--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/DeferredCompletionFailureHandler.java	Thu Sep 05 09:59:43 2019 +0200
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/DeferredCompletionFailureHandler.java	Thu Sep 05 12:39:48 2019 +0200
@@ -86,6 +86,26 @@
         }
     };
 
+    public final Handler speculativeCodeHandler = new Handler() {
+        private final Map<ClassSymbol, FlipSymbolDescription> class2Flip = new HashMap<>();
+
+        public void install() {
+        }
+        public void handleAPICompletionFailure(CompletionFailure cf) {
+            throw cf;
+        }
+        public void classSymbolCompleteFailed(ClassSymbol sym, Completer origCompleter) {
+            class2Flip.put(sym, new FlipSymbolDescription(sym, new DeferredCompleter(origCompleter)));
+        }
+        public void classSymbolRemoved(ClassSymbol sym) {
+            class2Flip.remove(sym);
+        }
+        public void uninstall() {
+            class2Flip.values().forEach(f -> f.flip());
+            class2Flip.clear();
+        }
+    };
+
     public final Handler javacCodeHandler = new Handler() {
         public void install() {
         }

--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java	Thu Sep 05 09:59:43 2019 +0200
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java	Thu Sep 05 12:39:48 2019 +0200
@@ -2774,6 +2774,8 @@
             resultInfo.checkContext.report(that, cause);
             result = that.type = types.createErrorType(pt());
             return;
+        } catch (CompletionFailure cf) {
+            chk.completionError(that.pos(), cf);
         } catch (Throwable t) {
             //when an unexpected exception happens, avoid attempts to attribute the same tree again
             //as that would likely cause the same exception again.

--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/DeferredAttr.java	Thu Sep 05 09:59:43 2019 +0200
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/DeferredAttr.java	Thu Sep 05 12:39:48 2019 +0200
@@ -96,6 +96,7 @@
     final Flow flow;
     final Names names;
     final TypeEnvs typeEnvs;
+    final DeferredCompletionFailureHandler dcfh;
 
     public static DeferredAttr instance(Context context) {
         DeferredAttr instance = context.get(deferredAttrKey);
@@ -121,6 +122,7 @@
         names = Names.instance(context);
         stuckTree = make.Ident(names.empty).setType(Type.stuckType);
         typeEnvs = TypeEnvs.instance(context);
+        dcfh = DeferredCompletionFailureHandler.instance(context);
         emptyDeferredAttrContext =
             new DeferredAttrContext(AttrMode.CHECK, null, MethodResolutionPhase.BOX, infer.emptyContext, null, null) {
                 @Override
@@ -481,12 +483,12 @@
      */
     JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo) {
         return attribSpeculative(tree, env, resultInfo, treeCopier,
-                (newTree)->new DeferredAttrDiagHandler(log, newTree), AttributionMode.SPECULATIVE, null);
+                newTree->new DeferredDiagnosticHandler(log), AttributionMode.SPECULATIVE, null);
     }
 
     JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo, LocalCacheContext localCache) {
         return attribSpeculative(tree, env, resultInfo, treeCopier,
-                (newTree)->new DeferredAttrDiagHandler(log, newTree), AttributionMode.SPECULATIVE, localCache);
+                newTree->new DeferredDiagnosticHandler(log), AttributionMode.SPECULATIVE, localCache);
     }
 
     <Z> JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo, TreeCopier<Z> deferredCopier,
@@ -496,12 +498,14 @@
         Env<AttrContext> speculativeEnv = env.dup(newTree, env.info.dup(env.info.scope.dupUnshared(env.info.scope.owner)));
         speculativeEnv.info.attributionMode = attributionMode;
         Log.DeferredDiagnosticHandler deferredDiagnosticHandler = diagHandlerCreator.apply(newTree);
+        DeferredCompletionFailureHandler.Handler prevCFHandler = dcfh.setHandler(dcfh.speculativeCodeHandler);
         int nwarnings = log.nwarnings;
         log.nwarnings = 0;
         try {
             attr.attribTree(newTree, speculativeEnv, resultInfo);
             return newTree;
         } finally {
+            dcfh.setHandler(prevCFHandler);
             log.nwarnings += nwarnings;
             enter.unenter(env.toplevel, newTree);
             log.popDiagnosticHandler(deferredDiagnosticHandler);
@@ -510,35 +514,6 @@
             }
         }
     }
-    //where
-        static class DeferredAttrDiagHandler extends Log.DeferredDiagnosticHandler {
-
-            static class PosScanner extends TreeScanner {
-                DiagnosticPosition pos;
-                boolean found = false;
-
-                PosScanner(DiagnosticPosition pos) {
-                    this.pos = pos;
-                }
-
-                @Override
-                public void scan(JCTree tree) {
-                    if (tree != null &&
-                            tree.pos() == pos) {
-                        found = true;
-                    }
-                    super.scan(tree);
-                }
-            }
-
-            DeferredAttrDiagHandler(Log log, JCTree newTree) {
-                super(log, d -> {
-                    PosScanner posScanner = new PosScanner(d.getDiagnosticPosition());
-                    posScanner.scan(newTree);
-                    return posScanner.found;
-                });
-            }
-        }
 
     /**
      * A deferred context is created on each method check. A deferred context is

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/T8177068/NoCompletionFailureSkipOnSpeculativeAttribution.java	Thu Sep 05 12:39:48 2019 +0200
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2019, 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 8177068
+ * @summary CompletionFailures occurring during speculative attribution should
+ *          not be lost forever.
+ * @library /tools/lib
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ *          jdk.compiler/com.sun.tools.javac.util
+ * @build toolbox.ToolBox
+ * @run main NoCompletionFailureSkipOnSpeculativeAttribution
+ */
+
+import java.io.File;
+import java.nio.file.Paths;
+import java.util.List;
+
+import com.sun.tools.javac.util.Assert;
+
+import toolbox.JavacTask;
+import toolbox.Task;
+import toolbox.ToolBox;
+
+public class NoCompletionFailureSkipOnSpeculativeAttribution {
+
+    private static final String TSrc =
+        "import one.A;\n" +
+        "class T {\n" +
+        "  {\n" +
+        "    System.err.println(two.C.D.g());\n" +
+        "  }\n" +
+        "}";
+
+    private static final String CSrc =
+        "package two;\n" +
+        "public class C {\n" +
+        "  public static class D {\n" +
+        "    public static int g() {\n" +
+        "      return 1;\n" +
+        "    }\n" +
+        "  }\n" +
+        "}";
+
+    private static final String ASrc =
+        "package one;\n" +
+        "public class A {\n" +
+        "  public A(two.C.D x) {}\n" +
+        "}";
+
+    public static void main(String[] args) throws Exception {
+        new NoCompletionFailureSkipOnSpeculativeAttribution().test();
+    }
+
+    public void test() throws Exception {
+        ToolBox tb = new ToolBox();
+        tb.writeJavaFiles(Paths.get("."), ASrc, CSrc, TSrc);
+
+        new JavacTask(tb)
+                .classpath(".")
+                .files("T.java")
+                .run();
+
+        tb.deleteFiles("two/C.class", "two/C$D.class");
+
+        List<String> output = new JavacTask(tb)
+                .sourcepath(File.pathSeparator)
+                .options("-XDrawDiagnostics", "-XDshould-stop.ifError=FLOW")
+                .classpath(".")
+                .files("T.java")
+                .run(Task.Expect.FAIL)
+                .writeAll()
+                .getOutputLines(Task.OutputKind.DIRECT);
+
+        List<String> expectedOutput = List.of(
+                "T.java:4:29: compiler.err.cant.access: two.C.D, (compiler.misc.class.file.not.found: two.C$D)",
+                "1 error"
+        );
+
+        Assert.check(output.equals(expectedOutput));
+    }
+}