|
111
|
1 *** Changes in GCC 3.4:
|
|
|
2
|
|
|
3 * Changes in GCC 3.4 are described in 'gcc-3.4/changes.html'
|
|
|
4
|
|
|
5 *** Changes in GCC 3.3:
|
|
|
6
|
|
|
7 * The "new X = 3" extension has been removed; you must now use "new X(3)".
|
|
|
8
|
|
|
9 * G++ no longer allows in-class initializations of static data members
|
|
|
10 that do not have arithmetic or enumeration type. For example:
|
|
|
11
|
|
|
12 struct S {
|
|
|
13 static const char* const p = "abc";
|
|
|
14 };
|
|
|
15
|
|
|
16 is no longer accepted.
|
|
|
17
|
|
|
18 Use the standards-conformant form:
|
|
|
19
|
|
|
20 struct S {
|
|
|
21 static const char* const p;
|
|
|
22 };
|
|
|
23
|
|
|
24 const char* const S::p = "abc";
|
|
|
25
|
|
|
26 instead.
|
|
|
27
|
|
|
28 (ISO C++ is even stricter; it does not allow in-class
|
|
|
29 initializations of floating-point types.)
|
|
|
30
|
|
|
31 *** Changes in GCC 3.1:
|
|
|
32
|
|
|
33 * -fhonor-std and -fno-honor-std have been removed. -fno-honor-std was
|
|
|
34 a workaround to allow std compliant code to work with the non-std
|
|
|
35 compliant libstdc++-v2. libstdc++-v3 is std compliant.
|
|
|
36
|
|
|
37 * The C++ ABI has been fixed so that `void (A::*)() const' is mangled as
|
|
|
38 "M1AKFvvE", rather than "MK1AFvvE" as before. This change only affects
|
|
|
39 pointer to cv-qualified member function types.
|
|
|
40
|
|
|
41 * The C++ ABI has been changed to correctly handle this code:
|
|
|
42
|
|
|
43 struct A {
|
|
|
44 void operator delete[] (void *, size_t);
|
|
|
45 };
|
|
|
46
|
|
|
47 struct B : public A {
|
|
|
48 };
|
|
|
49
|
|
|
50 new B[10];
|
|
|
51
|
|
|
52 The amount of storage allocated for the array will be greater than
|
|
|
53 it was in 3.0, in order to store the number of elements in the
|
|
|
54 array, so that the correct size can be passed to `operator delete[]'
|
|
|
55 when the array is deleted. Previously, the value passed to
|
|
|
56 `operator delete[]' was unpredictable.
|
|
|
57
|
|
|
58 This change will only affect code that declares a two-argument
|
|
|
59 `operator delete[]' with a second parameter of type `size_t'
|
|
|
60 in a base class, and does not override that definition in a
|
|
|
61 derived class.
|
|
|
62
|
|
|
63 * The C++ ABI has been changed so that:
|
|
|
64
|
|
|
65 struct A {
|
|
|
66 void operator delete[] (void *, size_t);
|
|
|
67 void operator delete[] (void *);
|
|
|
68 };
|
|
|
69
|
|
|
70 does not cause unnecessary storage to be allocated when an array of
|
|
|
71 `A' objects is allocated.
|
|
|
72
|
|
|
73 This change will only affect code that declares both of these
|
|
|
74 forms of `operator delete[]', and declared the two-argument form
|
|
|
75 before the one-argument form.
|
|
|
76
|
|
|
77 * The C++ ABI has been changed so that when a parameter is passed by value,
|
|
|
78 any cleanup for that parameter is performed in the caller, as specified
|
|
|
79 by the ia64 C++ ABI, rather than the called function as before. As a
|
|
|
80 result, classes with a non-trivial destructor but a trivial copy
|
|
|
81 constructor will be passed and returned by invisible reference, rather
|
|
|
82 than by bitwise copy as before.
|
|
|
83
|
|
|
84 * G++ now supports the "named return value optimization": for code like
|
|
|
85
|
|
|
86 A f () {
|
|
|
87 A a;
|
|
|
88 ...
|
|
|
89 return a;
|
|
|
90 }
|
|
|
91
|
|
|
92 G++ will allocate 'a' in the return value slot, so that the return
|
|
|
93 becomes a no-op. For this to work, all return statements in the function
|
|
|
94 must return the same variable.
|
|
|
95
|
|
|
96 *** Changes in GCC 3.0:
|
|
|
97
|
|
|
98 * Support for guiding declarations has been removed.
|
|
|
99
|
|
|
100 * G++ now supports importing member functions from base classes with a
|
|
|
101 using-declaration.
|
|
|
102
|
|
|
103 * G++ now enforces access control for nested types.
|
|
|
104
|
|
|
105 * In some obscure cases, functions with the same type could have the
|
|
|
106 same mangled name. This bug caused compiler crashes, link-time clashes,
|
|
|
107 and debugger crashes. Fixing this bug required breaking ABI
|
|
|
108 compatibility for the functions involved. The functions in questions
|
|
|
109 are those whose types involve non-type template arguments whose
|
|
|
110 mangled representations require more than one digit.
|
|
|
111
|
|
|
112 * Support for assignment to `this' has been removed. This idiom
|
|
|
113 was used in the very early days of C++, before users were allowed
|
|
|
114 to overload `operator new'; it is no longer allowed by the C++
|
|
|
115 standard.
|
|
|
116
|
|
|
117 * Support for signatures, a G++ extension, have been removed.
|
|
|
118
|
|
|
119 * Certain invalid conversions that were previously accepted will now
|
|
|
120 be rejected. For example, assigning function pointers of one type
|
|
|
121 to function pointers of another type now requires a cast, whereas
|
|
|
122 previously g++ would sometimes accept the code even without the
|
|
|
123 cast.
|
|
|
124
|
|
|
125 * G++ previously allowed `sizeof (X::Y)' where Y was a non-static
|
|
|
126 member of X, even if the `sizeof' expression occurred outside
|
|
|
127 of a non-static member function of X (or one of its derived classes,
|
|
|
128 or a member-initializer for X or one of its derived classes.) This
|
|
|
129 extension has been removed.
|
|
|
130
|
|
|
131 * G++ no longer allows you to overload the conditional operator (i.e.,
|
|
|
132 the `?:' operator.)
|
|
|
133
|
|
|
134 * The "named return value" extension:
|
|
|
135
|
|
|
136 int f () return r { r = 3; }
|
|
|
137
|
|
|
138 has been deprecated, and will be removed in a future version of G++.
|
|
|
139
|
|
|
140 *** Changes in GCC 2.95:
|
|
|
141
|
|
|
142 * Messages about non-conformant code that we can still handle ("pedwarns")
|
|
|
143 are now errors by default, rather than warnings. This can be reverted
|
|
|
144 with -fpermissive, and is overridden by -pedantic or -pedantic-errors.
|
|
|
145
|
|
|
146 * String constants are now of type `const char[n]', rather than `char[n]'.
|
|
|
147 This can be reverted with -fno-const-strings.
|
|
|
148
|
|
|
149 * References to functions are now supported.
|
|
|
150
|
|
|
151 * Lookup of class members during class definition now works in all cases.
|
|
|
152
|
|
|
153 * In overload resolution, type conversion operators are now properly
|
|
|
154 treated as always coming from the most derived class.
|
|
|
155
|
|
|
156 * C9x-style restricted pointers are supported, using the `__restrict'
|
|
|
157 keyword.
|
|
|
158
|
|
|
159 * You can now use -fno-implicit-inline-templates to suppress writing out
|
|
|
160 implicit instantiations of inline templates. Normally we do write them
|
|
|
161 out, even with -fno-implicit-templates, so that optimization doesn't
|
|
|
162 affect which instantiations are needed.
|
|
|
163
|
|
|
164 * -fstrict-prototype now also suppresses implicit declarations.
|
|
|
165
|
|
|
166 * Many obsolete options have been removed: -fall-virtual, -fmemoize-lookups,
|
|
|
167 -fsave-memoized, +e?, -fenum-int-equivalence, -fno-nonnull-objects.
|
|
|
168
|
|
|
169 * Unused virtual functions can be discarded on some targets by specifying
|
|
|
170 -ffunction-sections -fvtable-gc to the compiler and --gc-sections to the
|
|
|
171 linker. Unfortunately, this only works on GNU/Linux if you're linking
|
|
|
172 statically.
|
|
|
173
|
|
|
174 * Lots of bugs stomped.
|
|
|
175
|
|
|
176 *** Changes in EGCS 1.1:
|
|
|
177
|
|
|
178 * Namespaces are fully supported. The library has not yet been converted
|
|
|
179 to use namespace std, however, and the old std-faking code is still on by
|
|
|
180 default. To turn it off, you can use -fhonor-std.
|
|
|
181
|
|
|
182 * Massive template improvements:
|
|
|
183 + member template classes are supported.
|
|
|
184 + template friends are supported.
|
|
|
185 + template template parameters are supported.
|
|
|
186 + local classes in templates are supported.
|
|
|
187 + lots of bugs fixed.
|
|
|
188
|
|
|
189 * operator new now throws bad_alloc where appropriate.
|
|
|
190
|
|
|
191 * Exception handling is now thread safe, and supports nested exceptions and
|
|
|
192 placement delete. Exception handling overhead on x86 is much lower with
|
|
|
193 GNU as 2.9.
|
|
|
194
|
|
|
195 * protected virtual inheritance is now supported.
|
|
|
196
|
|
|
197 * Loops are optimized better; we now move the test to the end in most
|
|
|
198 cases, like the C frontend does.
|
|
|
199
|
|
|
200 * For class D derived from B which has a member 'int i', &D::i is now of
|
|
|
201 type 'int B::*' instead of 'int D::*'.
|
|
|
202
|
|
|
203 * An _experimental_ new ABI for g++ can be turned on with -fnew-abi. The
|
|
|
204 current features of this are more efficient allocation of base classes
|
|
|
205 (including the empty base optimization), and more compact mangling of C++
|
|
|
206 symbol names (which can be turned on separately with -fsquangle). This
|
|
|
207 ABI is subject to change without notice, so don't use it for anything
|
|
|
208 that you don't want to rebuild with every release of the compiler.
|
|
|
209
|
|
|
210 As with all ABI-changing flags, this flag is for experts only, as all
|
|
|
211 code (including the library code in libgcc and libstdc++) must be
|
|
|
212 compiled with the same ABI.
|
|
|
213
|
|
|
214 *** Changes in EGCS 1.0:
|
|
|
215
|
|
|
216 * A public review copy of the December 1996 Draft of the ISO/ANSI C++
|
|
|
217 standard is now available. See
|
|
|
218
|
|
|
219 http://www.cygnus.com/misc/wp/
|
|
|
220
|
|
|
221 for more information.
|
|
|
222
|
|
|
223 * g++ now uses a new implementation of templates. The basic idea is that
|
|
|
224 now templates are minimally parsed when seen and then expanded later.
|
|
|
225 This allows conformant early name binding and instantiation controls,
|
|
|
226 since instantiations no longer have to go through the parser.
|
|
|
227
|
|
|
228 What you get:
|
|
|
229
|
|
|
230 + Inlining of template functions works without any extra effort or
|
|
|
231 modifications.
|
|
|
232 + Instantiations of class templates and methods defined in the class
|
|
|
233 body are deferred until they are actually needed (unless
|
|
|
234 -fexternal-templates is specified).
|
|
|
235 + Nested types in class templates work.
|
|
|
236 + Static data member templates work.
|
|
|
237 + Member function templates are now supported.
|
|
|
238 + Partial specialization of class templates is now supported.
|
|
|
239 + Explicit specification of template parameters to function templates
|
|
|
240 is now supported.
|
|
|
241
|
|
|
242 Things you may need to fix in your code:
|
|
|
243
|
|
|
244 + Syntax errors in templates that are never instantiated will now be
|
|
|
245 diagnosed.
|
|
|
246 + Types and class templates used in templates must be declared
|
|
|
247 first, or the compiler will assume they are not types, and fail.
|
|
|
248 + Similarly, nested types of template type parameters must be tagged
|
|
|
249 with the 'typename' keyword, except in base lists. In many cases,
|
|
|
250 but not all, the compiler will tell you where you need to add
|
|
|
251 'typename'. For more information, see
|
|
|
252
|
|
|
253 http://www.cygnus.com/misc/wp/dec96pub/template.html#temp.res
|
|
|
254
|
|
|
255 + Guiding declarations are no longer supported. Function declarations,
|
|
|
256 including friend declarations, do not refer to template instantiations.
|
|
|
257 You can restore the old behavior with -fguiding-decls until you fix
|
|
|
258 your code.
|
|
|
259
|
|
|
260 Other features:
|
|
|
261
|
|
|
262 + Default function arguments in templates will not be evaluated (or
|
|
|
263 checked for semantic validity) unless they are needed. Default
|
|
|
264 arguments in class bodies will not be parsed until the class
|
|
|
265 definition is complete.
|
|
|
266 + The -ftemplate-depth-NN flag can be used to increase the maximum
|
|
|
267 recursive template instantiation depth, which defaults to 17. If you
|
|
|
268 need to use this flag, the compiler will tell you.
|
|
|
269 + Explicit instantiation of template constructors and destructors is
|
|
|
270 now supported. For instance:
|
|
|
271
|
|
|
272 template A<int>::A(const A&);
|
|
|
273
|
|
|
274 Still not supported:
|
|
|
275
|
|
|
276 + Member class templates.
|
|
|
277 + Template friends.
|
|
|
278
|
|
|
279 * Exception handling support has been significantly improved and is on by
|
|
|
280 default. The compiler supports two mechanisms for walking back up the
|
|
|
281 call stack; one relies on static information about how registers are
|
|
|
282 saved, and causes no runtime overhead for code that does not throw
|
|
|
283 exceptions. The other mechanism uses setjmp and longjmp equivalents, and
|
|
|
284 can result in quite a bit of runtime overhead. You can determine which
|
|
|
285 mechanism is the default for your target by compiling a testcase that
|
|
|
286 uses exceptions and doing an 'nm' on the object file; if it uses __throw,
|
|
|
287 it's using the first mechanism. If it uses __sjthrow, it's using the
|
|
|
288 second.
|
|
|
289
|
|
|
290 You can turn EH support off with -fno-exceptions.
|
|
|
291
|
|
|
292 * RTTI support has been rewritten to work properly and is now on by default.
|
|
|
293 This means code that uses virtual functions will have a modest space
|
|
|
294 overhead. You can use the -fno-rtti flag to disable RTTI support.
|
|
|
295
|
|
|
296 * On ELF systems, duplicate copies of symbols with 'initialized common'
|
|
|
297 linkage (such as template instantiations, vtables, and extern inlines)
|
|
|
298 will now be discarded by the GNU linker, so you don't need to use -frepo.
|
|
|
299 This support requires GNU ld from binutils 2.8 or later.
|
|
|
300
|
|
|
301 * The overload resolution code has been rewritten to conform to the latest
|
|
|
302 C++ Working Paper. Built-in operators are now considered as candidates
|
|
|
303 in operator overload resolution. Function template overloading chooses
|
|
|
304 the more specialized template, and handles base classes in type deduction
|
|
|
305 and guiding declarations properly. In this release the old code can
|
|
|
306 still be selected with -fno-ansi-overloading, although this is not
|
|
|
307 supported and will be removed in a future release.
|
|
|
308
|
|
|
309 * Standard usage syntax for the std namespace is supported; std is treated
|
|
|
310 as an alias for global scope. General namespaces are still not supported.
|
|
|
311
|
|
|
312 * New flags:
|
|
|
313
|
|
|
314 + New warning -Wno-pmf-conversion (don't warn about
|
|
|
315 converting from a bound member function pointer to function
|
|
|
316 pointer).
|
|
|
317
|
|
|
318 + A flag -Weffc++ has been added for violations of some of the style
|
|
|
319 guidelines in Scott Meyers' _Effective C++_ books.
|
|
|
320
|
|
|
321 + -Woverloaded-virtual now warns if a virtual function in a base
|
|
|
322 class is hidden in a derived class, rather than warning about
|
|
|
323 virtual functions being overloaded (even if all of the inherited
|
|
|
324 signatures are overridden) as it did before.
|
|
|
325
|
|
|
326 + -Wall no longer implies -W. The new warning flag, -Wsign-compare,
|
|
|
327 included in -Wall, warns about dangerous comparisons of signed and
|
|
|
328 unsigned values. Only the flag is new; it was previously part of
|
|
|
329 -W.
|
|
|
330
|
|
|
331 + The new flag, -fno-weak, disables the use of weak symbols.
|
|
|
332
|
|
|
333 * Synthesized methods are now emitted in any translation units that need
|
|
|
334 an out-of-line copy. They are no longer affected by #pragma interface
|
|
|
335 or #pragma implementation.
|
|
|
336
|
|
|
337 * __FUNCTION__ and __PRETTY_FUNCTION__ are now treated as variables by the
|
|
|
338 parser; previously they were treated as string constants. So code like
|
|
|
339 `printf (__FUNCTION__ ": foo")' must be rewritten to
|
|
|
340 `printf ("%s: foo", __FUNCTION__)'. This is necessary for templates.
|
|
|
341
|
|
|
342 * local static variables in extern inline functions will be shared between
|
|
|
343 translation units.
|
|
|
344
|
|
|
345 * -fvtable-thunks is supported for all targets, and is the default for
|
|
|
346 GNU/Linux with glibc 2.x (also called libc 6.x).
|
|
|
347
|
|
|
348 * bool is now always the same size as another built-in type. Previously,
|
|
|
349 a 64-bit RISC target using a 32-bit ABI would have 32-bit pointers and a
|
|
|
350 64-bit bool. This should only affect Irix 6, which was not supported in
|
|
|
351 2.7.2.
|
|
|
352
|
|
|
353 * new (nothrow) is now supported.
|
|
|
354
|
|
|
355 * Synthesized destructors are no longer made virtual just because the class
|
|
|
356 already has virtual functions, only if they override a virtual destructor
|
|
|
357 in a base class. The compiler will warn if this affects your code.
|
|
|
358
|
|
|
359 * The g++ driver now only links against libstdc++, not libg++; it is
|
|
|
360 functionally identical to the c++ driver.
|
|
|
361
|
|
|
362 * (void *)0 is no longer considered a null pointer constant; NULL in
|
|
|
363 <stddef.h> is now defined as __null, a magic constant of type (void *)
|
|
|
364 normally, or (size_t) with -ansi.
|
|
|
365
|
|
|
366 * The name of a class is now implicitly declared in its own scope; A::A
|
|
|
367 refers to A.
|
|
|
368
|
|
|
369 * Local classes are now supported.
|
|
|
370
|
|
|
371 * __attribute__ can now be attached to types as well as declarations.
|
|
|
372
|
|
|
373 * The compiler no longer emits a warning if an ellipsis is used as a
|
|
|
374 function's argument list.
|
|
|
375
|
|
|
376 * Definition of nested types outside of their containing class is now
|
|
|
377 supported. For instance:
|
|
|
378
|
|
|
379 struct A {
|
|
|
380 struct B;
|
|
|
381 B* bp;
|
|
|
382 };
|
|
|
383
|
|
|
384 struct A::B {
|
|
|
385 int member;
|
|
|
386 };
|
|
|
387
|
|
|
388 * On the HPPA, some classes that do not define a copy constructor
|
|
|
389 will be passed and returned in memory again so that functions
|
|
|
390 returning those types can be inlined.
|
|
|
391
|
|
|
392 *** The g++ team thanks everyone that contributed to this release,
|
|
|
393 but especially:
|
|
|
394
|
|
|
395 * Joe Buck <jbuck@synopsys.com>, the maintainer of the g++ FAQ.
|
|
|
396 * Brendan Kehoe <brendan@cygnus.com>, who coordinates testing of g++.
|
|
|
397 * Jason Merrill <jason@cygnus.com>, the g++ maintainer.
|
|
|
398 * Mark Mitchell <mmitchell@usa.net>, who implemented member function
|
|
|
399 templates and explicit qualification of function templates.
|
|
|
400 * Mike Stump <mrs@wrs.com>, the previous g++ maintainer, who did most of
|
|
|
401 the exception handling work.
|
|
|
402
|
|
|
403
|
|
131
|
404 Copyright (C) 1997-2018 Free Software Foundation, Inc.
|
|
111
|
405
|
|
|
406 Copying and distribution of this file, with or without modification,
|
|
|
407 are permitted in any medium without royalty provided the copyright
|
|
|
408 notice and this notice are preserved.
|
