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gfortran.texi: Update documentation to catch up with BOZ changes.

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2019-09-03  Steven G. Kargl  <kargl@gcc.gnu.org>

	* gfortran.texi: Update documentation to catch up with BOZ changes.
	* invoke.texi: Fix English from previous BOZ changes commit.

From-SVN: r275364
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Steven G. Kargl 2019-09-04 03:43:40 +00:00
parent 48259207e6
commit f8e36f0aef
3 changed files with 22 additions and 33 deletions
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5
gcc/fortran/ChangeLog
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@ -1,3 +1,8 @@
2019-09-03 Steven G. Kargl <kargl@gcc.gnu.org>
* gfortran.texi: Update documentation to catch up with BOZ changes.
* invoke.texi: Fix English from previous BOZ changes commit.
2019-09-02 Paul Thomas <pault@gcc.gnu.org>
PR fortran/91589

46
gcc/fortran/gfortran.texi
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@ -1848,39 +1848,23 @@ Besides decimal constants, Fortran also supports binary (@code{b}),
octal (@code{o}) and hexadecimal (@code{z}) integer constants. The
syntax is: @samp{prefix quote digits quote}, were the prefix is
either @code{b}, @code{o} or @code{z}, quote is either @code{'} or
@code{"} and the digits are for binary @code{0} or @code{1}, for
octal between @code{0} and @code{7}, and for hexadecimal between
@code{0} and @code{F}. (Example: @code{b'01011101'}.)
@code{"} and the digits are @code{0} or @code{1} for binary,
between @code{0} and @code{7} for octal, and between @code{0} and
@code{F} for hexadecimal. (Example: @code{b'01011101'}.)
Up to Fortran 95, BOZ literals were only allowed to initialize
integer variables in DATA statements. Since Fortran 2003 BOZ literals
are also allowed as argument of @code{REAL}, @code{DBLE}, @code{INT}
and @code{CMPLX}; the result is the same as if the integer BOZ
literal had been converted by @code{TRANSFER} to, respectively,
@code{real}, @code{double precision}, @code{integer} or @code{complex}.
As GNU Fortran extension the intrinsic procedures @code{FLOAT},
@code{DFLOAT}, @code{COMPLEX} and @code{DCMPLX} are treated alike.
Up to Fortran 95, BOZ literal constants were only allowed to initialize
integer variables in DATA statements. Since Fortran 2003 BOZ literal
constants are also allowed as actual arguments to the @code{REAL},
@code{DBLE}, @code{INT} and @code{CMPLX} intrinsic functions.
The BOZ literal constant is simply a string of bits, which is padded
or truncated as needed, during conversion to a numeric type. The
Fortran standard states that the treatment of the sign bit is processor
dependent. Gfortran interprets the sign bit as a user would expect.
As an extension, GNU Fortran allows hexadecimal BOZ literal constants to
be specified using the @code{X} prefix, in addition to the standard
@code{Z} prefix. The BOZ literal can also be specified by adding a
suffix to the string, for example, @code{Z'ABC'} and @code{'ABC'Z} are
equivalent.
Furthermore, GNU Fortran allows using BOZ literal constants outside
DATA statements and the four intrinsic functions allowed by Fortran 2003.
In DATA statements, in direct assignments, where the right-hand side
only contains a BOZ literal constant, and for old-style initializers of
the form @code{integer i /o'0173'/}, the constant is transferred
as if @code{TRANSFER} had been used; for @code{COMPLEX} numbers, only
the real part is initialized unless @code{CMPLX} is used. In all other
cases, the BOZ literal constant is converted to an @code{INTEGER} value with
the largest decimal representation. This value is then converted
numerically to the type and kind of the variable in question.
(For instance, @code{real :: r = b'0000001' + 1} initializes @code{r}
with @code{2.0}.) As different compilers implement the extension
differently, one should be careful when doing bitwise initialization
of non-integer variables.
As a deprecated extension, GNU Fortran allows hexadecimal BOZ literal
constants to be specified using the @code{X} prefix. The BOZ literal
constant can also be specified by adding a suffix to the string, for
example, @code{Z'ABC'} and @code{'ABC'X} are equivalent.
@node Real array indices
@subsection Real array indices

4
gcc/fortran/invoke.texi
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@ -241,10 +241,10 @@ warning. This option is implied by @option{-std=legacy}.
@item -fallow-invalid-boz
@opindex @code{allow-invalid-boz}
A BOZ literal constant can occur in a limited number of context in
A BOZ literal constant can occur in a limited number of contexts in
standard conforming Fortran. This option degrades an error condition
to a warning, and allows a BOZ literal constant to appear where the
Fortran standard would otherwise prohibits it.
Fortran standard would otherwise prohibit its use.
@item -fd-lines-as-code
@itemx -fd-lines-as-comments