Merge "Add test for inlining of static interface methods"
diff --git a/compatibility-faq.md b/compatibility-faq.md
new file mode 100644
index 0000000..8b15be4
--- /dev/null
+++ b/compatibility-faq.md
@@ -0,0 +1,103 @@
+# R8 compatibility FAQ
+
+R8 uses the same configuration specification language as ProGuard, and tries to
+be compatible with ProGuard. However as R8 has different optimizations it can be
+necessary to change the configuration when switching to R8.
+
+This FAQ collects some of the common issues.
+
+## GSON
+
+### Member in a data object is always `null`
+
+For data classes used for serialization all fields that are used in the
+serialization must be kept by the configuration. R8 can decide to replace
+instances of types that are never instantiated with `null`. So if instances of a
+given class are only created through deserialization from JSON, R8 will not see
+that class as instantiated leaving it as always `null`.
+
+If the `@SerializedName` annotation is used consistently for data classes the
+following keep rule can be used:
+
+```
+-keepclassmembers,allowobfuscation class * {
+ @com.google.gson.annotations.SerializedName <fields>;
+}
+```
+
+This will ensure that all fields annotated with `SerializedName` will be
+kept. These fields can still be renamed during obfuscation as the
+`SerializedName` annotation (not the source field name) controls the name in the
+JSON serialization.
+
+If the `@SerializedName` annotation is _not_ used the following conservative
+rule can be used for each data class:
+
+```
+-keepclassmembers class MyDataClass {
+ !transient <fields>;
+}
+```
+
+This will ensure that all fields are kept and not renamed for these
+classes. Fields with modifier `transient` are never serialized and therefore
+keeping these is not needed.
+
+### Error `java.lang.IllegalArgumentException: class <class name> declares multiple JSON fields named <name>`
+
+This can be caused by obfuscation selecting the same name for private fields in
+several classes in a class hierachy. Consider the following example:
+
+```
+class A {
+ private String fieldInA;
+}
+
+class B extends A {
+ private String fieldInB;
+}
+```
+
+Here R8 can choose to rename both `fieldInA` and `fieldInB` to the same name,
+e.g. `a`. This creates a conflict when GSON is used to either serialize an
+instance of class `B` to JSON or create an instance of class `B` from JSON. If
+the fields should _not_ be serialized they should be marked `transient` so that
+they will be ignored by GSON:
+
+```
+class A {
+ private transient String fieldInA;
+}
+
+class B extends A {
+ private transient String fieldInB;
+}
+```
+
+If the fields _are_ to be serialized, the annotation `SerializedName` can be
+used to fix the `IllegalArgumentException` together the rule to keep fields
+annotated with `SerializedName`
+
+```
+class A {
+ @SerializedName("fieldInA")
+ private String fieldInA;
+}
+
+class B extends A {
+ @SerializedName("fieldInB")
+ private String fieldInB;
+}
+```
+
+```
+-keepclassmembers,allowobfuscation class * {
+ @com.google.gson.annotations.SerializedName <fields>;
+}
+```
+
+
+Both the use of `transient` and the use of the annotation `SerializedName` allow
+the fields to be renamed by R8 to the same name, but GSON serialization will
+work as expected.
+
diff --git a/tools/windows/README.dx b/tools/windows/README.dx
index 4d93487..c9f4c54 100644
--- a/tools/windows/README.dx
+++ b/tools/windows/README.dx
@@ -4,6 +4,8 @@
is removed and replaced by a direct reference to it.
This is done because this relies on a tool found in the SDK and not present in the
current package.
+Also, the deprecated java.ext.dirs argument has been removed.
+
Diff:
26,29c26,29
@@ -19,7 +21,7 @@
87c87
< call "%java_exe%" %javaOpts% -Djava.ext.dirs="%frameworkdir%" -jar "%jarpath%" %params%
---
-> call java %javaOpts% -Djava.ext.dirs="%frameworkdir%" -jar "%jarpath%" %params%
+> call java %javaOpts% -jar "%jarpath%" %params%
dexmerger.bat has been copied from dx.bat, and the command line has been updated
according to the SDK dexmerger bash script to call the right class.
\ No newline at end of file
diff --git a/tools/windows/dx.tar.gz.sha1 b/tools/windows/dx.tar.gz.sha1
index 867adab..d76e1b8 100644
--- a/tools/windows/dx.tar.gz.sha1
+++ b/tools/windows/dx.tar.gz.sha1
@@ -1 +1 @@
-47414f7ebc8a8cc14b29fc6732510a20947870aa
\ No newline at end of file
+1cd960db2115795a2599c56c58ce209c0f8d7476
\ No newline at end of file
