--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/InferenceContext.java	Thu Mar 09 12:08:02 2017 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/InferenceContext.java	Thu Mar 09 06:34:06 2017 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2017, 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
@@ -334,6 +334,9 @@
     }
 
     InferenceContext min(List<Type> roots, boolean shouldSolve, Warner warn) {
+        if (roots.length() == inferencevars.length()) {
+            return this;
+        }
         ReachabilityVisitor rv = new ReachabilityVisitor();
         rv.scan(roots);
         if (rv.min.size() == inferencevars.length()) {
@@ -347,8 +350,8 @@
         ListBuffer<Type> minUndetVars = new ListBuffer<>();
         for (Type minVar : minVars) {
             UndetVar uv = (UndetVar)asUndetVar(minVar);
-            Assert.check(uv.incorporationActions.size() == 0);
-            UndetVar uv2 = new UndetVar((TypeVar)minVar, infer.incorporationEngine(), types);
+            Assert.check(uv.incorporationActions.isEmpty());
+            UndetVar uv2 = uv.dup(types);
             for (InferenceBound ib : InferenceBound.values()) {
                 List<Type> newBounds = uv.getBounds(ib).stream()
                         .filter(b -> !redundantVars.contains(b))
@@ -363,15 +366,19 @@
         for (Type t : minContext.inferencevars) {
             //add listener that forwards notifications to original context
             minContext.addFreeTypeListener(List.of(t), (inferenceContext) -> {
-                    List<Type> depVars = List.from(rv.minMap.get(t));
-                    solve(depVars, warn);
-                    notifyChange();
+                ((UndetVar)asUndetVar(t)).setInst(inferenceContext.asInstType(t));
+                infer.doIncorporation(inferenceContext, warn);
+                solve(List.from(rv.minMap.get(t)), warn);
+                notifyChange();
             });
         }
         if (shouldSolve) {
             //solve definitively unreachable variables
             List<Type> unreachableVars = redundantVars.diff(List.from(rv.equiv));
-            solve(unreachableVars, warn);
+            minContext.addFreeTypeListener(minVars, (inferenceContext) -> {
+                solve(unreachableVars, warn);
+                notifyChange();
+            });
         }
         return minContext;
     }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/T8175235/InferenceRegressionTest01.java	Thu Mar 09 06:34:06 2017 -0800
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2017, 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 8175235
+ * @summary type inference regression after JDK-8046685
+ * @compile InferenceRegressionTest01.java
+ */
+
+import java.util.function.Predicate;
+
+abstract class InferenceRegressionTest01 {
+
+    void f(String r) {
+        a(r, c(o(p(s -> s.isEmpty()))));
+    }
+
+    abstract <U> U o(U u);
+    abstract <E> Predicate<E> c(Predicate<E> xs);
+    abstract <S> void a(S a, Predicate<S> m);
+    abstract <V> Predicate<V> p(Predicate<V> p);
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/T8175235/InferenceRegressionTest02.java	Thu Mar 09 06:34:06 2017 -0800
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2017, 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 8175235
+ * @summary type inference regression after JDK-8046685
+ * @library /tools/javac/lib
+ * @modules jdk.compiler/com.sun.source.util
+ *          jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.code
+ *          jdk.compiler/com.sun.tools.javac.file
+ *          jdk.compiler/com.sun.tools.javac.tree
+ *          jdk.compiler/com.sun.tools.javac.util
+ * @build DPrinter
+ * @run main InferenceRegressionTest02
+ */
+
+import java.io.*;
+import java.net.URI;
+import java.util.Arrays;
+
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.ToolProvider;
+
+import com.sun.source.tree.CompilationUnitTree;
+import com.sun.source.util.JavacTask;
+import com.sun.source.util.Trees;
+import com.sun.tools.javac.api.JavacTrees;
+import com.sun.tools.javac.file.JavacFileManager;
+import com.sun.tools.javac.tree.JCTree;
+import com.sun.tools.javac.util.Assert;
+import com.sun.tools.javac.util.Context;
+
+public class InferenceRegressionTest02 {
+    public static void main(String... args) throws Exception {
+        new InferenceRegressionTest02().run();
+    }
+
+    void run() throws Exception {
+        Context context = new Context();
+        JavacFileManager.preRegister(context);
+        Trees trees = JavacTrees.instance(context);
+        StringWriter strOut = new StringWriter();
+        PrintWriter pw = new PrintWriter(strOut);
+        DPrinter dprinter = new DPrinter(pw, trees);
+        final JavaCompiler tool = ToolProvider.getSystemJavaCompiler();
+        JavacTask ct = (JavacTask)tool.getTask(null, null, null, null, null, Arrays.asList(new JavaSource()));
+        Iterable<? extends CompilationUnitTree> elements = ct.parse();
+        ct.analyze();
+        Assert.check(elements.iterator().hasNext());
+        dprinter.treeTypes(true).printTree("", (JCTree)elements.iterator().next());
+        String output = strOut.toString();
+        Assert.check(!output.contains("java.lang.Object"), "there shouldn't be any type instantiated to Object");
+    }
+
+    static class JavaSource extends SimpleJavaFileObject {
+
+        String source =
+                "import java.util.function.*;\n" +
+                "import java.util.*;\n" +
+                "import java.util.stream.*;\n" +
+
+                "class Foo {\n" +
+                "    void test(List<Map.Entry<Foo, Foo>> ls) {\n" +
+                "        Map<Foo, Set<Foo>> res = ls.stream()\n" +
+                "                .collect(Collectors.groupingBy(Map.Entry::getKey,\n" +
+                "                        HashMap::new,\n" +
+                "                        Collectors.mapping(Map.Entry::getValue, Collectors.toSet())));\n" +
+                "    }\n" +
+                "}";
+
+        public JavaSource() {
+            super(URI.create("myfo:/Foo.java"), JavaFileObject.Kind.SOURCE);
+        }
+
+        @Override
+        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+            return source;
+        }
+    }
+}