Closed
Description
The big program at the very bottom of this note constructs a sequence of 100-, 200-,
400-, 800-, 1600-, ..., 2¹⁰⁰×100-bit constants.
There's no perfect way to handle this program.
A compiler with precision limits should print a graceful error about constants being too
large.
A compiler or type-checker without precision limits (like gotype) will grow until it
runs out of memory. (So probably all implementations should have some precision limit.)
cmd/gc handles this program particularly poorly, though. The 800-bit constant c3 is
somehow equal to zero, so that the println(c3/c3) line prints a "division by
zero" compilation error.
Similarly, this shorter program prints 0:
package main
const (
c0 = 1 << 100
c1 = c0 * c0
c2 = c1 * c1
c3 = c2 * c2
)
func main() {
println(c3)
}
http://play.golang.org/p/qCpwgSrhCE
--- big program ---
package main
const (
c0 = 1 << 100
c1 = c0 * c0
c2 = c1 * c1
c3 = c2 * c2
c4 = c3 * c3
c5 = c4 * c4
c6 = c5 * c5
c7 = c6 * c6
c8 = c7 * c7
c9 = c8 * c8
c10 = c9 * c9
c11 = c10 * c10
c12 = c11 * c11
c13 = c12 * c12
c14 = c13 * c13
c15 = c14 * c14
c16 = c15 * c15
c17 = c16 * c16
c18 = c17 * c17
c19 = c18 * c18
c20 = c19 * c19
c21 = c20 * c20
c22 = c21 * c21
c23 = c22 * c22
c24 = c23 * c23
c25 = c24 * c24
c26 = c25 * c25
c27 = c26 * c26
c28 = c27 * c27
c29 = c28 * c28
c30 = c29 * c29
c31 = c30 * c30
c32 = c31 * c31
c33 = c32 * c32
c34 = c33 * c33
c35 = c34 * c34
c36 = c35 * c35
c37 = c36 * c36
c38 = c37 * c37
c39 = c38 * c38
c40 = c39 * c39
c41 = c40 * c40
c42 = c41 * c41
c43 = c42 * c42
c44 = c43 * c43
c45 = c44 * c44
c46 = c45 * c45
c47 = c46 * c46
c48 = c47 * c47
c49 = c48 * c48
c50 = c49 * c49
c51 = c50 * c50
c52 = c51 * c51
c53 = c52 * c52
c54 = c53 * c53
c55 = c54 * c54
c56 = c55 * c55
c57 = c56 * c56
c58 = c57 * c57
c59 = c58 * c58
c60 = c59 * c59
c61 = c60 * c60
c62 = c61 * c61
c63 = c62 * c62
c64 = c63 * c63
c65 = c64 * c64
c66 = c65 * c65
c67 = c66 * c66
c68 = c67 * c67
c69 = c68 * c68
c70 = c69 * c69
c71 = c70 * c70
c72 = c71 * c71
c73 = c72 * c72
c74 = c73 * c73
c75 = c74 * c74
c76 = c75 * c75
c77 = c76 * c76
c78 = c77 * c77
c79 = c78 * c78
c80 = c79 * c79
c81 = c80 * c80
c82 = c81 * c81
c83 = c82 * c82
c84 = c83 * c83
c85 = c84 * c84
c86 = c85 * c85
c87 = c86 * c86
c88 = c87 * c87
c89 = c88 * c88
c90 = c89 * c89
c91 = c90 * c90
c92 = c91 * c91
c93 = c92 * c92
c94 = c93 * c93
c95 = c94 * c94
c96 = c95 * c95
c97 = c96 * c96
c98 = c97 * c97
c99 = c98 * c98
c100 = c99 * c99
)
func main() {
println(c1/c1)
println(c2/c2)
println(c3/c3)
println(c4/c4)
println(c5/c5)
println(c6/c6)
println(c7/c7)
println(c8/c8)
println(c9/c9)
println(c10/c10)
println(c20/c20)
println(c30/c30)
println(c40/c40)
println(c50/c50)
println(c60/c60)
println(c70/c70)
println(c80/c80)
println(c90/c90)
println(c100/c100)
}