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Commit | Line | Data |
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5bb2f1e7 MM |
1 | *** Changes in GCC 3.0: |
2 | ||
858a0ff1 MM |
3 | * In some obscure cases, functions with the same type could have the |
4 | same mangled name. This bug caused compiler crashes, link-time clashes, | |
5 | and debugger crahses. Fixing this bug required breaking ABI | |
6 | compatibility for the functions involved. The functions in questions | |
7 | are those whose types involve non-type template arguments whose | |
8 | mangled representations require more than one digit. | |
9 | ||
9bfadf57 MM |
10 | * Support for assignment to `this' has been removed. This idiom |
11 | was used in the very early days of C++, before users were allowed | |
12 | to overload `operator new'; it is no longer allowed by the C++ | |
13 | standard. | |
14 | ||
cf7cf3d2 MM |
15 | * Support for signatures, a G++ extension, have been removed. |
16 | ||
5bb2f1e7 MM |
17 | * Certain invalid conversions that were previously accepted will now |
18 | be rejected. For example, assigning function pointers of one type | |
19 | to function pointers of another type now requires a cast, whereas | |
20 | previously g++ would sometimes accept the code even without the | |
21 | cast. | |
22 | ||
23 | * G++ previously allowed `sizeof (X::Y)' where Y was a non-static | |
24 | member of X, even if the `sizeof' expression occurred outside | |
25 | of a non-static member function of X (or one of its derived classes, | |
26 | or a member-initializer for X or one of its derived classes.) This | |
27 | extension has been removed. | |
28 | ||
29 | * G++ no longer allows you to overload the conditional operator (i.e., | |
30 | the `?:' operator.) | |
31 | ||
b1b9b120 | 32 | *** Changes in GCC 2.95: |
2642b9bf JM |
33 | |
34 | * Messages about non-conformant code that we can still handle ("pedwarns") | |
35 | are now errors by default, rather than warnings. This can be reverted | |
36 | with -fpermissive, and is overridden by -pedantic or -pedantic-errors. | |
37 | ||
b1b9b120 JM |
38 | * String constants are now of type `const char[n]', rather than `char[n]'. |
39 | This can be reverted with -fno-const-strings. | |
40 | ||
41 | * References to functions are now supported. | |
42 | ||
43 | * Lookup of class members during class definition now works in all cases. | |
44 | ||
45 | * In overload resolution, type conversion operators are now properly | |
46 | treated as always coming from the most derived class. | |
47 | ||
48 | * C9x-style restricted pointers are supported, using the `__restrict' | |
49 | keyword. | |
50 | ||
51 | * You can now use -fno-implicit-inline-templates to suppress writing out | |
52 | implicit instantiations of inline templates. Normally we do write them | |
53 | out, even with -fno-implicit-templates, so that optimization doesn't | |
54 | affect which instantiations are needed. | |
55 | ||
56 | * -fstrict-prototype now also suppresses implicit declarations. | |
57 | ||
58 | * Many obsolete options have been removed: -fall-virtual, -fmemoize-lookups, | |
59 | -fsave-memoized, +e?, -fenum-int-equivalence, -fno-nonnull-objects. | |
60 | ||
61 | * Unused virtual functions can be discarded on some targets by specifying | |
62 | -ffunction-sections -fvtable-gc to the compiler and --gc-sections to the | |
63 | linker. Unfortunately, this only works on Linux if you're linking | |
64 | statically. | |
65 | ||
66 | * Lots of bugs stomped. | |
67 | ||
1a408d07 | 68 | *** Changes in EGCS 1.1: |
be343556 | 69 | |
d1fec180 JM |
70 | * Namespaces are fully supported. The library has not yet been converted |
71 | to use namespace std, however, and the old std-faking code is still on by | |
72 | default. To turn it off, you can use -fhonor-std. | |
73 | ||
570221c2 JM |
74 | * Massive template improvements: |
75 | + member template classes are supported. | |
76 | + template friends are supported. | |
77 | + template template parameters are supported. | |
78 | + local classes in templates are supported. | |
79 | + lots of bugs fixed. | |
be343556 JM |
80 | |
81 | * operator new now throws bad_alloc where appropriate. | |
82 | ||
d1fec180 JM |
83 | * Exception handling is now thread safe, and supports nested exceptions and |
84 | placement delete. Exception handling overhead on x86 is much lower with | |
85 | GNU as 2.9. | |
570221c2 JM |
86 | |
87 | * protected virtual inheritance is now supported. | |
88 | ||
89 | * Loops are optimized better; we now move the test to the end in most | |
90 | cases, like the C frontend does. | |
91 | ||
92 | * For class D derived from B which has a member 'int i', &D::i is now of | |
93 | type 'int B::*' instead of 'int D::*'. | |
94 | ||
d1fec180 JM |
95 | * An _experimental_ new ABI for g++ can be turned on with -fnew-abi. The |
96 | current features of this are more efficient allocation of base classes | |
97 | (including the empty base optimization), and more compact mangling of C++ | |
98 | symbol names (which can be turned on separately with -fsquangle). This | |
99 | ABI is subject to change without notice, so don't use it for anything | |
100 | that you don't want to rebuild with every release of the compiler. | |
101 | ||
cb99b4a0 JM |
102 | As with all ABI-changing flags, this flag is for experts only, as all |
103 | code (including the library code in libgcc and libstdc++) must be | |
104 | compiled with the same ABI. | |
105 | ||
be343556 | 106 | *** Changes in EGCS 1.0: |
fb52f6de | 107 | |
19754d4c JM |
108 | * A public review copy of the December 1996 Draft of the ISO/ANSI C++ |
109 | standard is now available. See | |
fb52f6de JM |
110 | |
111 | http://www.cygnus.com/misc/wp/ | |
112 | ||
113 | for more information. | |
114 | ||
1e60a96e JM |
115 | * g++ now uses a new implementation of templates. The basic idea is that |
116 | now templates are minimally parsed when seen and then expanded later. | |
117 | This allows conformant early name binding and instantiation controls, | |
118 | since instantiations no longer have to go through the parser. | |
119 | ||
120 | What you get: | |
121 | ||
122 | + Inlining of template functions works without any extra effort or | |
123 | modifications. | |
1e60a96e JM |
124 | + Instantiations of class templates and methods defined in the class |
125 | body are deferred until they are actually needed (unless | |
126 | -fexternal-templates is specified). | |
1e60a96e | 127 | + Nested types in class templates work. |
1e60a96e | 128 | + Static data member templates work. |
1e60a96e | 129 | + Member function templates are now supported. |
1e60a96e | 130 | + Partial specialization of class templates is now supported. |
386b8a85 JM |
131 | + Explicit specification of template parameters to function templates |
132 | is now supported. | |
1e60a96e | 133 | |
405a745b | 134 | Things you may need to fix in your code: |
1e60a96e | 135 | |
405a745b JM |
136 | + Syntax errors in templates that are never instantiated will now be |
137 | diagnosed. | |
1e60a96e JM |
138 | + Types and class templates used in templates must be declared |
139 | first, or the compiler will assume they are not types, and fail. | |
1e60a96e | 140 | + Similarly, nested types of template type parameters must be tagged |
405a745b JM |
141 | with the 'typename' keyword, except in base lists. In many cases, |
142 | but not all, the compiler will tell you where you need to add | |
143 | 'typename'. For more information, see | |
1e60a96e | 144 | |
405a745b | 145 | http://www.cygnus.com/misc/wp/dec96pub/template.html#temp.res |
1e60a96e | 146 | |
386b8a85 JM |
147 | + Guiding declarations are no longer supported. Function declarations, |
148 | including friend declarations, do not refer to template instantiations. | |
149 | You can restore the old behavior with -fguiding-decls until you fix | |
150 | your code. | |
151 | ||
1e60a96e JM |
152 | Other features: |
153 | ||
154 | + Default function arguments in templates will not be evaluated (or | |
155 | checked for semantic validity) unless they are needed. Default | |
156 | arguments in class bodies will not be parsed until the class | |
157 | definition is complete. | |
1e60a96e | 158 | + The -ftemplate-depth-NN flag can be used to increase the maximum |
405a745b JM |
159 | recursive template instantiation depth, which defaults to 17. If you |
160 | need to use this flag, the compiler will tell you. | |
386b8a85 JM |
161 | + Explicit instantiation of template constructors and destructors is |
162 | now supported. For instance: | |
163 | ||
164 | template A<int>::A(const A&); | |
1e60a96e JM |
165 | |
166 | Still not supported: | |
167 | ||
405a745b | 168 | + Member class templates. |
405a745b | 169 | + Template friends. |
1e60a96e JM |
170 | |
171 | * Exception handling support has been significantly improved and is on by | |
19754d4c JM |
172 | default. The compiler supports two mechanisms for walking back up the |
173 | call stack; one relies on static information about how registers are | |
174 | saved, and causes no runtime overhead for code that does not throw | |
175 | exceptions. The other mechanism uses setjmp and longjmp equivalents, and | |
176 | can result in quite a bit of runtime overhead. You can determine which | |
177 | mechanism is the default for your target by compiling a testcase that | |
178 | uses exceptions and doing an 'nm' on the object file; if it uses __throw, | |
179 | it's using the first mechanism. If it uses __sjthrow, it's using the | |
180 | second. | |
181 | ||
182 | You can turn EH support off with -fno-exceptions. | |
1e60a96e | 183 | |
405a745b JM |
184 | * RTTI support has been rewritten to work properly and is now on by default. |
185 | This means code that uses virtual functions will have a modest space | |
186 | overhead. You can use the -fno-rtti flag to disable RTTI support. | |
1e60a96e JM |
187 | |
188 | * On ELF systems, duplicate copies of symbols with 'initialized common' | |
189 | linkage (such as template instantiations, vtables, and extern inlines) | |
190 | will now be discarded by the GNU linker, so you don't need to use -frepo. | |
191 | This support requires GNU ld from binutils 2.8 or later. | |
5c825fc2 | 192 | |
405a745b JM |
193 | * The overload resolution code has been rewritten to conform to the latest |
194 | C++ Working Paper. Built-in operators are now considered as candidates | |
195 | in operator overload resolution. Function template overloading chooses | |
196 | the more specialized template, and handles base classes in type deduction | |
197 | and guiding declarations properly. In this release the old code can | |
198 | still be selected with -fno-ansi-overloading, although this is not | |
199 | supported and will be removed in a future release. | |
200 | ||
201 | * Standard usage syntax for the std namespace is supported; std is treated | |
202 | as an alias for global scope. General namespaces are still not supported. | |
3041f77a | 203 | |
1e60a96e JM |
204 | * New flags: |
205 | ||
19754d4c JM |
206 | + New warning -Wno-pmf-conversion (don't warn about |
207 | converting from a bound member function pointer to function | |
208 | pointer). | |
1e60a96e JM |
209 | |
210 | + A flag -Weffc++ has been added for violations of some of the style | |
211 | guidelines in Scott Meyers' _Effective C++_ books. | |
212 | ||
213 | + -Woverloaded-virtual now warns if a virtual function in a base | |
214 | class is hidden in a derived class, rather than warning about | |
215 | virtual functions being overloaded (even if all of the inherited | |
216 | signatures are overridden) as it did before. | |
217 | ||
218 | + -Wall no longer implies -W. The new warning flag, -Wsign-compare, | |
219 | included in -Wall, warns about dangerous comparisons of signed and | |
220 | unsigned values. Only the flag is new; it was previously part of | |
221 | -W. | |
222 | ||
223 | + The new flag, -fno-weak, disables the use of weak symbols. | |
8eeda2ec | 224 | |
405a745b JM |
225 | * Synthesized methods are now emitted in any translation units that need |
226 | an out-of-line copy. They are no longer affected by #pragma interface | |
227 | or #pragma implementation. | |
228 | ||
229 | * __FUNCTION__ and __PRETTY_FUNCTION__ are now treated as variables by the | |
230 | parser; previously they were treated as string constants. So code like | |
231 | `printf (__FUNCTION__ ": foo")' must be rewritten to | |
232 | `printf ("%s: foo", __FUNCTION__)'. This is necessary for templates. | |
233 | ||
8eeda2ec JM |
234 | * local static variables in extern inline functions will be shared between |
235 | translation units. | |
236 | ||
8eeda2ec | 237 | * -fvtable-thunks is supported for all targets, and is the default for |
1e60a96e | 238 | Linux with glibc 2.x (also called libc 6.x). |
8eeda2ec | 239 | |
fb52f6de JM |
240 | * bool is now always the same size as another built-in type. Previously, |
241 | a 64-bit RISC target using a 32-bit ABI would have 32-bit pointers and a | |
242 | 64-bit bool. This should only affect Irix 6, which was not supported in | |
243 | 2.7.2. | |
244 | ||
245 | * new (nothrow) is now supported. | |
246 | ||
fb52f6de JM |
247 | * Synthesized destructors are no longer made virtual just because the class |
248 | already has virtual functions, only if they override a virtual destructor | |
249 | in a base class. The compiler will warn if this affects your code. | |
250 | ||
8e69329a | 251 | * The g++ driver now only links against libstdc++, not libg++; it is |
fb52f6de JM |
252 | functionally identical to the c++ driver. |
253 | ||
254 | * (void *)0 is no longer considered a null pointer constant; NULL in | |
255 | <stddef.h> is now defined as __null, a magic constant of type (void *) | |
256 | normally, or (size_t) with -ansi. | |
257 | ||
fb52f6de JM |
258 | * The name of a class is now implicitly declared in its own scope; A::A |
259 | refers to A. | |
260 | ||
e1467ff2 | 261 | * Local classes are now supported. |
fb52f6de | 262 | |
fb52f6de JM |
263 | * __attribute__ can now be attached to types as well as declarations. |
264 | ||
fb52f6de JM |
265 | * The compiler no longer emits a warning if an ellipsis is used as a |
266 | function's argument list. | |
267 | ||
fb52f6de | 268 | * Definition of nested types outside of their containing class is now |
405a745b | 269 | supported. For instance: |
fb52f6de JM |
270 | |
271 | struct A { | |
272 | struct B; | |
273 | B* bp; | |
274 | }; | |
275 | ||
276 | struct A::B { | |
277 | int member; | |
278 | }; | |
279 | ||
fb52f6de JM |
280 | * On the HPPA, some classes that do not define a copy constructor |
281 | will be passed and returned in memory again so that functions | |
282 | returning those types can be inlined. | |
386b8a85 JM |
283 | |
284 | *** The g++ team thanks everyone that contributed to this release, | |
285 | but especially: | |
286 | ||
287 | * Joe Buck <jbuck@synopsys.com>, the maintainer of the g++ FAQ. | |
288 | * Brendan Kehoe <brendan@cygnus.com>, who coordinates testing of g++. | |
289 | * Jason Merrill <jason@cygnus.com>, the g++ maintainer. | |
290 | * Mark Mitchell <mmitchell@usa.net>, who implemented member function | |
291 | templates and explicit qualification of function templates. | |
292 | * Mike Stump <mrs@wrs.com>, the previous g++ maintainer, who did most of | |
293 | the exception handling work. |