8199910: Compiler crashes with -g option and variables of intersection type inferred by var

Javac should skip non-denotable types in the LocalVariableTypeTable attribute

Reviewed-by: jlahoda

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java

@@ -828,7 +828,7 @@ public class Check {
         return buf.toList();
     }
 
-    boolean checkDenotable(Type t) {
+    public boolean checkDenotable(Type t) {
         return denotableChecker.visit(t, null);
     }
         // where

src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassWriter.java

@@ -43,6 +43,7 @@ import com.sun.tools.javac.code.Directive.*;
 import com.sun.tools.javac.code.Symbol.*;
 import com.sun.tools.javac.code.Type.*;
 import com.sun.tools.javac.code.Types.UniqueType;
+import com.sun.tools.javac.comp.Check;
 import com.sun.tools.javac.file.PathFileObject;
 import com.sun.tools.javac.jvm.Pool.DynamicMethod;
 import com.sun.tools.javac.jvm.Pool.Method;
@@ -101,6 +102,8 @@ public class ClassWriter extends ClassFile {
     /** Type utilities. */
     private Types types;
 
+    private Check check;
+
     /**
      * If true, class files will be written in module-specific subdirectories
      * of the CLASS_OUTPUT location.
@@ -178,6 +181,7 @@ public class ClassWriter extends ClassFile {
         target = Target.instance(context);
         source = Source.instance(context);
         types = Types.instance(context);
+        check = Check.instance(context);
         fileManager = context.get(JavaFileManager.class);
         signatureGen = new CWSignatureGenerator(types);
 
@@ -1294,10 +1298,10 @@ public class ClassWriter extends ClassFile {
     //where
     private boolean needsLocalVariableTypeEntry(Type t) {
         //a local variable needs a type-entry if its type T is generic
-        //(i.e. |T| != T) and if it's not an intersection type (not supported
-        //in signature attribute grammar)
-        return (!types.isSameType(t, types.erasure(t)) &&
-                !t.isCompound());
+        //(i.e. |T| != T) and if it's not an non-denotable type (non-denotable
+        // types are not supported in signature attribute grammar!)
+        return !types.isSameType(t, types.erasure(t)) &&
+                check.checkDenotable(t);
     }
 
     void writeStackMap(Code code) {

test/langtools/tools/javac/T8199910.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8199910
+ * @summary Compile variables of intersection type inferred by `var` with -g option
+ * @compile -g T8199910.java
+ */
+import java.util.List;
+
+class T8199910 {
+    <T> T first(T... ts) {
+        return ts[0];
+    }
+
+    void m() {
+        var list1 = List.of("", 1);
+        var list2 = List.of(1, 2.0);
+        var a = first("", 1);
+        var b = first(1, 2.0);
+    }
+}

test/langtools/tools/javac/lvti/harness/LocalVariableInferenceTester.java

@@ -80,12 +80,16 @@ public class LocalVariableInferenceTester {
 
     void compileAndCheck(JavaFileObject input) throws IOException {
         JavaCompiler c = ToolProvider.getSystemJavaCompiler();
-        JavacTask task = (JavacTask) c.getTask(null, fm, null, null, null, Arrays.asList(input));
+        JavacTask task = (JavacTask) c.getTask(null, fm, null, Arrays.asList("-g"), null, Arrays.asList(input));
         JavacTrees trees = JavacTrees.instance(task);
         Types types = Types.instance(((JavacTaskImpl)task).getContext());
         Iterable<? extends CompilationUnitTree> roots = task.parse();
-        task.analyze(); //force attribution
         Log log = Log.instance(((JavacTaskImpl)task).getContext());
+        //force code generation (to shake out non-denotable issues)
+        boolean hasClasses = task.generate().iterator().hasNext();
+        if (!hasClasses) {
+            throw new AssertionError("Errors occurred during compilation!");
+        }
         errors += log.nerrors;
         new LocalVarTypeChecker(trees, types).scan(roots, null);
         System.err.println("Checks executed: " + checks);