ProGuard versions >= 7.4.0 make even trivial Compose desktop apps crash when optimizing

[mipastgt]

I created a Compose desktop app template with the Jetbrains wizard and then just added a ProGuard configuration block to the build.gradle.kts

        buildTypes.release {
            proguard {
                // Versions "7.2.2" up to "7.3.0" work
                // Versions "7.4.0" up to "7.6.0" crash
                // When optimization is switched off, the newer versions work too.
                version.set("7.6.0")
                isEnabled.set(true)
                optimize.set(true)
                obfuscate.set(false)
            }
        }

With versions >= 7.4.0 the resulting app crashes with a

Exception in thread "DefaultDispatcher-worker-1" java.lang.VerifyError: Bad type on operand stack

This does not happen when ProGuard is disabled or optimization is switched off.
See attached error log and sample project.

In order to reproduce the problem with the attached sample project, you can just run the Gradle task :composeApp:runRelease which applies ProGuard to the build automatically.

I tested this on macOS 14.7 with Java 17.

I stumbled over this issue while I was trying to track down another ProGuard issue which may be related. See discussion on Slack
and #443

errors_log.txt.zip
ProGuardGeoError.zip

[mrjameshamilton]

Hi @mipastgt !

It looks like something is going wrong with method type specialization. As a workaround, you can disable that particular optimization if you don't want to disable all optimizations. I could build the sample by disabling the optimization with the following:

// build.gradle.kts
        buildTypes.release {
            proguard {
                version.set("7.6.0")
                isEnabled.set(true)
                optimize.set(true)
                obfuscate.set(false)
               // Add a configuration file.
		configurationFiles.from(project.file("compose-desktop.pro"))
            }
        }

// compose-desktop.pro
-optimizations !method/specialization/**

[mipastgt]

Thanks, but normally I switch off optimizations anyway. I accidentally stumbled over this one with optimizations on.

The much more critical issue which I was actually investigating is this one: #443