TypeAdapters assertion looses causing throwable

[realdadfish]

In line https://github.com/google/gson/blob/master/gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java#L799
an AssertionError is thrown in case a NoSuchFieldException is triggered. The assertion however looses all context information what field is missing and makes debugging this issue very hard, especially on proguarded builds.

[swankjesse]

Seems like disabling proguard will always simplify debugging.

[realdadfish]

Not this time, though. I usually ran my tests on non-obfuscated proguard builds that share the same proguard configuration like my release builds, but this time the obfuscation was actually the issue that somehow made the field "vanish", because the proguarded debug build did not show the issue.

Figured it out that I had a wrong OkHttp proguard configuration after I could hint myself at the missing field by using a custom gson build. Feel free to take this code over:

diff --git a/gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java b/gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java
index d284dd5..6bb4a1f 100644
--- a/gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java
+++ b/gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java
@@ -796,7 +796,7 @@ public final class TypeAdapters {
           constantToName.put(constant, name);
         }
       } catch (NoSuchFieldException e) {
-        throw new AssertionError();
+        throw new AssertionError("missing field in " + classOfT, e);
       }
     }
     @Override public T read(JsonReader in) throws IOException {

[gupta-sachin]

The AssertionError constructor with Throwable is added since Java 1.7 so it will be better to have only a detailed error message here.

[Marcono1234]

The detailed error message was added by #738 but because the constructor used in these changes does not exist in Java 6, it was later adjusted by #857 to only set the cause.
However, this code was refactored by #1495 to better handle obfuscated enum constant names, so this issue is probably resolved.

[eamonnmcmanus]

Given how old this issue is and the summary from @Marcono1234 I'm going to close this now. Feel free to reopen or log a new issue if there is still a genuine issue here.