News About GNU Fortran

In 0.5.20:

• The `-fno-typeless-boz' option is now the default. This option specifies that non-decimal-radix constants using the prefixed-radix form (such as `Z'1234'') are to be interpreted as INTEGER constants. Specify `-ftypeless-boz' to cause such constants to be interpreted as typeless. (Version 0.5.19 introduced `-fno-typeless-boz' and its inverse.)
• Options `-ff90-intrinsics-enable' and `-fvxt-intrinsics-enable' now are the defaults. Some programs might use names that clash with intrinsic names defined (and now enabled) by these options or by the new libU77 intrinsics. Users of such programs might need to compile them differently (using, for example, `-ff90-intrinsics-disable') or, better yet, insert appropriate EXTERNAL statements specifying that these names are not intended to be names of intrinsics.
• The `ALWAYS_FLUSH' macro is no longer defined when building libf2c, which should result in improved I/O performance, especially over NFS. Note: If you have code that depends on the behavior of libf2c when built with `ALWAYS_FLUSH' defined, you will have to modify libf2c accordingly before building it from this and future versions of g77.
• Dave Love's implementation of libU77 has been added to the version of libf2c distributed with and built as part of g77. g77 now knows about the routines in this library as intrinsics.
• New option `-fvxt' specifies that the source file is written in VXT Fortran, instead of GNU Fortran.
• The `-fvxt-not-f90' option has been deleted, along with its inverse, `-ff90-not-vxt'. If you used one of these deleted options, you should re-read the pertinent documentation to determine which options, if any, are appropriate for compiling your code with this version of g77.
• The `-fugly' option now issues a warning, as it likely will be removed in a future version. (Enabling all the `-fugly-*' options is unlikely to be feasible, or sensible, in the future, so users should learn to specify only those `-fugly-*' options they really need for a particular source file.)
• The `-fugly-assumed' option, introduced in version 0.5.19, has been changed to better accommodate old and new code.
• Make a number of fixes to the g77 front end and the gcc back end to better support Alpha (AXP) machines. This includes providing at least one bug-fix to the gcc back end for Alphas.
• Related to supporting Alpha (AXP) machines, the LOC() intrinsic and %LOC() construct now return values of integer type that is the same width (holds the same number of bits) as the pointer type on the machine. On most machines, this won't make a difference, whereas on Alphas, the type these constructs return is INTEGER*8 instead of the more common INTEGER*4.
• Emulate COMPLEX arithmetic in the g77 front end, to avoid bugs in complex support in the gcc back end. New option `-fno-emulate-complex' causes g77 to revert the 0.5.19 behavior.
• Fix bug whereby `REAL A(1)', for example, caused a compiler crash if `-fugly-assumed' was in effect and A was a local (automatic) array. That case is no longer affected by the new handling of `-fugly-assumed'.
• Fix g77 command driver so that `g77 -o foo.f' no longer deletes `foo.f' before issuing other diagnostics, and so the `-x' option is properly handled.
• Enable inlining of subroutines and functions by the gcc back end. This works as it does for gcc itself--program units may be inlined for invocations that follow them in the same program unit, as long as the appropriate compile-time options are specified.
• Dummy arguments are no longer assumed to potentially alias (overlap) other dummy arguments or COMMON areas when any of these are defined (assigned to) by Fortran code. This can result in faster and/or smaller programs when compiling with optimization enabled, though on some systems this effect is observed only when `-fforce-addr' also is specified. New options `-falias-check', `-fargument-alias', `-fargument-noalias', and `-fno-argument-noalias-global' control the way g77 handles potential aliasing.
• The CONJG() and DCONJG() intrinsics now are compiled in-line.
• The bug-fix for 0.5.19.1 has been re-done. The g77 compiler has been changed back to assume libf2c has no aliasing problems in its implementations of the COMPLEX (and DOUBLE COMPLEX) intrinsics. The libf2c has been changed to have no such problems. As a result, 0.5.20 is expected to offer improved performance over 0.5.19.1, perhaps as good as 0.5.19 in most or all cases, due to this change alone. Note: This change requires version 0.5.20 of libf2c, at least, when linking code produced by any versions of g77 other than 0.5.19.1. Use `g77 -v' to determine the version numbers of the libF77, libI77, and libU77 components of the libf2c library. (If these version numbers are not printed--in particular, if the linker complains about unresolved references to names like `g77__fvers__'---that strongly suggests your installation has an obsolete version of libf2c.)
• New option `-fugly-assign' specifies that the same memory locations are to be used to hold the values assigned by both statements `I = 3' and `ASSIGN 10 TO I', for example. (Normally, g77 uses a separate memory location to hold assigned statement labels.)
• FORMAT and ENTRY statements now are allowed to precede IMPLICIT NONE statements.
• Produce diagnostic for unsupported SELECT CASE on CHARACTER type, instead of crashing, at compile time.
• Fix crashes involving diagnosed or invalid code.
• Change approach to building libf2c archive (`libf2c.a') so that members are added to it only when truly necessary, so the user that installs an already-built g77 doesn't need to have write access to the build tree (whereas the user doing the build might not have access to install new software on the system).
• Support gcc version 2.7.2.2 (modified by g77 into version 2.7.2.2.f.2), and remove support for prior versions of gcc.
• Upgrade to libf2c as of 1997-02-08, and fix up some of the build procedures.
• Improve general build procedures for g77, fixing minor bugs (such as deletion of any file named `f771' in the parent directory of gcc/).
• Enable full support of INTEGER*8 available in libf2c and `f2c.h' so that f2c users may make full use of its features via the g77 version of `f2c.h' and the INTEGER*8 support routines in the g77 version of libf2c.
• Improve g77 driver and libf2c so that `g77 -v' yields version information on the library.
• The SNGL and FLOAT intrinsics now are specific intrinsics, instead of synonyms for the generic intrinsic REAL.
• New intrinsics have been added. These are REALPART, IMAGPART, COMPLEX, LONG, and SHORT.
• A new group of intrinsics, `gnu', has been added to contain the new REALPART, IMAGPART, and COMPLEX intrinsics. An old group, `dcp', has been removed.
• Complain about industry-wide ambiguous references `REAL(expr)' and `AIMAG(expr)', where expr is DOUBLE COMPLEX (or any complex type other than COMPLEX), unless `-ff90' option specifies Fortran 90 interpretation or new `-fugly-complex' option, in conjunction with `-fnot-f90', specifies f2c interpretation.
• Make improvements to diagnostics.
• Speed up compiler a bit.
• Improvements to documentation and indexing, including a new chapter containing information on one, later more, diagnostics that users are directed to pull up automatically via a message in the diagnostic itself. (Hence the menu item `M' for the node `Diagnostics' in the top-level menu of the Info documentation.)

In 0.5.19.1:

• Code-generation bugs afflicting operations on complex data have been fixed. These bugs occurred when assigning the result of an operation to a complex variable (or array element) that also served as an input to that operation. The operations affected by this bug were: `CONJG()', `DCONJG()', `CCOS()', `CDCOS()', `CLOG()', `CDLOG()', `CSIN()', `CDSIN()', `CSQRT()', `CDSQRT()', complex division, and raising a DOUBLE COMPLEX operand to an INTEGER power. (The related generic and `Z'-prefixed intrinsics, such as `ZSIN()', also were affected.) For example, `C = CSQRT(C)', `Z = Z/C', and `Z = Z**I' (where `C' is COMPLEX and `Z' is DOUBLE COMPLEX) have been fixed.

In 0.5.19:

• Fix FORMAT statement parsing so negative values for specifiers such as `P' (e.g. `FORMAT(-1PF8.1)') are correctly processed as negative.
• Fix SIGNAL intrinsic so it once again accepts a procedure as its second argument.
• A temporary kludge option provides bare-bones information on COMMON and EQUIVALENCE members at debug time.
• New `-fonetrip' option specifies FORTRAN-66-style one-trip DO loops.
• New `-fno-silent' option causes names of program units to be printed as they are compiled, in a fashion similar to UNIX f77 and f2c.
• New `-fugly-assumed' option specifies that arrays dimensioned via `DIMENSION X(1)', for example, are to be treated as assumed-size.
• New `-fno-typeless-boz' option specifies that non-decimal-radix constants using the prefixed-radix form (such as `Z'1234'') are to be interpreted as INTEGER constants.
• New `-ff66' option is a "shorthand" option that specifies behaviors considered appropriate for FORTRAN 66 programs.
• New `-ff77' option is a "shorthand" option that specifies behaviors considered appropriate for UNIX f77 programs.
• New `-fugly-comma' and `-fugly-logint' options provided to perform some of what `-fugly' used to do. `-fugly' and `-fno-ugly' are now "shorthand" options, in that they do nothing more than enable (or disable) other `-fugly-*' options.
• Fix parsing of assignment statements involving targets that are substrings of elements of CHARACTER arrays having names such as `READ', `WRITE', `GOTO', and `REALFUNCTIONFOO'.
• Fix crashes involving diagnosed code.
• Fix handling of local EQUIVALENCE areas so certain cases of valid Fortran programs are not misdiagnosed as improperly extending the area backwards.
• Support gcc version 2.7.2.1.
• Upgrade to libf2c as of 1996-09-26, and fix up some of the build procedures.
• Change code generation for list-directed I/O so it allows for new versions of libf2c that might return non-zero status codes for some operations previously assumed to always return zero. This change not only affects how IOSTAT= variables are set by list-directed I/O, it also affects whether END= and ERR= labels are reached by these operations.
• Add intrinsic support for new FTELL and FSEEK procedures in libf2c.
• Modify fseek_() in libf2c to be more portable (though, in practice, there might be no systems where this matters) and to catch invalid `whence' arguments.
• Some useless warnings from the `-Wunused' option have been eliminated.
• Fix a problem building the `f771' executable on AIX systems by linking with the `-bbigtoc' option.
• Abort configuration if gcc has not been patched using the patch file provided in the `gcc/f/gbe/' subdirectory.
• Add options `--help' and `--version' to the g77 command, to conform to GNU coding guidelines. Also add printing of g77 version number when the `--verbose' (`-v') option is used.
• Change internally generated name for local EQUIVALENCE areas to one based on the alphabetically sorted first name in the list of names for entities placed at the beginning of the areas.
• Improvements to documentation and indexing.

In 0.5.18:

• Add some rudimentary support for INTEGER*1, INTEGER*2, INTEGER*8, and their LOGICAL equivalents. (This support works on most, maybe all, gcc targets.) Thanks to Scott Snyder (@email{snyder@d0sgif.fnal.gov}) for providing the patch for this! Among the missing elements from the support for these features are full intrinsic support and constants.
• Add some rudimentary support for the BYTE and WORD type-declaration statements. BYTE corresponds to INTEGER*1, while WORD corresponds to INTEGER*2. Thanks to Scott Snyder (@email{snyder@d0sgif.fnal.gov}) for providing the patch for this!
• The compiler code handling intrinsics has been largely rewritten to accommodate the new types. No new intrinsics or arguments for existing intrinsics have been added, so there is, at this point, no intrinsic to convert to INTEGER*8, for example.
• Support automatic arrays in procedures.
• Reduce space/time requirements for handling large sparsely initialized aggregate arrays. This improvement applies to only a subset of the general problem to be addressed in 0.6.
• Treat initial values of zero as if they weren't specified (in DATA and type-declaration statements). The initial values will be set to zero anyway, but the amount of compile time processing them will be reduced, in some cases significantly (though, again, this is only a subset of the general problem to be addressed in 0.6). A new option, `-fzeros', is introduced to enable the traditional treatment of zeros as any other value.
• With `-ff90' in force, g77 incorrectly interpreted `REAL(Z)' as returning a REAL result, instead of as a DOUBLE PRECISION result. (Here, `Z' is DOUBLE COMPLEX.) With `-fno-f90' in force, the interpretation remains unchanged, since this appears to be how at least some F77 code using the DOUBLE COMPLEX extension expected it to work. Essentially, `REAL(Z)' in F90 is the same as `DBLE(Z)', while in extended F77, it appears to be the same as `REAL(REAL(Z))'.
• An expression involving exponentiation, where both operands were type INTEGER and the right-hand operand was negative, was erroneously evaluated.
• Fix bugs involving DATA implied-DO constructs (these involved an errant diagnostic and a crash, both on good code, one involving subsequent statement-function definition).
• Close INCLUDE files after processing them, so compiling source files with lots of INCLUDE statements does not result in being unable to open INCLUDE files after all the available file descriptors are used up.
• Speed up compiling, especially of larger programs, and perhaps slightly reduce memory utilization while compiling (this is not the improvement planned for 0.6 involving large aggregate areas)---these improvements result from simply turning off some low-level code to do self-checking that hasn't been triggered in a long time.
• Introduce three new options that implement optimizations in the gcc back end (GBE). These options are `-fmove-all-movables', `-freduce-all-givs', and `-frerun-loop-opt', which are enabled, by default, for Fortran compilations. These optimizations are intended to help toon Fortran programs.
• Patch the GBE to do a better job optimizing certain kinds of references to array elements.
• Due to patches to the GBE, the version number of gcc also is patched to make it easier to manage installations, especially useful if it turns out a g77 change to the GBE has a bug. The g77-modified version number is the gcc version number with the string `.f.n' appended, where `f' identifies the version as enhanced for Fortran, and n is `1' for the first Fortran patch for that version of gcc, `2' for the second, and so on. So, this introduces version 2.7.2.f.1 of gcc.
• Make several improvements and fixes to diagnostics, including the removal of two that were inappropriate or inadequate.
• Warning about two successive arithmetic operators, produced by `-Wsurprising', now produced only when both operators are, indeed, arithmetic (not relational/boolean).
• `-Wsurprising' now warns about the remaining cases of using non-integral variables for implied-DO loops, instead of these being rejected unless `-fpedantic' or `-fugly' specified.
• Allow SAVE of a local variable or array, even after it has been given an initial value via DATA, for example.
• Introduce an Info version of g77 documentation, which supercedes `gcc/f/CREDITS', `gcc/f/DOC', and `gcc/f/PROJECTS'. These files will be removed in a future release. The files `gcc/f/BUGS', `gcc/f/INSTALL', and `gcc/f/NEWS' now are automatically built from the texinfo source when distributions are made. This effort was inspired by a first pass at translating `g77-0.5.16/f/DOC' that was contributed to Craig by David Ronis (@email{ronis@onsager.chem.mcgill.ca}).
• New `-fno-second-underscore' option to specify that, when `-funderscoring' is in effect, a second underscore is not to be appended to Fortran names already containing an underscore.
• Change the way iterative DO loops work to follow the F90 standard. In particular, calculation of the iteration count is still done by converting the start, end, and increment parameters to the type of the DO variable, but the result of the calculation is always converted to the default INTEGER type. (This should have no effect on existing code compiled by g77, but code written to assume that use of a wider type for the DO variable will result in an iteration count being fully calculated using that wider type (wider than default INTEGER) must be rewritten.)
• Support gcc version 2.7.2.
• Upgrade to libf2c as of 1996-03-23, and fix up some of the build procedures. Note that the email addresses related to f2c have changed--the distribution site now is named netlib.bell-labs.com, and the maintainer's new address is @email{dmg@bell-labs.com}.

In 0.5.17:

• Fix serious bug in `g77 -v' command that can cause removal of a system's `/dev/null' special file if run by user `root'. All users of version 0.5.16 should ensure that they have not removed `/dev/null' or replaced it with an ordinary file (e.g. by comparing the output of `ls -l /dev/null' with `ls -l /dev/zero'. If the output isn't basically the same, contact your system administrator about restoring `/dev/null' to its proper status). This bug is particularly insidious because removing `/dev/null' as a special file can go undetected for quite a while, aside from various applications and programs exhibiting sudden, strange behaviors. I sincerely apologize for not realizing the implications of the fact that when `g77 -v' runs the ld command with `-o /dev/null' that ld tries to remove the executable it is supposed to build (especially if it reports unresolved references, which it should in this case)!
• Fix crash on `CHARACTER*(*) FOO' in a main or block data program unit.
• Fix crash that can occur when diagnostics given outside of any program unit (such as when input file contains `@foo').
• Fix crashes, infinite loops (hangs), and such involving diagnosed code.
• Fix ASSIGN'ed variables so they can be SAVE'd or dummy arguments, and issue clearer error message in cases where target of ASSIGN or ASSIGNed GOTO/FORMAT is too small (which should never happen).
• Make libf2c build procedures work on more systems again by eliminating unnecessary invocations of `ld -r -x' and `mv'.
• Fix omission of `-funix-intrinsics-...' options in list of permitted options to compiler.
• Fix failure to always diagnose missing type declaration for IMPLICIT NONE.
• Fix compile-time performance problem (which could sometimes crash the compiler, cause a hang, or whatever, due to a bug in the back end) involving exponentiation with a large INTEGER constant for the right-hand operator (e.g. `I**32767').
• Fix build procedures so cross-compiling g77 (the fini utility in particular) is properly built using the host compiler.
• Add new `-Wsurprising' option to warn about constructs that are interpreted by the Fortran standard (and g77) in ways that are surprising to many programmers.
• Add ERF() and ERFC() as generic intrinsics mapping to existing ERF/DERF and ERFC/DERFC specific intrinsics. Note: You should specify `INTRINSIC ERF,ERFC' in any code where you might use these as generic intrinsics, to improve likelihood of diagnostics (instead of subtle run-time bugs) when using a compiler that doesn't support these as intrinsics (e.g. f2c).
• Remove from `-fno-pedantic' the diagnostic about DO with non-INTEGER index variable; issue that under `-Wsurprising' instead.
• Clarify some diagnostics that say things like "ignored" when that's misleading.
• Clarify diagnostic on use of .EQ./.NE. on LOGICAL operands.
• Minor improvements to code generation for various operations on LOGICAL operands.
• Minor improvement to code generation for some DO loops on some machines.
• Support gcc version 2.7.1.
• Upgrade to libf2c as of 1995-11-15.

In 0.5.16:

• Fix a code-generation bug involving complicated EQUIVALENCE statements not involving COMMON.
• Fix code-generation bugs involving invoking "gratis" library procedures in libf2c from code compiled with `-fno-f2c' by making these procedures known to g77 as intrinsics (not affected by -fno-f2c). This is known to fix code invoking ERF(), ERFC(), DERF(), and DERFC().
• Update libf2c to include netlib patches through 1995-08-16, and #define `WANT_LEAD_0' to 1 to make g77-compiled code more consistent with other Fortran implementations by outputting leading zeros in formatted and list-directed output.
• Fix a code-generation bug involving adjustable dummy arrays with high bounds whose primaries are changed during procedure execution, and which might well improve code-generation performance for such arrays compared to f2c plus gcc (but apparently only when using `gcc-2.7.0' or later).
• Fix a code-generation bug involving invocation of COMPLEX and DOUBLE COMPLEX FUNCTIONs and doing COMPLEX and DOUBLE COMPLEX divides, when the result of the invocation or divide is assigned directly to a variable that overlaps one or more of the arguments to the invocation or divide.
• Fix crash by not generating new optimal code for `X**I' if `I' is nonconstant and the expression is used to dimension a dummy array, since the gcc back end does not support the necessary mechanics (and the gcc front end rejects the equivalent construct, as it turns out).
• Fix crash on expressions like `COMPLEX**INTEGER'.
• Fix crash on expressions like `(1D0,2D0)**2', i.e. raising a DOUBLE COMPLEX constant to an INTEGER constant power.
• Fix crashes and such involving diagnosed code.
• Diagnose, instead of crashing on, statement function definitions having duplicate dummy argument names.
• Fix bug causing rejection of good code involving statement function definitions.
• Fix bug resulting in debugger not knowing size of local equivalence area when any member of area has initial value (via DATA, for example).
• Fix installation bug that prevented installation of g77 driver. Provide for easy selection of whether to install copy of g77 as f77 to replace the broken code.
• Fix gcc driver (affects g77 thereby) to not gratuitously invoke the f771 program (e.g. when `-E' is specified).
• Fix diagnostic to point to correct source line when it immediately follows an INCLUDE statement.
• Support more compiler options in gcc/g77 when compiling Fortran files. These options include `-p', `-pg', `-aux-info', `-P', correct setting of version-number macros for preprocessing, full recognition of `-O0', and automatic insertion of configuration-specific linker specs.
• Add new intrinsics that interface to existing routines in libf2c: ABORT, DERF, DERFC, ERF, ERFC, EXIT, FLUSH, GETARG, GETENV, IARGC, SIGNAL, and SYSTEM. Note that ABORT, EXIT, FLUSH, SIGNAL, and SYSTEM are intrinsic subroutines, not functions (since they have side effects), so to get the return values from SIGNAL and SYSTEM, append a final argument specifying an INTEGER variable or array element (e.g. `CALL SYSTEM('rm foo',ISTAT)').
• Add new intrinsic group named `unix' to contain the new intrinsics, and by default enable this new group.
• Move LOC() intrinsic out of the `vxt' group to the new `unix' group.
• Improve g77 so that `g77 -v' by itself (or with certain other options, including `-B', `-b', `-i', `-nostdlib', and `-V') reports lots more useful version info, and so that long-form options gcc accepts are understood by g77 as well (even in truncated, unambiguous forms).
• Add new g77 option `--driver=name' to specify driver when default, gcc, isn't appropriate.
• Add support for `#' directives (as output by the preprocessor) in the compiler, and enable generation of those directives by the preprocessor (when compiling `.F' files) so diagnostics and debugging info are more useful to users of the preprocessor.
• Produce better diagnostics, more like gcc, with info such as `In function `foo':' and `In file included from...:'.
• Support gcc's `-fident' and `-fno-ident' options.
• When `-Wunused' in effect, don't warn about local variables used as statement-function dummy arguments or DATA implied-DO iteration variables, even though, strictly speaking, these are not uses of the variables themselves.
• When `-W -Wunused' in effect, don't warn about unused dummy arguments at all, since there's no way to turn this off for individual cases (g77 might someday start warning about these)---applies to gcc versions 2.7.0 and later, since earlier versions didn't warn about unused dummy arguments.
• New option `-fno-underscoring' that inhibits transformation of names (by appending one or two underscores) so users may experiment with implications of such an environment.
• Minor improvement to `gcc/f/info' module to make it easier to build g77 using the native (non-gcc) compiler on certain machines (but definitely not all machines nor all non-gcc compilers). Please do not report bugs showing problems compilers have with macros defined in `gcc/f/target.h' and used in places like `gcc/f/expr.c'.
• Add warning to be printed for each invocation of the compiler if the target machine INTEGER, REAL, or LOGICAL size is not 32 bits, since g77 is known to not work well for such cases (to be fixed in Version 0.6---see section Actual Bugs We Haven't Fixed Yet).
• Lots of new documentation (though work is still needed to put it into canonical GNU format).
• Build libf2c with `-g0', not `-g2', in effect (by default), to produce smaller library without lots of debugging clutter.

In 0.5.15:

• Fix bad code generation involving `X**I' and temporary, internal variables generated by g77 and the back end (such as for DO loops).
• Fix crash given `CHARACTER A;DATA A/.TRUE./'.
• Replace crash with diagnostic given `CHARACTER A;DATA A/1.0/'.
• Fix crash or other erratic behavior when null character constant (`"') is encountered.
• Fix crash or other erratic behavior involving diagnosed code.
• Fix code generation for external functions returning type REAL when the `-ff2c' option is in force (which it is by default) so that f2c compatibility is indeed provided.
• Disallow `COMMON I(10)' if `I' has previously been specified with an array declarator.
• New `-ffixed-line-length-n' option, where n is the maximum length of a typical fixed-form line, defaulting to 72 columns, such that characters beyond column n are ignored, or n is `none', meaning no characters are ignored. does not affect lines with `&' in column 1, which are always processed as if `-ffixed-line-length-none' was in effect.
• No longer generate better code for some kinds of array references, as gcc back end is to be fixed to do this even better, and it turned out to slow down some code in some cases after all.
• In COMMON and EQUIVALENCE areas with any members given initial values (e.g. via DATA), uninitialized members now always initialized to binary zeros (though this is not required by the standard, and might not be done in future versions of g77). Previously, in some COMMON/EQUIVALENCE areas (essentially those with members of more than one type), the uninitialized members were initialized to spaces, to cater to CHARACTER types, but it seems no existing code expects that, while much existing code expects binary zeros.

In 0.5.14:

• Don't emit bad code when low bound of adjustable array is nonconstant and thus might vary as an expression at run time.
• Emit correct code for calculation of number of trips in DO loops for cases where the loop should not execute at all. (This bug affected cases where the difference between the begin and end values was less than the step count, though probably not for floating-point cases.)
• Fix crash when extra parentheses surround item in DATA implied-DO list.
• Fix crash over minor internal inconsistencies in handling diagnostics, just substitute dummy strings where necessary.
• Fix crash on some systems when compiling call to MVBITS() intrinsic.
• Fix crash on array assignment `TYPEddd(...)=...', where ddd is a string of one or more digits.
• Fix crash on DCMPLX() with a single INTEGER argument.
• Fix various crashes involving code with diagnosed errors.
• Support `-I' option for INCLUDE statement, plus gcc's `header.gcc' facility for handling systems like MS-DOS.
• Allow INCLUDE statement to be continued across multiple lines, even allow it to coexist with other statements on the same line.
• Incorporate Bellcore fixes to libf2c through 1995-03-15--this fixes a bug involving infinite loops reading EOF with empty list-directed I/O list.
• Remove all the g77-specific auto-configuration scripts, code, and so on, except for temporary substitutes for bsearch() and strtoul(), as too many configure/build problems were reported in these areas. People will have to fix their systems' problems themselves, or at least somewhere other than g77, which expects a working ANSI C environment (and, for now, a GNU C compiler to compile g77 itself).
• Complain if initialized common redeclared as larger in subsequent program unit.
• Warn if blank common initialized, since its size can vary and hence related warnings that might be helpful won't be seen.
• New `-fbackslash' option, on by default, that causes `\' within CHARACTER and Hollerith constants to be interpreted a la GNU C. Note that this behavior is somewhat different from f2c's, which supports only a limited subset of backslash (escape) sequences.
• Make `-fugly-args' the default.
• New `-fugly-init' option, on by default, that allows typeless/Hollerith to be specified as initial values for variables or named constants (PARAMETER), and also allows character<->numeric conversion in those contexts--turn off via `-fno-ugly-init'.
• New `-finit-local-zero' option to initialize local variables to binary zeros. This does not affect whether they are SAVEd, i.e. made automatic or static.
• New `-Wimplicit' option to warn about implicitly typed variables, arrays, and functions. (Basically causes all program units to default to IMPLICIT NONE.)
• `-Wall' now implies `-Wuninitialized' as with gcc (i.e. unless `-O' not specified, since `-Wuninitialized' requires `-O'), and implies `-Wunused' as well.
• `-Wunused' no longer gives spurious messages for unused EXTERNAL names (since they are assumed to refer to block data program units, to make use of libraries more reliable).
• Support %LOC() and LOC() of character arguments.
• Support null (zero-length) character constants and expressions.
• Support f2c's IMAG() generic intrinsic.
• Support ICHAR(), IACHAR(), and LEN() of character expressions that are valid in assignments but not normally as actual arguments.
• Support f2c-style `&' in column 1 to mean continuation line.
• Allow NAMELIST, EXTERNAL, INTRINSIC, and VOLATILE in BLOCK DATA, even though these are not allowed by the standard.
• Allow RETURN in main program unit.
• Changes to Hollerith-constant support to obey Appendix C of the standard:
  • Now padded on the right with zeros, not spaces.
  • Hollerith "format specifications" in the form of arrays of non-character allowed.
  • Warnings issued when non-space truncation occurs when converting to another type.
  • When specified as actual argument, now passed by reference to INTEGER (padded on right with spaces if constant too small, otherwise fully intact if constant wider the INTEGER type) instead of by value.
  Warning: f2c differs on the interpretation of `CALL FOO(1HX)', which it treats exactly the same as `CALL FOO('X')', but which the standard and g77 treat as `CALL FOO(%REF('X '))' (padded with as many spaces as necessary to widen to INTEGER), essentially.
• Changes and fixes to typeless-constant support:
  • Now treated as a typeless double-length INTEGER value.
  • Warnings issued when overflow occurs.
  • Padded on the left with zeros when converting to a larger type.
  • Should be properly aligned and ordered on the target machine for whatever type it is turned into.
  • When specified as actual argument, now passed as reference to a default INTEGER constant.
• %DESCR() of a non-CHARACTER expression now passes a pointer to the expression plus a length for the expression just as if it were a CHARACTER expression. For example, `CALL FOO(%DESCR(D))', where `D' is REAL*8, is the same as `CALL FOO(D,%VAL(8)))'.
• Name of multi-entrypoint master function changed to incorporate the name of the primary entry point instead of a decimal value, so the name of the master function for `SUBROUTINE X' with alternate entry points is now `__g77_masterfun_x'.
• Remove redundant message about zero-step-count DO loops.
• Clean up diagnostic messages, shortening many of them.
• Fix typo in g77 man page.
• Clarify implications of constant-handling bugs in `f/BUGS'.
• Generate better code for `**' operator with a right-hand operand of type INTEGER.
• Generate better code for SQRT() and DSQRT(), also when `-ffast-math' specified, enable better code generation for SIN() and COS().
• Generate better code for some kinds of array references.
• Speed up lexing somewhat (this makes the compilation phase noticeably faster).