news.texi

gcc-2.95.3 Linux下最常用的C编译器

@c Copyright (C) 1995-1999 Free Software Foundation, Inc.
@c This is part of the G77 manual.
@c For copying conditions, see the file g77.texi.

@c The text of this file appears in the file NEWS
@c in the G77 distribution, as well as in the G77 manual.

@c Keep this the same as the dates above, since it's used
@c in the standalone derivations of this file (e.g. NEWS).
@set copyrights-news 1995-1999

@set last-update-news 1999-07-08

@include root.texi

@ifset DOC-NEWS
@c The immediately following lines apply to the NEWS file
@c which is derived from this file.
@emph{Note:} This file is automatically generated from the files
@file{news0.texi} and @file{news.texi}.
@file{NEWS} is @emph{not} a source file,
although it is normally included within source distributions.

This file lists news about the @value{which-g77} version
(and some other versions) of the GNU Fortran compiler.
Copyright (C) @value{copyrights-news} Free Software Foundation, Inc.
You may copy, distribute, and modify it freely as long as you preserve
this copyright notice and permission notice.

@node Top,,, (dir)
@chapter News About GNU Fortran
@end ifset

@ifset DOC-G77
@ifset USERVISONLY
@node Changes
@chapter User-visible Changes
@cindex versions, recent
@cindex recent versions
@cindex changes, user-visible
@cindex user-visible changes

This chapter describes changes to @code{g77} that are visible
to the programmers who actually write and maintain Fortran
code they compile with @code{g77}.
Information on changes to installation procedures,
changes to the documentation, and bug fixes is
not provided here, unless it is likely to affect how
users use @code{g77}.
@xref{News,,News About GNU Fortran}, for information on
such changes to @code{g77}.
@end ifset

@ifclear USERVISONLY
@node News
@chapter News About GNU Fortran
@cindex versions, recent
@cindex recent versions
@end ifclear
@end ifset

@ifclear USERVISONLY
Changes made to recent versions of GNU Fortran are listed
below, with the most recent version first.

The changes are generally listed in order:

@enumerate
@item
Code-generation and run-time-library bug-fixes

@item
Compiler and run-time-library crashes involving valid code
that have been fixed

@item
New features

@item
Fixes and enhancements to existing features

@item
New diagnostics

@item
Internal improvements

@item
Miscellany
@end enumerate

This order is not strict---for example, some items
involve a combination of these elements.
@end ifclear

Note that two variants of @code{g77} are tracked below.
The @code{egcs} variant is described vis-a-vis
previous versions of @code{egcs} and/or
an official FSF version,
as appropriate.

Therefore, @code{egcs} versions sometimes have multiple listings
to help clarify how they differ from other versions,
though this can make getting a complete picture
of what a particular @code{egcs} version contains
somewhat more difficult.

@ifset DOC-G77
For information on bugs in the @value{which-g77} version of @code{g77},
see @ref{Known Bugs,,Known Bugs In GNU Fortran}.
@end ifset

@ifset DOC-BUGS
For information on bugs in the @value{which-g77} version of @code{g77},
see @file{@value{path-g77}/BUGS}.
@end ifset

@ifset DEVELOPMENT
@emph{Warning:} The information below is still under development,
and might not accurately reflect the @code{g77} code base
of which it is a part.
Efforts are made to keep it somewhat up-to-date,
but they are particularly concentrated
on any version of this information
that is distributed as part of a @emph{released} @code{g77}.

In particular, while this information is intended to apply to
the @value{which-g77} version of @code{g77},
only an official @emph{release} of that version
is expected to contain documentation that is
most consistent with the @code{g77} product in that version.

Nevertheless, information on @emph{previous} releases of @code{g77}, below,
is likely to be more up-to-date and accurate
than the equivalent information that accompanied
those releases,
assuming the last-updated date of the information below
is later than the dates of those releases.

That's due to attempts to keep this development version
of news about previous @code{g77} versions up-to-date.
@end ifset

@ifclear USERVISONLY
An online, ``live'' version of this document
(derived directly from the mainline, development version
of @code{g77} within @code{egcs})
is available at
@uref{http://www.gnu.org/software/gcc/onlinedocs/g77_news.html}.
@end ifclear

The following information was last updated on @value{last-update-news}:

@heading In 0.5.25, @code{GCC} 2.95 (@code{EGCS} 1.2) versus @code{EGCS} 1.1.2:
@itemize @bullet
@ifclear USERVISONLY
@item
@code{g77} no longer generates bad code for assignments,
or other conversions,
of @code{REAL} or @code{COMPLEX} constant expressions
to type @code{INTEGER(KIND=2)}
(often referred to as @code{INTEGER*8}).

For example, @samp{INTEGER*8 J; J = 4E10} now works as documented.
@end ifclear

@ifclear USERVISONLY
@item
@code{g77} no longer truncates @code{INTEGER(KIND=2)}
(usually @code{INTEGER*8})
subscript expressions when evaluating array references
on systems with pointers widers than @code{INTEGER(KIND=1)}
(such as Alphas).
@end ifclear

@ifclear USERVISONLY
@item
@code{g77} no longer generates bad code
for an assignment to a @code{COMPLEX} variable or array
that partially overlaps one or more of the sources
of the same assignment
(a very rare construction).
It now assigns through a temporary,
in cases where such partial overlap is deemed possible.
@end ifclear

@ifclear USERVISONLY
@item
@code{libg2c} (@code{libf2c}) no longer loses track
of the file being worked on
during a @code{BACKSPACE} operation.
@end ifclear

@ifclear USERVISONLY
@item
@code{libg2c} (@code{libf2c}) fixes a bug whereby
input to a @code{NAMELIST} read involving a repeat count,
such as @samp{K(5)=10*3},
was not properly handled by @code{libf2c}.
The first item was written to @samp{K(5)},
but the remaining nine were written elsewhere (still within the array),
not necessarily starting at @samp{K(6)}.
@end ifclear

@ifclear USERVISONLY
@item
@c Tim Prince reported this, regarding the TEST_FPU benchmark.
Automatic arrays now seem to be working on HP-UX systems.
@end ifclear

@ifclear USERVISONLY
@item
The @code{Date} intrinsic now returns the correct result
on big-endian systems.
@end ifclear

@ifclear USERVISONLY
@item
Fix @code{g77} so it no longer crashes when compiling
I/O statements using keywords that define @code{INTEGER} values,
such as @samp{IOSTAT=@var{j}},
where @var{j} is other than default @code{INTEGER}
(such as @code{INTEGER*2}).
Instead, it issues a diagnostic.
@end ifclear

@ifclear USERVISONLY
@item
Fix @code{g77} so it properly handles @samp{DATA A/@var{rpt}*@var{val}/},
where @var{rpt} is not default @code{INTEGER}, such as @code{INTEGER*2},
instead of producing a spurious diagnostic.
Also fix @samp{DATA (A(I),I=1,N)},
where @samp{N} is not default @code{INTEGER}
to work instead of crashing @code{g77}.
@end ifclear

@ifclear USERVISONLY
@item
The @samp{-ax} option is now obeyed when compiling Fortran programs.
(It is passed to the @file{f771} driver.)
@end ifclear

@item
The new @samp{-fbounds-check} option
causes @code{g77} to compile run-time bounds checks
of array subscripts, as well as of substring start and end points.

@item
@code{libg2c} now supports building as multilibbed library,
which provides better support for systems
that require options such as @samp{-mieee}
to work properly.

@item
Source file names with the suffixes @samp{.FOR} and @samp{.FPP}
now are recognized by @code{g77}
as if they ended in @samp{.for} and @samp{.fpp}, respectively.

@item
The order of arguments to the @emph{subroutine} forms of the
@code{CTime}, @code{DTime}, @code{ETime}, and @code{TtyNam}
intrinsics has been swapped.
The argument serving as the returned value
for the corresponding function forms
now is the @emph{second} argument,
making these consistent with the other subroutine forms
of @code{libU77} intrinsics.

@item
@code{g77} now warns about a reference to an intrinsic
that has an interface that is not Year 2000 (Y2K) compliant.
Also, @code{libg2c} has been changed to increase the likelihood
of catching references to the implementations of these intrinsics
using the @code{EXTERNAL} mechanism
(which would avoid the new warnings).

@ifset DOC-G77
@xref{Year 2000 (Y2K) Problems}, for more information.
@end ifset

@ifclear USERVISONLY
@item
@code{g77} now warns about a reference to a function
when the corresponding @emph{subsequent} function program unit
disagrees with the reference concerning the type of the function.
@end ifclear

@item
@samp{-fno-emulate-complex} is now the default option.
This should result in improved performance
of code that uses the @code{COMPLEX} data type.

@cindex alignment
@cindex double-precision performance
@cindex -malign-double
@item
The @samp{-malign-double} option
now reliably aligns @emph{all} double-precision variables and arrays
on Intel x86 targets.

@ifclear USERVISONLY
@item
Even without the @samp{-malign-double} option,
@code{g77} reliably aligns local double-precision variables
that are not in @code{EQUIVALENCE} areas
and not @code{SAVE}'d.
@end ifclear

@ifclear USERVISONLY
@item
@code{g77} now open-codes (``inlines'') division of @code{COMPLEX} operands
instead of generating a run-time call to
the @code{libf2c} routines @code{c_div} or @code{z_div},
unless the @samp{-Os} option is specified.
@end ifclear

@item
@code{g77} no longer generates code to maintain @code{errno},
a C-language concept,
when performing operations such as the @code{SqRt} intrinsic.

@ifclear USERVISONLY
@item
@code{g77} developers can temporarily use
the @samp{-fflatten-arrays} option
to compare how the compiler handles code generation
using C-like constructs as compared to the
Fortran-like method constructs normally used.
@end ifclear

@ifclear USERVISONLY
@item
A substantial portion of the @code{g77} front end's code-generation component
was rewritten.
It now generates code using facilities more robustly supported
by the @code{gcc} back end.
One effect of this rewrite is that some codes no longer produce
a spurious ``label @var{lab} used before containing binding contour''
message.
@end ifclear

@item
Support for the @samp{-fugly} option has been removed.

@ifclear USERVISONLY
@item
Improve documentation and indexing,
including information on Year 2000 (Y2K) compliance,
and providing more information on internals of the front end.
@end ifclear

@ifclear USERVISONLY
@item
Upgrade to @code{libf2c} as of 1999-05-10.
@end ifclear
@end itemize

@heading In 0.5.24 versus 0.5.23:

There is no @code{g77} version 0.5.24 at this time,
or planned.
0.5.24 is the version number designated for bug fixes and,
perhaps, some new features added,
to 0.5.23.
Version 0.5.23 requires @code{gcc} 2.8.1,
as 0.5.24 was planned to require.

Due to @code{EGCS} becoming @code{GCC}
(which is now an acronym for ``GNU Compiler Collection''),
and @code{EGCS} 1.2 becoming officially designated @code{GCC} 2.95,
there seems to be no need for an actual 0.5.24 release.

To reduce the confusion already resulting from use of 0.5.24
to designate @code{g77} versions within @code{EGCS} versions 1.0 and 1.1,
as well as in versions of @code{g77} documentation and notices
during that period,
``mainline'' @code{g77} version numbering resumes
at 0.5.25 with @code{GCC} 2.95 (@code{EGCS} 1.2),
skipping over 0.5.24 as a placeholder version number.

To repeat, there is no @code{g77} 0.5.24, but there is now a 0.5.25.
Please remain calm and return to your keypunch units.

@c 1999-03-15: EGCS 1.1.2 released.
@heading In @code{EGCS} 1.1.2 versus @code{EGCS} 1.1.1:
@ifclear USERVISONLY
@itemize @bullet
@item
Fix the @code{IDate} intrinsic (VXT) (in @code{libg2c})
so the returned year is in the documented, non-Y2K-compliant range
of 0-99,
instead of being returned as 100 in the year 2000.

@ifset DOC-G77
@xref{IDate Intrinsic (VXT)},
for more information.
@end ifset

@item
Fix the @code{Date_and_Time} intrinsic (in @code{libg2c})
to return the milliseconds value properly
in @var{Values}(8).

@item
Fix the @code{LStat} intrinsic (in @code{libg2c})
to return device-ID information properly
in @var{SArray}(7).

@item
Improve documentation.
@end itemize
@end ifclear

@c 1998-12-04: EGCS 1.1.1 released.
@heading In @code{EGCS} 1.1.1 versus @code{EGCS} 1.1:
@ifclear USERVISONLY
@itemize @bullet
@item
Fix @code{libg2c} so it performs an implicit @code{ENDFILE} operation
(as appropriate)
whenever a @code{REWIND} is done.

(This bug was introduced in 0.5.23 and @code{egcs} 1.1 in
@code{g77}'s version of @code{libf2c}.)

@item
Fix @code{libg2c} so it no longer crashes with a spurious diagnostic
upon doing any I/O following a direct formatted write.

(This bug was introduced in 0.5.23 and @code{egcs} 1.1 in
@code{g77}'s version of @code{libf2c}.)

@item
Fix @code{g77} so it no longer crashes compiling references
to the @code{Rand} intrinsic on some systems.

@item
Fix @code{g77} portion of installation process so it works
better on some systems
(those with shells requiring @samp{else true} clauses
on @code{if} constructs
for the completion code to be set properly).
@end itemize
@end ifclear

@c 1998-09-03: EGCS 1.1 released.
@heading In @code{EGCS} 1.1 versus @code{EGCS} 1.0.3:
@itemize @bullet
@ifclear USERVISONLY
@item
Fix bugs in the @code{libU77} intrinsic @code{HostNm}
that wrote one byte beyond the end of its @code{CHARACTER}
argument,
and in the @code{libU77} intrinsics
@code{GMTime} and @code{LTime}