SI-8253 Fix incorrect parsing of <elem xmlns={f("a")}/>

The spliced application was placed in the `attrMap` in
`SymbolicXMLBuilder` and later incorrectly matched by a pattern
intended only to match:

    xml.Text(s)

That attribute value is generated by parsing:

   <elem xmlns='a'/>

So the net effect was that the two fragments of XML were identical!

This commit sharpens up the match to really look for a syntactic
`_root_.scala.xml.Text("...")`.

The test just prints the parse trees of a variety of cases, as we
we should not test the modularized XML library in scala/scala.

2 files changed, 54 insertions, 0 deletions

diff --git a/test/files/run/t8253.check b/test/files/run/t8253.check
new file mode 100644
index 0000000000..0b4cb2d1f7
--- /dev/null
+++ b/test/files/run/t8253.check
@@ -0,0 +1,40 @@
+
+<sample xmlns='ns1'/>
+{
+  var $tmpscope: _root_.scala.xml.NamespaceBinding = $scope;
+  $tmpscope = new _root_.scala.xml.NamespaceBinding(null, "ns1", $tmpscope);
+  {
+    val $scope: _root_.scala.xml.NamespaceBinding = $tmpscope;
+    new _root_.scala.xml.Elem(null, "sample", _root_.scala.xml.Null, $scope, true)
+  }
+}
+
+<sample xmlns={identity(ns1)}/>
+{
+  var $tmpscope: _root_.scala.xml.NamespaceBinding = $scope;
+  $tmpscope = new _root_.scala.xml.NamespaceBinding(null, ns1, $tmpscope);
+  {
+    val $scope: _root_.scala.xml.NamespaceBinding = $tmpscope;
+    new _root_.scala.xml.Elem(null, "sample", _root_.scala.xml.Null, $scope, true)
+  }
+}
+
+<sample xmlns:foo='ns1'/>
+{
+  var $tmpscope: _root_.scala.xml.NamespaceBinding = $scope;
+  $tmpscope = new _root_.scala.xml.NamespaceBinding("foo", "ns1", $tmpscope);
+  {
+    val $scope: _root_.scala.xml.NamespaceBinding = $tmpscope;
+    new _root_.scala.xml.Elem(null, "sample", _root_.scala.xml.Null, $scope, true)
+  }
+}
+
+<sample xmlns:foo={identity(ns1)}/>
+{
+  var $tmpscope: _root_.scala.xml.NamespaceBinding = $scope;
+  $tmpscope = new _root_.scala.xml.NamespaceBinding("foo", ns1, $tmpscope);
+  {
+    val $scope: _root_.scala.xml.NamespaceBinding = $tmpscope;
+    new _root_.scala.xml.Elem(null, "sample", _root_.scala.xml.Null, $scope, true)
+  }
+}
diff --git a/test/files/run/t8253.scala b/test/files/run/t8253.scala
new file mode 100644
index 0000000000..c4800b4491
--- /dev/null
+++ b/test/files/run/t8253.scala
@@ -0,0 +1,14 @@
+object Test extends App {
+  import reflect.runtime.universe._ // not using the XML library in compiler tests
+
+  def show(code: String, t: Tree) = println(s"\n$code\n$t")
+
+  val ns1 = "ns1"
+  show("<sample xmlns='ns1'/>", q"<sample xmlns='ns1'/>")
+  show("<sample xmlns={identity(ns1)}/>", q"<sample xmlns={ns1}/>")
+  show("<sample xmlns:foo='ns1'/>", q"<sample xmlns:foo='ns1'/>")
+  show("<sample xmlns:foo={identity(ns1)}/>", q"<sample xmlns:foo={ns1}/>")
+
+  // `identity(foo)` used to match the overly permissive match in SymbolXMLBuilder
+  // which was intented to more specifically match `_root_.scala.xml.Text(...)`
+}