chore(r8): drop R8 options that no longer do anything - #1371
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Four options at the top of proguard-rules.pro and three rules at the bottom were either inert or already supplied by the libraries that need them. -optimizationpasses is a ProGuard option; R8 parses and ignores it. -dontusemixedcaseclassnames only matters when writing class files to a case-insensitive filesystem, which R8 does not do when it emits DEX. The two obfuscation dictionaries point at shuffled-dictionary.txt, whose 811 entries are all exactly four characters. Without it R8 assigns names by frequency, so 736k of 1.2M member mappings get one-character names. Feeding it a fixed four-character alphabet is strictly worse, but only slightly: DEX interns strings, so the dictionary only displaced 911 of 18,601 renamed classes and cost 2,828 bytes of DEX (16,103,860 -> 16,101,032). Removing the dictionary is about dropping an 811-line file nothing else reads, not size. The retrofit2.Call/Response and kotlin.coroutines.Continuation signature rules ship in Retrofit's own META-INF/proguard/retrofit2.pro, along with the -keepattributes Signature they depend on. Retrofit 3.0.0 keeps Response and Continuation with identical rule text, and covers Call through its conditional return-type rule rather than a literal keep. -keep class * extends androidx.room.RoomDatabase in services/flipcash is subsumed by the equivalent rule Room already ships. Release R8 output is unchanged: both builds keep 21,361 classes and 1,330,404 members. Only the assigned names differ.
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Four options at the top of
proguard-rules.proand three rules at the bottom were either inert or already supplied by the libraries that need them.The two inert options
-optimizationpassesis a ProGuard option; R8 parses and ignores it.-dontusemixedcaseclassnamesonly matters when writing class files to a case-insensitive filesystem, which R8 does not do when it emits DEX.The obfuscation dictionaries
Both point at
shuffled-dictionary.txt, whose 811 entries are all exactly four characters. Without it R8 assigns names by frequency: 736k of 1.2M member mappings get one-character names. Feeding R8 a fixed four-character alphabet is strictly worse, but only slightly — DEX interns strings, so a longer name costs pool bytes once rather than per reference.Measured on two release builds of this branch's parent:
2,828 bytes. Removing the dictionary is about dropping an 811-line file nothing else reads, not about size.
The Retrofit signature rules
retrofit2.Call,retrofit2.Responseandkotlin.coroutines.Continuationare kept by Retrofit's ownMETA-INF/proguard/retrofit2.pro, which also carries the-keepattributes Signature, InnerClasses, EnclosingMethodthey depend on. Retrofit 3.0.0 keepsResponseandContinuationwith identical rule text;Callis covered by its conditional return-type rule (-if interface * { @retrofit2.http.* public *** *(...); } -keep,allowoptimization,allowshrinking,allowobfuscation class <3>) rather than a literal keep.Room
-keep class * extends androidx.room.RoomDatabaseinservices/flipcash/consumer-rules.prois subsumed by the equivalent rule Room already ships.Release R8 output is unchanged across the two builds: both keep 21,361 classes and 1,330,404 members. Only the assigned names differ.