[Issue 4198] New: [FreeBSD] imprecision in decimal floating-point literals

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=4198

           Summary: [FreeBSD] imprecision in decimal floating-point
                    literals
           Product: D
           Version: unspecified
          Platform: x86
        OS/Version: FreeBSD
            Status: NEW
          Keywords: patch, rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: rsinfu at gmail.com


--- Comment #0 from Shin Fujishiro <rsinfu at gmail.com> 2010-05-16 04:42:15 PDT ---
Created an attachment (id=632)
Patch for DMD (svn r490)

This assertion fails with DMD built on FreeBSD 8:
--------------------
static assert(1.0L == 0x1.0p+0L);
    // Error: static assert  (0x1.00000000000004p+0L == 1L) is false
--------------------
The left decimal floating-point literal is slightly wrong.

The compiler uses some tables (negtab and postab) for converting decimal
strings to long double values, but GCC on FreeBSD/i386 slightly changes them by
rounding everything in the table to double precision.  This causes precision
loss of decimal floating-point literals.

The attached patch fixes the problem, by adding byte sequence version of the
numeric tables to backend/strtold.c so that the tables' contents will not be
rounded by GCC.

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