[Issue 942] New: a delegate defaults to 8 byte alignment when 4 byte is sufficient

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=942

           Summary: a delegate defaults to 8 byte alignment when 4 byte is
                    sufficient
           Product: D
           Version: 1.005
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: patch
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: guido at grumpy-cat.com


Delegate variables default to 8 byte alignment.  Delegates consist of two
pointer elements and should use 4 byte alignment instead.

The TypeDelegate struct does not override "unsigned alignsize()" from Type and
defaults to using "d_uns64 size(Loc loc)" to determine the alignment, which is
PTRSIZE * 2.  mtype.c could be updated as follows:

struct TypeDelegate : Type
{
    TypeDelegate(Type *t);
    Type *syntaxCopy();
    Type *semantic(Loc loc, Scope *sc);
    d_uns64 size(Loc loc);
+   unsigned alignsize();
    void toCBuffer2(OutBuffer *buf, Identifier *ident, HdrGenState *hgs);
    Expression *defaultInit();
    int isZeroInit();
    int checkBoolean();
    TypeInfoDeclaration *getTypeInfoDeclaration();
    Expression *dotExp(Scope *sc, Expression *e, Identifier *ident);
    int hasPointers();

    type *toCtype();
};

d_uns64 TypeDelegate::size(Loc loc)
{
    return PTRSIZE * 2;
}

+unsigned TypeDelegate::alignsize()
+{
+    // A Delegate consists of two ptr-sized values, so align it on pointer
size
+    // boundary
+    return PTRSIZE;
+}


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