Remove compat-break bool from ABI detection protocol

src/common/IPC/Common.h

@@ -71,17 +71,15 @@ namespace IPC {
 	};
 
     // Version of the protocol for detecting what ABI version the VM has upon startup
-    constexpr uint32_t ABI_VERSION_DETECTION_ABI_VERSION = 4;
+    constexpr uint32_t ABI_VERSION_DETECTION_ABI_VERSION = 5;
 
     // Version for the syscall signatures between engine and VM. This must change if the syscall
     // IDs, argument types, or return types change, or if serialization procedures change.
-    // Follows Daemon major versions.
-    // This should be updated only by update-version-number.py when a "major" release is indicated
-    constexpr const char* SYSCALL_ABI_VERSION = "0.55";
-
-    // This should be manually set to true when starting a 'for-X.Y.Z/sync' branch.
-    // This should be set to false by update-version-number.py when a (major) release is created.
-    constexpr bool DAEMON_HAS_COMPATIBILITY_BREAKING_SYSCALL_CHANGES = true;
+    // For the master branch with a stable ABI, this follows Daemon major versions.
+    // For next-release branches, the convention is to use "testing/<next release version>" On
+    // the next-release branch the ABI is unstable so any two commits may be incompatible.
+    // This is updated by update-version-number.py when a "major" release is indicated.
+    constexpr const char* SYSCALL_ABI_VERSION = "testing/0.56.0";
 
     /*
      * The messages sent between the VM and the engine are defined by a numerical

src/engine/framework/VirtualMachine.cpp

@@ -60,8 +60,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 static Cvar::Cvar<std::string> abiVersionCvar(
 	"version.daemon.abi", "Virtual machine IPC ABI version", Cvar::SERVERINFO | Cvar::ROM,
-	std::string(IPC::SYSCALL_ABI_VERSION) +
-	(IPC::DAEMON_HAS_COMPATIBILITY_BREAKING_SYSCALL_CHANGES ? "+compatbreak" : ""));
+	IPC::SYSCALL_ABI_VERSION);
 
 static Cvar::Cvar<bool> workaround_naclArchitecture_arm64_disableQualification(
 	"workaround.linux.arm64.naclDisableQualification",
@@ -533,17 +532,6 @@ void VMBase::Create()
 		          this->name, vmABI, IPC::SYSCALL_ABI_VERSION);
 	}
 
-	bool vmCompatBreaking = reader.Read<bool>();
-	if (vmCompatBreaking && !IPC::DAEMON_HAS_COMPATIBILITY_BREAKING_SYSCALL_CHANGES) {
-		Sys::Drop("Couldn't load the %s gamelogic module: it has compatibility-breaking ABI changes but Daemon engine uses the vanilla %s ABI",
-		          this->name, IPC::SYSCALL_ABI_VERSION);
-	} else if (!vmCompatBreaking && IPC::DAEMON_HAS_COMPATIBILITY_BREAKING_SYSCALL_CHANGES) {
-		Sys::Drop("Couldn't load the %s gamelogic module: Daemon has compatibility-breaking ABI changes but the VM uses the vanilla %s ABI",
-		          this->name, IPC::SYSCALL_ABI_VERSION);
-	} else if (IPC::DAEMON_HAS_COMPATIBILITY_BREAKING_SYSCALL_CHANGES) {
-		Log::Notice("^6Using %s VM with unreleased ABI changes", this->name);
-	}
-
 	Log::Notice("Loaded %s VM module in %d msec", this->name, Sys::Milliseconds() - loadStartTime);
 }
 

src/shared/VMMain.cpp

@@ -69,7 +69,6 @@ static void CommonInit(Sys::OSHandle rootSocket)
 	Util::Writer writer;
 	writer.Write<uint32_t>(IPC::ABI_VERSION_DETECTION_ABI_VERSION);
 	writer.Write<std::string>(IPC::SYSCALL_ABI_VERSION);
-	writer.Write<bool>(IPC::DAEMON_HAS_COMPATIBILITY_BREAKING_SYSCALL_CHANGES);
 	VM::rootChannel.SendMsg(writer);
 
 	// Start the main loop