-*** Changes since G++ version 2.7.2:
+*** Changes in GCC 3.4:
-* A public review copy of the December 1996 Draft of the ANSI C++
- proto-standard is now available. See
+* Changes in GCC 3.4 are described in 'gcc-3.4/changes.html'
- http://www.cygnus.com/misc/wp/
+*** Changes in GCC 3.3:
- for more information.
+* The "new X = 3" extension has been removed; you must now use "new X(3)".
-* Default function arguments in templates will not be evaluated (or
- checked for semantic validity) unless they are needed.
+* G++ no longer allows in-class initializations of static data members
+ that do not have arithmetic or enumeration type. For example:
-* The -ftemplate-depth-NN flag can be used to increase the maximum
- recursive template instantiation depth, defaulting to 17. If you need
- to use this flag, the compiler will tell you.
+ struct S {
+ static const char* const p = "abc";
+ };
-* The internal interface between RTTI-using code and the RTTI support
- library has changed, so code that uses dynamic_cast should be
- recompiled. The RTTI support library has moved from libstdc++ to
- libgcc, so you no longer need to link against libstdc++ for a program
- that doesn't use the "hosted" library.
+ is no longer accepted.
-* bool is now always the same size as another built-in type. Previously,
- a 64-bit RISC target using a 32-bit ABI would have 32-bit pointers and a
- 64-bit bool. This should only affect Irix 6, which was not supported in
- 2.7.2.
+ Use the standards-conformant form:
-* new (nothrow) is now supported.
+ struct S {
+ static const char* const p;
+ };
-* A flag -Weffc++ has been added for violations of some of the style
- guidelines in Scott Meyers' _Effective C++_ books.
+ const char* const S::p = "abc";
-* On ELF systems, duplicate copies of symbols with 'initialized common'
- linkage (such as template instantiations, vtables, and extern inlines)
- will now be discarded by the GNU linker, so you don't need to use -frepo.
- This support requires GNU ld from binutils 2.8 or later.
+ instead.
-* Partial specialization of class templates is now supported.
+ (ISO C++ is even stricter; it does not allow in-class
+ initializations of floating-point types.)
-* The overload resolution code has been rewritten to conform to the latest
- C++ Working Paper. Built-in operators are now considered as candidates
- in operator overload resolution. Function template overloading chooses
- the more specialized template, and handles base classes in type deduction
- and guiding declarations properly. In this release the old code can
- still be selected with -fno-ansi-overloading, although this is not
- supported and will be removed in a future release.
+*** Changes in GCC 3.1:
-* 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
- overhead. You can use the -fno-rtti flag to disable RTTI support.
+* -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.
-* Synthesized destructors are no longer made virtual just because the class
- already has virtual functions, only if they override a virtual destructor
- in a base class. The compiler will warn if this affects your code.
+* 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 g++ driver no longer links with libg++ by default; it is now
- functionally identical to the c++ driver.
+* The C++ ABI has been changed to correctly handle this code:
-* (void *)0 is no longer considered a null pointer constant; NULL in
- <stddef.h> is now defined as __null, a magic constant of type (void *)
- normally, or (size_t) with -ansi.
+ struct A {
+ void operator delete[] (void *, size_t);
+ };
-* The new 'template <>' specialization syntax is now accepted and ignored.
+ struct B : public A {
+ };
-* The name of a class is now implicitly declared in its own scope; A::A
- refers to 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/
+
+ for more information.
* g++ now uses a new implementation of templates. The basic idea is that
now templates are minimally parsed when seen and then expanded later.
-fexternal-templates is specified).
+ Nested types in class templates work.
+ Static data member templates work.
+ + Member function templates are now supported.
+ + Partial specialization of class templates is now supported.
+ + Explicit specification of template parameters to function templates
+ is now supported.
- Possible problems:
+ Things you may need to fix in your code:
+ + Syntax errors in templates that are never instantiated will now be
+ diagnosed.
+ Types and class templates used in templates must be declared
first, or the compiler will assume they are not types, and fail.
+ Similarly, nested types of template type parameters must be tagged
- with the 'typename' keyword. In many cases, the compiler will tell
- you where you need to add 'typename'.
- + Syntax errors in templates that are never instantiated will now be
- diagnosed.
+ with the 'typename' keyword, except in base lists. In many cases,
+ 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
+
+ + 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.
+
+ Other features:
+
+ + Default function arguments in templates will not be evaluated (or
+ checked for semantic validity) unless they are needed. Default
+ arguments in class bodies will not be parsed until the class
+ definition is complete.
+ + The -ftemplate-depth-NN flag can be used to increase the maximum
+ recursive template instantiation depth, which defaults to 17. If you
+ need to use this flag, the compiler will tell you.
+ + Explicit instantiation of template constructors and destructors is
+ now supported. For instance:
+
+ template A<int>::A(const A&);
+
+ Still not supported:
+
+ + Member class templates.
+ + Template friends.
+
+* Exception handling support has been significantly improved and is on by
+ 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
+ overhead. You can use the -fno-rtti flag to disable RTTI support.
+
+* On ELF systems, duplicate copies of symbols with 'initialized common'
+ linkage (such as template instantiations, vtables, and extern inlines)
+ will now be discarded by the GNU linker, so you don't need to use -frepo.
+ This support requires GNU ld from binutils 2.8 or later.
+
+* The overload resolution code has been rewritten to conform to the latest
+ C++ Working Paper. Built-in operators are now considered as candidates
+ in operator overload resolution. Function template overloading chooses
+ the more specialized template, and handles base classes in type deduction
+ and guiding declarations properly. In this release the old code can
+ still be selected with -fno-ansi-overloading, although this is not
+ supported and will be removed in a future release.
+
+* Standard usage syntax for the std namespace is supported; std is treated
+ as an alias for global scope. General namespaces are still not supported.
+
+* New flags:
+
+ + 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
+ guidelines in Scott Meyers' _Effective C++_ books.
+
+ + -Woverloaded-virtual now warns if a virtual function in a base
+ class is hidden in a derived class, rather than warning about
+ virtual functions being overloaded (even if all of the inherited
+ 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.
+
+ + The new flag, -fno-weak, disables the use of weak symbols.
* Synthesized methods are now emitted in any translation units that need
an out-of-line copy. They are no longer affected by #pragma interface
or #pragma implementation.
-* Local classes are now supported.
+* __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 ("%s: foo", __FUNCTION__)'. This is necessary for templates.
-* -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.
+* local static variables in extern inline functions will be shared between
+ translation units.
-* The new flag, -fno-weak, disables the use of weak symbols.
+* -fvtable-thunks is supported for all targets, and is the default for
+ Linux with glibc 2.x (also called libc 6.x).
-* __attribute__ can now be attached to types as well as declarations.
+* bool is now always the same size as another built-in type. Previously,
+ a 64-bit RISC target using a 32-bit ABI would have 32-bit pointers and a
+ 64-bit bool. This should only affect Irix 6, which was not supported in
+ 2.7.2.
-* -Woverloaded-virtual now warns if a virtual function in a base class is
- hidden in a derived class, rather than warning about virtual functions
- being overloaded (even if all of the inherited signatures are
- overridden) as it did before.
+* new (nothrow) is now supported.
+
+* Synthesized destructors are no longer made virtual just because the class
+ already has virtual functions, only if they override a virtual destructor
+ in a base class. The compiler will warn if this affects your code.
+
+* The g++ driver now only links against libstdc++, not libg++; it is
+ functionally identical to the c++ driver.
+
+* (void *)0 is no longer considered a null pointer constant; NULL in
+ <stddef.h> is now defined as __null, a magic constant of type (void *)
+ normally, or (size_t) with -ansi.
+
+* The name of a class is now implicitly declared in its own scope; A::A
+ refers to A.
+
+* Local classes are now supported.
+
+* __attribute__ can now be attached to types as well as declarations.
* The compiler no longer emits a warning if an ellipsis is used as a
function's argument list.
-* 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.
-
* Definition of nested types outside of their containing class is now
- supported. Use the following source code, as an example.
+ supported. For instance:
struct A {
- struct B;
- B* bp;
+ struct B;
+ B* bp;
};
struct A::B {
- int member;
+ int member;
};
-* Explicit instantiation of template constructors and destructors is now
- supported. Use the following source code, as an example.
-
- template A<int>::A(const A&);
-
* On the HPPA, some classes that do not define a copy constructor
will be passed and returned in memory again so that functions
returning those types can be inlined.
+
+*** The g++ team thanks everyone that contributed to this release,
+ but especially:
+
+* 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
+ 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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