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Diffstat (limited to 'gcc/doc/trouble.texi')
| -rw-r--r-- | gcc/doc/trouble.texi | 82 |
1 files changed, 41 insertions, 41 deletions
diff --git a/gcc/doc/trouble.texi b/gcc/doc/trouble.texi index 02fe03b96f5..524944c53e7 100644 --- a/gcc/doc/trouble.texi +++ b/gcc/doc/trouble.texi @@ -1,5 +1,5 @@ @c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, -@c 1999, 2000, 2001, 2003 Free Software Foundation, Inc. +@c 1999, 2000, 2001, 2003, 2004 Free Software Foundation, Inc. @c This is part of the GCC manual. @c For copying conditions, see the file gcc.texi. @@ -374,11 +374,11 @@ because of problems in DEC's versions of the X11 header files @option{-I/usr/include/mit} to use the MIT versions of the header files, or fixing the header files by adding this: -@example +@smallexample #ifdef __STDC__ #define NeedFunctionPrototypes 0 #endif -@end example +@end smallexample @item On various 386 Unix systems derived from System V, including SCO, ISC, @@ -393,17 +393,17 @@ is available as a separate package, and also in the file If you have installed GNU malloc as a separate library package, use this option when you relink GCC: -@example +@smallexample MALLOC=/usr/local/lib/libgmalloc.a -@end example +@end smallexample Alternatively, if you have compiled @file{gmalloc.c} from Emacs 19, copy the object file to @file{gmalloc.o} and use this option when you relink GCC: -@example +@smallexample MALLOC=gmalloc.o -@end example +@end smallexample @end itemize @node Incompatibilities @@ -454,9 +454,9 @@ Negating this value yields 2147483648 again. GCC does not substitute macro arguments when they appear inside of string constants. For example, the following macro in GCC -@example +@smallexample #define foo(a) "a" -@end example +@end smallexample @noindent will produce output @code{"a"} regardless of what the argument @var{a} is. @@ -469,7 +469,7 @@ variables guaranteed to remain valid are those declared @code{volatile}. This is a consequence of automatic register allocation. Consider this function: -@example +@smallexample jmp_buf j; foo () @@ -484,7 +484,7 @@ foo () /* @r{@code{longjmp (j)} may occur in @code{fun3}.} */ return a + fun3 (); @} -@end example +@end smallexample Here @code{a} may or may not be restored to its first value when the @code{longjmp} occurs. If @code{a} is allocated in a register, then @@ -500,13 +500,13 @@ Programs that use preprocessing directives in the middle of macro arguments do not work with GCC@. For example, a program like this will not work: -@example +@smallexample @group foobar ( #define luser hack) @end group -@end example +@end smallexample ISO C does not permit such a construct. @@ -530,10 +530,10 @@ rest of the file even if it happens within a block. In traditional C, you can combine @code{long}, etc., with a typedef name, as shown here: -@example +@smallexample typedef int foo; typedef long foo bar; -@end example +@end smallexample In ISO C, this is not allowed: @code{long} and other type modifiers require an explicit @code{int}. @@ -546,10 +546,10 @@ PCC allows typedef names to be used as function parameters. Traditional C allows the following erroneous pair of declarations to appear together in a given scope: -@example +@smallexample typedef int foo; typedef foo foo; -@end example +@end smallexample @item GCC treats all characters of identifiers as significant. According to @@ -574,11 +574,11 @@ comments enclosed in conditionals that are guaranteed to fail; if these comments contain apostrophes, GCC will probably report an error. For example, this code would produce an error: -@example +@smallexample #if 0 You can't expect this to work. #endif -@end example +@end smallexample The best solution to such a problem is to put the text into an actual C comment delimited by @samp{/*@dots{}*/}. @@ -758,14 +758,14 @@ executable and your source code, when you use optimization. Users often think it is a bug when GCC reports an error for code like this: -@example +@smallexample int foo (struct mumble *); struct mumble @{ @dots{} @}; int foo (struct mumble *x) @{ @dots{} @} -@end example +@end smallexample This code really is erroneous, because the scope of @code{struct mumble} in the prototype is limited to the argument list containing it. @@ -866,14 +866,14 @@ give rise to questions of this sort. When a class has static data members, it is not enough to @emph{declare} the static member; you must also @emph{define} it. For example: -@example +@smallexample class Foo @{ @dots{} void method(); static int bar; @}; -@end example +@end smallexample This declaration only establishes that the class @code{Foo} has an @code{int} named @code{Foo::bar}, and a member function named @@ -882,9 +882,9 @@ This declaration only establishes that the class @code{Foo} has an standard, you must supply an initializer in one (and only one) source file, such as: -@example +@smallexample int Foo::bar = 0; -@end example +@end smallexample Other C++ compilers may not correctly implement the standard behavior. As a result, when you switch to @command{g++} from one of these compilers, @@ -908,7 +908,7 @@ template parameters. This shorter term will also be used in the rest of this section.} Only names that are dependent are looked up at the point of instantiation. For example, consider -@example +@smallexample void foo(double); struct A @{ @@ -923,7 +923,7 @@ of instantiation. For example, consider static const int N; @}; -@end example +@end smallexample Here, the names @code{foo} and @code{N} appear in a context that does not depend on the type of @code{T}. The compiler will thus require that @@ -947,7 +947,7 @@ since version 3.4. Two-stage name lookup sometimes leads to situations with behavior different from non-template codes. The most common is probably this: -@example +@smallexample template <typename T> struct Base @{ int i; @}; @@ -955,7 +955,7 @@ different from non-template codes. The most common is probably this: template <typename T> struct Derived : public Base<T> @{ int get_i() @{ return i; @} @}; -@end example +@end smallexample In @code{get_i()}, @code{i} is not used in a dependent context, so the compiler will look for a name declared at the enclosing namespace scope @@ -976,7 +976,7 @@ into scope by a @code{using}-declaration. Another, similar example involves calling member functions of a base class: -@example +@smallexample template <typename T> struct Base @{ int f(); @}; @@ -984,7 +984,7 @@ class: template <typename T> struct Derived : Base<T> @{ int g() @{ return f(); @}; @}; -@end example +@end smallexample Again, the call to @code{f()} is not dependent on template arguments (there are no arguments that depend on the type @code{T}, and it is also @@ -993,13 +993,13 @@ Thus a global declaration of such a function must be available, since the one in the base class is not visible until instantiation time. The compiler will consequently produce the following error message: -@example +@smallexample x.cc: In member function `int Derived<T>::g()': x.cc:6: error: there are no arguments to `f' that depend on a template parameter, so a declaration of `f' must be available x.cc:6: error: (if you use `-fpermissive', G++ will accept your code, but allowing the use of an undeclared name is deprecated) -@end example +@end smallexample To make the code valid either use @code{this->f()}, or @code{Base<T>::f()}. Using the @code{-fpermissive} flag will also let @@ -1035,7 +1035,7 @@ For example, a program may use a function @code{strfunc} that returns @code{string} objects, and another function @code{charfunc} that operates on pointers to @code{char}: -@example +@smallexample string strfunc (); void charfunc (const char *); @@ -1048,7 +1048,7 @@ f () @dots{} charfunc (p); @} -@end example +@end smallexample @noindent In this situation, it may seem reasonable to save a pointer to the C @@ -1067,10 +1067,10 @@ The safe way to write such code is to give the temporary a name, which forces it to remain until the end of the scope of the name. For example: -@example +@smallexample string& tmp = strfunc (); charfunc (tmp.c_str ()); -@end example +@end smallexample @node Copy Assignment @subsection Implicit Copy-Assignment for Virtual Bases @@ -1080,7 +1080,7 @@ belongs to each full object. Also, the constructors and destructors are invoked only once, and called from the most-derived class. However, such objects behave unspecified when being assigned. For example: -@example +@smallexample struct Base@{ char *name; Base(char *n) : name(strdup(n))@{@} @@ -1108,7 +1108,7 @@ void func(Derived &d1, Derived &d2) @{ d1 = d2; @} -@end example +@end smallexample The C++ standard specifies that @samp{Base::Base} is only called once when constructing or copy-constructing a Derived object. It is @@ -1404,12 +1404,12 @@ It is never safe to depend on the order of evaluation of side effects. For example, a function call like this may very well behave differently from one compiler to another: -@example +@smallexample void func (int, int); int i = 2; func (i++, i++); -@end example +@end smallexample There is no guarantee (in either the C or the C++ standard language definitions) that the increments will be evaluated in any particular |
