On Thursday, 13 April 2017 at 21:06:52 UTC, Jesse Phillips wrote:
I realize that this is likely really pushing the compile time
generation but a recent change to the switch statement[1] is
surfacing because of this usage.
uninitswitch2.d(13): Deprecation: 'switch' skips declaration of
variable uninits
witch2.main.li at uninitswitch2.d(14)
---------------------
import std.traits;
import std.typecons;
import std.meta;
private static immutable list = AliasSeq!(
tuple("a", "q"),
tuple("b", "r"),
);
void main() {
import std.stdio;
string search;
switch(search) {
---> foreach(li; list) { // li initialization is skipped
mixin("case li[0]:");
mixin("writeln(li[1]);");
return;
}
default:
break;
}
// Works
mixin(genSwitch("search"));
}
---------------------
I realize I can build out the entire switch and mix it in:
---------------------
string genSwitch(string search) {
auto ans = "switch(" ~ search ~ ") {\n";
foreach(li; list) {
ans ~= "case \"" ~ li[0] ~ "\":\n";
ans ~= "writeln(\"" ~ li[1] ~ "\");\n";
ans ~= "return;\n";
}
ans ~= "default:\n";
ans ~= "break;\n";
ans ~= "}";
return ans;
}
---------------------
But I'm just wondering if the new initialization check should
not be triggered from this utilization.
---------------------
// Unrolled based on
//
https://wiki.dlang.org/User:Quickfur/Compile-time_vs._compile-time description
version(none)
void func2243(Tuple param0, Tuple param1) {
{
{
case param0[0]:
writeln(param0[1]);
return;
}
{
case param1[0]:
writeln(param1[1]);
return;
}
}
}
---------------------
Thoughts?
1. https://issues.dlang.org/show_bug.cgi?id=14532
This is what is generated by your example:
switch (search)
{
unrolled {
{ // does not actually open a new scope
immutable
immutable(Tuple!(string, string)) li = __list_field_0;
case "a":
{
}
writeln(li.__expand_field_1);
return 0;
}
{ // same here we do not actually open a
new scope.
immutable
immutable(Tuple!(string, string)) li = __list_field_1;
case "b":
{
}
writeln(li.__expand_field_1);
return 0;
}
}
default:
{
break;
}
}
return 0;
it should be clear to sww why li's initialisation is referred to
as skipped.
