SI-8192 adds ClassSymbol.isPrimaryConstructor

Exposes a popular code pattern in macros as a dedicated reflection API.
This simple commit, however, ended up being not so simple, as it often
happens with our compiler.

When writing a test for the new API, I realized that our (pre-existing)
MethodSymbol.isPrimaryConstructor API returns nonsensical results for
implementation artifacts (trait mixin ctors, module class ctors).

What’s even more funny is that according to our reflection internals,
even Java classes have primary constructors. Well, that’s not surprising,
because `primaryConstructor` is just `decl(ctorName).alternatives.head`.
Good thing that package classes don’t have constructors or that would
elevate the situation to three fries short of a happy meal.

At the moment, I’m too scared to fiddle with internal#Symbol.primaryConstructor,
because that could easily break someone right before RC1, so I simply
documented the findings in SI-8193 and postponed the actual work, except
for one thing - isJavaDefined symbols no longer have primary constructors.

5 files changed, 129 insertions, 2 deletions

diff --git a/test/files/run/t6392b.check b/test/files/run/t6392b.check
index c2cc103373..3f191c7960 100644
--- a/test/files/run/t6392b.check
+++ b/test/files/run/t6392b.check
@@ -1 +1 @@
-ModuleDef(Modifiers(), TermName("C")#MOD, Template(List(Select(Ident(scala#PK), TypeName("AnyRef")#TPE)), noSelfType, List(DefDef(Modifiers(), nme.CONSTRUCTOR#PCTOR, List(), List(List()), TypeTree(), Block(List(Apply(Select(Super(This(TypeName("C")), tpnme.EMPTY), nme.CONSTRUCTOR#PCTOR), List())), Literal(Constant(())))))))
+ModuleDef(Modifiers(), TermName("C")#MOD, Template(List(Select(Ident(scala#PK), TypeName("AnyRef")#TPE)), noSelfType, List(DefDef(Modifiers(), nme.CONSTRUCTOR#PCTOR, List(), List(List()), TypeTree(), Block(List(Apply(Select(Super(This(TypeName("C")), tpnme.EMPTY), nme.CONSTRUCTOR#CTOR), List())), Literal(Constant(())))))))
diff --git a/test/files/run/t7582-private-within.check b/test/files/run/t7582-private-within.check
index b2743ffa06..1b9a0910af 100644
--- a/test/files/run/t7582-private-within.check
+++ b/test/files/run/t7582-private-within.check
@@ -2,7 +2,7 @@ private[package pack] class JavaPackagePrivate
 private[package pack] module JavaPackagePrivate
 private[package pack] module class JavaPackagePrivate
 private[package pack] field field
-private[package pack] primary constructor <init>
+private[package pack] constructor <init>
 private[package pack] method meth
 private[package pack] field staticField
 private[package pack] method staticMeth
diff --git a/test/files/run/t8192.check b/test/files/run/t8192.check
new file mode 100644
index 0000000000..7195703e19
--- /dev/null
+++ b/test/files/run/t8192.check
@@ -0,0 +1,44 @@
+compile-time
+class File
+primary constructor: NoSymbol
+def <init>(x$1: String): java.io.File => false
+def <init>(x$1: String,x$2: String): java.io.File => false
+def <init>(x$1: java.io.File,x$2: String): java.io.File => false
+def <init>(x$1: java.net.URI): java.io.File => false
+package scala
+primary constructor: NoSymbol
+object List
+primary constructor: def <init>(): scala.collection.immutable.List.type => true
+def <init>(): scala.collection.immutable.List.type => true
+trait Product1
+primary constructor: def $init$(): Unit => true
+class UninitializedFieldError
+primary constructor: def <init>(msg: String): UninitializedFieldError => true
+def <init>(msg: String): UninitializedFieldError => true
+def <init>(obj: Any): UninitializedFieldError => false
+class C
+primary constructor: def <init>(x: Int): C => true
+def <init>(x: Int): C => true
+def <init>(x: String): C => false
+runtime
+class File
+primary constructor: NoSymbol
+def <init>(x$1: java.io.File,x$2: java.lang.String): java.io.File => false
+def <init>(x$1: java.lang.String): java.io.File => false
+def <init>(x$1: java.lang.String,x$2: java.lang.String): java.io.File => false
+def <init>(x$1: java.net.URI): java.io.File => false
+package scala
+primary constructor: NoSymbol
+object List
+primary constructor: def <init>(): scala.collection.immutable.List.type => true
+def <init>(): scala.collection.immutable.List.type => true
+trait Product1
+primary constructor: def $init$(): Unit => true
+class UninitializedFieldError
+primary constructor: def <init>(msg: String): UninitializedFieldError => true
+def <init>(msg: String): UninitializedFieldError => true
+def <init>(obj: Any): UninitializedFieldError => false
+class C
+primary constructor: def <init>(x: Int): C => true
+def <init>(x: Int): C => true
+def <init>(x: String): C => false
diff --git a/test/files/run/t8192/Macros_1.scala b/test/files/run/t8192/Macros_1.scala
new file mode 100644
index 0000000000..2089273d6d
--- /dev/null
+++ b/test/files/run/t8192/Macros_1.scala
@@ -0,0 +1,44 @@
+import scala.reflect.macros.whitebox._
+import scala.language.experimental.macros
+import java.io._
+
+object Macros {
+  def impl(c: Context) = {
+    var messages = List[String]()
+    def println(msg: String) = messages :+= msg
+
+    import c.universe._
+    def test(sym: ClassSymbol): Unit = {
+      def fullyInitializeSymbol(sym: Symbol): Unit = {
+        val internal = c.universe.asInstanceOf[scala.reflect.internal.SymbolTable]
+        internal.definitions.fullyInitializeSymbol(sym.asInstanceOf[internal.Symbol])
+      }
+      def defString(sym: Symbol): String = {
+        val internal = c.universe.asInstanceOf[scala.reflect.internal.SymbolTable]
+        sym.asInstanceOf[internal.Symbol].defString
+      }
+      def showCtor(sym: Symbol): String = {
+        fullyInitializeSymbol(sym)
+        if (sym == NoSymbol) "NoSymbol"
+        else s"${defString(sym)} => ${sym.asMethod.isPrimaryConstructor}"
+      }
+      sym.typeSignature
+      println(sym.toString)
+      println(s"primary constructor: ${showCtor(sym.primaryConstructor)}")
+      val ctors = sym.typeSignature.members.filter(_.name == nme.CONSTRUCTOR).map(sym => showCtor(sym))
+      ctors.toList.sorted.foreach(println)
+    }
+
+    println("compile-time")
+    test(typeOf[File].typeSymbol.asClass)
+    test(definitions.ScalaPackageClass)
+    test(definitions.ListModule.moduleClass.asClass)
+    test(typeOf[Product1[_]].typeSymbol.asClass)
+    test(typeOf[UninitializedFieldError].typeSymbol.asClass)
+    test(c.mirror.staticClass("C").asClass)
+
+    q"..${messages.map(msg => q"println($msg)")}"
+  }
+
+  def foo: Any = macro impl
+}
\ No newline at end of file
diff --git a/test/files/run/t8192/Test_2.scala b/test/files/run/t8192/Test_2.scala
new file mode 100644
index 0000000000..15f684eb3f
--- /dev/null
+++ b/test/files/run/t8192/Test_2.scala
@@ -0,0 +1,39 @@
+import java.io._
+import scala.reflect.runtime.universe._
+import scala.reflect.runtime.{universe => ru}
+
+class C(x: Int) {
+  def this(x: String) = this(x.toInt)
+}
+
+object Test extends App {
+  def test(sym: ClassSymbol): Unit = {
+    def fullyInitializeSymbol(sym: Symbol): Unit = {
+      val internal = ru.asInstanceOf[scala.reflect.internal.SymbolTable]
+      internal.definitions.fullyInitializeSymbol(sym.asInstanceOf[internal.Symbol])
+    }
+    def defString(sym: Symbol): String = {
+      val internal = ru.asInstanceOf[scala.reflect.internal.SymbolTable]
+      sym.asInstanceOf[internal.Symbol].defString
+    }
+    def showCtor(sym: Symbol): String = {
+      fullyInitializeSymbol(sym)
+      if (sym == NoSymbol) "NoSymbol"
+      else s"${defString(sym)} => ${sym.asMethod.isPrimaryConstructor}"
+    }
+    sym.typeSignature
+    println(sym.toString)
+    println(s"primary constructor: ${showCtor(sym.primaryConstructor)}")
+    val ctors = sym.typeSignature.members.filter(_.name == nme.CONSTRUCTOR).map(sym => showCtor(sym))
+    ctors.toList.sorted.foreach(println)
+  }
+
+  Macros.foo
+  println("runtime")
+  test(typeOf[File].typeSymbol.asClass)
+  test(definitions.ScalaPackageClass)
+  test(definitions.ListModule.moduleClass.asClass)
+  test(typeOf[Product1[_]].typeSymbol.asClass)
+  test(typeOf[UninitializedFieldError].typeSymbol.asClass)
+  test(typeOf[C].typeSymbol.asClass)
+}