-*** 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/
+ Inlining of template functions works without any extra effort or
modifications.
-
+ Instantiations of class templates and methods defined in the class
body are deferred until they are actually needed (unless
-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.
- + The new 'template <>' specialization syntax is now accepted and
- ignored.
-
- + Explicit instantiation of template constructors and destructors is
- now supported. Use the following source code, as an example.
-
- template A<int>::A(const A&);
-
- Possible problems (caused by complying with the ANSI/ISO draft):
+ 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'.
+ 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
- + Syntax errors in templates that are never instantiated will now be
- diagnosed.
+ 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:
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, defaulting to 17. If you need
- to use this flag, the compiler will tell you.
+ 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:
- + Template template parameters.
+ + Member class templates.
+ + 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.
-* 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.
+* 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.
-* __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.
+* 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 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.
+* 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.
+
+* __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.
+
* local static variables in extern inline functions will be shared between
translation units.
-* Standard usage syntax for the std namespace is supported; std is treated
- as an alias for global scope. General namespaces are still not supported.
-
-* -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).
-* 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.
-
-* 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.
-
* 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
* new (nothrow) is now supported.
-* 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.
-
* 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.
function's argument list.
* 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;
};
* 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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