JAR differ
A tool for generating bytecode diffs
Requires JDK 11+
About
JarDiff is a tool for generating detailed but comprehensible diffs of sets (JAR or directory) of Java classfiles.
Class files are rendered with ASM's Textifier
and with scalap. Other files are rendered as-is.
The rendered files are commited into a Git repository, one commit per provided command line argument.
The diffs between these are rendered to standard out (unless --quiet is provided). If only a single
argument is provided, the initial commit is rendered.
By default, a temporary git repository is used and deleted on exit. Use --git to provide a custom
location for the repository that can be inspected after the tool has run.
Installing
macOS
macOS users may install with:
brew install retronym/formulas/jardiff
Other Platforms
- Download
jardiff.jarfrom https://github.com/scala/jardiff/releases/latest - Wrap in a shell function or script to run
java -jar jardiff.jar "$@"
Usage
% jardiff -h
usage: jardiff [-c] [-g <dir>] [-h] [-i <arg>] [-p] [-q] [-r] [-U <n>] VERSION1 [VERSION2 ...]
Each VERSION may designate a single file, a directory, JAR file or a
`:`-delimited classpath
-c,--suppress-code Suppress method bodies
-g,--git <dir> Directory to output a git repository containing the
diff
-h,--help Display this message
-i,--ignore <arg> File pattern to ignore rendered files in gitignore
format
-p,--suppress-privates Display only non-private members
-q,--quiet Don't output diffs to standard out
-r,--raw Disable sorting and filtering of classfile contents
-U,--unified <n> Number of context lines in diff
% jardiff dir1 dir2
% jardiff v1/A.class v2/A.class
% jardiff --git /tmp/diff-repo --quiet v1.jar v2.jar v3.jar
Building
After cloning this project, use sbt clean core/assembly.
Sample Output
Scala 2.11 vs 2.12 trait encoding changes
// test.scala
trait T { def foo = 4 }
class C extends T% ~/scala/2.11/bin/scalac -d /tmp/v1 test.scala && ~/scala/2.12/bin/scalac -d /tmp/v2 test.scala
% jardiff /tmp/v1 /tmp/v2
diff --git a/C.class.asm b/C.class.asm
index f3a33f1..33b9282 100644
--- a/C.class.asm
+++ b/C.class.asm
@@ -1,4 +1,4 @@
-// class version 50.0 (50)
+// class version 52.0 (52)
// access flags 0x21
public class C implements T {
@@ -8,7 +8,7 @@
ALOAD 0
INVOKESPECIAL java/lang/Object.<init> ()V
ALOAD 0
- INVOKESTATIC T$class.$init$ (LT;)V
+ INVOKESTATIC T.$init$ (LT;)V
RETURN
MAXSTACK = 1
MAXLOCALS = 1
@@ -16,7 +16,7 @@
// access flags 0x1
public foo()I
ALOAD 0
- INVOKESTATIC T$class.foo (LT;)I
+ INVOKESTATIC T.foo$ (LT;)I
IRETURN
MAXSTACK = 1
MAXLOCALS = 1
diff --git a/T.class.asm b/T.class.asm
index 9180093..fcac19f 100644
--- a/T.class.asm
+++ b/T.class.asm
@@ -1,8 +1,28 @@
-// class version 50.0 (50)
+// class version 52.0 (52)
// access flags 0x601
public abstract interface T {
- // access flags 0x401
- public abstract foo()I
+ // access flags 0x9
+ public static $init$(LT;)V
+ // parameter final synthetic $this
+ RETURN
+ MAXSTACK = 0
+ MAXLOCALS = 1
+
+ // access flags 0x1
+ public default foo()I
+ ICONST_4
+ IRETURN
+ MAXSTACK = 1
+ MAXLOCALS = 1
+
+ // access flags 0x1009
+ public static synthetic foo$(LT;)I
+ // parameter final synthetic $this
+ ALOAD 0
+ INVOKESPECIAL T.foo ()I
+ IRETURN
+ MAXSTACK = 1
+ MAXLOCALS = 1
}Scala standard library changes during 2.11 minor releases
% jardiff --quiet --git /tmp/scala-library-diff /Users/jz/scala/2.11.*/lib/scala-library.jar
Browsable Repo: scala-library-diff
API changes visible in bytecode descriptors / generic signature / scalap output
// V1.scala
trait C {
def m1(a: String)
def m2(a: Option[String])
def m3(a: String)
}// V2.scala
trait C {
def m1(a: AnyRef)
def m2(a: Option[AnyRef])
def m3(a: scala.collection.immutable.StringOps) // value class
}diff --git a/C.class.asm b/C.class.asm
index 52a43d5..bdb0541 100644
--- a/C.class.asm
+++ b/C.class.asm
@@ -4,12 +4,12 @@
// access flags 0x401
- public abstract m1(Ljava/lang/String;)V
+ public abstract m1(Ljava/lang/Object;)V
// parameter final a
// access flags 0x401
- // signature (Lscala/Option<Ljava/lang/String;>;)V
- // declaration: void m2(scala.Option<java.lang.String>)
+ // signature (Lscala/Option<Ljava/lang/Object;>;)V
+ // declaration: void m2(scala.Option<java.lang.Object>)
public abstract m2(Lscala/Option;)V
// parameter final a
diff --git a/C.class.scalap b/C.class.scalap
index 78f7d91..637cd98 100644
--- a/C.class.scalap
+++ b/C.class.scalap
@@ -1,5 +1,5 @@
trait C extends scala.AnyRef {
- def m1(a: scala.Predef.String): scala.Unit
- def m2(a: scala.Option[scala.Predef.String]): scala.Unit
- def m3(a: scala.Predef.String): scala.Unit
+ def m1(a: scala.AnyRef): scala.Unit
+ def m2(a: scala.Option[scala.AnyRef]): scala.Unit
+ def m3(a: scala.collection.immutable.StringOps): scala.Unit
}Validating a Scala compiler nightly
% git clone --quiet --depth 1 akka/akka; cd akka
% cat ~/.sbt/0.13/resolver.sbt
resolvers ++= (
if (scalaVersion.value.contains("-bin"))
List("scala-integration" at "https://scala-ci.typesafe.com/artifactory/scala-integration/")
else Nil
)
% for v in 2.12.2 2.12.3-bin-bd6294d; do \
echo $v; \
mkdir -p /tmp/akka-$v; \
time sbt ++$v clean package &>/dev/null; \
for f in $(find . -name '*.jar'); do cp $f /tmp/akka-$v/; done; \
done
2.12.2
real 3m19.468s
user 8m56.947s
sys 0m17.343s
2.12.3-bin-bd6294d
real 2m57.631s
user 8m40.168s
sys 0m16.172s
% jardiff -q --git /tmp/akka-diff $(find /tmp/akka-2.12.2 | paste -s -d : -) $(find /tmp/akka-2.12.3-bin-bd6294d | paste -s -d : -)
The resulting diff shows that the only change in the generated bytecode is due to scala/scala#5857, "Fix lambda deserialization in classes with 252+ lambdas"
% git --git-dir /tmp/akka-diff/.git log -p -1
commit 83f0e0a5dabbdf1b7677363bf238d81e4c5b032e (HEAD -> master)
Author: Jason Zaugg <[email protected]>
Date: Mon Jun 5 17:08:17 2017 +1000
jardiff textified output of: /tmp/akka-2.12.3-bin-bd6294d:/tmp/akka-2.12.3-bin-bd6294d/akka-2.5-SNAPSHOT.jar:...
diff --git a/akka/stream/scaladsl/GraphApply.class.asm b/akka/stream/scaladsl/GraphApply.class.asm
index 5672560..4d1fafb 100644
--- a/akka/stream/scaladsl/GraphApply.class.asm
+++ b/akka/stream/scaladsl/GraphApply.class.asm
@@ -2802,6 +2802,8 @@ public abstract interface akka/stream/scaladsl/GraphApply {
// access flags 0x100A
private static synthetic $deserializeLambda$(Ljava/lang/invoke/SerializedLambda;)Ljava/lang/Object;
+ TRYCATCHBLOCK L0 L1 L1 java/lang/IllegalArgumentException
+ L0
ALOAD 0
INVOKEDYNAMIC lambdaDeserialize(Ljava/lang/invoke/SerializedLambda;)Ljava/lang/Object; [
// handle kind 0x6 : INVOKESTATIC
@@ -3308,12 +3310,20 @@ public abstract interface akka/stream/scaladsl/GraphApply {
// handle kind 0x6 : INVOKESTATIC
akka/stream/scaladsl/GraphApply.$anonfun$create$250(Lscala/Function1;Ljava/lang/Object;)Ljava/lang/Object;,
// handle kind 0x6 : INVOKESTATIC
- akka/stream/scaladsl/GraphApply.$anonfun$create$251(Lscala/Function1;Ljava/lang/Object;)Ljava/lang/Object;,
+ akka/stream/scaladsl/GraphApply.$anonfun$create$251(Lscala/Function1;Ljava/lang/Object;)Ljava/lang/Object;
+ ]
+ ARETURN
+ L1
+ ALOAD 0
+ INVOKEDYNAMIC lambdaDeserialize(Ljava/lang/invoke/SerializedLambda;)Ljava/lang/Object; [
+ // handle kind 0x6 : INVOKESTATIC
+ scala/runtime/LambdaDeserialize.bootstrap(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;[Ljava/lang/invoke/MethodHandle;)Ljava/lang/invoke/CallSite;
+ // arguments:
// handle kind 0x6 : INVOKESTATIC
akka/stream/scaladsl/GraphApply.$anonfun$create$252(Lscala/Function1;Ljava/lang/Object;)Ljava/lang/Object;
]
ARETURN
- MAXSTACK = 1
+ MAXSTACK = 2
MAXLOCALS = 1
// access flags 0x9