debian-packages/taggedalgebraic
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Enable proper default initialization.

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Since @disable this() still leaves an invalid .init open, TaggedAlgebraic.init has now been changed to always contain the .init value of the first specified sub type.

Note that this change is restricted to DMD 2.072 and up, because earlier versions of DMD do not allow postblits or destructors within unions and using a union appears to be the only way to implement this.
This commit is contained in:
Sönke Ludwig 2017-06-12 20:43:15 +02:00
parent b4a4b3617b
commit 513729bf59
1 changed files with 29 additions and 7 deletions
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36
source/taggedalgebraic.d
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@ -56,7 +56,16 @@ struct TaggedAlgebraic(U) if (is(U == union) || is(U == struct))
private {
void[Largest!FieldTypes.sizeof] m_data;
static if (is(FieldTypes[0] == typeof(null)) || is(FieldTypes[0] == Void) || __VERSION__ < 2072) {
void[Largest!FieldTypes.sizeof] m_data;
} else {
union Dummy {
FieldTypes[0] initField;
void[Largest!FieldTypes.sizeof] data;
alias data this;
}
Dummy m_data = { initField: FieldTypes[0].init };
}
Kind m_kind;
}
@ -556,6 +565,17 @@ unittest {
assert(c[0] == "hello");
}
static if (__VERSION__ >= 2072) unittest { // default initialization
struct S {
int i = 42;
}
union U { S s; int j; }
TaggedAlgebraic!U ta;
assert(ta.i == 42);
}
/** Tests if the algebraic type stores a value of a certain data type.
*/
@ -981,12 +1001,14 @@ private string generateConstructors(U)()
string ret;
// disable default construction if first type is not a null/Void type
static if (!is(FieldTypeTuple!U[0] == typeof(null)) && !is(FieldTypeTuple!U[0] == Void))
{
ret ~= q{
@disable this();
};
static if (__VERSION__ < 2072) {
// disable default construction if first type is not a null/Void type
static if (!is(FieldTypeTuple!U[0] == typeof(null)) && !is(FieldTypeTuple!U[0] == Void))
{
ret ~= q{
@disable this();
};
}
}
// normal type constructors