digitalmars.D.bugs - [Issue 2821] New: struct alignment inconsistent with C for { int, long }
- d-bugmail puremagic.com (46/46) Apr 08 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2821
- d-bugmail puremagic.com (10/10) Apr 09 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2821
- d-bugmail puremagic.com (8/8) Apr 09 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2821
- d-bugmail puremagic.com (11/11) May 15 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2821
http://d.puremagic.com/issues/show_bug.cgi?id=2821 Summary: struct alignment inconsistent with C for { int, long } Product: D Version: 1.043 Platform: PC OS/Version: Linux Status: NEW Keywords: wrong-code Severity: normal Priority: P2 Component: DMD AssignedTo: bugzilla digitalmars.com ReportedBy: kamm-removethis incasoftware.de I couldn't find it in the spec right now, but as far as I remember D and C structs are supposed to be aligned identically when the same types are used. struct S { int i; long l; } In C (using gcc 4.1.2), the S.l.offsetof is 4 and the total size is 12. With dmd the offsetof is 8 and the total size is 16. Test code: -- D code import std.stdio; struct S { int i; long l; } void main() { writefln("%d %d", S.sizeof, S.l.offsetof); } -- C code #include <stdio.h> struct S { int i; long long l; }; int main() { struct S s; printf("%d %d\n", sizeof(s), (void*)&s.l - (void*)&s); return 1; } -- --
Apr 08 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2821 smjg iname.com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |smjg iname.com Have you tried DMC and GDC to compare? One would expect GDC to do the same as GCC, and DMD to do the same as DMC. But how does each decide what alignment to default to in the first place? --
Apr 09 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2821 DMD on Win32 should obviously match DMC, but DMD on other platforms should match the companion C compiler there, which is GCC. GCC on x86-32 aligns int64 to 4 bytes (at least on Linux). There was a similar issue with double that was fixed in 1.042: http://d.puremagic.com/issues/show_bug.cgi?id=2692 --
Apr 09 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2821 Walter Bright <bugzilla digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED 12:15:29 PDT --- Fixed dmd 1.045 and 2.030 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 15 2009