Support building without support for old ABIs.

CMakeLists.txt

@@ -31,7 +31,6 @@ set(libobjc_OBJC_SRCS
 	blocks_runtime.m
 	properties.m)
 set(libobjc_C_SRCS 
-	abi_version.c
 	alias_table.c
 	block_to_imp.c
 	caps.c
@@ -43,8 +42,6 @@ set(libobjc_C_SRCS
 	hash_table.c
 	hooks.c
 	ivar.c
-	legacy_malloc.c
-	legacy.c
 	loader.c
 	mutation.m
 	protocol.c
@@ -120,8 +117,17 @@ else ()
 	list(APPEND libobjc_OBJC_SRCS gc_none.c)
 endif ()
 
+set(OLDABI_COMPAT TRUE CACHE BOOL
+	"Enable compatibility with GCC and old GNUstep ABIs")
+
 set(LEGACY_COMPAT FALSE CACHE BOOL
 	"Enable legacy compatibility features")
+
+if (OLDABI_COMPAT)
+	list(APPEND libobjc_C_SRCS legacy.c abi_version.c)
+	add_definitions(-DOLDABI_COMPAT=1)
+endif()
+
 if (LEGACY_COMPAT)
 	list(APPEND libobjc_C_SRCS legacy_malloc.c)
 else ()

Test/CMakeLists.txt

@@ -91,7 +91,7 @@ function(addtest_variants TEST TEST_SOURCE LEGACY)
 	target_sources(${TEST} PRIVATE $<TARGET_OBJECTS:test_runtime>)
 	addtest_flags("${TEST}_optimised" "-O3 -fobjc-runtime=gnustep-2.0 -UNDEBUG -DGS_RUNTIME_V2" "${TEST_SOURCE}")
 	target_sources("${TEST}_optimised" PRIVATE $<TARGET_OBJECTS:test_runtime>)
-	if (LEGACY)
+	if (${LEGACY} AND ${OLDABI_COMPAT})
 		addtest_flags("${TEST}_legacy" "-O0 -fobjc-runtime=gnustep-1.7 -UNDEBUG" "${TEST_SOURCE}")
 		target_sources("${TEST}_legacy" PRIVATE $<TARGET_OBJECTS:test_runtime_legacy>)
 		addtest_flags("${TEST}_legacy_optimised" "-O3 -fobjc-runtime=gnustep-1.7 -UNDEBUG" "${TEST_SOURCE}")

class_table.c

@@ -165,6 +165,7 @@ PRIVATE BOOL objc_resolve_class(Class cls)
 			}
 		}
 	}
+#ifdef OLDABI_COMPAT
 	else
 	{
 		struct objc_class_gsv1 *ocls = objc_legacy_class_for_class(cls);
@@ -183,6 +184,7 @@ PRIVATE BOOL objc_resolve_class(Class cls)
 			}
 		}
 	}
+#endif
 
 
 	// Remove the class from the unresolved class list
@@ -258,12 +260,14 @@ PRIVATE BOOL objc_resolve_class(Class cls)
 
 	// Fix up the ivar offsets
 	objc_compute_ivar_offsets(cls);
+#ifdef OLDABI_COMPAT
 	struct objc_class_gsv1 *oldCls = objc_legacy_class_for_class(cls);
 	if (oldCls)
 	{
 		oldCls->super_class = cls->super_class;
 		oldCls->isa->super_class = cls->isa->super_class;
 	}
+#endif
 	// Send the +load message, if required
 	if (!objc_test_class_flag(cls, objc_class_flag_user_created))
 	{

ivar.c

@@ -89,6 +89,7 @@ PRIVATE void objc_compute_ivar_offsets(Class class)
 				}
 				*ivar->offset += ivar_start;
 			}
+#ifdef OLDABI_COMPAT
 			// If we have a legacy ivar list, update the offset in it too -
 			// code from older compilers may access this directly!
 			struct objc_class_gsv1* legacy = objc_legacy_class_for_class(class);
@@ -99,6 +100,7 @@ PRIVATE void objc_compute_ivar_offsets(Class class)
 					legacy->ivars->ivar_list[i].offset = *ivar_at_index(class->ivars, i)->offset;
 				}
 			}
+#endif
 		}
 	}
 }

loader.c

@@ -281,6 +281,7 @@ void __objc_load(struct objc_init *init)
 	init->version = 0xffffffffffffffffULL;
 }
 
+#ifdef OLDABI_COMPAT
 void __objc_exec_class(struct objc_module_abi_8 *module)
 {
 	init_runtime();
@@ -351,3 +352,4 @@ void __objc_exec_class(struct objc_module_abi_8 *module)
 		}
 	}
 }
+#endif

protocol.c

@@ -220,6 +220,7 @@ static BOOL init_protocols(struct objc_protocol_list *protocols)
 			default:
 				fprintf(stderr, "Unknown protocol version");
 				abort();
+#ifdef OLDABI_COMPAT
 			case protocol_version_gcc:
 				protocols->list[i] = aProto = objc_upgrade_protocol_gcc((struct objc_protocol_gcc *)aProto);
 				assert(aProto->isa == protocol_class_gcc);
@@ -228,6 +229,7 @@ static BOOL init_protocols(struct objc_protocol_list *protocols)
 				protocols->list[i] = aProto = objc_upgrade_protocol_gsv1((struct objc_protocol_gsv1 *)aProto);
 				assert(aProto->isa == protocol_class_gsv2);
 				break;
+#endif
 			case protocol_version_gsv2:
 				aProto->isa = protocol_class_gsv2;
 				break;