Improved AutoFactory error message

RELNOTES=Better error message for failed factory write.

One known cause of this error is using an impl class name that is the same
as the declared interface (in which case this new message will tell you
that you are attempting to recreate an existing file name).

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=277308587

1 files changed, 1 insertions, 1 deletions

diff --git a/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java b/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java
index 7c842491..cf3d5ebd 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java
@@ -175,7 +175,7 @@ public final class AutoFactoryProcessor extends AbstractProcessor {
                   implementationMethodDescriptors.get(entry.getKey()),
                   allowSubclasses));
         } catch (IOException e) {
-          messager.printMessage(Kind.ERROR, "failed");
+          messager.printMessage(Kind.ERROR, "failed: " + e);
         }
       }
     }