-*** Changes since G++ version 2.7.2:
+*** Changes in GCC 3.4:
-* A public review copy of the December 1996 Draft of the ANSI/ISO C++
- proto-standard is now available. See
+* Changes in GCC 3.4 are described in 'gcc-3.4/changes.html'
+
+*** Changes in GCC 3.3:
+
+* The "new X = 3" extension has been removed; you must now use "new X(3)".
+
+* G++ no longer allows in-class initializations of static data members
+ that do not have arithmetic or enumeration type. For example:
+
+ struct S {
+ static const char* const p = "abc";
+ };
+
+ is no longer accepted.
+
+ Use the standards-conformant form:
+
+ struct S {
+ static const char* const p;
+ };
+
+ const char* const S::p = "abc";
+
+ instead.
+
+ (ISO C++ is even stricter; it does not allow in-class
+ initializations of floating-point types.)
+
+*** Changes in GCC 3.1:
+
+* -fhonor-std and -fno-honor-std have been removed. -fno-honor-std was
+ a workaround to allow std compliant code to work with the non-std
+ compliant libstdc++-v2. libstdc++-v3 is std compliant.
+
+* The C++ ABI has been fixed so that `void (A::*)() const' is mangled as
+ "M1AKFvvE", rather than "MK1AFvvE" as before. This change only affects
+ pointer to cv-qualified member function types.
+
+* The C++ ABI has been changed to correctly handle this code:
+
+ struct A {
+ void operator delete[] (void *, size_t);
+ };
+
+ struct B : public A {
+ };
+
+ new B[10];
+
+ The amount of storage allocated for the array will be greater than
+ it was in 3.0, in order to store the number of elements in the
+ array, so that the correct size can be passed to `operator delete[]'
+ when the array is deleted. Previously, the value passed to
+ `operator delete[]' was unpredictable.
+
+ This change will only affect code that declares a two-argument
+ `operator delete[]' with a second parameter of type `size_t'
+ in a base class, and does not override that definition in a
+ derived class.
+
+* The C++ ABI has been changed so that:
+
+ struct A {
+ void operator delete[] (void *, size_t);
+ void operator delete[] (void *);
+ };
+
+ does not cause unnecessary storage to be allocated when an array of
+ `A' objects is allocated.
+
+ This change will only affect code that declares both of these
+ forms of `operator delete[]', and declared the two-argument form
+ before the one-argument form.
+
+* The C++ ABI has been changed so that when a parameter is passed by value,
+ any cleanup for that parameter is performed in the caller, as specified
+ by the ia64 C++ ABI, rather than the called function as before. As a
+ result, classes with a non-trivial destructor but a trivial copy
+ constructor will be passed and returned by invisible reference, rather
+ than by bitwise copy as before.
+
+* G++ now supports the "named return value optimization": for code like
+
+ A f () {
+ A a;
+ ...
+ return a;
+ }
+
+ G++ will allocate 'a' in the return value slot, so that the return
+ becomes a no-op. For this to work, all return statements in the function
+ must return the same variable.
+
+*** Changes in GCC 3.0:
+
+* Support for guiding declarations has been removed.
+
+* G++ now supports importing member functions from base classes with a
+ using-declaration.
+
+* G++ now enforces access control for nested types.
+
+* In some obscure cases, functions with the same type could have the
+ same mangled name. This bug caused compiler crashes, link-time clashes,
+ and debugger crashes. Fixing this bug required breaking ABI
+ compatibility for the functions involved. The functions in questions
+ are those whose types involve non-type template arguments whose
+ mangled representations require more than one digit.
+
+* Support for assignment to `this' has been removed. This idiom
+ was used in the very early days of C++, before users were allowed
+ to overload `operator new'; it is no longer allowed by the C++
+ standard.
+
+* Support for signatures, a G++ extension, have been removed.
+
+* Certain invalid conversions that were previously accepted will now
+ be rejected. For example, assigning function pointers of one type
+ to function pointers of another type now requires a cast, whereas
+ previously g++ would sometimes accept the code even without the
+ cast.
+
+* G++ previously allowed `sizeof (X::Y)' where Y was a non-static
+ member of X, even if the `sizeof' expression occurred outside
+ of a non-static member function of X (or one of its derived classes,
+ or a member-initializer for X or one of its derived classes.) This
+ extension has been removed.
+
+* G++ no longer allows you to overload the conditional operator (i.e.,
+ the `?:' operator.)
+
+* The "named return value" extension:
+
+ int f () return r { r = 3; }
+
+ has been deprecated, and will be removed in a future version of G++.
+
+*** Changes in GCC 2.95:
+
+* Messages about non-conformant code that we can still handle ("pedwarns")
+ are now errors by default, rather than warnings. This can be reverted
+ with -fpermissive, and is overridden by -pedantic or -pedantic-errors.
+
+* String constants are now of type `const char[n]', rather than `char[n]'.
+ This can be reverted with -fno-const-strings.
+
+* References to functions are now supported.
+
+* Lookup of class members during class definition now works in all cases.
+
+* In overload resolution, type conversion operators are now properly
+ treated as always coming from the most derived class.
+
+* C9x-style restricted pointers are supported, using the `__restrict'
+ keyword.
+
+* You can now use -fno-implicit-inline-templates to suppress writing out
+ implicit instantiations of inline templates. Normally we do write them
+ out, even with -fno-implicit-templates, so that optimization doesn't
+ affect which instantiations are needed.
+
+* -fstrict-prototype now also suppresses implicit declarations.
+
+* Many obsolete options have been removed: -fall-virtual, -fmemoize-lookups,
+ -fsave-memoized, +e?, -fenum-int-equivalence, -fno-nonnull-objects.
+
+* Unused virtual functions can be discarded on some targets by specifying
+ -ffunction-sections -fvtable-gc to the compiler and --gc-sections to the
+ linker. Unfortunately, this only works on Linux if you're linking
+ statically.
+
+* Lots of bugs stomped.
+
+*** Changes in EGCS 1.1:
+
+* Namespaces are fully supported. The library has not yet been converted
+ to use namespace std, however, and the old std-faking code is still on by
+ default. To turn it off, you can use -fhonor-std.
+
+* Massive template improvements:
+ + member template classes are supported.
+ + template friends are supported.
+ + template template parameters are supported.
+ + local classes in templates are supported.
+ + lots of bugs fixed.
+
+* operator new now throws bad_alloc where appropriate.
+
+* Exception handling is now thread safe, and supports nested exceptions and
+ placement delete. Exception handling overhead on x86 is much lower with
+ GNU as 2.9.
+
+* protected virtual inheritance is now supported.
+
+* Loops are optimized better; we now move the test to the end in most
+ cases, like the C frontend does.
+
+* For class D derived from B which has a member 'int i', &D::i is now of
+ type 'int B::*' instead of 'int D::*'.
+
+* An _experimental_ new ABI for g++ can be turned on with -fnew-abi. The
+ current features of this are more efficient allocation of base classes
+ (including the empty base optimization), and more compact mangling of C++
+ symbol names (which can be turned on separately with -fsquangle). This
+ ABI is subject to change without notice, so don't use it for anything
+ that you don't want to rebuild with every release of the compiler.
+
+ As with all ABI-changing flags, this flag is for experts only, as all
+ code (including the library code in libgcc and libstdc++) must be
+ compiled with the same ABI.
+
+*** Changes in EGCS 1.0:
+
+* A public review copy of the December 1996 Draft of the ISO/ANSI C++
+ standard is now available. See
http://www.cygnus.com/misc/wp/
but not all, the compiler will tell you where you need to add
'typename'. For more information, see
- http://www.cygnus.com/misc/wp/dec96pub/template.html#temp.res
+ http://www.cygnus.com/misc/wp/dec96pub/template.html#temp.res
- + Guiding declarations are no longer supported. Function declarations,
+ + Guiding declarations are no longer supported. Function declarations,
including friend declarations, do not refer to template instantiations.
You can restore the old behavior with -fguiding-decls until you fix
your code.
+ Explicit instantiation of template constructors and destructors is
now supported. For instance:
- template A<int>::A(const A&);
+ template A<int>::A(const A&);
Still not supported:
+ Member class templates.
- + Template template parameters.
+ Template friends.
* Exception handling support has been significantly improved and is on by
- default. This can result in significant runtime overhead. You can turn
- it off with -fno-exceptions.
+ default. The compiler supports two mechanisms for walking back up the
+ call stack; one relies on static information about how registers are
+ saved, and causes no runtime overhead for code that does not throw
+ exceptions. The other mechanism uses setjmp and longjmp equivalents, and
+ can result in quite a bit of runtime overhead. You can determine which
+ mechanism is the default for your target by compiling a testcase that
+ uses exceptions and doing an 'nm' on the object file; if it uses __throw,
+ it's using the first mechanism. If it uses __sjthrow, it's using the
+ second.
+
+ You can turn EH support off with -fno-exceptions.
* RTTI support has been rewritten to work properly and is now on by default.
This means code that uses virtual functions will have a modest space
* New flags:
- + New flags -Wsign-promo (warn about potentially confusing promotions
- in overload resolution), -Wno-pmf-conversion (don't warn about
- converting from a bound member function pointer to function pointer).
+ + New warning -Wno-pmf-conversion (don't warn about
+ converting from a bound member function pointer to function
+ pointer).
- + A flag -Weffc++ has been added for violations of some of the style
+ + A flag -Weffc++ has been added for violations of some of the style
guidelines in Scott Meyers' _Effective C++_ books.
+ -Woverloaded-virtual now warns if a virtual function in a base
signatures are overridden) as it did before.
+ -Wall no longer implies -W. The new warning flag, -Wsign-compare,
- included in -Wall, warns about dangerous comparisons of signed and
- unsigned values. Only the flag is new; it was previously part of
- -W.
+ included in -Wall, warns about dangerous comparisons of signed and
+ unsigned values. Only the flag is new; it was previously part of
+ -W.
+ The new flag, -fno-weak, disables the use of weak symbols.
* __FUNCTION__ and __PRETTY_FUNCTION__ are now treated as variables by the
parser; previously they were treated as string constants. So code like
- `printf (__FUNCTION__ ": foo")' must be rewritten to
+ `printf (__FUNCTION__ ": foo")' must be rewritten to
`printf ("%s: foo", __FUNCTION__)'. This is necessary for templates.
* local static variables in extern inline functions will be shared between
translation units.
-* -fvtable-thunks is supported for all targets, and is the default for
+* -fvtable-thunks is supported for all targets, and is the default for
Linux with glibc 2.x (also called libc 6.x).
* bool is now always the same size as another built-in type. Previously,
supported. For instance:
struct A {
- struct B;
- B* bp;
+ struct B;
+ B* bp;
};
struct A::B {
- int member;
+ int member;
};
* On the HPPA, some classes that do not define a copy constructor
* Joe Buck <jbuck@synopsys.com>, the maintainer of the g++ FAQ.
* Brendan Kehoe <brendan@cygnus.com>, who coordinates testing of g++.
* Jason Merrill <jason@cygnus.com>, the g++ maintainer.
-* Mark Mitchell <mmitchell@usa.net>, who implemented member function
+* Mark Mitchell <mmitchell@usa.net>, who implemented member function
templates and explicit qualification of function templates.
* Mike Stump <mrs@wrs.com>, the previous g++ maintainer, who did most of
the exception handling work.
+
+\f
+Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003,
+2005 Free Software Foundation, Inc.
+
+Copying and distribution of this file, with or without modification,
+are permitted in any medium without royalty provided the copyright
+notice and this notice are preserved.
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