From 760df9843a910d6c3618e490c752eb03fb6924bd Mon Sep 17 00:00:00 2001
From: Den Shabalin <den.shabalin@gmail.com>
Date: Fri, 6 Dec 2013 18:01:05 +0100
Subject: SI-8030 force symbols on presentation compiler initialization
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This commit forces a number of built-in symbols in presentation
compiler to prevent them from being entered during parsing.

The property “parsing doesn’t enter new symbols” is tested on
a rich source file that contains significant number of variations
of Scala syntax.
---
 .../files/presentation/parse-invariants/Test.scala | 107 +++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 test/files/presentation/parse-invariants/Test.scala

(limited to 'test/files/presentation/parse-invariants/Test.scala')

diff --git a/test/files/presentation/parse-invariants/Test.scala b/test/files/presentation/parse-invariants/Test.scala
new file mode 100644
index 0000000000..128896ccaa
--- /dev/null
+++ b/test/files/presentation/parse-invariants/Test.scala
@@ -0,0 +1,107 @@
+import scala.tools.nsc.interactive.tests.InteractiveTest
+import scala.reflect.internal.util.SourceFile
+import scala.tools.nsc.interactive.Response
+
+object Test extends InteractiveTest {
+
+  override def execute(): Unit = {
+    val sf = sourceFiles.find(_.file.name == "A.scala").head
+    noNewSymbols(sf)
+    uniqueParseTree(sf)
+    unattributedParseTree(sf)
+    neverModifyParseTree(sf)
+    shouldAlwaysReturnParseTree(sf)
+  }
+
+  /**
+   * Asking for a parseTree should not enter any new symbols.
+   */
+  private def noNewSymbols(sf: SourceFile) {
+    def nextId() = compiler.NoSymbol.newTermSymbol(compiler.TermName("dummy"), compiler.NoPosition, compiler.NoFlags).id
+    val id = nextId()
+    val tree = compiler.parseTree(sf)
+    val id2 = nextId()
+    if (id2 == id + 1) {
+      reporter.println("NoNewSymbolsEntered OK")
+    } else {
+      reporter.println("NoNewSymbolsEntered FAILED")
+    }
+  }
+
+  /**
+   * Asking twice for a parseTree on the same source should always return a new tree
+   */
+  private def uniqueParseTree(sf: SourceFile) {
+    val parseTree1 = compiler.parseTree(sf)
+    val parseTree2 = compiler.parseTree(sf)
+    if (parseTree1 != parseTree2) {
+      reporter.println("Unique OK")
+    } else {
+      reporter.println("Unique FAILED")
+    }
+  }
+
+  /**
+   * A parseTree should never contain any symbols or types
+   */
+  private def unattributedParseTree(sf: SourceFile) {
+    if (noSymbolsOrTypes(compiler.parseTree(sf))) {
+      reporter.println("Unattributed OK")
+    } else {
+      reporter.println("Unattributed FAILED")
+    }
+  }
+
+  /**
+   * Once you have obtained a parseTree it should never change
+   */
+  private def neverModifyParseTree(sf: SourceFile) {
+    val parsedTree = compiler.parseTree(sf)
+    loadSourceAndWaitUntilTypechecked(sf)
+    if (noSymbolsOrTypes(parsedTree)) {
+      reporter.println("NeverModify OK")
+    } else {
+      reporter.println("NeverModify FAILED")
+    }
+  }
+
+  /**
+   * Should always return a parse tree
+   */
+   private def shouldAlwaysReturnParseTree(sf: SourceFile) {
+     loadSourceAndWaitUntilTypechecked(sf)
+     if (noSymbolsOrTypes(compiler.parseTree(sf))) {
+       reporter.println("AlwaysParseTree OK")
+     } else {
+       reporter.println("AlwaysParseTree FAILED")
+     }
+   }
+
+  /**
+   * Load a source and block while it is type-checking.
+   */
+  private def loadSourceAndWaitUntilTypechecked(sf: SourceFile): Unit = {
+    compiler.askToDoFirst(sf)
+    val res = new Response[Unit]
+    compiler.askReload(List(sf), res)
+    res.get
+    askLoadedTyped(sf).get
+  }
+
+  /**
+   * Traverses a tree and makes sure that there are no types or symbols present in the tree with
+   * the exception of the symbol for the package 'scala'. This is because that symbol will be
+   * present in some of the nodes that the compiler generates.
+   */
+  private def noSymbolsOrTypes(tree: compiler.Tree): Boolean = {
+    tree.forAll { t =>
+      (t.symbol == null ||
+       t.symbol == compiler.NoSymbol ||
+       t.symbol == compiler.definitions.ScalaPackage // ignore the symbol for the scala package for now
+      ) && (
+       t.tpe == null ||
+       t.tpe == compiler.NoType)
+    }
+  }
+
+}
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