Hello everybody, the following piece of code demonstrates the problem. It compiles and prints out "T'Size: 63". Thus, with the commented line used instead, the result should be "T'Size: 64". But in that case GNAT terminates with the following error message: "main.adb:5:04: size required (65) for type "t" too large, maximum allowed is 64".
with Ada.Text_IO; procedure Main is -- T_Delta : constant := 0.1 * (2.0**(-64 + 9)); -- Gnat bug T_Delta : constant := 0.1 * (2.0**(-63 + 9)); type T is delta T_Delta range 0.0 .. 51.1; for T'Small use T_Delta; begin Ada.Text_IO.Put_Line("T'Size: " & Integer'Image(T'Size)); end Main; One possible reason is, that GNAT counts a sign bit, which is not counted when the 'Size attribute is queried. In any case, I assume that this inconsistency is unintended. Here's the versions that I am using: > gnatmake --version GNATMAKE 4.3.4 ... > gcc -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 4.3.4-2' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-targets=all --with-tune=generic --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.3.4 (Debian 4.3.4-2) Friendly regards, Dirk Herrmann -- Summary: GNAT rejects type with 64 bits, claiming it has 65 bits Product: gcc Version: 4.3.4 Status: UNCONFIRMED Severity: normal Priority: P3 Component: ada AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: dirk dot herrmann-privat at gmx dot de http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41675