cmd/compile: overflow in int -> string
dvyukov opened this issue · comments
Gc rejects to compile the following program:
package a
var a = string(9223372036854775808)saying:
overflow in int -> string
go/types compile it successfully.
Compilers must agree on whether it is a valid Go program or not.
on commit af81789
Given the spec as is, I believe this should compile w/o errors. The spec says:
http://tip.golang.org/ref/spec#Conversions
A constant value x can be converted to type T in any of these cases:
...
x is an integer constant and T is a string type. The same rule as for non-constant x applies in this case.
and:
http://tip.golang.org/ref/spec#Conversions_to_and_from_a_string_type
Converting a signed or unsigned integer value to a string type yields a string containing the UTF-8 representation of the integer. Values outside the range of valid Unicode code points are converted to "\uFFFD".
There's no mention of a compile-time (or even run-time) error. The integer should be converted into "\uFFFD".
Closed by mistake.
Then this is a bug in gc, right?
@dvyukov yes, I believe this is a gc compiler bug.
Note that we already return "\ufffd" for values < 0:
Too late for Go 1.5. The only possible visible effect of making changes to fix hypothetical bugs like this one is introducing real ones.
This was fixed via https://go-review.googlesource.com/#/c/21344/ (fix for #15039).