Fix #4306: Implement -scansource for Java files

Also document `OutlineParser` with what I needed to discover.

Author: Blaisorblade

compiler/src/dotty/tools/dotc/Run.scala

@@ -19,9 +19,10 @@ import transform.TreeChecker
 import rewrite.Rewrites
 import java.io.{BufferedWriter, OutputStreamWriter}
 
-import dotty.tools.dotc.profile.Profiler
+import profile.Profiler
 import printing.XprintMode
 import parsing.Parsers.Parser
+import parsing.JavaParsers.JavaParser
 import typer.ImplicitRunInfo
 import collection.mutable
 
@@ -209,7 +210,9 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
       lateFiles += file
       val unit = new CompilationUnit(getSource(file.path))
       def process()(implicit ctx: Context) = {
-        unit.untpdTree = new Parser(unit.source).parse()
+        unit.untpdTree =
+          if (unit.isJava) new JavaParser(unit.source).parse()
+          else new Parser(unit.source).parse()
         ctx.typer.lateEnter(unit.untpdTree)
         def typeCheckUnit() = unit.tpdTree = ctx.typer.typedExpr(unit.untpdTree)
         if (typeCheck)

compiler/src/dotty/tools/dotc/core/SymbolLoaders.scala

@@ -16,6 +16,7 @@ import Decorators._
 import scala.util.control.NonFatal
 import ast.Trees._
 import ast.tpd
+import parsing.JavaParsers.OutlineJavaParser
 import parsing.Parsers.OutlineParser
 import reporting.trace
 
@@ -154,7 +155,10 @@ object SymbolLoaders {
             case _ =>
           }
 
-          traverse(new OutlineParser(unit.source).parse(), Nil)
+          traverse(
+            if (unit.isJava) new OutlineJavaParser(unit.source).parse()
+            else new OutlineParser(unit.source).parse(),
+            Nil)
         }
 
         val unit = new CompilationUnit(ctx.run.getSource(src.path))

compiler/src/dotty/tools/dotc/parsing/JavaParsers.scala

@@ -907,4 +907,28 @@ object JavaParsers {
       unit
     }
   }
+
+
+  /**
+   * OutlineJavaParser parses top-level declarations in `source` to find declared classes, ignoring their bodies (which
+   * must only have balanced braces). This is used to map class names to defining sources.
+   * This is necessary even for Java, because the filename defining a non-public classes cannot be determined from the
+   * classname alone.
+   */
+  class OutlineJavaParser(source: SourceFile)(implicit ctx: Context) extends JavaParser(source) {
+
+    def skipBraces[T](body: T): T = {
+      accept(LBRACE)
+      var openBraces = 1
+      while (in.token != EOF && openBraces > 0) {
+        if (in.token == LBRACE) openBraces += 1
+        else if (in.token == RBRACE) openBraces -= 1
+        in.nextToken()
+      }
+      body
+    }
+
+    override def typeBody(leadingToken: Int, parentName: Name, parentTParams: List[TypeDef]): (List[Tree], List[Tree]) =
+      skipBraces((List(EmptyValDef), List(EmptyTree)))
+  }
 }

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -2638,6 +2638,10 @@ object Parsers {
   }
 
 
+  /**
+   * OutlineParser parses top-level declarations in `source` to find declared classes, ignoring their bodies (which must
+   * only have balanced braces). This is used to map class names to defining sources.
+   */
   class OutlineParser(source: SourceFile)(implicit ctx: Context) extends Parser(source) {
 
     def skipBraces[T](body: T): T = {

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -47,6 +47,7 @@ class CompilationTests extends ParallelTesting {
     compileFile("tests/pos-special/completeFromSource/Test.scala", defaultOptions.and("-sourcepath", "tests/pos-special")) +
     compileFile("tests/pos-special/completeFromSource/Test2.scala", defaultOptions.and("-sourcepath", "tests/pos-special")) +
     compileFile("tests/pos-special/completeFromSource/Test3.scala", defaultOptions.and("-sourcepath", "tests/pos-special", "-scansource")) +
+    compileFile("tests/pos-special/completeFromSource/nested/Test4.scala", defaultOptions.and("-sourcepath", "tests/pos-special", "-scansource")) +
     compileFilesInDir("tests/pos-special/fatal-warnings", defaultOptions.and("-Xfatal-warnings")) +
     compileList(
       "compileMixed",
@@ -158,7 +159,8 @@ class CompilationTests extends ParallelTesting {
     compileFile("tests/neg-custom-args/i4372.scala", allowDeepSubtypes) +
     compileFile("tests/neg-custom-args/i1754.scala", allowDeepSubtypes) +
     compileFilesInDir("tests/neg-custom-args/isInstanceOf", allowDeepSubtypes and "-Xfatal-warnings") +
-    compileFile("tests/neg-custom-args/i3627.scala", allowDeepSubtypes)
+    compileFile("tests/neg-custom-args/i3627.scala", allowDeepSubtypes) +
+    compileFile("tests/neg-custom-args/completeFromSource/nested/Test1.scala", defaultOptions.and("-sourcepath", "tests/neg-custom-args", "-scansource"))
   }.checkExpectedErrors()
 
   // Run tests -----------------------------------------------------------------

tests/neg-custom-args/completeFromSource/nested/D.java

@@ -0,0 +1,18 @@
+package completeFromSource.nested;
+
+public class D {
+    public D(int i) {
+
+    }
+    public String thisIsD(int i) {
+        return java.lang.Integer.toString(i);
+    }
+}
+
+class E {
+    public E(String s) {}
+
+    public String thisIsE(int i) {
+        return java.lang.Integer.toString(i);
+    }
+}

tests/neg-custom-args/completeFromSource/nested/Test1.scala

@@ -0,0 +1,10 @@
+package completeFromSource.nested
+
+class Test4 {
+
+  val d = new D(1)
+  val e = new E("xx")
+
+  d.thisIsD(1)
+  e.thisIsE() // error
+}

tests/pos-special/completeFromSource/nested/D.java

@@ -0,0 +1,18 @@
+package completeFromSource.nested;
+
+public class D {
+    public D(int i) {
+
+    }
+    public String thisIsD(int i) {
+        return java.lang.Integer.toString(i);
+    }
+}
+
+class E {
+    public E(String s) {}
+
+    public String thisIsE(int i) {
+        return java.lang.Integer.toString(i);
+    }
+}

tests/pos-special/completeFromSource/nested/Test4.scala

@@ -0,0 +1,10 @@
+package completeFromSource.nested
+
+class Test4 {
+
+  val d = new D(1)
+  val e = new E("xx")
+
+  d.thisIsD(1)
+  e.thisIsE(2)
+}