Release 3.3 Copyright ã1995 by NeXT Computer, Inc.  All Rights Reserved.

3.3 Release Notes: 
Objective C++ Compiler

  
This file contains developer release notes for the 3.3, 3.2, 3.1, and 3.0 releases of the Objective C++ Compiler.

Notes Specific to Release 3.2

The Release 3.2 Objective-C++ compiler is based on version 2.2.2 of the GNU compiler.

New Features
·	The new language features supported by the 2.2.2 version are described in the GNU documentation that accompanies the compiler sources.

·	The list of C++ extensions is now: .C, .cc, .cxx, .cpp and .M.

·	The -ObjC++ flag overrides the auto-language-selection so that, for example, a .c file can be compiled as Objective-C++ code. However, the /bin/cc++ shell script which calls the /bin/cc driver with the -ObjC++ flag continues to be supported.

·	The new system header path for C++-specific headers is /NextDeveloper/Headers/g++. Currently this directory only contains headers specific to libg++ and C++ compatible system header files.

·	The cc(1) driver has been modified to invoke the script ld++ to demangle symbol names in ld output for a more user-friendly error messages.

            Notes
·	The current version of the compiler does not support templates.

·	Most system headers still require that Objective-C++ source files wrap inclusions to them with the extern "C" or extern "Objective-C" syntax.  For example,
			
		extern "C" {
		#import <stddef.h>
		#import <streams/streams.h>
		};

Notes Specific to Release 3.0

The Release 3.0 Objective-C++ compiler is based on version 1.39.1 of the GNU Compiler which directly supports version 2.0 of the C++ language, as specified by AT&T (the Release 2.0 compiler was based on version 1.36.4 of G++).  The GNU compiler has been extended to recognize Objective-C constructs within C++ source files.

New Features

Integrated Compiler Driver

The Release 3.0 compiler driver /bin/cc handles C, Objective-C, C++ and Objective-C++ source files.  The C++ compiler driver program /bin/cc++ is no longer needed (but is still present for compatibility).  The compiler driver determines the appropriate language from the suffix of the source files or command line options.  Files ending in .c are taken to be C source files, .m indicates an Objective-C source file, and .cc, .cxx, and .C are recognized as C++ source files.  The -ObjC flag specifies that source files should be considered to be Objective C source files regardless of their extension.  Similarly, the -ObjC+ flag specifies that source files should be considered to be Objective-C++ source files.  The /bin/cc++ driver is simply a shell script which calls the /bin/cc driver with the -ObjC+ flag.

New Constructor and Destructor Sections

The Release 3.0 compiler no longer uses the collect program to gather references to C++ constructors and destructors (which requires linking twice).  The compiler now automatically places these references in the new __constructor and __destructor sections of the __TEXT segment, which are automatically coalesced by the linker.  Link time should be substantially decreased.

C++ constructors are called from startup routines in crt0.o, and destructors are registered to be called in the reverse order when the program terminates using atexit().  The archive library /usr/lib/libc++.a present in Release 2.0 is no longer needed.