Update full mode documentation
Change-Id: I2e4f20727a47dbbdae250f6b83a63486815424e5
diff --git a/compatibility-faq.md b/compatibility-faq.md
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+++ b/compatibility-faq.md
@@ -29,6 +29,10 @@
`-keep[classmembers],allowshrinking,allowoptimization,allowobfuscation,allowaccessmodification class-specification`
Additionally, for attributes describing a relationship such as `InnerClass` and
`EnclosingMethod`, non-compat mode requires both endpoints being kept.
+- When optimizing or minifying the `SourceFile` attribute will always be
+rewritten to `SourceFile` unless `-renamesourcefileattribute` is used in which
+case the provided value is used. The original source file name is in the mapping
+file and when optimizing or minifying a mapping file is always produced.
## Stack traces and retracing
When compiling with R8, a mapping file can be produced to support mapping stack
