mdt@YAHI.STANFORD.EDU (Michael Tiemann) (03/16/89)
GNU C++ 1.34.1 and GDB 3.1.1 are now on speaking terms. All C++
features which were supported in GDB+ 2.8.1 should still be supported
in GDB 3.1.1. This should be cause for much rejoicing. These packages
are available from yahi.stanford.edu by anonymous ftp:
-rw-rw-rw- 1 mdt 777829 Mar 15 09:54 g++-1.34.1.tar.Z
-rw-rw-rw- 1 mdt 749347 Mar 15 09:33 gdb-3.1.1.tar.Z
I have fixed up the Makefile and the README. There is now a
config.g++. Please report any machines for which this config file
fails when it should not. (i.e., it probably won't work on a VMS VAX,
but that's ok with me). Specifically, this file should fix problems
for Sun3 (-os3 and -os4 clients).
GNU C++ 1.34.1 contains all the changes I have had to make since
1.34.0 to let our internal version of InterViews compile. It should
not break much existing code. I also took the liberty of fixing other
random bugs and reducing the number of shift-reduce conflicts in the
grammar by using some more precedence rules. One of these bugfixes
required the following patch to compile libg++:
yahi% diff -c2 builtin.h~ builtin.h
*** builtin.h~ Sat Mar 4 07:29:42 1989
--- builtin.h Wed Mar 15 00:27:48 1989
***************
*** 43,46 ****
--- 43,48 ----
overload sqr;
overload testbit;
+ overload even;
+ overload odd;
#include <std.h>
GNU C++ 1.34.1 also has three new experimental features.
1. Named return values. Example:
struct A { ... A (); A (A&); ... };
// old way
A foo ()
{
A tmp; // calls A() constructor
... things which modify `tmp' ...
return tmp; // calls A(A&) constructor
}
// new way
A foo () return tmp; // calls A () constructor on entry
{
... things which modify `tmp' ...
return tmp; // call to A (A&) constructor not needed
}
This feature is not controlled by a flag. If you use it, you get it.
For all the syntactic variations, please see the grammar.
2. Better constructor elision
With the -felide-constructors, the compiler tries to be smarter about
when it can elide constructors. With out this flag, GNU C++ and
cfront both generate effectively the same code for:
A foo ();
A x (foo ()); // x is initialized by `foo ()', no ctor called here
A y = foo (); // call to `foo ()' heads to temporary,
y is initialized from the temporary. Note difference!
With this flag, GNU C++ initializes `y' directly from the call to `foo
()' without going through a temporary.
This feature breaks implementation-dependent code written by Doug Lea,
so use it with caution.
3. The +e0 and +e1 flags are implemented.
The +e0 flag means "use externally declared virtual function tables for this file".
The +e1 flag means "declare and define public virtual function tables for this file"
With neither flag, the compiler does what it did all along: each
virtual function table which the compiler needs in a given file is
private to that file and laid out.
The use of these flags may reduce the amount of space consumed by
virtual function tables in some programs. Since GNU C++ already tries
to be smart about not writing out virtual function tables if it knows
that it does not need them (in that file), these flags will be less
useful then they are reputed to be in other C++ compilers.
Michael