Merge pull request #15218 from dotty-staging/fix-15155

odersky · web-flow · commit 56ca1ba51d7c · 2022-05-29T18:18:11.000+02:00
Show a match type trace for "not a class type" errors
diff --git a/compiler/src/dotty/tools/dotc/reporting/ErrorMessageID.scala b/compiler/src/dotty/tools/dotc/reporting/ErrorMessageID.scala
@@ -183,7 +183,8 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case LossyWideningConstantConversionID // errorNumber: 167
   case ImplicitSearchTooLargeID // errorNumber: 168
   case TargetNameOnTopLevelClassID // errorNumber: 169
-
+  case NotClassTypeID // errorNumber 170
+  
   def errorNumber = ordinal - 1
 
 object ErrorMessageID:
diff --git a/compiler/src/dotty/tools/dotc/reporting/messages.scala b/compiler/src/dotty/tools/dotc/reporting/messages.scala
@@ -2521,3 +2521,8 @@ import transform.SymUtils._
           |  $annot $symbol { ... }
           |
           |${hl("export")} Wrapper.${symbol.name}  ${hl("// optional")}"""
+
+  class NotClassType(tp: Type)(using Context)
+  extends TypeMsg(NotClassTypeID), ShowMatchTrace(tp):
+    def msg = ex"$tp is not a class type"
+    def explain = ""
diff --git a/compiler/src/dotty/tools/dotc/typer/Checking.scala b/compiler/src/dotty/tools/dotc/typer/Checking.scala
@@ -937,7 +937,7 @@ trait Checking {
         if (stablePrefixReq && ctx.phase <= refchecksPhase) checkStable(tref.prefix, pos, "class prefix")
         tp
       case _ =>
-        report.error(ex"$tp is not a class type", pos)
+        report.error(NotClassType(tp), pos)
         defn.ObjectType
     }
 
diff --git a/tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.check b/tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.check
@@ -2,39 +2,39 @@
 13 |  val a = js.constructorOf[NativeJSTrait] // error
    |                           ^^^^^^^^^^^^^
    |                           non-trait class type required but NativeJSTrait found
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:14:27 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:14:27 -----------------------------
 14 |  val b = js.constructorOf[NativeJSObject.type] // error
    |                           ^^^^^^^^^^^^^^^^^^^
    |                           NativeJSObject.type is not a class type
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:16:27 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:16:27 -----------------------------
 16 |  val c = js.constructorOf[NativeJSClass with NativeJSTrait] // error
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                           NativeJSClass & NativeJSTrait is not a class type
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:17:27 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:17:27 -----------------------------
 17 |  val d = js.constructorOf[NativeJSClass { def bar: Int }] // error
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                           NativeJSClass{bar: Int} is not a class type
 -- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:19:27 -----------------------------------------
 19 |  val e = js.constructorOf[JSTrait] // error
    |                           ^^^^^^^
    |                           non-trait class type required but JSTrait found
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:20:27 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:20:27 -----------------------------
 20 |  val f = js.constructorOf[JSObject.type] // error
    |                           ^^^^^^^^^^^^^
    |                           JSObject.type is not a class type
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:22:27 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:22:27 -----------------------------
 22 |  val g = js.constructorOf[JSClass with JSTrait] // error
    |                           ^^^^^^^^^^^^^^^^^^^^
    |                           JSClass & JSTrait is not a class type
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:23:27 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:23:27 -----------------------------
 23 |  val h = js.constructorOf[JSClass { def bar: Int }] // error
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^
    |                           JSClass{bar: Int} is not a class type
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:25:42 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:25:42 -----------------------------
 25 |  def foo[A <: js.Any] = js.constructorOf[A] // error
    |                                          ^
    |                                          A is not a class type
--- Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:26:66 -----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructorof-error-in-prepjsinterop.scala:26:66 -----------------------------
 26 |  def bar[A <: js.Any: scala.reflect.ClassTag] = js.constructorOf[A] // error
    |                                                                  ^
    |                                                                  A is not a class type
diff --git a/tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.check b/tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.check
@@ -2,39 +2,39 @@
 13 |  val a = js.constructorTag[NativeJSTrait] // error
    |                                          ^
    |                                          non-trait class type required but NativeJSTrait found
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:14:48 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:14:48 ----------------------------
 14 |  val b = js.constructorTag[NativeJSObject.type] // error
    |                                                ^
    |                                                NativeJSObject.type is not a class type
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:16:61 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:16:61 ----------------------------
 16 |  val c = js.constructorTag[NativeJSClass with NativeJSTrait] // error
    |                                                             ^
    |                                                             (NativeJSClass & NativeJSTrait) is not a class type
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:17:59 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:17:59 ----------------------------
 17 |  val d = js.constructorTag[NativeJSClass { def bar: Int }] // error
    |                                                           ^
    |                                                           NativeJSClass{bar: Int} is not a class type
 -- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:19:36 ----------------------------------------
 19 |  val e = js.constructorTag[JSTrait] // error
    |                                    ^
    |                                    non-trait class type required but JSTrait found
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:20:42 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:20:42 ----------------------------
 20 |  val f = js.constructorTag[JSObject.type] // error
    |                                          ^
    |                                          JSObject.type is not a class type
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:22:49 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:22:49 ----------------------------
 22 |  val g = js.constructorTag[JSClass with JSTrait] // error
    |                                                 ^
    |                                                 (JSClass & JSTrait) is not a class type
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:23:53 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:23:53 ----------------------------
 23 |  val h = js.constructorTag[JSClass { def bar: Int }] // error
    |                                                     ^
    |                                                     JSClass{bar: Int} is not a class type
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:25:45 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:25:45 ----------------------------
 25 |  def foo[A <: js.Any] = js.constructorTag[A] // error
    |                                             ^
    |                                             A is not a class type
--- Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:26:69 ----------------------------------------
+-- [E170] Type Error: tests/neg-scalajs/jsconstructortag-error-in-prepjsinterop.scala:26:69 ----------------------------
 26 |  def bar[A <: js.Any: scala.reflect.ClassTag] = js.constructorTag[A] // error
    |                                                                     ^
    |                                                                     A is not a class type
diff --git a/tests/neg/classOf.check b/tests/neg/classOf.check
@@ -1,14 +1,14 @@
--- Error: tests/neg/classOf.scala:6:22 ---------------------------------------------------------------------------------
+-- [E170] Type Error: tests/neg/classOf.scala:6:22 ---------------------------------------------------------------------
 6 |  def f1[T] = classOf[T] // error
   |                      ^
   |                      T is not a class type
--- Error: tests/neg/classOf.scala:7:32 ---------------------------------------------------------------------------------
+-- [E170] Type Error: tests/neg/classOf.scala:7:32 ---------------------------------------------------------------------
 7 |  def f2[T <: String] = classOf[T] // error
   |                                ^
   |                                T is not a class type
   |
   |                                where:    T is a type in method f2 with bounds <: String
--- Error: tests/neg/classOf.scala:9:18 ---------------------------------------------------------------------------------
+-- [E170] Type Error: tests/neg/classOf.scala:9:18 ---------------------------------------------------------------------
 9 |  val y = classOf[C { type I = String }] // error
   |                  ^^^^^^^^^^^^^^^^^^^^^
   |                  Test.C{I = String} is not a class type
diff --git a/tests/neg/i13808.check b/tests/neg/i13808.check
@@ -1,8 +1,8 @@
--- Error: tests/neg/i13808.scala:13:37 ---------------------------------------------------------------------------------
+-- [E170] Type Error: tests/neg/i13808.scala:13:37 ---------------------------------------------------------------------
 13 |case class Boom[A](value: A) derives OpaqueType, Foo // error // error
    |                                     ^^^^^^^^^^
    |                                     OpaqueTypes.OpaqueType is not a class type
--- Error: tests/neg/i13808.scala:13:49 ---------------------------------------------------------------------------------
+-- [E170] Type Error: tests/neg/i13808.scala:13:49 ---------------------------------------------------------------------
 13 |case class Boom[A](value: A) derives OpaqueType, Foo // error // error
    |                                                 ^^^
    |                                                 FooModule.Foo is not a class type
diff --git a/tests/neg/i15155.check b/tests/neg/i15155.check
@@ -0,0 +1,11 @@
+-- [E170] Type Error: tests/neg/i15155.scala:10:33 ---------------------------------------------------------------------
+10 |  val EnumerationClass = classOf[EnumValue[E]] // error
+   |                                 ^^^^^^^^^^^^
+   |                                 EnumValue[E] is not a class type
+   |
+   |                                 Note: a match type could not be fully reduced:
+   |
+   |                                   trying to reduce  EnumValue[E]
+   |                                   failed since selector  E
+   |                                   does not match  case Aux[a] => a
+   |                                   and cannot be shown to be disjoint from it either.
diff --git a/tests/neg/i15155.scala b/tests/neg/i15155.scala
@@ -0,0 +1,11 @@
+import scala.reflect.ClassTag
+// https://github.com/json4s/json4s/blob/355d8751391773e0d79d04402a4f9fb7bfc684ec/ext/src/main/scala-3/org/json4s/ext/package.scala#L4-L8
+type Aux[A] = { type Value = A }
+type EnumValue[A <: Enumeration] = A match {
+  case Aux[a] => a
+}
+
+// https://github.com/json4s/json4s/blob/355d8751391773e0d79d04402a4f9fb7bfc684ec/ext/src/main/scala/org/json4s/ext/EnumSerializer.scala#L25-L26
+class EnumSerializer[E <: Enumeration: ClassTag](enumeration: E) {
+  val EnumerationClass = classOf[EnumValue[E]] // error
+}

Original file line number	Diff line number	Diff line change
`@@ -2521,3 +2521,8 @@ import transform.SymUtils._`
`2521`	`2521`	`\| $annot $symbol { ... }`
`2522`	`2522`	`\|`
`2523`	`2523`	`\|${hl("export")} Wrapper.${symbol.name} ${hl("// optional")}"""`
	`2524`	`+`
	`2525`	`+ class NotClassType(tp: Type)(using Context)`
	`2526`	`+ extends TypeMsg(NotClassTypeID), ShowMatchTrace(tp):`
	`2527`	`+ def msg = ex"$tp is not a class type"`
	`2528`	`+ def explain = ""`
Original file line number	Diff line number	Diff line change
`@@ -937,7 +937,7 @@ trait Checking {`
`937`	`937`	`if (stablePrefixReq && ctx.phase <= refchecksPhase) checkStable(tref.prefix, pos, "class prefix")`
`938`	`938`	`tp`
`939`	`939`	`case _ =>`
`940`		`- report.error(ex"$tp is not a class type", pos)`
	`940`	`+ report.error(NotClassType(tp), pos)`
`941`	`941`	`defn.ObjectType`
`942`	`942`	`}`
`943`	`943`