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doc: remove IRIX from manual
* doc/autoconf.texi: Remove references to IRIX, except for the obsolete macro AC_IRIX_SUN. IRIX has not been supported by its vendor since 2013, and is no longer a documented Autoconf target.
This commit is contained in:
Paul Eggert
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f73d74d453
@ -4822,62 +4822,6 @@ declared, due to C++ problems of some sort or another. For this reason
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we suggest that test programs not invoke @code{exit}, but return from
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@code{main} instead.
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@item @code{isinf}
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@itemx @code{isnan}
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@c @fuindex isinf
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@c @fuindex isnan
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@prindex @code{isinf}
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@prindex @code{isnan}
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In C99 and later, @code{isinf} and @code{isnan} are
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macros. On some systems just macros are available
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(e.g., HP-UX and Solaris 10), on
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some systems both macros and functions (e.g., glibc 2.3.2), and on some
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systems only functions (e.g., IRIX 6). In some cases
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these functions are declared in nonstandard headers like
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@code{<sunmath.h>} and defined in non-default libraries like
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@option{-lm} or @option{-lsunmath}.
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In C99 and later, @code{isinf} and @code{isnan} macros work correctly with
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@code{long double} arguments, but pre-C99 systems that use functions
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typically assume @code{double} arguments. On such a system,
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@code{isinf} incorrectly returns true for a finite @code{long double}
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argument that is outside the range of @code{double}.
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The best workaround for these issues is to use Gnulib modules
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@code{isinf} and @code{isnan} (@pxref{Gnulib}). But a lighter weight
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solution involves code like the following.
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@smallexample
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#include <math.h>
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#ifndef isnan
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# define isnan(x) \
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(sizeof (x) == sizeof (long double) ? isnan_ld (x) \
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: sizeof (x) == sizeof (double) ? isnan_d (x) \
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: isnan_f (x))
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static int isnan_f (float x) @{ return x != x; @}
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static int isnan_d (double x) @{ return x != x; @}
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static int isnan_ld (long double x) @{ return x != x; @}
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#endif
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#ifndef isinf
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# define isinf(x) \
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(sizeof (x) == sizeof (long double) ? isinf_ld (x) \
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: sizeof (x) == sizeof (double) ? isinf_d (x) \
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: isinf_f (x))
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static int isinf_f (float x)
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@{ return !isnan (x) && isnan (x - x); @}
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static int isinf_d (double x)
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@{ return !isnan (x) && isnan (x - x); @}
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static int isinf_ld (long double x)
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@{ return !isnan (x) && isnan (x - x); @}
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#endif
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@end smallexample
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Some optimizing compilers mishandle these definitions, but systems with that bug
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typically have many other floating point corner-case compliance problems
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anyway, so it's probably not worth worrying about.
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@item @code{malloc}
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@c @fuindex malloc
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@prindex @code{malloc}
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@ -4934,9 +4878,15 @@ available, rather than @code{signal}.
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In C99 and later, if the output array isn't big enough
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and if no other errors occur, @code{snprintf} and @code{vsnprintf}
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truncate the output and return the number of bytes that ought to have
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been produced. Some ancient systems returned the truncated length (e.g.,
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GNU C Library 2.0.x or IRIX 6.5), and some a negative value
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(e.g., earlier GNU C Library versions).
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been produced. Some older systems, notably Microsoft Windows before
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Visual Studio 2015 and Windows 10, do not null-terminate the output
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and return @minus{}1 instead.
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Portable code can check the return value of @code{snprintf (buf, sizeof
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buf, ...)}: if the value is negative or is not less than @code{sizeof
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buf}, an error occurred and the contents of @code{buf} can be ignored.
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Alternatively, one of the Gnulib modules related to @code{snprintf} can
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be used. @xref{Gnulib}.
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@item @code{strerror_r}
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@c @fuindex strerror_r
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@ -5335,8 +5285,7 @@ use Gnulib's @code{getloadavg} module. @xref{Gnulib}.
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@prindex @code{getmntent}
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@caindex search_getmntent
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Check for @code{getmntent} in the standard C library, and then in the
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@file{sun}, @file{seq}, and @file{gen} libraries, for UNICOS,
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IRIX 4, PTX, and UnixWare, respectively. Then, if
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@file{sun}, @file{seq}, and @file{gen} libraries. Then, if
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@code{getmntent} is available, define @code{HAVE_GETMNTENT} and set
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@code{ac_cv_func_getmntent} to @code{yes}. Otherwise set
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@code{ac_cv_func_getmntent} to @code{no}.
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@ -7365,15 +7314,6 @@ This can cause problems if you observe the output of the compiler to
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detect failures. Invoking @samp{cc -c a.c && cc -c b.c && cc -o c a.o
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b.o} solves the issue.
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@item Don't rely on @code{#error} failing
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The IRIX C compiler does not fail when #error is preprocessed; it
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simply emits a diagnostic and continues, exiting successfully. So,
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instead of an error directive like @code{#error "Unsupported word size"}
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it is more portable to use an invalid directive like @code{#Unsupported
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word size} in Autoconf tests. In ordinary source code, @code{#error} is
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OK, since installers with inadequate compilers like IRIX can simply
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examine these compilers' diagnostic output.
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@item Don't rely on correct @code{#line} support
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On Solaris, @command{c89} (at least through Oracle Developer Studio 12.6)
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diagnoses @code{#line} directives whose line
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@ -8804,9 +8744,6 @@ therefore, when using this macro in concert with
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@code{AC_CONFIG_HEADERS}, make sure that @file{config.h} is included
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before any system headers.
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On obsolete IRIX systems, also change the output variable @code{CC} to
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add compiler options needed for wide @code{off_t}.
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Large-file support can be disabled by configuring with the
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@option{--disable-largefile} option, and year-2038 support can
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be enabled and disabled via the @option{--enable-year2038} and
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@ -17444,9 +17381,7 @@ points to the wrong directory. Use @samp{`pwd`} rather than
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@item RANDOM
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@evindex RANDOM
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Many shells provide @code{RANDOM}, a variable that returns a different
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integer each time it is used. Most of the time, its value does not
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change when it is not used, but on IRIX 6.5 the value changes all
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the time. This can be observed by using @command{set}. It is common
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integer each time it is used. It is common
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practice to use @code{$RANDOM} as part of a file name, but code
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shouldn't rely on @code{$RANDOM} expanding to a nonempty string.
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@ -17525,8 +17460,7 @@ uses the prefix @samp{as_fn_} for its functions.
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Handling of positional parameters and shell options varies among shells.
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For example, Korn shells reset and restore trace output (@samp{set -x})
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and other options upon function entry and exit. Inside a function,
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IRIX sh sets @samp{$0} to the function name.
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and other options upon function entry and exit.
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It is not portable to pass temporary environment variables to shell
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functions. Solaris 10 @command{/bin/sh} does not see the variable.
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@ -18081,9 +18015,7 @@ of the environment variables. Conversely, each environment variable
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received by the shell when it is launched should be imported as a shell
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variable marked as exported.
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Alas, many shells, such as Solaris 10 @command{/bin/sh},
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IRIX 6.3, IRIX 5.2,
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AIX 4.1.5, and Digital Unix 4.0, forget to
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Alas, some older shells, such as Solaris 10 @command{/bin/sh}, forget to
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@command{export} the environment variables they receive. As a result,
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two variables coexist: the environment variable and the shell
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variable. The following code demonstrates this failure:
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@ -19015,7 +18947,7 @@ The original version of Awk had a limit of at most 99 bytes per
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per run of non-special characters in a @code{printf} format, but these
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bugs have been fixed on all practical hosts that we know of.
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HP-UX 11.00 and IRIX 6.5 Awk require that input files have a line length
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HP-UX 11.00 Awk requires that input files have a line length
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of at most 3070 bytes.
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@item @command{basename}
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@ -19426,9 +19358,8 @@ Posix allows either behavior.
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@prindex @command{grep}
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Portable scripts can rely on the @command{grep} options @option{-c},
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@option{-l}, @option{-n}, and @option{-v}, but should avoid other
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options. For example, don't use @option{-w}, as Posix does not require
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it and Irix 6.5.16m's @command{grep} does not support it. Also,
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portable scripts should not combine @option{-c} with @option{-l},
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options. For example, don't use @option{-w}, as Posix does not require it.
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Also, portable scripts should not combine @option{-c} with @option{-l},
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as Posix does not allow this.
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Some of the options required by Posix are not portable in practice.
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@ -19450,11 +19381,8 @@ Some traditional @command{grep} implementations do not work on long
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input lines. On AIX the default @code{grep} silently truncates long
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lines on the input before matching.
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Also, traditional implementations do not support multiple regexps
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with @option{-e}: they either reject @option{-e} entirely (e.g., Solaris 10)
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or honor only the last pattern (e.g., IRIX 6.5 and NeXT). To
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work around these problems, invoke @code{AC_PROG_GREP} and then use
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@code{$GREP}.
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Also, Solaris 10 @command{grep} does not support @option{-e}.
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To work around this, invoke @code{AC_PROG_GREP} and then use @code{$GREP}.
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Another possible workaround for the multiple @option{-e} problem is to
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separate the patterns by newlines, for example:
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@ -19573,8 +19501,8 @@ through @code{uniq}.
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Combining the @option{-m} and @option{-p} options, as in @samp{mkdir -m
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go-w -p @var{dir}}, often leads to trouble. FreeBSD
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@command{mkdir} incorrectly attempts to change the permissions of
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@var{dir} even if it already exists. HP-UX 11.23 and
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IRIX 6.5 @command{mkdir} often assign the wrong permissions to
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@var{dir} even if it already exists. HP-UX 11.23
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@command{mkdir} often assigns the wrong permissions to
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any newly-created parents of @var{dir}.
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Posix does not clearly specify whether @samp{mkdir -p foo}
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@ -19981,68 +19909,17 @@ busybox yes yes error
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@item @command{sed} (@samp{t})
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@c ---------------------------
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@prindex @command{sed} (@samp{t})
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Some old systems have @command{sed} that ``forget'' to reset their
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@samp{t} flag when starting a new cycle. For instance on MIPS
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RISC/OS, and on IRIX 5.3, if you run the following @command{sed}
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script (the line numbers are not actual part of the texts):
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@example
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s/keep me/kept/g # a
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t end # b
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s/.*/deleted/g # c
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:end # d
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@end example
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@noindent
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on
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@example
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delete me # 1
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delete me # 2
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keep me # 3
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delete me # 4
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@end example
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@noindent
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you get
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@example
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deleted
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delete me
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kept
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deleted
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@end example
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@noindent
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instead of
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@example
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deleted
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deleted
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kept
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deleted
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@end example
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Why? When processing line 1, (c) matches, therefore sets the @samp{t}
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flag, and the output is produced. When processing
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line 2, the @samp{t} flag is still set (this is the bug). Command (a)
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fails to match, but @command{sed} is not supposed to clear the @samp{t}
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flag when a substitution fails. Command (b) sees that the flag is set,
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therefore it clears it, and jumps to (d), hence you get @samp{delete me}
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instead of @samp{deleted}. When processing line (3), @samp{t} is clear,
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(a) matches, so the flag is set, hence (b) clears the flags and jumps.
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Finally, since the flag is clear, line 4 is processed properly.
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There are two things one should remember about @samp{t} in @command{sed}.
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Firstly, always remember that @samp{t} jumps if @emph{some} substitution
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First, @samp{t} jumps if @emph{some} substitution
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succeeded, not only the immediately preceding substitution. Therefore,
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always use a fake @samp{t clear} followed by a @samp{:clear} on the next
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line, to reset the @samp{t} flag where needed.
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Secondly, you cannot rely on @command{sed} to clear the flag at each new
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cycle.
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Second, do not rely on @command{sed} to clear the flag at each new cycle.
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One portable implementation of the script above is:
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For example, the following script replaces all instances of ``keep me''
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with ``kept'', and replaces the contents of all lines that did not
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contain ``keep me'' with ``deleted''.
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@example
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t clear
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