This patch updates one comment regarding "logical":
* The Fortran standard requires that (default-kind) "logical" and
"integer" have the same size; that's generally the case, i.e. also for
arrays or in structures (derived types)
* Fortran does not use zero/nonzero semantics but only .true. and
.false. However, the standard does not specify the value of .true. and
.false. While .false. seems to be universally 0, I have seen .true.
being 1 (majority of compilers) and -1 (few compilers, but one popular
among them). GCC's gfortran uses 0 and 1 - and will give wrong code with
a "-1" .true. (when ".not." is applied to it, it will become -2, which
is also regarded as ".true."). Hence, for GCC/gfortran interop, the
semantic matches gnat's; but for wider compatibility, keeping the
nonzero/zero semantics is reasonable.
In addition, Ada 2012 allows optionally to define types for Fortran's
"real*8" and "integer(kind=2)". The former syntax is not permitted by
any Fortran standard but an extremely common vendor extension,
effectively supported by all compilers. The second one is standard
conform since Fortran 90; however, the value (here "2") is not defined
by the standard. By far most compilers use the byte size for that value.
I know of one compiler, which doesn't by default (only with -kind=byte).
Thus, that addition should be interop with effectively all compilers.
See Fortran interop appendix B.5 to Ada 2012. Quickest link to the
standard: Look at the attachment of the email
http://mailman.j3-fortran.org/pipermail/j3/2013-February/006162.html –
or in the standard itself (also linked from that email).
I would like if some of the Ada/GNAT experts could have a look - as this
is really my first look at Ada code.
Tobias
2013-03-19 Tobias Burnus <bur...@net-b.de>
* i-fortra.ads: Update comment, add Ada 2012's optional
Star and Kind data types for enhanced interoperability.
diff --git a/gcc/ada/i-fortra.ads b/gcc/ada/i-fortra.ads
index 992eb28..270c819 100644
--- a/gcc/ada/i-fortra.ads
+++ b/gcc/ada/i-fortra.ads
@@ -26,11 +26,11 @@ package Interfaces.Fortran is
type Logical is new Boolean;
for Logical'Size use Integer'Size;
pragma Convention (Fortran, Logical);
- -- As required by Fortran standard, stand alone logical allocates same
- -- space as integer (but what about the array case???). The convention
- -- is important, since in Fortran, Booleans have zero/non-zero semantics
- -- for False/True, and the pragma Convention (Fortran) activates the
- -- special handling required in this case.
+ -- As required by Fortran standard, logical allocates same space as
+ -- an integer. The convention is important, since in Fortran, Booleans
+ -- are implemented with zero/non-zero semantics for False/True, and the
+ -- pragma Convention (Fortran) activates the special handling required
+ -- in this case.
package Single_Precision_Complex_Types is
new Ada.Numerics.Generic_Complex_Types (Real);
@@ -50,6 +50,53 @@ package Interfaces.Fortran is
type Fortran_Character is array (Positive range <>) of Character_Set;
+ -- Additional declarations as permitted by Ada 2012, p.608, paragraph 21.
+ -- Interoperability with Fortran 77's vendor extension using star
+ -- notation and Fortran 90's intrinsic types with kind=n parameter.
+ -- The following assumes that `n' matches the byte size, which
+ -- most Fortran compiler, including GCC's follow.
+
+ type Integer_Star_1 is new Integer_8;
+ type Integer_Kind_1 is new Integer_8;
+ type Integer_Star_2 is new Integer_16;
+ type Integer_Kind_2 is new Integer_16;
+ type Integer_Star_4 is new Integer_32;
+ type Integer_Kind_4 is new Integer_32;
+ type Integer_Star_8 is new Integer_64;
+ type Integer_Kind_8 is new Integer_64;
+
+ type Logical_Star_1 is new Boolean;
+ type Logical_Star_2 is new Boolean;
+ type Logical_Star_4 is new Boolean;
+ type Logical_Star_8 is new Boolean;
+ for Logical_Star_1'Size use Integer_8'Size;
+ for Logical_Star_2'Size use Integer_16'Size;
+ for Logical_Star_4'Size use Integer_32'Size;
+ for Logical_Star_8'Size use Integer_64'Size;
+ pragma Convention (Fortran, Logical_Star_1);
+ pragma Convention (Fortran, Logical_Star_2);
+ pragma Convention (Fortran, Logical_Star_4);
+ pragma Convention (Fortran, Logical_Star_8);
+
+ type Logical_Kind_1 is new Logical_Star_1;
+ type Logical_Kind_2 is new Logical_Star_2;
+ type Logical_Kind_4 is new Logical_Star_4;
+ type Logical_Kind_8 is new Logical_Star_8;
+
+ type Real_Star_4 is new Float;
+ type Real_Kind_4 is new Float;
+ type Real_Star_8 is new Long_Float;
+ type Real_Kind_8 is new Long_Float;
+
+ -- In the kind syntax, n is the same as the associated real kind.
+ -- In the star syntax, n is twice as large (real+imaginary size)
+ type Complex_Star_8 is new Complex;
+ type Complex_Kind_4 is new Complex;
+ type Complex_Star_16 is new Double_Complex;
+ type Complex_Kind_8 is new Double_Complex;
+
+ type Character_Kind_n is new Fortran_Character;
+
function To_Fortran (Item : Character) return Character_Set;
function To_Ada (Item : Character_Set) return Character;
