--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/util/RichDiagnosticFormatter.java	Tue May 22 13:37:05 2018 +0100
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/util/RichDiagnosticFormatter.java	Tue May 22 12:26:17 2018 +0200
@@ -556,7 +556,7 @@
                 //has not been attributed the bound is not set
                 List<Type> bounds = (bound != null) &&
                         (bound.hasTag(CLASS) || bound.hasTag(TYPEVAR)) ?
-                    types.getBounds(t) :
+                    getBounds(bound) :
                     List.nil();
 
                 nameSimplifier.addUsage(t.tsym);
@@ -584,6 +584,10 @@
             }
             return null;
         }
+        //where:
+            private List<Type> getBounds(Type bound) {
+                return bound.isCompound() ? types.directSupertypes(bound) : List.of(bound);
+            }
     };
     // </editor-fold>
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/diags/CompletionFailureInDiags.java	Tue May 22 12:26:17 2018 +0200
@@ -0,0 +1,161 @@
+/*
+ * 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 8198315
+ * @summary Verify that diagnostics can be printed without throwing CompletionFailures
+ * @library /tools/lib
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ * @build toolbox.TestRunner toolbox.ToolBox CompletionFailureInDiags
+ * @run main CompletionFailureInDiags
+ */
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.Objects;
+
+import toolbox.JavacTask;
+import toolbox.Task.Expect;
+import toolbox.Task.OutputKind;
+import toolbox.TestRunner;
+import toolbox.TestRunner.Test;
+import toolbox.ToolBox;
+
+public class CompletionFailureInDiags extends TestRunner {
+
+    public static void main(String... args) throws Exception {
+        new CompletionFailureInDiags().runTests(m -> new Object[] { Paths.get(m.getName()) });
+    }
+
+    private final ToolBox tb = new ToolBox();
+
+    public CompletionFailureInDiags() {
+        super(System.err);
+    }
+
+    @Test
+    public void testCrashInDiagReport(Path outerBase) throws Exception {
+        int c = 0;
+
+        for (Bound bound : Bound.values()) {
+            for (AdditionalParams params : AdditionalParams.values()) {
+                for (Delete delete : Delete.values()) {
+                    doRunCrashTest(outerBase.resolve(String.valueOf(c++)), bound, params, delete);
+                }
+            }
+        }
+    }
+
+    private enum Bound {
+        A("A"),
+        AA2("A&A2");
+        private final String bound;
+
+        private Bound(String bound) {
+            this.bound = bound;
+        }
+
+    }
+
+    private enum AdditionalParams {
+        NONE(new String[0], null),
+        RAD_DIAGS(new String[] {"-XDrawDiagnostics"},
+                  List.of("Test.java:3:10: compiler.err.cant.apply.symbol: kindname.method, " +
+                                                                          "f, " +
+                                                                          "java.lang.String, " +
+                                                                          "compiler.misc.type.null,compiler.misc.type.null, " +
+                                                                          "kindname.class, " +
+                                                                          "D<T>, " +
+                                                                          "(compiler.misc.arg.length.mismatch)",
+                        "1 error"));
+        private final String[] options;
+        private final List<String> expected;
+
+        private AdditionalParams(String[] options, List<String> expected) {
+            this.options = options;
+            this.expected = expected;
+        }
+
+    }
+
+    private enum Delete {
+        NONE(),
+        A("A.class"),
+        AA2("A.class", "A2.class");
+        private final String[] toDelete;
+
+        private Delete(String... toDelete) {
+            this.toDelete = toDelete;
+        }
+
+    }
+
+    private void doRunCrashTest(Path outerBase, Bound bound, AdditionalParams params, Delete delete) throws Exception {
+        Path libSrc = outerBase.resolve("lib-src");
+        tb.writeJavaFiles(libSrc,
+                          "public class A {}",
+                          "public interface A2 {}",
+                          "public class B extends A implements A2 {}",
+                          "public class C extends D<B> {}\n",
+                          "public class D<T extends " + bound.bound + "> {\n" +
+                          "    public void f(String s) {}\n" +
+                          "}");
+        Path lib = outerBase.resolve("lib");
+        Files.createDirectories(lib);
+        new JavacTask(tb)
+                .outdir(lib.toString())
+                .files(tb.findJavaFiles(libSrc))
+                .run()
+                .writeAll();
+        for (String del : delete.toDelete) {
+            Files.delete(lib.resolve(del));
+        }
+        Path src = outerBase.resolve("src");
+        tb.writeJavaFiles(src,
+                          "public class Test {\n" +
+                          "    public void test(C c) {\n" +
+                          "        c.f(null, null);\n" +
+                          "    }\n" +
+                          "}");
+        Path classes = outerBase.resolve("classes");
+        Files.createDirectories(classes);
+        List<String> actual = new JavacTask(tb)
+                .options(params.options)
+                .classpath(lib)
+                .outdir(classes.toString())
+                .sourcepath()
+                .files(tb.findJavaFiles(src))
+                .run(Expect.FAIL)
+                .writeAll()
+                .getOutputLines(OutputKind.DIRECT);
+
+        if (params.expected != null && !Objects.equals(params.expected, actual)) {
+            throw new AssertionError("Unexpected output!");
+        }
+    }
+
+}