = {
-    val a: String = "5"
+    inline val a = "5"
     assert(typeChecks("|1 + 1".stripMargin))
     assert(scala.compiletime.testing.typeChecks("|1 + 1".stripMargin))
     assert(("|3 + " + a).stripMargin == "3 + 5")