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Diffstat (limited to 'gcc/doc/trouble.texi')
| -rw-r--r-- | gcc/doc/trouble.texi | 57 |
1 files changed, 17 insertions, 40 deletions
diff --git a/gcc/doc/trouble.texi b/gcc/doc/trouble.texi index 09026fe57f0..7cc7e8a53c9 100644 --- a/gcc/doc/trouble.texi +++ b/gcc/doc/trouble.texi @@ -443,8 +443,7 @@ Parse errors may occur compiling X11 on a Decstation running Ultrix 4.2 because of problems in DEC's versions of the X11 header files @file{X11/Xlib.h} and @file{X11/Xutil.h}. People recommend adding @option{-I/usr/include/mit} to use the MIT versions of the header files, -using the @option{-traditional} switch to turn off ISO C, or fixing the -header files by adding this: +or fixing the header files by adding this: @example #ifdef __STDC__ @@ -484,9 +483,7 @@ MALLOC=gmalloc.o @opindex traditional There are several noteworthy incompatibilities between GNU C and K&R -(non-ISO) versions of C@. The @option{-traditional} option -eliminates many of these incompatibilities, @emph{but not all}, by -telling GCC to behave like a K&R C compiler. +(non-ISO) versions of C@. @itemize @bullet @cindex string constants @@ -516,7 +513,6 @@ The best solution to these problems is to change the program to use purposes instead of string constants. But if this is not possible, you can use the @option{-fwritable-strings} flag, which directs GCC to handle string constants the same way most C compilers do. -@option{-traditional} also has this effect, among others. @item @code{-2147483648} is positive. @@ -536,9 +532,6 @@ string constants. For example, the following macro in GCC @noindent will produce output @code{"a"} regardless of what the argument @var{a} is. -The @option{-traditional} option directs GCC to handle such cases -(among others) in the old-fashioned (non-ISO) fashion. - @cindex @code{setjmp} incompatibilities @cindex @code{longjmp} incompatibilities @item @@ -573,11 +566,6 @@ in it. If you use the @option{-W} option with the @option{-O} option, you will get a warning when GCC thinks such a problem might be possible. -The @option{-traditional} option directs GCC to put variables in -the stack by default, rather than in registers, in functions that -call @code{setjmp}. This results in the behavior found in -traditional C compilers. - @item Programs that use preprocessing directives in the middle of macro arguments do not work with GCC@. For example, a program like this @@ -591,9 +579,7 @@ foobar ( @end group @end example -ISO C does not permit such a construct. It would make sense to support -it when @option{-traditional} is used, but it is too much work to -implement. +ISO C does not permit such a construct. @item K&R compilers allow comments to cross over an inclusion boundary @@ -611,9 +597,6 @@ have the same scope as any other declaration in the same place. In some other C compilers, a @code{extern} declaration affects all the rest of the file even if it happens within a block. -The @option{-traditional} option directs GCC to treat all @code{extern} -declarations as global, like traditional compilers. - @item In traditional C, you can combine @code{long}, etc., with a typedef name, as shown here: @@ -624,18 +607,15 @@ typedef long foo bar; @end example In ISO C, this is not allowed: @code{long} and other type modifiers -require an explicit @code{int}. Because this criterion is expressed -by Bison grammar rules rather than C code, the @option{-traditional} -flag cannot alter it. +require an explicit @code{int}. @cindex typedef names as function parameters @item -PCC allows typedef names to be used as function parameters. The -difficulty described immediately above applies here too. +PCC allows typedef names to be used as function parameters. @item -When in @option{-traditional} mode, GCC allows the following erroneous -pair of declarations to appear together in a given scope: +Traditional C allows the following erroneous pair of declarations to +appear together in a given scope: @example typedef int foo; @@ -643,19 +623,18 @@ typedef foo foo; @end example @item -GCC treats all characters of identifiers as significant, even when in -@option{-traditional} mode. According to K&R-1 (2.2), ``No more than the -first eight characters are significant, although more may be used.''. -Also according to K&R-1 (2.2), ``An identifier is a sequence of letters -and digits; the first character must be a letter. The underscore _ -counts as a letter.'', but GCC also allows dollar signs in identifiers. +GCC treats all characters of identifiers as significant. According to +K&R-1 (2.2), ``No more than the first eight characters are significant, +although more may be used.''. Also according to K&R-1 (2.2), ``An +identifier is a sequence of letters and digits; the first character must +be a letter. The underscore _ counts as a letter.'', but GCC also +allows dollar signs in identifiers. @cindex whitespace @item PCC allows whitespace in the middle of compound assignment operators such as @samp{+=}. GCC, following the ISO standard, does not -allow this. The difficulty described immediately above applies here -too. +allow this. @cindex apostrophes @cindex ' @@ -673,8 +652,7 @@ You can't expect this to work. @end example The best solution to such a problem is to put the text into an actual -C comment delimited by @samp{/*@dots{}*/}. However, -@option{-traditional} suppresses these error messages. +C comment delimited by @samp{/*@dots{}*/}. @item Many user programs contain the declaration @samp{long time ();}. In the @@ -1296,12 +1274,11 @@ they write programs which have the same meaning in both C dialects.) @item @opindex ansi -@opindex traditional @opindex std Undefining @code{__STDC__} when @option{-ansi} is not used. -Currently, GCC defines @code{__STDC__} as long as you don't use -@option{-traditional}. This provides good results in practice. +Currently, GCC defines @code{__STDC__} unconditionally. This provides +good results in practice. Programmers normally use conditionals on @code{__STDC__} to ask whether it is safe to use certain features of ISO C, such as function |