fix issue 462 - MatchError in Output[String] -> Output[NonEmptyString] inference

core/src/main/scala/besom/util/NonEmptyString.scala

@@ -51,6 +51,10 @@ object NonEmptyString:
           handleParts(parts)
         case '{ scala.StringContext.apply(${ Varargs(parts) }: _*).pulumi(${ Varargs(_) }: _*)(using ${ xd }: Context) } =>
           handleParts(parts)
+        case _ =>
+          report.errorAndAbort(
+            "This is an Output of a dynamic String which can't be inferred to be a NonEmptyString! Use `.flatMap(_.toNonEmptyOutput)` instead."
+          )
 
     end fromStringOutputImpl
 

core/src/test/scala/besom/util/CompileAssertions.scala

@@ -10,13 +10,13 @@ trait CompileAssertions:
 
   private val NL = System.lineSeparator()
 
-  inline def failsToCompile(inline code: String): Unit =
+  transparent inline def failsToCompile(inline code: String): Unit =
     assert(
       !scala.compiletime.testing.typeChecks(code),
       s"Code compiled correctly when expecting type errors:$NL$code"
     )
 
-  inline def compiles(inline code: String): Unit =
+  transparent inline def compiles(inline code: String): Unit =
     val errors = scala.compiletime.testing.typeCheckErrors(code)
     if errors.nonEmpty then
       val errorMessages = errors.map(_.message).mkString(NL)

core/src/test/scala/besom/util/NonEmptyStringTest.scala

@@ -360,4 +360,31 @@ class NonEmptyStringTest extends munit.FunSuite with CompileAssertions:
       case None    => ()
       case Some(_) => fail("apply doesn't work")
   }
+
+  test("issue 462") {
+    val errors = scala.compiletime.testing.typeCheckErrors("""
+    import besom.*
+    given Context = ???
+
+    def requireString(key: NonEmptyString)(using Context): Output[String] = ???
+
+    val s: Output[NonEmptyString] = requireString("stuff")
+    """)
+
+    assert(errors.size == 1)
+    assert(
+      errors.head.message.contains(
+        "This is an Output of a dynamic String which can't be inferred to be a NonEmptyString! Use `.flatMap(_.toNonEmptyOutput)` instead."
+      )
+    )
+
+    compiles("""
+    import besom.*
+    given Context = ???
+
+    def requireString(key: NonEmptyString)(using Context): Output[String] = ???
+
+    val s: Output[NonEmptyString] = requireString("stuff").flatMap(_.toNonEmptyOutput)
+    """)
+  }
 end NonEmptyStringTest