macroExpandAll is now triggered by typed

Previously delayed macro expansions (the sole purpose of macroExpandAll)
were triggered by `typedArgs`. Probably I wanted to save CPU cycles on
not checking whether we have pending macro expansions on every iteration
of typecheck.

However this optimization is uncalled for, because the check just entails
reading a var, therefore benefits of the current approach are negliible,
whereas the robustness hit is tangible.

After delayed macro expansion mechanism became more robust, it exposed
a bug, well-hidden before. If one first delays a macro and then finds out
that the expandee is erroneous, subsequent `macroExpandAll` will crash,
because it expects a macro runtime attachment to be present. Previously
the erroneous code path never got triggered, because the macro expansion
never commenced. Luckily the fix was easy.

6 files changed, 18 insertions, 10 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Macros.scala b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
index fa90b4963a..3828dfe94b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Macros.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
@@ -951,7 +951,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
     new Transformer {
       override def transform(tree: Tree) = super.transform(tree match {
         // todo. expansion should work from the inside out
-        case tree if (delayed contains tree) && calculateUndetparams(tree).isEmpty =>
+        case tree if (delayed contains tree) && calculateUndetparams(tree).isEmpty && !tree.isErroneous =>
           val context = tree.attachments.get[MacroRuntimeAttachment].get.typerContext
           delayed -= tree
           context.implicitsEnabled = typer.context.implicitsEnabled
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index b0b1341a07..73d7f8928a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2892,7 +2892,6 @@ trait Typers extends Modes with Adaptations with Tags {
             else BYVALmode
           )
           var tree = typedArg(args.head, mode, typedMode, adapted.head)
-          if (hasPendingMacroExpansions) tree = macroExpandAll(this, tree)
           // formals may be empty, so don't call tail
           tree :: loop(args.tail, formals drop 1, adapted.tail)
         }
@@ -5208,7 +5207,12 @@ trait Typers extends Modes with Adaptations with Tags {
         }
 
         tree1 modifyType (addAnnotations(tree1, _))
-        val result = if (tree1.isEmpty) tree1 else adapt(tree1, mode, pt, tree)
+        val result =
+          if (tree1.isEmpty) tree1
+          else {
+            val result = adapt(tree1, mode, pt, tree)
+            if (hasPendingMacroExpansions) macroExpandAll(this, result) else result
+          }
 
         if (!alreadyTyped) {
           printTyping("adapted %s: %s to %s, %s".format(
diff --git a/test/files/neg/t5353.check b/test/files/neg/t5353.check
deleted file mode 100644
index bc3f77a4d6..0000000000
--- a/test/files/neg/t5353.check
+++ /dev/null
@@ -1,4 +0,0 @@
-t5353.scala:2: error: macro has not been expanded
-  def f(x: Boolean) = if (x) Array("abc") else Array()
-                                                    ^
-one error found
diff --git a/test/files/neg/t5353.scala b/test/files/neg/t5353.scala
deleted file mode 100644
index 1ee869aac1..0000000000
--- a/test/files/neg/t5353.scala
+++ /dev/null
@@ -1,3 +0,0 @@
-class A {
-  def f(x: Boolean) = if (x) Array("abc") else Array()
-}
diff --git a/test/files/run/t5353.check b/test/files/run/t5353.check
new file mode 100644
index 0000000000..a2906793ed
--- /dev/null
+++ b/test/files/run/t5353.check
@@ -0,0 +1,2 @@
+1
+[Ljava.lang.Object; cannot be cast to [Ljava.lang.String;
diff --git a/test/files/run/t5353.scala b/test/files/run/t5353.scala
new file mode 100644
index 0000000000..5208fe527f
--- /dev/null
+++ b/test/files/run/t5353.scala
@@ -0,0 +1,9 @@
+object Test extends App {
+  def f(x: Boolean) = if (x) Array("abc") else Array()
+  try {
+    println(f(true).length)
+    println(f(false).length)
+  } catch {
+    case ex: Throwable => println(ex.getMessage)
+  }
+}