I am new in D, but saw some strage behavour.
Overlapping is detected for + and * array operation, but not for - and /.
import std.stdio;
void main()
{
int[] slice = [2, 2, 2, 2];
int[] slice2 = slice[0 .. $ - 1];
int[] slice3 = slice[1 .. $];
writeln("slice before: ", slice);
writeln("slice2 before: ", slice2);
writeln("slice3 before: ", slice3);
const auto cmd = "slice3[] = slice2[] + slice3[];";
writeln( "cmd: ", cmd );
mixin( cmd );
writeln("slice after : ", slice);
writeln("slice2 after : ", slice2);
writeln("slice3 after : ", slice3);
}
When this code is run at 'dlang.org'
slice before: [2, 2, 2, 2]
slice2 before: [2, 2, 2]
slice3 before: [2, 2, 2]
cmd: slice3[] = slice2[] + slice3[];
object.Error@(0): Overlapping arrays in vector operation: 8 byte(s) overlap of 12
----------------
??:? nothrow @safe void rt.util.array._enforceNoOverlap(const(char[]), ulong, ulong, const(ulong)) [0x44f7f3]
??:? _arraySliceSliceAddSliceAssign_i [0x44c1b6]
??:? _Dmain [0x4408bb]
??:? _D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv [0x44c8a6]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate()) [0x44c7f0]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).runAll() [0x44c862]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate()) [0x44c7f0]
??:? _d_run_main [0x44c761]
??:? main [0x44a389]
??:? __libc_start_main [0x40d80a14]
If change + to -
const auto cmd = "slice3[] = slice2[] - slice3[];";
When it is run at 'dlang.org'
slice before: [2, 2, 2, 2]
slice2 before: [2, 2, 2]
slice3 before: [2, 2, 2]
cmd: slice3[] = slice2[] - slice3[];
slice after : [2, 0, -2, -4]
slice2 after : [2, 0, -2]
slice3 after : [0, -2, -4]
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